利用MediaExtractor和MediaMuxer实现视频剪切

public class VideoDecoder { private final static String TAG = "VideoDecoder"; private MediaCodec mediaDecoder; private MediaExtractor mediaExtractor; private MediaFormat mediaFormat; private MediaMuxer mediaMuxer; private String mime = null; public boolean decodeVideo(String url, long clipPoint, long clipDuration) { int videoTrackIndex = -1; int audioTrackIndex = -1; int videoMaxInputSize = 0; int audioMaxInputSize = 0; int sourceVTrack = 0; int sourceATrack = 0; long videoDuration, audioDuration; //创建分离器 mediaExtractor = new MediaExtractor(); try { //设置文件路径 mediaExtractor.setDataSource(url); //创建合成器 mediaMuxer = new MediaMuxer(url.substring(0, url.lastIndexOf(".")) + "_output.mp4", OutputFormat.MUXER_OUTPUT_MPEG_4); } catch (Exception e) { Log.e(TAG, "error path" + e.getMessage()); } //获取每个轨道的信息 for (int i = 0; i < mediaExtractor.getTrackCount(); i++) { try { mediaFormat = mediaExtractor.getTrackFormat(i); mime = mediaFormat.getString(MediaFormat.KEY_MIME); if (mime.startsWith("video/")) { sourceVTrack = i; int width = mediaFormat.getInteger(MediaFormat.KEY_WIDTH); int height = mediaFormat.getInteger(MediaFormat.KEY_HEIGHT); videoMaxInputSize = mediaFormat.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE); videoDuration = mediaFormat.getLong(MediaFormat.KEY_DURATION); //检测剪辑点和剪辑时长是否正确 if (clipPoint >= videoDuration) { Log.e(TAG, "clip point is error!"); return false; } if ((clipDuration != 0) && ((clipDuration + clipPoint) >= videoDuration)) { Log.e(TAG, "clip duration is error!"); return false; } Log.d(TAG, "width and height is " + width + " " + height + ";maxInputSize is " + videoMaxInputSize + ";duration is " + videoDuration ); //向合成器添加视频轨 videoTrackIndex = mediaMuxer.addTrack(mediaFormat); } else if (mime.startsWith("audio/")) { sourceATrack = i; int sampleRate = mediaFormat.getInteger(MediaFormat.KEY_SAMPLE_RATE); int channelCount = mediaFormat.getInteger(MediaFormat.KEY_CHANNEL_COUNT); audioMaxInputSize = mediaFormat.getInteger(MediaFormat.KEY_MAX_INPUT_SIZE); audioDuration = mediaFormat.getLong(MediaFormat.KEY_DURATION); Log.d(TAG, "sampleRate is " + sampleRate + ";channelCount is " + channelCount + ";audioMaxInputSize is " + audioMaxInputSize + ";audioDuration is " + audioDuration ); //添加音轨 audioTrackIndex = mediaMuxer.addTrack(mediaFormat); } Log.d(TAG, "file mime is " + mime); } catch (Exception e) { Log.e(TAG, " read error " + e.getMessage()); } } //分配缓冲 ByteBuffer inputBuffer = ByteBuffer.allocate(videoMaxInputSize); //根据官方文档的解释MediaMuxer的start一定要在addTrack之后 mediaMuxer.start(); //视频处理部分 mediaExtractor.selectTrack(sourceVTrack); MediaCodec.BufferInfo videoInfo = new MediaCodec.BufferInfo(); videoInfo.presentationTimeUs = 0; long videoSampleTime; //获取源视频相邻帧之间的时间间隔。(1) { mediaExtractor.readSampleData(inputBuffer, 0); //skip first I frame if (mediaExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC) mediaExtractor.advance(); mediaExtractor.readSampleData(inputBuffer, 0); long firstVideoPTS = mediaExtractor.getSampleTime(); mediaExtractor.advance(); mediaExtractor.readSampleData(inputBuffer, 0); long SecondVideoPTS = mediaExtractor.getSampleTime(); videoSampleTime = Math.abs(SecondVideoPTS - firstVideoPTS); Log.d(TAG, "videoSampleTime is " + videoSampleTime); } //选择起点 mediaExtractor.seekTo(clipPoint, MediaExtractor.SEEK_TO_PREVIOUS_SYNC); while (true) { int sampleSize = mediaExtractor.readSampleData(inputBuffer, 0); if (sampleSize < 0) { //这里一定要释放选择的轨道，不然另一个轨道就无法选中了 mediaExtractor.unselectTrack(sourceVTrack); break; } int trackIndex = mediaExtractor.getSampleTrackIndex(); //获取时间戳 long presentationTimeUs = mediaExtractor.getSampleTime(); //获取帧类型，只能识别是否为I帧 int sampleFlag = mediaExtractor.getSampleFlags(); Log.d(TAG, "trackIndex is " + trackIndex + ";presentationTimeUs is " + presentationTimeUs + ";sampleFlag is " + sampleFlag + ";sampleSize is " + sampleSize); //剪辑时间到了就跳出 if ((clipDuration != 0) && (presentationTimeUs > (clipPoint + clipDuration))) { mediaExtractor.unselectTrack(sourceVTrack); break; } mediaExtractor.advance(); videoInfo.offset = 0; videoInfo.size = sampleSize; videoInfo.flags = sampleFlag; mediaMuxer.writeSampleData(videoTrackIndex, inputBuffer, videoInfo); videoInfo.presentationTimeUs += videoSampleTime;//presentationTimeUs; } //音频部分 mediaExtractor.selectTrack(sourceATrack); MediaCodec.BufferInfo audioInfo = new MediaCodec.BufferInfo(); audioInfo.presentationTimeUs = 0; long audioSampleTime; //获取音频帧时长 { mediaExtractor.readSampleData(inputBuffer, 0); //skip first sample if (mediaExtractor.getSampleTime() == 0) mediaExtractor.advance(); mediaExtractor.readSampleData(inputBuffer, 0); long firstAudioPTS = mediaExtractor.getSampleTime(); mediaExtractor.advance(); mediaExtractor.readSampleData(inputBuffer, 0); long SecondAudioPTS = mediaExtractor.getSampleTime(); audioSampleTime = Math.abs(SecondAudioPTS - firstAudioPTS); Log.d(TAG, "AudioSampleTime is " + audioSampleTime); } mediaExtractor.seekTo(clipPoint, MediaExtractor.SEEK_TO_CLOSEST_SYNC); while (true) { int sampleSize = mediaExtractor.readSampleData(inputBuffer, 0); if (sampleSize < 0) { mediaExtractor.unselectTrack(sourceATrack); break; } int trackIndex = mediaExtractor.getSampleTrackIndex(); long presentationTimeUs = mediaExtractor.getSampleTime(); Log.d(TAG, "trackIndex is " + trackIndex + ";presentationTimeUs is " + presentationTimeUs); if ((clipDuration != 0) && (presentationTimeUs > (clipPoint + clipDuration))) { mediaExtractor.unselectTrack(sourceATrack); break; } mediaExtractor.advance(); audioInfo.offset = 0; audioInfo.size = sampleSize; mediaMuxer.writeSampleData(audioTrackIndex, inputBuffer, audioInfo); audioInfo.presentationTimeUs += audioSampleTime;//presentationTimeUs; } //全部写完后释放MediaMuxer和MediaExtractor mediaMuxer.stop(); mediaMuxer.release(); mediaExtractor.release(); mediaExtractor = null; return true; } }