Decode with mediacodec

asked 2013-12-05 06:35:12 -0500

itay gravatar image

updated 2013-12-05 12:21:17 -0500

berak gravatar image

Hi, I'm developing an app on galaxy s3 (only galaxy s3) that using OpenCV to do some image processing. After a lot of search in the web for how can I decode a video and convert him to matrix, I found that the fastest way to do it is with MediaCodec.

I saw a really longs tutorials that first of all didn't works for me, and second too long for my use.

I just want to convert a video to 300 frames in size of 1920x1080.

If someone use this class and can explain me how to work, or have a good idea how can I decode mp4 file in the fastest way, I really appreciate this.

I found this code to decode the video and send the frames to a Surface, but I don't know what I need to change in order to save the frames in another object:

extractor = new MediaExtractor();
        extractor.setDataSource(SAMPLE);

        for (int i = 0; i < extractor.getTrackCount(); i++) {
            MediaFormat format = extractor.getTrackFormat(i);
            String mime = format.getString(MediaFormat.KEY_MIME);
            if (mime.startsWith("video/")) {
                extractor.selectTrack(i);
                decoder = MediaCodec.createDecoderByType(mime);
                decoder.configure(format, surface, null, 0);

                break;
            }
        }

        if (decoder == null) {
            Log.e("DecodeActivity", "Can't find video info!");
            return;
        }

        decoder.start();

        ByteBuffer[] inputBuffers = decoder.getInputBuffers();
        ByteBuffer[] outputBuffers = decoder.getOutputBuffers();

        BufferInfo info = new BufferInfo();

        boolean isEOS = false;
        long startMs = System.currentTimeMillis();

        while (!Thread.interrupted()) {
            if (!isEOS) {
                int inIndex = decoder.dequeueInputBuffer(10000);
                if (inIndex >= 0) {
                    ByteBuffer buffer = inputBuffers[inIndex];
                    int sampleSize = extractor.readSampleData(buffer, 0);
                    if (sampleSize < 0) {
                        Log.d("DecodeActivity", "InputBuffer BUFFER_FLAG_END_OF_STREAM");
                        decoder.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                        isEOS = true;
                    } else {
                        decoder.queueInputBuffer(inIndex, 0, sampleSize, extractor.getSampleTime(), 0);
                        extractor.advance();
                    }

                }
            }

                                    } catch (FileNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    } finally {
                        if (bos != null)
                            try {
                                bos.close();
                            } catch (IOException e) {
                                // TODO Auto-generated catch block
                                e.printStackTrace();
                            }
                    }
             }

            int outIndex = decoder.dequeueOutputBuffer(info, 10000);
            switch (outIndex) {
            case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
                Log.d("DecodeActivity", "INFO_OUTPUT_BUFFERS_CHANGED");
                outputBuffers = decoder.getOutputBuffers();
                break;
            case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
                Log.d("DecodeActivity", "New format " + decoder.getOutputFormat());
                break;
            case MediaCodec.INFO_TRY_AGAIN_LATER:
                Log.d("DecodeActivity", "dequeueOutputBuffer timed out!");
                break;
            default:
                ByteBuffer buffer = outputBuffers[outIndex];

                Log.v("DecodeActivity", "We can't use this buffer but render it due to the API limit, " + buffer);
                //byte[] b = new byte[buffer.remaining()];

                // We use a very simple clock to keep the video FPS, or the video
                // playback will be too fast
                while (info.presentationTimeUs / 1000 > System.currentTimeMillis() - startMs) {
                    try {
                        sleep(10);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                        break;
                    }
                }

                decoder.releaseOutputBuffer(outIndex, true);
                break;
            }

            // All decoded frames have been rendered, we can stop playing now
            if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                Log.d("DecodeActivity", "OutputBuffer BUFFER_FLAG_END_OF_STREAM");
                break;
            }

Thanks

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