VP09, V_Quicktime and VLC

Help
,
1

I recently downloaded and converted a couple of YouTube ‘VP09’/mp4 videos, to an mkv container. The format was now listed as ‘V_Quicktime’ instead of ‘VP09’. VLC, the popular video player, will not recognize the format, and , therefore, not play the files. MPC, however, will play the videos without issue. The error message :
“Codec not supported:”
“VLC could not decode the format " " (No description for this codec)”

Anyone have any ideas on how to resolve this incompatibility?

Thanks.

2

Do you have a sample MP4 file for me to look at? Please upload it to my file server. Thanks.

3

I didn’t have an issue number, so I imply uploaded the file. I have two. The uploaded file is a brief trailer for the re-release of the 1927 film ‘Napoleon’. The YouTube number is part of the filename and in brackets. The other is aailable in small and large (4K) resolutions and has the film ‘Greed’ (1924) [bMms4c9jqZc].
“https://www.youtube.com/watch?v=YoQkFQTe9cM” - the Napoleon trailer.
The videos were downloaded using yt-dlp with no command line options.

4

Thanks. Looks like you’re using an older version of MKVToolNix as the current one can recognize VP9 in that file properly & creates a VP9-in-Matroska-compliant file with Matroska codec ID V_VP9. The resulting file plays just fine in my VLC. Just upgrade to the latest version.