1. 寻找视频流的第一帧
旧：
int videoStream = -1;
for (int i = 0; i < pFormatCtx->nb_streams; i++) {if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO&& videoStream < 0) {videoStream = i;}
}
新：
int videoStream = -1;
for (int i = 0; i < pFormatCtx->nb_streams; i++) {if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && videoStream < 0){videoStream = i;}
}
2 获取codec上下文指针
旧：
AVCodecContext * pCodecCtx = pFormatCtx->streams[videoStream]->codec;
新：
AVCodecContext *pCodecCtx = avcodec_alloc_context3(NULL);
if (pCodecCtx == NULL)
{printf("Could not allocate AVCodecContext\n");return -1;
}
avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoStream]->codecpar);
3. 对该帧进行解码
旧：
while(av_read_frame(pFormatCtx, &packet)>=0) {//判断是否为视频流if(packet.stream_index==videoStream) {//对该帧进行解码，该方法已经过时弃用avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);if (frameFinished) {// lock native windowANativeWindow_lock(nativeWindow, &windowBuffer, 0);// 格式转换sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,pFrame->linesize, 0, pCodecCtx->height,pFrameRGBA->data, pFrameRGBA->linesize);// 获取strideuint8_t * dst = windowBuffer.bits;int dstStride = windowBuffer.stride * 4;uint8_t * src = pFrameRGBA->data[0];int srcStride = pFrameRGBA->linesize[0];// 由于window的stride和帧的stride不同,因此需要逐行复制int h;for (h = 0; h < videoHeight; h++) {memcpy(dst + h * dstStride, src + h * srcStride, (size_t) srcStride);}ANativeWindow_unlockAndPost(nativeWindow);}//延迟等待usleep((unsigned long) (1000 * 40 * play_rate));}av_packet_unref(&packet);
}
新：
while (av_read_frame(pFormatCtx,&packet) >= 0){//判断是否为视频流if (packet.stream_index == videoStream) {//解码该帧if (avcodec_send_packet(pCodecCtx,&packet) == 0) {// 一个avPacket可能包含多帧数据，所以需要使用while循环一直读取while (avcodec_receive_frame(pCodecCtx,pFrame) == 0){// 1.lock window// 设置缓冲区的属性：宽高、像素格式（需要与Java层的格式一致）ANativeWindow_setBuffersGeometry(nativeWindow,videoWidth,videoHeight,WINDOW_FORMAT_RGBA_8888);ANativeWindow_lock(nativeWindow,&windowBuffer,NULL);// 格式转换sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,pFrame->linesize, 0, pCodecCtx->height,pFrameRGBA->data, pFrameRGBA->linesize);// 获取strideuint8_t *dst =(uint8_t *) windowBuffer.bits;int dstStride = windowBuffer.stride * 4;uint8_t * src = pFrameRGBA->data[0];int srcStride = pFrameRGBA->linesize[0];// 由于window的stride和帧的stride不同,因此需要逐行复制int h;for (h = 0; h < videoHeight; h++) {memcpy(dst + h * dstStride, src + h * srcStride, (size_t) srcStride);}ANativeWindow_unlockAndPost(nativeWindow);}} else {LOGE("Error sending a packet for decoding");return -1;}// 每绘制一帧便休眠16毫秒，避免绘制过快导致播放的视频速度加快usleep(1000 * 16);}av_packet_unref(&packet);
}
4. 编码参数上下文的拷贝
旧：
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
if (ret < 0){printf("Failed to copy context from input to output stream codec context\n");goto end;
}out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
新：
AVCodecContext *codec_ctx = avcodec_alloc_context3(in_codec);
ret = avcodec_parameters_to_context(codec_ctx, in_stream->codecpar);
if (ret < 0){printf("Failed to copy in_stream codecpar to codec context\n");goto end;
}codec_ctx->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;ret = avcodec_parameters_from_context(out_stream->codecpar, codec_ctx);
if (ret < 0){printf("Failed to copy codec context to out_stream codecpar context\n");goto end;
}