Which encoder does Android MediaRecorder use?

Question

Does anyone know which audio/video encoders does MediaRecorder use?

I know we can choose the audio / video mimeTypes with mediaRecorder.setVideoEncoder() and mediaRecorder.setAudioEncoder():

mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);

But this won't tell me which encoder implementation is being used, as each device can have multple encoders for H264 (for example, a hardware accelerated one and a software one like OMX.google.h264.encoder).

Is there a way to know this?

Can anyone link to native source code where we can discover this?

When using low-level MediaCodec, we can access all encoders through MediaCodecList, get their name and capabilities, and finally instantiate the correct MediaCodec. I'm sure that MediaRecorder is doing the same in native code, I just can't find any source code reference. Thanks!

The answers I would expect are...

• MediaRecorder just uses the first matching encoder, just like using MediaCodec.createEncoderByType(type)
• MediaRecorder explicitly prefers hardware encoders
• Something else

Answer 1

MediaRecoders native implementation is StagefrightRecorder.cpp. In method setupVideoEncoder, line #1782 you can see it is using MediaCodecSource::Create with a format that has 'video/avc' as 'mime' (Line #1660).

In MediaCodecSource.cpp in method initEncoder in line #515 the best suited encoder is selected.

How the Codec gets selected can be found here

I hope this helps navigating through androids native media impementations.