Does MediaCodec always give 16-bit audio output?

Question

I'm using Android's MediaCodec class to read raw data from audio files. That works just fine.

The problem is that I don't know if it's safe to assume that the output data will always be 16-bit?

I can tell, experimentally, that the output is 16-bit, but I don't know how to check that at runtime. The MediaCodec documentation doesn't appear to tell me. The MediaFormat KEY_CHANNEL_MASK could tell me, but MediaCodec doesn't appear to set those flags. It sets the sample rate, and the mime-type, but nothing that can tell me the bit-size explicitly.

I suppose that given the difference between presentation times of subsequent blocks, and the sample rate, I should be able to calculate it, but that doesn't seem very satisfactory.

Is there a way to tell, or is it written somewhere that I don't have to?

score 7 · Accepted Answer · answered May 09 '14 at 22:27

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Currently the output is always 16 bit in stock Android. If that changes in the future we'll add an additional format key that specifies the format. Note that KEY_CHANNEL_MASK would only tell you which channels are included (e.g. left, right, center, etc), not the sample format.

answered May 09 '14 at 22:27

marcone

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So, if I assume 16-bit that will be future proof? – ams May 10 '14 at 11:03
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Yes, that should be safe. – marcone May 13 '14 at 16:45
16 bit is already *not* future proof. Since 24bit and other formats are already supported – yano Jun 06 '16 at 18:21

score 1 · Answer 2 · edited May 23 '17 at 12:15

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No it does not. If you have 24 bit PCM (WAV) files, it will give you 24 bit audio. And seemingly no way to determine this. I have added a question here MediaCodec and 24 bit PCM

edited May 23 '17 at 12:15

Community

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answered May 14 '15 at 20:27

yano

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Does MediaCodec always give 16-bit audio output?

2 Answers2