youtube-dl is downloading incorrect audio/mp4 files

[saundershayes]

Recently youtube-dl has been downloading audio/mp4 files with a file size different from the file size specified in the MPEG-DASH MPD. For example, if I get the MPEG-DASH MPD using youtube-dl

curl $(youtube-dl https://www.youtube.com/watch?v=x9vmoQ5WABU --youtube-include-dash-manifest --dump-intermediate-pages -s | grep manifest.google | cut -d ' ' -f 5)

you can see that the content length of the audio/mp4 files is supposed to be 3702900 and 7431829 bytes, but instead youtube-dl gives audo/mp4 files that are 3740463 and 7469392 bytes. When the youtube client javascript makes requests for the audio/mp4 files, it expects the files to be the ones specified in the MPD with the above command, so it would seem that youtube-dl is downloading incorrect/modified audio/mp4 files.

[dstftw]

Metadata served by DASH manifest is incorrect.

[saundershayes]

If the metadata is incorrect then are you also saying that audio file requests from youtube.com specify an incorrect content length in their request parameters? The file size returned by youtube-dl matches the content length in the manifest for every other audio/video format. Why do you think the metadata from the DASH manifest is incorrect?

[dstftw]

Sorry, I've misread your post (it's the bitrate that is usually incorrect). Filesize shift is due to youtube-dl fixup policy to fix known issues with media files (you may notice [ffmpeg] Correcting container in is output). In particular this happens for m4a_dash container. You can pass --fixup never to disable this completely. Then you'll get files of the same size as in manifest.

[saundershayes]

Great thanks! That did the trick. Appreciate the help.