Firefox transcodes when it can direct play

[billcw 2]

Now that Firefox finally supports MKV, I have been doing some experimenting.  Running 4.9.5.0 with Firefox 151, if transcoding is enabled for the user, Emby transcodes compatible video and audio streams.  If I disable transcoding, then Emby direct plays the file just fine.

MKV file with transcoding enabled:

 

The same file with transcoding disabled:

In my case, having transcoding disabled is fine, but this could probably be improved.

[Luke 42887]

Hi, the reason is indicated in your first screenshot.

[billcw 2]

Well, the only difference that I see is the "selecting secondary audio track" bit, but it uses the same audio track in either case.