Does Canvas transcode audio file submissions?

[djphiliptan]

My students are submitting MP3 and AAC/MP4 audio files for their final assignment, but when I download their submissions through SpeedGrader, I'm getting lower bitrate than what they had originally uploaded. Plus, the files all appear to be transcoded into AAC/MP4.

So if a student uploads a 320Kbps MP3, Canvas provides the instructor with a 128Kbps AAC file instead, losing quite a bit of high frequency information. The files are about 1/3 the size of their original upload. This is a problem, since the students are being assessed on the quality of their recordings.

Is Canvas transcoding these files or assigning the wrong file headers? Is there an option in Canvas to prevent this from happening?

[cromijn]

Hello @djphiliptan ,

I checked into this and found that the audio/media files that are uploaded to Canvas are converted at the time of the upload based on the browser's support file types. This would likely include any bitrate limitations during the file conversion process. There may be a way to work around this if the files were uploaded to a cloud service that retains the original file bit rate and file format, possibly something like a SoundCloud file, or it may also work in something like DropBox. 

I hope this helps you determine how to approach this situation with the audio submissions!