本文共 7005 字，大约阅读时间需要 23 分钟。

OMX_FillThisBuffer

#define OMX_FillThisBuffer (hComponent,pBuffer)((OMX_COMPONENTTYPE*)hComponent)->FillThisBuffer(hComponent,pBuffer)

作用：向组件的输出端口发送空白buffer

allocateOutputBuffersFromNativeWindow

status_t ACodec::allocateOutputBuffersFromNativeWindow() {
                                                                                                                              // This method only handles the non-metadata mode (or simulating legacy    // mode with metadata, which is transparent to ACodec).    CHECK(!storingMetadataInDecodedBuffers());    OMX_U32 bufferCount, bufferSize, minUndequeuedBuffers;    status_t err = configureOutputBuffersFromNativeWindow(            &bufferCount, &bufferSize, &minUndequeuedBuffers, true /* preregister */);    if (err != 0)        return err;    mNumUndequeuedBuffers = minUndequeuedBuffers;    static_cast
   
    (mNativeWindow.get())            ->getIGraphicBufferProducer()->allowAllocation(true);    ALOGV("[%s] Allocating %u buffers from a native window of size %u on "         "output port",         mComponentName.c_str(), bufferCount, bufferSize);    // Dequeue buffers and send them to OMX    for (OMX_U32 i = 0; i < bufferCount; i++) {
           ANativeWindowBuffer *buf;        int fenceFd;        err = mNativeWindow->dequeueBuffer(mNativeWindow.get(), &buf, &fenceFd);        if (err != 0) {
               ALOGE("dequeueBuffer failed: %s (%d)", strerror(-err), -err);            break;        }        sp
    
      graphicBuffer(GraphicBuffer::from(buf));        BufferInfo info;        info.mStatus = BufferInfo::OWNED_BY_US;        info.mFenceFd = fenceFd;        info.mIsReadFence = false;        info.mRenderInfo = NULL;        info.mGraphicBuffer = graphicBuffer;        info.mNewGraphicBuffer = false;        info.mDequeuedAt = mDequeueCounter;        // TODO: We shouln't need to create MediaCodecBuffer. In metadata mode        //       OMX doesn't use the shared memory buffer, but some code still        //       access info.mData. Create an ABuffer as a placeholder.        info.mData = new MediaCodecBuffer(mOutputFormat, new ABuffer(bufferSize));        info.mCodecData = info.mData;        mBuffers[kPortIndexOutput].push(info);        IOMX::buffer_id bufferId;        err = mOMXNode->useBuffer(kPortIndexOutput, graphicBuffer, &bufferId);        if (err != 0) {
               ALOGE("registering GraphicBuffer %u with OMX IL component failed: "                 "%d", i, err);            break;        }        mBuffers[kPortIndexOutput].editItemAt(i).mBufferID = bufferId;        ALOGV("[%s] Registered graphic buffer with ID %u (pointer = %p)",             mComponentName.c_str(),             bufferId, graphicBuffer.get());    }    OMX_U32 cancelStart;    OMX_U32 cancelEnd;    if (err != OK) {
                // If an error occurred while dequeuing we need to cancel any buffers        // that were dequeued. Also cancel all if we're in legacy metadata mode.        cancelStart = 0;        cancelEnd = mBuffers[kPortIndexOutput].size();    } else {
           // Return the required minimum undequeued buffers to the native window.        cancelStart = bufferCount - minUndequeuedBuffers;        cancelEnd = bufferCount;    }    for (OMX_U32 i = cancelStart; i < cancelEnd; i++) {
           BufferInfo *info = &mBuffers[kPortIndexOutput].editItemAt(i);        if (info->mStatus == BufferInfo::OWNED_BY_US) {
               status_t error = cancelBufferToNativeWindow(info);            if (err == 0) {
                   err = error;            }        }    }    static_cast
     
      (mNativeWindow.get())            ->getIGraphicBufferProducer()->allowAllocation(false);    return err;}
     
    
   

从显示那边拿到buffer后对mBuffers[kPortIndexOutput]进行填充

fillBuffer

status_t ACodec::fillBuffer(BufferInfo *info) {
       status_t err;    // Even in dynamic ANW buffer mode, if the graphic buffer is not changing,    // send sPreset instead of the same graphic buffer, so that OMX server    // side doesn't update the meta. In theory it should make no difference,    // however when the same buffer is parcelled again, a new handle could be    // created on server side, and some decoder doesn't recognize the handle                                                                                                         // even if it's the same buffer.        if (!storingMetadataInDecodedBuffers() || !info->mNewGraphicBuffer) {
                                                                                                                   err = mOMXNode->fillBuffer(            info->mBufferID, OMXBuffer::sPreset, info->mFenceFd);                                                                                                                    } else {
           err = mOMXNode->fillBuffer(            info->mBufferID, info->mGraphicBuffer, info->mFenceFd);                                                                                                                  }      info->mNewGraphicBuffer = false;        info->mFenceFd = -1;    if (err == OK) {
           info->mStatus = BufferInfo::OWNED_BY_COMPONENT;                                                                                                                              }      return err;}

status_t OMXNodeInstance::fillBuffer(        IOMX::buffer_id buffer, const OMXBuffer &omxBuffer, int fenceFd) {
       Mutex::Autolock autoLock(mLock);    if (mHandle == NULL) {
           return DEAD_OBJECT;    }    OMX_BUFFERHEADERTYPE *header = findBufferHeader(buffer, kPortIndexOutput);    if (header == NULL) {
           ALOGE("b/25884056");        return BAD_VALUE;    }    if (omxBuffer.mBufferType == OMXBuffer::kBufferTypeANWBuffer) {
           status_t err = updateGraphicBufferInMeta_l(                kPortIndexOutput, omxBuffer.mGraphicBuffer, buffer, header);        if (err != OK) {
               CLOG_ERROR(fillBuffer, err, FULL_BUFFER(                    (intptr_t)header->pBuffer, header, fenceFd));            return err;        }    } else if (omxBuffer.mBufferType != OMXBuffer::kBufferTypePreset) {
           return BAD_VALUE;    }    header->nFilledLen = 0;    header->nOffset = 0;    header->nFlags = 0;    // meta now owns fenceFd    status_t res = storeFenceInMeta_l(header, fenceFd, kPortIndexOutput);    if (res != OK) {
           CLOG_ERROR(fillBuffer::storeFenceInMeta, res, EMPTY_BUFFER(buffer, header, fenceFd));        return res;    }    {
           Mutex::Autolock _l(mDebugLock);        mOutputBuffersWithCodec.add(header);        CLOG_BUMPED_BUFFER(fillBuffer, WITH_STATS(EMPTY_BUFFER(buffer, header, fenceFd)));    }    OMX_ERRORTYPE err = OMX_FillThisBuffer(mHandle, header);    if (err != OMX_ErrorNone) {
           CLOG_ERROR(fillBuffer, err, EMPTY_BUFFER(buffer, header, fenceFd));        Mutex::Autolock _l(mDebugLock);        mOutputBuffersWithCodec.remove(header);    }    return StatusFromOMXError(err);}

xxx_OMX_FillThisBuffer

pOMXComponent->FillThisBuffer  = &xxx_OMX_FillThisBuffer;

在对应的插件中实现此函数

转载地址：http://obzin.baihongyu.com/