stagefright框架（三）選擇VideoDecoder

status_t AwesomePlayer::initVideoDecoder()
{
  mVideoSource &＃61; OMXCodec::Create(mClient.interface(),
                                  mVideoTrack->getFormat(),
                                  false,
                                  mVideoTrack);
}

sp OMXCodec::Create(&omx, &meta, createEncoder, &source, matchComponentName)
{
  meta->findCString(kKeyMIMEType, &mime);

  findMatchingCodecs(mime, ..., &matchingCodecs); ........ (2)

  for (size_t i &＃61; 0; i   {
    componentName &＃61; matchingCodecs[i].string();

    softwareCodec &＃61;
        InstantiateSoftwareCodec(componentName, ...); ..... (3)

    if (softwareCodec !&＃61; NULL) return softwareCodec;
        
    err &＃61; omx->allocateNode(componentName, ..., &node); ... (4)

    if (err &＃61;&＃61; OK)
    {
      codec &＃61; new OMXCodec(..., componentName, ...); ...... (5)
      return codec;
    }
  }
}


void OMXCodec::findMatchingCodecs(mime, ..., matchingCodecs)
{
  for (int index &＃61; 0;; &＃43;&＃43;index)
  {
    componentName &＃61; GetCodec(
                       kDecoderInfo,
                       sizeof(kDecoderInfo)/sizeof(kDecoderInfo[0]),
                       mime,
                       index);

    matchingCodecs->push(String8(componentName));
  }
}

static const CodecInfo kDecoderInfo[] &＃61;
{
  ...
  { MEDIA_MIMETYPE_VIDEO_MPEG4, "OMX.qcom.video.decoder.mpeg4" },
  { MEDIA_MIMETYPE_VIDEO_MPEG4, "OMX.TI.Video.Decoder" },
  { MEDIA_MIMETYPE_VIDEO_MPEG4, "M4vH263Decoder" },
  ...
}


static sp InstantiateSoftwareCodec(name, ...)
{
  FactoryInfo kFactoryInfo[] &＃61;
  {
    ...
    FACTORY_REF(M4vH263Decoder)
    ...
  };

  for (i &＃61; 0; i   {
    if (!strcmp(name, kFactoryInfo[i].name))
      return (*kFactoryInfo[i].CreateFunc)(source);
  }
}


status_t OMX::allocateNode(name, ..., node)
{
  mMaster->makeComponentInstance(
                           name,
                           &OMXNodeInstance::kCallbacks,
                           instance,
                           handle);
}

OMX_ERRORTYPE OMXMaster::makeComponentInstance(name, ...)
{
  plugin->makeComponentInstance(name, ...);
}

OMX_ERRORTYPE OMXPVCodecsPlugin::makeComponentInstance(name, ...)
{
  return OMX_MasterGetHandle(..., name, ...);
}

OMX_ERRORTYPE OMX_MasterGetHandle(...)
{
  return OMX_GetHandle(...);
}