Stretching WAV audio file with rubberband in fffmpeg causes invalid audio format

Question

Having an issue here using ffmpeg's add-on Rubberband. When I try to stretch a WAV audio file with a given ratio, the WAV file is generated fine but then, when I want to parse its header, I can see an invalid audio format.

'Unknwon format: 22127'

Have reported this issue on this GitHub tracker. All details are there: https://github.com/rackfx/Node-WAV-File-Info/issues/11

But now I am very unsure and wonder if it's not a Rubberband bug? Or am I missing something in the ffmpeg command to ensure correct audio format is set?

That's the ffmpeg command I used to generate that stretched WAV file with the invalid audio format (using ffmpeg v3.0.2 here)

ffmpeg -thread_queue_size 2048 -i /home/michael-heuberger/binarykitchen/code/videomail.io/var/local/tmp/clients/videomail.io/11e6-aebd-f5430180-84c7-074d5706928b/videomail_preview.wav -y -acodec libvorbis -ac 1 -filter:a rubberband=tempo=1.454366279637038 -loglevel warning /home/michael-heuberger/binarykitchen/code/videomail.io/var/local/tmp/clients/videomail.io/11e6-aebd-f5430180-84c7-074d5706928b/videomail_preview_for_webm_stretched.wav

Any clues?

Answer 1

Remove -c:a libvorbis. ffmpeg will then automatically choose a common and compatible audio format for WAV.