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();
}
}
}
if (decodeCount < 300) {
Log.v("My Error","decodeCount = " + decodeCount);
File outputFile = new File(Environment.getExternalStorageDirectory() + "/DCIM/Frames", String.format("frame-%02d.png", decodeCount));
decodeCount++;
//Canvas can = SH.lockCanvas();
//Bitmap bmp = null;
//bmp = Bitmap.createBitmap(1920, 1080, Bitmap.Config.ARGB_4444);
//can.drawBitmap(bmp, 0, 0,null);
ByteBuffer buf = ByteBuffer.allocateDirect(1920 * 1080 * 4);
buf.order(ByteOrder.LITTLE_ENDIAN);
GLES20.glReadPixels(0, 0, 1920, 1080, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buf);
buf.rewind();
BufferedOutputStream bos = null;
try {
bos = new BufferedOutputStream(new FileOutputStream(outputFile.toString()));
Bitmap bmp = Bitmap.createBitmap(colors, 1920, 1080, Bitmap.Config.ARGB_8888);
bmp.compress(Bitmap.CompressFormat.PNG, 90, bos);
bmp.recycle();
} 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
