MediaMuxer的作用是生成音频或视频文件；还可以把音频与视频混合成一个音视频文件。
相关API介绍
MediaMuxer(String path , int format)：path：输出文件的名称，format：输出文件的格式；当前只支持MP4格式
addTrack（MediaFormat format）：添加通道；我们更多的是使用MediaCodec.getOutpurForma()或Extractor.getTrackFormat(int index)来获取MediaFormat;也可以自己创建；
start()：开始合成文件
writeSampleData(int trackIndex, ByteBuffer byteBuf, MediaCodec.BufferInfo bufferInfo)：把ByteBuffer中的数据写入到在构造器设置的文件中；
stop()：停止合成文件
release()：释放资源
使用示例：
public class MediaMuxerUtils
{
private WeakReference<Context> mContext;
public MediaMuxerUtils(Context context)
{
mContext = new WeakReference<Context>(context);
}
//分离MP4中的视频保存成新的MP4文件
public void videoMuxer(String videoPath)
{
MediaExtractor mediaExtractor = new MediaExtractor();
int videoIndex = -1;
try
{
mediaExtractor.setDataSource(videoPath+"/1.mp4");
int trackCount = mediaExtractor.getTrackCount();
for (int i = 0; i < trackCount; i++)
{
MediaFormat trackFormat = mediaExtractor.getTrackFormat(i);
if(trackFormat.getString(MediaFormat.KEY_MIME).startsWith("video/"))
{
videoIndex = i;
break;
}
}
mediaExtractor.selectTrack(videoIndex);
MediaFormat videoTrackFormat = mediaExtractor.getTrackFormat(videoIndex);
MediaMuxer mediaMuxer = new MediaMuxer(videoPath + "/2.mp4", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
//追踪此信道
int trackIndex = mediaMuxer.addTrack(videoTrackFormat);
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
mediaMuxer.start();
int frameSize = videoTrackFormat.getInteger(MediaFormat.KEY_FRAME_RATE);
mediaExtractor.selectTrack(videoIndex);
bufferInfo.presentationTimeUs = 0;
while(true)
{
int readSampleData = mediaExtractor.readSampleData(byteBuffer, 0);
if(readSampleData < 0)
{
break;
}
bufferInfo.size = readSampleData;
bufferInfo.offset = 0;
bufferInfo.flags = mediaExtractor.getSampleFlags();
bufferInfo.presentationTimeUs += 1000 * 1000 / frameSize;
//写入帧数据
mediaMuxer.writeSampleData(trackIndex,byteBuffer,bufferInfo);
mediaExtractor.advance();
}
mediaMuxer.stop();
mediaExtractor.release();
mediaMuxer.release();
} catch (IOException e)
{
e.printStackTrace();
}
}
//分离MP4中的音频保存成新的MP4文件
public void audioMuxer(String videoPath)
{
int audioIndex = -1;
MediaExtractor mediaExtractor = new MediaExtractor();
try
{
mediaExtractor.setDataSource(videoPath+"/1.mp4");
int trackCount = mediaExtractor.getTrackCount();
for (int i = 0; i < trackCount; i++)
{
MediaFormat trackFormat = mediaExtractor.getTrackFormat(i);
if(trackFormat.getString(MediaFormat.KEY_MIME).startsWith("audio/"))
{
audioIndex = i;
break;
}
}
MediaFormat trackFormat = mediaExtractor.getTrackFormat(audioIndex);
MediaMuxer mediaMuxer = new MediaMuxer(videoPath + "/output_audio.mp4", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int audioTrackIndex = mediaMuxer.addTrack(trackFormat);
mediaMuxer.start();
mediaExtractor.selectTrack(audioIndex);
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
long audioSampleTime = 0;
{
mediaExtractor.readSampleData(byteBuffer, 0);
if(mediaExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC)
mediaExtractor.advance();
mediaExtractor.readSampleData(byteBuffer, 0);
long firstSampleTime = mediaExtractor.getSampleTime();
mediaExtractor.advance();
mediaExtractor.readSampleData(byteBuffer, 0);
long secondSampleTime = mediaExtractor.getSampleTime();
mediaExtractor.advance();
audioSampleTime = Math.abs(secondSampleTime - firstSampleTime);
}
while (true)
{
int readSampleData = mediaExtractor.readSampleData(byteBuffer, 0);
if(readSampleData < 0)
break;
bufferInfo.offset = 0;
bufferInfo.flags = mediaExtractor.getSampleFlags();
bufferInfo.size = readSampleData;
bufferInfo.presentationTimeUs += audioSampleTime;
mediaMuxer.writeSampleData(audioTrackIndex,byteBuffer,bufferInfo);
mediaExtractor.advance();
}
mediaMuxer.stop();
mediaMuxer.release();
mediaExtractor.release();
} catch (IOException e)
{
e.printStackTrace();
}
}
//将1.mp4视频、testfile.mp4音频各自分离出来然后合成新的mp4
public void videoAudioMuxer(String videoPath)
{
MediaExtractor videoMediaExtractor = new MediaExtractor();
MediaExtractor audioMediaExtractor = new MediaExtractor();
try
{
videoMediaExtractor.setDataSource(videoPath+"/1.mp4");
audioMediaExtractor.setDataSource(videoPath+"/testfile.mp4");
int videoTrackCount = videoMediaExtractor.getTrackCount();
int audioTrackCount = audioMediaExtractor.getTrackCount();
int videoTrackIndex = -1;
int audioTrackIndex = -1;
for (int i = 0; i < videoTrackCount; i++)
{
MediaFormat trackFormat = videoMediaExtractor.getTrackFormat(i);
if(trackFormat.getString(MediaFormat.KEY_MIME).startsWith("video/"))
{
videoTrackIndex = i;
break;
}
}
for (int i = 0; i < audioTrackCount; i++)
{
MediaFormat trackFormat = audioMediaExtractor.getTrackFormat(i);
if(trackFormat.getString(MediaFormat.KEY_MIME).startsWith("audio/"))
{
audioTrackIndex = i;
break;
}
}
MediaFormat videoTrackFormat = videoMediaExtractor.getTrackFormat(videoTrackIndex);
MediaFormat audioTrackFormat = audioMediaExtractor.getTrackFormat(audioTrackIndex);
videoMediaExtractor.selectTrack(videoTrackIndex);
audioMediaExtractor.selectTrack(audioTrackIndex);
MediaMuxer mediaMuxer = new MediaMuxer(videoPath + "/output.mp4", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int videoAddTrackIndex = mediaMuxer.addTrack(videoTrackFormat);
int audioAddTrackIndex = mediaMuxer.addTrack(audioTrackFormat);
mediaMuxer.start();
int frameSize = videoTrackFormat.getInteger(MediaFormat.KEY_FRAME_RATE);
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
bufferInfo.presentationTimeUs = 0;
while (true)
{
int readSampleData = videoMediaExtractor.readSampleData(byteBuffer, 0);
if(readSampleData < 0)
break;
bufferInfo.size = readSampleData;
bufferInfo.flags = videoMediaExtractor.getSampleFlags();
bufferInfo.offset = 0;
bufferInfo.presentationTimeUs += 1000*1000/frameSize;
mediaMuxer.writeSampleData(videoAddTrackIndex,byteBuffer,bufferInfo);
videoMediaExtractor.advance();
}
bufferInfo.presentationTimeUs = 0;
while (true)
{
int readSampleData = audioMediaExtractor.readSampleData(byteBuffer, 0);
if(readSampleData < 0)
break;
bufferInfo.size = readSampleData;
bufferInfo.flags = audioMediaExtractor.getSampleFlags();
bufferInfo.offset = 0;
bufferInfo.presentationTimeUs += 1000*1000/frameSize;
mediaMuxer.writeSampleData(audioAddTrackIndex,byteBuffer,bufferInfo);
audioMediaExtractor.advance();
}
mediaMuxer.stop();
mediaMuxer.release();
videoMediaExtractor.release();
audioMediaExtractor.release();
} catch (IOException e)
{
e.printStackTrace();
}
}
}
