跟上篇FFmpeg 将MP4转为YUV420P大致一样，直播过将解码的流放到surface实现原生播放。

一、代码：

java：

public native void decode(String inputPath, Surface surface);

注意：转换的是RGBA_8888,所以别忘了：

surfaceView.getHolder.setFormat(PixelFormat.RGBA_8888);

c：

JNIEXPORT void JNICALL
Java_com_example_testffmpeg_MainActivity_decode(
        JNIEnv *env,
        jobject /* this */, jstring input_, jobject surface) {

    const char *input = env->GetStringUTFChars(input_, 0);

    av_register_all();

    AVFormatContext *pFormatCtx = avformat_alloc_context();

    if (avformat_open_input(&pFormatCtx, input, NULL, NULL) != 0) {
        LOGE("打开失败");
        return;
    }

    if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        LOGE("获取信息失败");
        return;
    }

    int video_stream_idx = -1;

    for (int i = 0; i < pFormatCtx->nb_streams; ++i) {
        LOGE("循环流 %d", i);
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_idx = i;
            break;
        }
    }

    //    获取到解码器上下文
    AVCodecContext *pCodecCtx = pFormatCtx->streams[video_stream_idx]->codec;

    AVCodec *pCodex = avcodec_find_decoder(pCodecCtx->codec_id);

    if (avcodec_open2(pCodecCtx, pCodex, NULL) < 0) {
        LOGE("解码失败");
        return;
    }

    AVPacket *avPacket = (AVPacket *) av_malloc(sizeof(AVPacket));

    AVFrame *frame ;
    frame= av_frame_alloc();

    //surface只支持RGB
    AVFrame *rgb_frame = av_frame_alloc();

    //缓冲区分配内存
    uint8_t   *out_buffer= (uint8_t *) av_malloc(avpicture_get_size(AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height));

    LOGE("宽  %d,  高  %d  ",pCodecCtx->width,pCodecCtx->height);

    //设置yuvFrame的缓冲区，像素格式
    int re= avpicture_fill((AVPicture *) rgb_frame, out_buffer, AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height);

    int length = 0;
    int got_frame;

    int frameCount = 0;

    SwsContext *swsContext = sws_getContext(pCodecCtx->width,pCodecCtx->height,pCodecCtx->pix_fmt,
                                            pCodecCtx->width,pCodecCtx->height,AV_PIX_FMT_RGBA,SWS_BICUBIC,NULL,NULL,NULL
    );

    //需用到Android的window 
    ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);

    //视频缓冲区
    ANativeWindow_Buffer outBuffer;

    while (av_read_frame(pFormatCtx, avPacket) >= 0) {

        if (avPacket->stream_index == video_stream_idx) {
            length = avcodec_decode_video2(pCodecCtx, frame, &got_frame, avPacket);
            LOGE(" 获得长度   %d ", length);
            LOGE(" 获得   %d ", got_frame);
            if (got_frame ) {
                LOGE("解码=%d", frameCount++);

                //设置window 缓冲器的 format 和size等
                ANativeWindow_setBuffersGeometry(nativeWindow,
                                                 pCodecCtx->width,
                                                 pCodecCtx->height,
                                                 WINDOW_FORMAT_RGBA_8888);

                ANativeWindow_lock(nativeWindow, &outBuffer, NULL);
                //转换为RGB
                sws_scale(swsContext, (const uint8_t *const *) frame->data, frame->linesize, 0
                        , pCodecCtx->height, rgb_frame->data,
                          rgb_frame->linesize);


                //window缓冲区 的内存首地址
                uint8_t *dst = (uint8_t *) outBuffer.bits;

                //window缓冲区一行内存大小 R G B A 所以*4
                int destStride = outBuffer.stride * 4;
                
                //解码出的 rgb_frame数据首地址
                uint8_t *src = rgb_frame->data[0];

                //解码出的 rgb_frame数据一行 大小
                int srcStride = rgb_frame->linesize[0];
                
                //一行一行的 拷贝 
                for (int i = 0; i < pCodecCtx->height; ++i) {
                    memcpy(dst + i * destStride, src + i * srcStride, srcStride);
                }

                ANativeWindow_unlockAndPost(nativeWindow);

                //模拟速度
                usleep(1000 * 16);
            }
        }
        av_free_packet(avPacket);
    }
    ANativeWindow_release(nativeWindow);
    av_frame_free(&frame);
    avcodec_close(pCodecCtx);
    avformat_free_context(pFormatCtx);
    env->ReleaseStringUTFChars(input_, input);
}