SDK / exoplayer

Currently FlacDecoder/FlacExtractor always perform resampling to 16bit. In some
case (with 24bit audio), this might lower the audio quality if the system
supports 24bit audio.
Since AudioTrack implementation supports resampling, we will remove the
resampling step, and return an output with the same bits-per-sample as the original stream.
User can choose to re-sample to 16bit in AudioTrack if necessary.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=167494350