Android音视频开发之MediaCodec的使用教程

// 加载资源
extractor.setDataSource(path);
// 获取视频轨道
int trackIndex = getTrackIndex(extractor,"video/");
// 获取视频轨道参数
MediaFormatInfo mediaFormatInfo = MediaFormatInfo.buildUpVideoMediaFormatInfo(extractor.getTrackFormat(trackIndex));
// 选取上述的视频轨道
extractor.selectTrack(trackIndex);
MediaCodecInfo mediaCodecInfo = CodecInfoInstance.getInstance().selectDeCodec(mediaFormatInfo.getMime());
// 判断设备是否支持该视频解码，创建视频编码器
if(mediaCodecInfo != null){
    mediaCodec = MediaCodec.createDecoderByType(mediaFormatInfo.getMime());
    mediaCodec.configure(mediaFormatInfo.getMediaFormat(),surface,null,0);
}

while (!isEnd && !isInterrupted()){
    if (!mIsEOS) {
        mIsEOS = dequeueInputBuffers();
    }
    isEnd = dequeueOutputBuffers();
}

//输入缓冲区
private boolean dequeueInputBuffers() {
    boolean isMediaEOS = false;
    //  等待编码器输入缓冲区数据出队
    int inputBufferId = mediaCodec.dequeueInputBuffer(TIMEOUT_US);
    if (inputBufferId >= 0) {
        // 获取缓存区数据
        ByteBuffer inputBuffer = mediaCodec.getInputBuffer(inputBufferId);
        // 读取数据 返回值sampleSize大于0表示还有数据，否则表示结束
        int sampleSize = extractor.readSampleData(inputBuffer, 0);
        if (sampleSize < 0) {
            // 数据末尾 必须再次调用queueInputBuffer使用BUFFER_FLAG_END_OF_STREAM标识符输入到编码器
            mediaCodec.queueInputBuffer(inputBufferId, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
            isMediaEOS = true;
            MediaLogUtils.printI(TAG + "end of stream");
        } else {
            // 输入缓冲区数据入队
            mediaCodec.queueInputBuffer(inputBufferId, 0, sampleSize, extractor.getSampleTime(), 0);
            extractor.advance();
        }
    }
    return isMediaEOS;
}

//输出缓冲区
private synchronized boolean dequeueOutputBuffers() {
    MediaCodec.BufferInfo outBufferInfo = new MediaCodec.BufferInfo();
    //输出缓冲区
    int outputBufferId = mediaCodec.dequeueOutputBuffer(outBufferInfo, TIMEOUT_US);
    switch (outputBufferId) {
        case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
            MediaLogUtils.printI(TAG+"INFO_OUTPUT_FORMAT_CHANGED");
            break;
        case MediaCodec.INFO_TRY_AGAIN_LATER:
            MediaLogUtils.printI(TAG+ "INFO_TRY_AGAIN_LATER");
            break;
        case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
            MediaLogUtils.printI(TAG+ "INFO_OUTPUT_BUFFERS_CHANGED");
            break;
        default:
            // 延迟解码
            decodeDelay(outBufferInfo, mStartMs);
            // 释放输出缓冲区数据 render为true渲染到surface上
            mediaCodec.releaseOutputBuffer(outputBufferId, true);
            break;
    }
    // 结尾
    if ((outBufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
        MediaLogUtils.printI(TAG+"buffer stream end");
        return true;
    }
    return false;
}