Preserve audio chunk length when dropping samples

When we commit a transcription, we drop the corresponding audio data.
Audio data is represented as a list of chunks. Each chunk contains a few
hundred samples of audio data, representing O(10ms) of audio.

If we want to drop a few seconds of data, this means simply deleting
many chunks of audio. There's usually a chunk where we want to drop some
portion of audio data.

Instead of slicing away that part of the chunk, which would change its
length, this change zeroes it out. This preserves the assumption that
each chunk has the same temporal length.

0 files changed, 0 insertions, 0 deletions