How to determine the value of Android MediaFormat.KEY_SAMPLE_RATE

Question

I'm trying to encode

Audio data:

• Sample rate = 44100 Hz
• Monoral Channel
• PCM_16BIT

to some AAC by MediaCodec

The codec configuration is a bit confusing, but so far I did as follows at least with no error.

    codec = MediaCodec.createEncoderByType("audio/mp4a-latm");
    MediaFormat format = new MediaFormat();
    format.setString(MediaFormat.KEY_MIME, "audio/mp4a-latm");
    format.setInteger(MediaFormat.KEY_CHANNEL_COUNT, 1);
    format.setInteger(MediaFormat.KEY_SAMPLE_RATE, 44100);
    format.setInteger(MediaFormat.KEY_BIT_RATE, 1*44100*16);
    format.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectHE);
    codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);

Here's only my guess so if you find it wrong please tell me so.

KEY_CHANNEL_COUNT = 1 corresponds to the audio source attribute: Monoral Channel = 1,

KEY_SAMPLE_RATE = 44100 to the audio source attribute: Sample rate = 44100 Hz,

and since the audio source attribute is PCM_16BIT, KEY_BIT_RATE should be 1*44100*16.

Am I correct? I try to find documentation, but could not find on the web. Thanks.

Answer 1

For the encoders, KEY_BIT_RATE refers to the desired output bit rate, not the input bit rate. The official doc is here, but the descriptions are a bit terse.

The CTS EncoderTest encodes audio. It's not much to go on, but it has the basic elements.