Manually fixing malformed AAC bitstreams

Published: Oct 22, 2019
Reading time: 1 min
Tags: Formats, Guides, Media, Snippets, Software, Windows

Recently while running youtube-dl on Windows, ffmpeg wasn’t found in %PATH%, so it was unable to automatically fix the AAC bitstream. The file will play fine, but in the interest of completeness I still wanted this to be applied to my new files.

Not wanting to alter my path variable for a one-off fix, I investigated the source code a little and found the FFmpegFixupM3u8PP function here.

With that, you can now run:

ffmpeg -i "input_file.mp4" -c copy -f mp4 -bsf:a aac_adtstoasc "output_file.mp4"

And you’re done.