AndroidMediaCodec

Android Media codec for video encoding and decoding from C++ for use with QT. By using the native codec we have the possibility of leveraging hardware acceleration for compression and decoding, if available on the device.

Not fully tested yet, ergo not stable!

I am using API 23, lower versions (>18?) are probably possible. I am not able to provide any support but thought this might help some people to get through the partially quite rough documeentation for the ndk.

NativeCodecReader opens and decodes a media file (such as mp4 with h264 or webm) You can query OpenCV's cv::Mat via read() Frame counts are calculated from video duration / current sample timestamps and the framerate. TODO Might be worth having a look at the asynchronous functions so that we can actually push the frames out instead of querying them, which might allow for faster playback without a buffering layer.

NativeCodecWriter encodes frames to a video and muxes them to a media file (such as mp4 with h264 or webm) You can push OpenCV's cv::Mat via write() After recording you need to call end() to finish the writing process and to flush the remaining buffers. This might take a while. The object can be deleted once the recordingFinished() signal is emitted (and no earlier!)

You might want to run the encoding in a separate thread, e.g.

QThread* mEncodingThread = new QThread(); NativeCodecWriter* videoWriter = new NativeCodecWriter(videofile, fps, Size(data.input.cols, data.input.rows)); videoWriter->moveToThread(mEncodingThread); mEncodingThread->start(); QMetaObject::invokeMethod(videoWriter, &NativeCodecWriter::prepareEncoder); connect(this, &DataRecorder::pushFrame, videoWriter, &NativeCodecWriter::write);