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<div class=" wh_topic_content body "><main role="main"><article class="- topic/topic concept/concept topic concept" role="article" aria-labelledby="ariaid-title1"><span class="edit-link" style="font-size:12px; opacity:0.6; text-align:right; vertical-align:middle"><a target="_blank" href="http://172.16.35.88/tasks/jdssno1uvvbf2mltu9kb9v3if05d5gopuakboe8hlud18rma/edit/F:/aicdita/aicdita-cn/topics/sdk/mpp/mpp-decode.dita">Edit online</a></span><h1 class="- topic/title title topictitle1" id="ariaid-title1">MPP Decoder 设计及接口说明</h1><div class="date inPage">5 Dec 2024</div><div style="color: gray;">
Read time: 10 minute(s)
</div><div class="- topic/body concept/conbody body conbody"><div class="- topic/p p" data-ofbid="d41009e22__20250121171516">MPP Decoder 由三个主要模块组成：<ul class="- topic/ul ul simple" id="mpp_decode__ul_ntn_2nt_2dc" data-ofbid="mpp_decode__ul_ntn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e25__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e27__20250121171516">解码模块（H264、JPEG、PNG 等）：负责将码流数据解码成视频图像</p>
</li><li class="- topic/li li" data-ofbid="d41009e30__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e32__20250121171516">输入码流数据管理模块（<a class="- topic/xref xref" href="mpp-decode.html#mpp_decode__packet">Packet
manager</a>）：负责视频、图片码流数据和 buffer 的管理</p>
</li><li class="- topic/li li" data-ofbid="d41009e39__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e41__20250121171516">显示帧管理模块（<a class="- topic/xref xref" href="mpp-decode.html#mpp_decode__packet">Frame manager</a>）：负责解码图像 buffer
的管理</p>
</li></ul></div><section class="- topic/section section" id="mpp_decode__packet" data-ofbid="mpp_decode__packet"><h2 class="- topic/title title sectiontitle">Packet 管理机制</h2>
<p class="- topic/p p" data-ofbid="d41009e53__20250121171516">Packet manager 负责管理码流数据和 buffer。初始化时，该模块申请一块物理连续的内存（buffer
大小可由外部配置），用于存放视频/图片码流数据。</p>
<p class="- topic/p p" data-ofbid="d41009e56__20250121171516">Packet manager 管理的数据单元为 packet，packet 表示一笔码流数据，它可以是完整的一帧数据，也支持不是完整的一帧数据。 每个 packet
与物理内存中的码流数据一一对应，它记录了每一笔码流的物理内存基地址、物理内存结束地址、物理内存偏移、虚拟内存地址、码流数据长度等信息。</p>
<figure class="- topic/fig fig fignone" id="mpp_decode__id13" data-ofbid="mpp_decode__id13"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_otn_2nt_2dc" src="../../../images/mpp/packet_manager.png" width="576" alt="packet_manager"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 1</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">packet 管理</span></figcaption></figure>
<p class="- topic/p p" data-ofbid="d41009e66__20250121171516">packet 通过 empty list 和 ready list 两个链表进行管理。 其中，empty list 用于存放空闲的 packet，ready list
用于存放待解码的 packet。</p>
<p class="- topic/p p" data-ofbid="d41009e70__20250121171516">送码流数据时，从 empty list 获取一个空闲 packet，填充数据后，再把 packet 放入 ready list；</p>
<p class="- topic/p p" data-ofbid="d41009e73__20250121171516">解码前，解码器从 ready list 获取一个填充数据的 packet，使用完后再把该 packet 放入 empty list。</p>
<figure class="- topic/fig fig fignone" id="mpp_decode__id14" data-ofbid="mpp_decode__id14"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_ptn_2nt_2dc" src="../../../images/mpp/pm_flow.png" width="576" alt="pm_flow"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 2</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">packet manager 调用流程</span></figcaption></figure>
</section><section class="- topic/section section" id="mpp_decode__frame" data-ofbid="mpp_decode__frame"><h2 class="- topic/title title sectiontitle">Frame 管理机制</h2>
<p class="- topic/p p" data-ofbid="d41009e88__20250121171516">Frame manager 负责管理图像 buffer。Frame manager 内部通过两个链表来管理图像 buffer：empty list 和 render
list。 其中，empty list 存放可以给解码输出使用的图像 buffer，render list 存放解码完成但还未显示的图像 buffer。
在运行过程中，正在显示的图像 buffer 和用于参考的图像 buffer 可能不在这两个 list 中。</p>
<ol class="- topic/ol ol arabic simple" id="mpp_decode__ol_qtn_2nt_2dc" data-ofbid="mpp_decode__ol_qtn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e92__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e94__20250121171516">frame 状态迁移</p>
<div class="- topic/p p" data-ofbid="d41009e97__20250121171516">初始化时，该模块申请指定个数的图像 buffer（个数可由外部配置），每个图像 buffer 的信息存放在内部数组中。 每个图像 buffer 有 4
种状态：<ul class="- topic/ul ul simple" id="mpp_decode__ul_rtn_2nt_2dc" data-ofbid="mpp_decode__ul_rtn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e100__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e102__20250121171516">Decoding: 该帧正在被解码器使用（用于解码输出或作为参考帧）</p>
</li><li class="- topic/li li" data-ofbid="d41009e105__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e107__20250121171516">wait_render: 该帧在 render list 中，等待显示</p>
</li><li class="- topic/li li" data-ofbid="d41009e110__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e112__20250121171516">Rendering: 该帧正在被显示占用</p>
</li><li class="- topic/li li" data-ofbid="d41009e115__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e117__20250121171516">IDLE: 该帧处于空闲状态（既没有被显示占用，也没有被解码器用作参考帧）</p>
</li></ul></div>
<div class="- topic/p p" data-ofbid="d41009e121__20250121171516">其状态转移如下图所示：<ul class="- topic/ul ul simple" id="mpp_decode__ul_stn_2nt_2dc" data-ofbid="mpp_decode__ul_stn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e124__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e126__20250121171516">初始化时，所有图像 buffer 都在 empty list 中，此时处于 IDLE 状态；</p>
</li><li class="- topic/li li" data-ofbid="d41009e129__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e131__20250121171516">解码模块从 empty list 链表头部获取一个空图像 buffer，此时 buffer 被解码模块占用，从 IDLE 状态变为
Decoding 状态;</p>
</li><li class="- topic/li li" data-ofbid="d41009e134__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e136__20250121171516">解码完成后，解码模块还图像数据。此时分两种情况：</p>
<ul class="- topic/ul ul" id="mpp_decode__ul_ttn_2nt_2dc" data-ofbid="mpp_decode__ul_ttn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e140__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e142__20250121171516">如果当前帧还未被显示，该帧加入 render list 链表尾部，从 Decoding 状态变为 wait
render 状态；</p>
</li><li class="- topic/li li" data-ofbid="d41009e145__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e147__20250121171516">该帧不再用做参考帧且已显示完成，此时该帧加入 empty list 链表尾部，由 Decoding 状态进入
IDLE 状态；</p>
</li></ul>
</li><li class="- topic/li li" data-ofbid="d41009e151__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e153__20250121171516">显示模块从 render list 链表头部取一帧图像，此时当前帧由 wait render 状态进入 Rendering
状态；</p>
</li><li class="- topic/li li" data-ofbid="d41009e156__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e158__20250121171516">显示模块还图像 buffer，分两种情况：</p>
<ul class="- topic/ul ul" id="mpp_decode__ul_utn_2nt_2dc" data-ofbid="mpp_decode__ul_utn_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e162__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e164__20250121171516">如果当前帧不用于参考，此时由 Rendering 状态回到 IDLE 状态，该帧加入 empty list
链表尾部；</p>
</li><li class="- topic/li li" data-ofbid="d41009e167__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e169__20250121171516">如果当前帧用于参考，此时由 Rendering 状态进入 Decoding 状态，该图像 buffer
不进入任何队列，等待解码器还参考帧；</p>
</li></ul>
</li></ul><figure class="- topic/fig fig fignone" id="mpp_decode__id15" data-ofbid="mpp_decode__id15"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_vtn_2nt_2dc" src="../../../images/mpp/frame_status.png" width="480" alt="frame_status"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 3</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">frame 状态迁移</span></figcaption></figure></div>
</li><li class="- topic/li li" data-ofbid="d41009e180__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e182__20250121171516">frame manager 调用流程</p>
<p class="- topic/p p" data-ofbid="d41009e185__20250121171516">对于 JPEG、PNG 这类没有参考帧概念的编码格式，每一帧的状态是唯一的，解码后的数据帧可直接送 render list</p>
<figure class="- topic/fig fig fignone" id="mpp_decode__id16" data-ofbid="mpp_decode__id16"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_xtn_2nt_2dc" src="../../../images/mpp/frame_manager_jpeg.png" width="576" alt="frame_manager_jpeg"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 4</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">frame manager 调用流程（JPEG/PNG）</span></figcaption></figure>
<p class="- topic/p p" data-ofbid="d41009e195__20250121171516">但对于 H264 这类有参考帧的编码格式，解码后的视频帧可能既被显示占用也会被解码器用作参考帧，并且由于双向参考帧的存在， 视频帧需要重排序后才能送显示。
不同于 JPG，H264 解码库内部存在一个 delay list 用于为显示帧重排序。</p>
<figure class="- topic/fig fig fignone" id="mpp_decode__id17" data-ofbid="mpp_decode__id17"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_ytn_2nt_2dc" src="../../../images/mpp/frame_manager_264.png" width="576" alt="frame_manager_264"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 5</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">frame manager 调用流程（H264）</span></figcaption></figure>
</li></ol>
</section><section class="- topic/section section" id="mpp_decode__id4" data-ofbid="mpp_decode__id4"><h2 class="- topic/title title sectiontitle"> 物理连续内存使用情况</h2>
<p class="- topic/p p" data-ofbid="d41009e211__20250121171516">H264 解码所需的物理连续内存如下所示：</p>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_ztn_2nt_2dc" data-ofbid="mpp_decode__table_ztn_2nt_2dc" data-cols="3"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 1</span><span class="table--title-label-punctuation">. </span></span><span class="table--title"></span></caption><colgroup><col style="width:34.527687296416936%"/><col style="width:32.57328990228013%"/><col style="width:32.89902280130293%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_ztn_2nt_2dc__entry__1">内存占用模块</th><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_ztn_2nt_2dc__entry__2">计算方式</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_ztn_2nt_2dc__entry__3">说明</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">输入码流</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">-</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">大小由应用层配置</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">输出帧</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">width*height*3/2*frame_num</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">
<div class="- topic/div div">
<div class="- topic/div div"> frame_num 至少需要（参考帧个数+1）个</div>
<div class="- topic/div div"> 显示占用个数可由应用层通过 struct decode_config</div>
<div class="- topic/div div"> 结构体中的 extra_frame_num 配置</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">帧内预测(需要上一行数据)</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">帧格式：width*2</div>
<div class="- topic/div div">MBAFF：width*4</div>
</div>
</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">-</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">宏块信息</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">固定 12K</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">-</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">dblk 模块(上一个宏块行最后 4 行数据)</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">帧格式：width*8</div>
<div class="- topic/div div">MBAFF：width*16</div>
</div>
</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">-</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">co-located 信息</td><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">固定 68K</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">-</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_ztn_2nt_2dc__entry__1">每一帧 co-located 数据缓存</td><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_ztn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">(width/16)*(height/16)*32*frame_num</div>
</div>
</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_ztn_2nt_2dc__entry__3">-</td></tr></tbody></table></div>
<div class="- topic/note note note note_note" id="mpp_decode__note_ttp_qn3_ddc" data-ofbid="mpp_decode__note_ttp_qn3_ddc"><span class="note__title">注：</span>
<p class="- topic/p p" data-ofbid="d41009e317__20250121171516">co-located 两个 buffer，I、P 帧解码时会往 buffer 里写数据，B 帧解码时从 buffer 读数据。 如果当前码流中没有 B
帧，这两块内存也需要申请。</p>
</div>
</section><section class="- topic/section section" id="mpp_decode__id5" data-ofbid="mpp_decode__id5"><h2 class="- topic/title title sectiontitle">MPP Decoder 调用流程</h2>
<ol class="- topic/ol ol" id="mpp_decode__ol_ht4_25h_d1c" data-ofbid="mpp_decode__ol_ht4_25h_d1c"><li class="- topic/li li" data-ofbid="d41009e327__20250121171516">在调用 MPP Decoder 的解码函数时，解码模块从 Packet manager 取一笔码流，同时从 Frame maneger 取一个空闲图像
buffer，对码流进行解码 并输出图像到图像 buffer。</li><li class="- topic/li li" data-ofbid="d41009e329__20250121171516">解码后，解码模块将码流 buffer 归还 Packet manager，将解码图像 buffer 归还 Frame maneger。</li><li class="- topic/li li" data-ofbid="d41009e331__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e333__20250121171516">为保证解码效率，建议调用者创建 3 个线程实现解码功能：</p>
<ul class="- topic/ul ul" id="mpp_decode__ul_sxt_fsh_d1c" data-ofbid="mpp_decode__ul_sxt_fsh_d1c"><li class="- topic/li li" data-ofbid="d41009e337__20250121171516"><span class="+ topic/ph ui-d/uicontrol ph uicontrol">send data thread</span><p class="- topic/p p" data-ofbid="d41009e340__20250121171516">通过 mpp_decoder_get_packet 和
mpp_decoder_put_packet 这两个接口把码流数据送到 packet 管理模块</p></li><li class="- topic/li li" data-ofbid="d41009e342__20250121171516"><span class="+ topic/ph ui-d/uicontrol ph uicontrol">decode thread</span><p class="- topic/p p" data-ofbid="d41009e345__20250121171516">通过调用 mpp_decoder_decode 控制解码，解码库从
packet 管理模块取一笔码流数据，解码完成后，将视频帧送入 frame 管理模块</p></li><li class="- topic/li li" data-ofbid="d41009e347__20250121171516"><span class="+ topic/ph ui-d/uicontrol ph uicontrol">render thread</span><p class="- topic/p p" data-ofbid="d41009e350__20250121171516">通过
<span class="+ topic/keyword pr-d/parmname keyword parmname">mpp_decoder_get_frame</span> 和
<span class="+ topic/keyword pr-d/parmname keyword parmname">mpp_decoder_put_frame</span> 两个接口从 frame
管理模块获取视频帧，并控制该帧显示时机</p><figure class="- topic/fig fig fignone" id="mpp_decode__fig_pmr_c5h_d1c" data-ofbid="mpp_decode__fig_pmr_c5h_d1c"><br/><div class="imagecenter"><img class="- topic/image image imagecenter" id="mpp_decode__image_wxt_fsh_d1c" src="../../../images/mpp/mpp_decoder_flow.png" width="384" alt="mpp_decoder_flow"/></div><br/><figcaption data-caption-side="bottom" class="- topic/title title figcapcenter"><span class="figtitleprefix fig--title-label">图<span class="fig--title-label-number"> 6</span><span class="fig--title-label-punctuation">. </span></span><span class="fig--title">mpp_decoder 调用流程</span></figcaption></figure></li></ul>
</li></ol>
</section><section class="- topic/section section" id="mpp_decode__id6" data-ofbid="mpp_decode__id6"><h2 class="- topic/title title sectiontitle">MPP Decoder 数据结构</h2>
<ul class="- topic/ul ul" id="mpp_decode__ul_aq3_lfn_4dc" data-ofbid="mpp_decode__ul_aq3_lfn_4dc"><li class="- topic/li li" data-ofbid="d41009e372__20250121171516">
<div class="- topic/div div section" id="mpp_decode__struct-decode-config">
<strong class="+ topic/ph hi-d/b ph b">struct decode_config</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_f5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_f5n_2nt_2dc"><strong class="hl-keyword">struct</strong> decode_config {
<strong class="hl-keyword">enum</strong> mpp_pixel_format pix_fmt; <em class="hl-comment">// output pixel format</em>
<strong class="hl-keyword">int</strong> bitstream_buffer_size; <em class="hl-comment">// bitstream buffer size in pm</em>
<strong class="hl-keyword">int</strong> packet_count; <em class="hl-comment">// packet number in pm</em>
<strong class="hl-keyword">int</strong> extra_frame_num; <em class="hl-comment">// extra frame number in fm</em>
};</pre><p class="- topic/p p" data-ofbid="d41009e381__20250121171516"><code class="+ topic/ph pr-d/codeph ph codeph">decode_config</code> 结构体用于配置解码器初始化使用的参数。</p><ul class="- topic/ul ul simple" id="mpp_decode__ul_g5n_2nt_2dc" data-ofbid="mpp_decode__ul_g5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e386__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e388__20250121171516">pix_fmt 表示解码输出的颜色格式</p>
</li><li class="- topic/li li" data-ofbid="d41009e391__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e393__20250121171516">bitstream_buffer_size 表示存放输入码流缓存的总长度</p>
</li><li class="- topic/li li" data-ofbid="d41009e396__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e398__20250121171516">packet_count 表示 packet manager 中 packet 的最大个数</p>
</li><li class="- topic/li li" data-ofbid="d41009e401__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e403__20250121171516">extra_frame_num 表示解码器额外分配的帧个数，主要用于缓存显示帧以保证显示平滑。</p>
</li></ul>
</div>
</li><li class="- topic/li li" data-ofbid="d41009e408__20250121171516">
<div class="- topic/div div section" id="mpp_decode__struct-mpp-packet">
<strong class="+ topic/ph hi-d/b ph b">struct mpp_packet</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_h5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_h5n_2nt_2dc"><strong class="hl-keyword">struct</strong> mpp_packet {
<strong class="hl-keyword">void</strong> *data;
<strong class="hl-keyword">int</strong> size;
<strong class="hl-keyword">long</strong> <strong class="hl-keyword">long</strong> pts;
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> flag;
};</pre><p class="- topic/p p" data-ofbid="d41009e417__20250121171516"><code class="+ topic/ph pr-d/codeph ph codeph">mpp_packet</code> 结构体用于表示输入码流信息。</p><ul class="- topic/ul ul simple" id="mpp_decode__ul_i5n_2nt_2dc" data-ofbid="mpp_decode__ul_i5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e422__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e424__20250121171516">data 表示码流数据存放的起始地址</p>
</li><li class="- topic/li li" data-ofbid="d41009e427__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e429__20250121171516">size 表示该笔码流数据长度</p>
</li><li class="- topic/li li" data-ofbid="d41009e432__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e434__20250121171516">pts 表示该笔码流的时间戳</p>
</li><li class="- topic/li li" data-ofbid="d41009e437__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e439__20250121171516">flag 表示该笔码流的标记位，目前仅用于确定该码流是否为最后一笔码流（PACKET_FLAG_EOS）</p>
</li></ul>
</div>
</li><li class="- topic/li li" data-ofbid="d41009e444__20250121171516">
<div class="- topic/div div section" id="mpp_decode__struct-mpp-frame">
<strong class="+ topic/ph hi-d/b ph b">struct mpp_frame</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_j5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_j5n_2nt_2dc"><strong class="hl-keyword">struct</strong> mpp_size {
<strong class="hl-keyword">int</strong> width;
<strong class="hl-keyword">int</strong> height;
};
<strong class="hl-keyword">struct</strong> mpp_rect {
<strong class="hl-keyword">int</strong> x;
<strong class="hl-keyword">int</strong> y;
<strong class="hl-keyword">int</strong> width;
<strong class="hl-keyword">int</strong> height;
};
<strong class="hl-keyword">enum</strong> mpp_buf_type {
MPP_DMA_BUF_FD,
MPP_PHY_ADDR,
};
<strong class="hl-keyword">struct</strong> mpp_buf {
<strong class="hl-keyword">enum</strong> mpp_buf_type buf_type;
<strong class="hl-keyword">union</strong> {
<strong class="hl-keyword">int</strong> fd[<span class="hl-number">3</span>];
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> phy_addr[<span class="hl-number">3</span>];
};
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> stride[<span class="hl-number">3</span>];
<strong class="hl-keyword">struct</strong> mpp_size size;
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> crop_en;
<strong class="hl-keyword">struct</strong> mpp_rect crop;
<strong class="hl-keyword">enum</strong> mpp_pixel_format format;
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> flags;
};</pre><ul class="- topic/ul ul simple" id="mpp_decode__ul_k5n_2nt_2dc" data-ofbid="mpp_decode__ul_k5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e454__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e456__20250121171516">buf_type：表示 mpp_buf 类型，以 fd 方式 MPP_DMA_BUF_FD 或 以物理地址方式
MPP_PHY_ADDR；</p>
</li><li class="- topic/li li" data-ofbid="d41009e459__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e461__20250121171516">fd[3]：表示 buffer 三个分量的 fd</p>
</li><li class="- topic/li li" data-ofbid="d41009e464__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e466__20250121171516">phy_addr[3]：表示 buffer 三个分量的物理地址</p>
</li><li class="- topic/li li" data-ofbid="d41009e469__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e471__20250121171516">stride[3]：表示 buffer 三个分量的 stride</p>
</li><li class="- topic/li li" data-ofbid="d41009e474__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e476__20250121171516">size：表示 buffer 的宽、高</p>
</li><li class="- topic/li li" data-ofbid="d41009e479__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e481__20250121171516">crop_en： 表示该 buffer 是否需要 crop</p>
</li><li class="- topic/li li" data-ofbid="d41009e484__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e486__20250121171516">crop：表示该 buffer 的 crop 信息</p>
</li><li class="- topic/li li" data-ofbid="d41009e489__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e491__20250121171516">format： 表示该 buffer 的颜色格式类型</p>
</li></ul><pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_l5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_l5n_2nt_2dc"><strong class="hl-keyword">struct</strong> mpp_frame {
<strong class="hl-keyword">struct</strong> mpp_buf buf;
<strong class="hl-keyword">long</strong> <strong class="hl-keyword">long</strong> pts;
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> id;
<strong class="hl-keyword">unsigned</strong> <strong class="hl-keyword">int</strong> flags;
};</pre>
<ul class="- topic/ul ul simple" id="mpp_decode__ul_m5n_2nt_2dc" data-ofbid="mpp_decode__ul_m5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e498__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e500__20250121171516">buf：表示 mpp_frame 的 buffer 信息</p>
</li><li class="- topic/li li" data-ofbid="d41009e503__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e505__20250121171516">pts：表示 mpp_frame 的时间戳</p>
</li><li class="- topic/li li" data-ofbid="d41009e508__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e510__20250121171516">id：表示 mpp_frame 的唯一标识</p>
</li><li class="- topic/li li" data-ofbid="d41009e513__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e515__20250121171516">flags：表示 mpp_frame 的标志位</p>
</li></ul>
</div>
</li><li class="- topic/li li" data-ofbid="d41009e520__20250121171516">
<div class="- topic/div div section" id="mpp_decode__enum-mpp-dec-errno">
<strong class="+ topic/ph hi-d/b ph b">enum mpp_dec_errno</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_n5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_n5n_2nt_2dc"><strong class="hl-keyword">enum</strong> mpp_dec_errno {
DEC_ERR_NOT_SUPPORT = <span class="hl-number">0x90000001</span>,
DEC_ERR_NO_EMPTY_PACKET = <span class="hl-number">0x90000002</span>, <em class="hl-comment">// no packet in empty list</em>
DEC_ERR_NO_READY_PACKET = <span class="hl-number">0x90000003</span>, <em class="hl-comment">//</em>
DEC_ERR_NO_EMPTY_FRAME = <span class="hl-number">0x90000004</span>, <em class="hl-comment">//</em>
DEC_ERR_NO_RENDER_FRAME = <span class="hl-number">0x90000005</span>, <em class="hl-comment">//</em>
DEC_ERR_NULL_PTR = <span class="hl-number">0x90000006</span>,
DEC_ERR_FM_NOT_CREATE = <span class="hl-number">0x90000006</span>,
};</pre><ul class="- topic/ul ul simple" id="mpp_decode__ul_o5n_2nt_2dc" data-ofbid="mpp_decode__ul_o5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e530__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e532__20250121171516">DEC_ERR_NOT_SUPPORT：该码流不支持</p>
</li><li class="- topic/li li" data-ofbid="d41009e535__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e537__20250121171516">DEC_ERR_NO_EMPTY_PACKET：packet manager 中缺少空闲的 packet，可能是解码速度小于送
packet 速度，此时需要等待一段时间；</p>
</li><li class="- topic/li li" data-ofbid="d41009e540__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e542__20250121171516">DEC_ERR_NO_READY_PACKET：packet manager 中缺少填好码流数据的 packet，可能是送
packet 速度小于解码速度，此时需要等待一段时间；</p>
</li><li class="- topic/li li" data-ofbid="d41009e545__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e547__20250121171516">DEC_ERR_NO_EMPTY_FRAME：frame manager 中缺少空闲的
frame，表示所有帧都处于使用状态，通常是解码速度大于显示速度导致，此时需要等待一段时间；</p>
</li><li class="- topic/li li" data-ofbid="d41009e550__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e552__20250121171516">DEC_ERR_NO_RENDER_FRAME：frame manager 中缺少待显示的
frame，表示所有帧都处于空闲状态，通常是解码速度小于显示速度导致，此时需要等待一段时间；</p>
</li><li class="- topic/li li" data-ofbid="d41009e555__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e557__20250121171516">DEC_ERR_NULL_PTR：表示接口函数输入参数存在空指针</p>
</li><li class="- topic/li li" data-ofbid="d41009e560__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e562__20250121171516">DEC_ERR_FM_NOT_CREATE：表示在获取待显示 frame 时 frame manager 还未创建</p>
</li></ul>
</div>
</li><li class="- topic/li li" data-ofbid="d41009e567__20250121171516">
<div class="- topic/div div section" id="mpp_decode__enum-mpp-codec-type">
<strong class="+ topic/ph hi-d/b ph b">enum mpp_codec_type</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_p5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_p5n_2nt_2dc"><strong class="hl-keyword">enum</strong> mpp_codec_type {
MPP_CODEC_VIDEO_DECODER_H264 = <span class="hl-number">0x1000</span>, <em class="hl-comment">// decoder</em>
MPP_CODEC_VIDEO_DECODER_MJPEG,
MPP_CODEC_VIDEO_DECODER_PNG,
MPP_CODEC_VIDEO_ENCODER_H264 = <span class="hl-number">0x2000</span>, <em class="hl-comment">// encoder</em>
};</pre><p class="- topic/p p" data-ofbid="d41009e576__20250121171516">mpp_codec_type 枚举类型表示支持的编解码格式。</p>
</div>
</li><li class="- topic/li li" data-ofbid="d41009e580__20250121171516">
<div class="- topic/div div section" id="mpp_decode__enum-mpp-dec-cmd">
<strong class="+ topic/ph hi-d/b ph b">enum mpp_dec_cmd</strong>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_q5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_q5n_2nt_2dc"><strong class="hl-keyword">enum</strong> mpp_dec_cmd {
MPP_DEC_INIT_CMD_SET_EXT_FRAME_ALLOCATOR, <em class="hl-comment">// frame buffer allocator</em>
MPP_DEC_INIT_CMD_SET_ROT_FLIP_FLAG,
MPP_DEC_INIT_CMD_SET_SCALE,
MPP_DEC_INIT_CMD_SET_CROP_INFO,
MPP_DEC_INIT_CMD_SET_OUTPUT_POS,
};</pre><ul class="- topic/ul ul simple" id="mpp_decode__ul_r5n_2nt_2dc" data-ofbid="mpp_decode__ul_r5n_2nt_2dc"><li class="- topic/li li" data-ofbid="d41009e590__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e592__20250121171516"> MPP_DEC_INIT_CMD_SET_EXT_FRAME_ALLOCATOR：表示由外部设置帧 buffer 分配器</p>
</li><li class="- topic/li li" data-ofbid="d41009e595__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e597__20250121171516">MPP_DEC_INIT_CMD_SET_ROT_FLIP_FLAG: 表示设置旋转、镜像后处理，只用于 JPEG</p>
</li><li class="- topic/li li" data-ofbid="d41009e600__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e602__20250121171516">MPP_DEC_INIT_CMD_SET_SCALE： 表示设置缩放系数，只用于 JPEG</p>
</li><li class="- topic/li li" data-ofbid="d41009e605__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e607__20250121171516">MPP_DEC_INIT_CMD_SET_CROP_INFO：表示设置输出 crop 信息</p>
</li><li class="- topic/li li" data-ofbid="d41009e610__20250121171516">
<p class="- topic/p p" data-ofbid="d41009e612__20250121171516"> MPP_DEC_INIT_CMD_SET_OUTPUT_POS：表示设置解码图像在输出缓存的位置</p>
</li></ul>
</div>
</li></ul>
</section><section class="- topic/section section" id="mpp_decode__id7" data-ofbid="mpp_decode__id7"><h2 class="- topic/title title sectiontitle">MPP Decoder 接口设计</h2>
<p class="- topic/p p" data-ofbid="d41009e623__20250121171516">接口如下 :</p>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_s5n_2nt_2dc" data-ofbid="mpp_decode__codeblock_s5n_2nt_2dc"><strong class="hl-keyword">struct</strong> decode_config {
<strong class="hl-keyword">enum</strong> mpp_pixel_format pix_fmt; <em class="hl-comment">// output pixel format</em>
<strong class="hl-keyword">int</strong> bitstream_buffer_size; <em class="hl-comment">// bitstream buffer size in pm</em>
<strong class="hl-keyword">int</strong> packet_count; <em class="hl-comment">// packet number in pm</em>
<strong class="hl-keyword">int</strong> extra_frame_num; <em class="hl-comment">// extra frame number in fm</em>
};
<strong class="hl-keyword">struct</strong> mpp_decoder* create_mpp_decoder(<strong class="hl-keyword">enum</strong> mpp_codec_type type);
<strong class="hl-keyword">void</strong> destory_mpp_decoder(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder);
<strong class="hl-keyword">int</strong> mpp_decoder_init(<strong class="hl-keyword">struct</strong> mpp_decoder *decoder, <strong class="hl-keyword">struct</strong> decode_config *config);
<strong class="hl-keyword">int</strong> mpp_decoder_decode(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder);
<strong class="hl-keyword">int</strong> mpp_decoder_control(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder, <strong class="hl-keyword">int</strong> cmd, <strong class="hl-keyword">void</strong> *param);
<strong class="hl-keyword">int</strong> mpp_decoder_reset(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder);
<strong class="hl-keyword">int</strong> mpp_decoder_get_packet(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder, <strong class="hl-keyword">struct</strong> mpp_packet* packet, <strong class="hl-keyword">int</strong> size);
<strong class="hl-keyword">int</strong> mpp_decoder_put_packet(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder, <strong class="hl-keyword">struct</strong> mpp_packet* packet);
<strong class="hl-keyword">int</strong> mpp_decoder_get_frame(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder, <strong class="hl-keyword">struct</strong> mpp_frame* frame);
<strong class="hl-keyword">int</strong> mpp_decoder_put_frame(<strong class="hl-keyword">struct</strong> mpp_decoder* decoder, <strong class="hl-keyword">struct</strong> mpp_frame* frame);</pre>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_t5n_2nt_2dc" data-ofbid="mpp_decode__table_t5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 2</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_create</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_t5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_t5n_2nt_2dc__entry__2">struct mpp_decoder* mpp_decoder_create(enum mpp_codec_type
type)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__2">创建 mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__2">type: 解码器类型</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_t5n_2nt_2dc__entry__2">mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_t5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_t5n_2nt_2dc__entry__2">-</td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_u5n_2nt_2dc" data-ofbid="mpp_decode__table_u5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 3</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_destory</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_u5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_u5n_2nt_2dc__entry__2">void mpp_decoder_destory(struct mpp_decoder* decoder)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__2">销毁 mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__2">decoder: mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_u5n_2nt_2dc__entry__2">无</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_u5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_u5n_2nt_2dc__entry__2">-</td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_v5n_2nt_2dc" data-ofbid="mpp_decode__table_v5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 4</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_init</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_v5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_v5n_2nt_2dc__entry__2">int mpp_decoder_init(struct mpp_decoder *decoder, struct
decode_config *config)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__2">初始化解码器</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
<div class="- topic/div div"> config：解码器的配置参数</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_v5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_v5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_v5n_2nt_2dc__entry__2">-</td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_w5n_2nt_2dc" data-ofbid="mpp_decode__table_w5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 5</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_decode</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_w5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_w5n_2nt_2dc__entry__2">int mpp_decoder_decode(struct mpp_decoder* decoder)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__2">解码一笔数据</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__2">decoder: mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_w5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_w5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_w5n_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_x5n_2nt_2dc" data-ofbid="mpp_decode__table_x5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 6</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_control</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_x5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_x5n_2nt_2dc__entry__2">int mpp_decoder_control(struct mpp_decoder* decoder, int cmd,
void* param)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__2">向 mpp_decoder 对象发送控制命令</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div"><span class="+ topic/keyword pr-d/parmname keyword parmname">decoder</span>: mpp_decoder 对象</div>
<div class="- topic/div div"><span class="+ topic/keyword pr-d/parmname keyword parmname">cmd</span>: 控制命令类型</div>
<div class="- topic/div div"><span class="+ topic/keyword pr-d/parmname keyword parmname">param</span>: 控制参数</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_x5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_x5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_x5n_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_y5n_2nt_2dc" data-ofbid="mpp_decode__table_y5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 7</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_reset</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_y5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_y5n_2nt_2dc__entry__2">int mpp_decoder_reset(struct mpp_decoder* decoder)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__2">重置 mpp_decoder 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_y5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_y5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_y5n_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_z5n_2nt_2dc" data-ofbid="mpp_decode__table_z5n_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 8</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_get_packet</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_z5n_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_z5n_2nt_2dc__entry__2">int mpp_decoder_get_packet(struct mpp_decoder* decoder, struct
mpp_packet* packet, int size)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__2">获取一个写码流数据的 packet</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
<div class="- topic/div div"> packet:码流数据结构指针</div>
<div class="- topic/div div"> size:上层应用申请 packet 的 buffer 大小</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_z5n_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_z5n_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_z5n_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_avn_2nt_2dc" data-ofbid="mpp_decode__table_avn_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 9</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_put_packet</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_avn_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_avn_2nt_2dc__entry__2">int mpp_decoder_put_packet(struct mpp_decoder* decoder, struct
mpp_packet* packet)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__2">归还码流数据的 packet 对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
<div class="- topic/div div"> packet:码流数据结构指针</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_avn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_avn_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_avn_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_bvn_2nt_2dc" data-ofbid="mpp_decode__table_bvn_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 10</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_get_frame</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_bvn_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_bvn_2nt_2dc__entry__2">int mpp_decoder_get_frame(struct mpp_decoder* decoder, struct
mpp_frame* frame)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__2">获取一个视频帧对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
<div class="- topic/div div"> frame:视频帧数据结构指针</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_bvn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_bvn_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_bvn_2nt_2dc__entry__2">- </td></tr></tbody></table></div>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_cvn_2nt_2dc" data-ofbid="mpp_decode__table_cvn_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 11</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_decoder_put_frame</span></caption><colgroup><col style="width:22.98850574712644%"/><col style="width:77.01149425287358%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_cvn_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_cvn_2nt_2dc__entry__2">int mpp_decoder_put_frame(struct mpp_decoder* decoder, struct
mpp_frame* frame)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__2">归还视频帧对象</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">decoder: mpp_decoder 对象</div>
<div class="- topic/div div"> frame:视频帧数据结构指针</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_cvn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0:成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_cvn_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_cvn_2nt_2dc__entry__2">-</td></tr></tbody></table></div>
</section><section class="- topic/section section" id="mpp_decode__mpp_decoder-demo" data-ofbid="mpp_decode__mpp_decoder-demo"><h2 class="- topic/title title sectiontitle">MPP Decoder 参考 Demo</h2>
<div class="- topic/p p" id="mpp_decode__ref-picture-decoder-test" data-ofbid="mpp_decode__ref-picture-decoder-test">以下 Demo 为基本流程调用，具体实现可以参考代码
<span class="+ topic/ph sw-d/filepath ph filepath">mpp/mpp_test/picture_decoder_test.c</span><pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="mpp_decode__codeblock_cfs_scw_3dc" data-ofbid="mpp_decode__codeblock_cfs_scw_3dc"><em class="hl-comment">//* 1.创建 mpp_decoder 对象</em>
<strong class="hl-keyword">struct</strong> mpp_decoder* dec = mpp_decoder_create(type);
<strong class="hl-keyword">struct</strong> decode_config config;
config.bitstream_buffer_size = (file_len + <span class="hl-number">1023</span>) &amp; (~<span class="hl-number">1023</span>);
config.extra_frame_num = <span class="hl-number">0</span>;
config.packet_count = <span class="hl-number">1</span>;
config.pix_fmt = MPP_FMT_ARGB_<span class="hl-number">8888</span>;
<em class="hl-comment">//* 2. 初始化 mpp_decoder</em>
mpp_decoder_init(dec, &amp;config);
<em class="hl-comment">//* 3. 获取一个空的 packet</em>
<strong class="hl-keyword">struct</strong> mpp_packet packet;
memset(&amp;packet, <span class="hl-number">0</span>, <strong class="hl-keyword">sizeof</strong>(<strong class="hl-keyword">struct</strong> mpp_packet));
mpp_decoder_get_packet(dec, &amp;packet, file_len);
<em class="hl-comment">//* 4. 把视频码流数据拷贝到 packet</em>
fread(packet.data, <span class="hl-number">1</span>, file_len, fp);
packet.size = file_len;
packet.flag = PACKET_FLAG_EOS;
<em class="hl-comment">//* 5. 归还 packet</em>
mpp_decoder_put_packet(dec, &amp;packet);
<em class="hl-comment">//* 6. 解码该笔码流数据</em>
mpp_decoder_decode(dec);
<em class="hl-comment">//* 7. 获取解码后视频帧数据</em>
<strong class="hl-keyword">struct</strong> mpp_frame frame;
memset(&amp;frame, <span class="hl-number">0</span>, <strong class="hl-keyword">sizeof</strong>(<strong class="hl-keyword">struct</strong> mpp_frame));
mpp_decoder_get_frame(dec, &amp;frame);
<em class="hl-comment">//* 8. 显示该视频帧</em>
<em class="hl-comment">// render_frame...</em>
<em class="hl-comment">//* 9. 归还该视频帧</em>
mpp_decoder_put_frame(dec, &amp;frame);
<em class="hl-comment">//* 10. 销毁 mpp_decoder</em>
mpp_decoder_destory(dec);</pre></div>
</section><section class="- topic/section section" id="mpp_decode__id8" data-ofbid="mpp_decode__id8"><h2 class="- topic/title title sectiontitle">接口设计</h2>
<p class="- topic/p p" data-ofbid="d41009e1132__20250121171516">输出 JPEG 图片的缓存 buffer 由调用者申请，但调用者并不知道编码后图片的实际大小， 为避免 VE 写输出数据时越界，该 buffer
需要预先申请较大的内存。</p>
<div class="table-container"><table class="- topic/table table frame-all" id="mpp_decode__table_evn_2nt_2dc" data-ofbid="mpp_decode__table_evn_2nt_2dc" data-cols="2"><caption class="- topic/title title tablecap" data-caption-side="top" data-is-repeated="true"><span class="table--title-label">表<span class="table--title-label-number"> 12</span><span class="table--title-label-punctuation">. </span></span><span class="table--title">mpp_encode_jpeg</span></caption><colgroup><col style="width:16.666666666666664%"/><col style="width:83.33333333333334%"/></colgroup><thead class="- topic/thead thead"><tr class="- topic/row"><th class="- topic/entry entry colsep-1 rowsep-1" id="mpp_decode__table_evn_2nt_2dc__entry__1">函数原型</th><th class="- topic/entry entry colsep-0 rowsep-1" id="mpp_decode__table_evn_2nt_2dc__entry__2">int mpp_encode_jpeg(struct mpp_frame* frame, int quality, int
dma_buf_fd, int buf_len, int* len)</th></tr></thead><tbody class="- topic/tbody tbody"><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__1">功能说明</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__2">编码一帧 JPEG 图片</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__1">参数定义</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">frame: 待编码的原始 YUV 数据</div>
<div class="- topic/div div">quality: 编码质量，取值范围 1~100，1 表示编码图片质量最差，100 表示最好</div>
<div class="- topic/div div">dma_buf_fd：输出 JPEG 图片存放的 dma-buf fd</div>
<div class="- topic/div div">buf_len：输出 JPEG 图片 dma-buf 的长度</div>
<div class="- topic/div div">len: 输出 JPEG 图片的真实大小</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__1">返回值</td><td class="- topic/entry entry colsep-0 rowsep-1" headers="mpp_decode__table_evn_2nt_2dc__entry__2">
<div class="- topic/div div">
<div class="- topic/div div">0: 成功</div>
<div class="- topic/div div">&lt;0:失败</div>
</div>
</td></tr><tr class="- topic/row"><td class="- topic/entry entry colsep-1 rowsep-0" headers="mpp_decode__table_evn_2nt_2dc__entry__1">注意事项</td><td class="- topic/entry entry colsep-0 rowsep-0" headers="mpp_decode__table_evn_2nt_2dc__entry__2">-</td></tr></tbody></table></div>
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<div class=" wh_topic_toc "><div class="wh_topic_label">在本页上</div><ul><li class="section-item"><div class="section-title"><a href="#mpp_decode__packet" data-tocid="mpp_decode__packet">Packet 管理机制</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__frame" data-tocid="mpp_decode__frame">Frame 管理机制</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__id4" data-tocid="mpp_decode__id4"> 物理连续内存使用情况</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__id5" data-tocid="mpp_decode__id5">MPP Decoder 调用流程</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__id6" data-tocid="mpp_decode__id6">MPP Decoder 数据结构</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__id7" data-tocid="mpp_decode__id7">MPP Decoder 接口设计</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__mpp_decoder-demo" data-tocid="mpp_decode__mpp_decoder-demo">MPP Decoder 参考 Demo</a></div></li><li class="section-item"><div class="section-title"><a href="#mpp_decode__id8" data-tocid="mpp_decode__id8">接口设计</a></div></li></ul></div>
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