Firefox: No video with supported format and MIME type found

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1

I can’t play a local MP4 file with Firefox, on two different machines. However I can play it using vlc on the same machines. I’m using a Firefox profile with no plugins.

The file contains: “Video: hevc (Main 10), yuv420p10le(tv), 1920x1080, SAR 1:1 DAR 16:9, 24 fps, 24 tbr, 1k tbn (default)” & “Audio: eac3, 48000 Hz, 5.1(side), fltp, 256 kb/s”.

I have the multimedia group installed, and:

ffmpeg-libs-7.0.2-4.fc41.x86_64
gstreamer1-plugin-openh264-1.24.11-1.fc41.x86_64
libde265-1.0.15-4.fc41.x86_64
mozilla-openh264-2.4.1-2.fc41.x86_64
openh264-2.4.1-2.fc41.x86_64
x264-libs-0.164-15.20231001git31e19f92.fc41.x86_64
x265-3.6-3.fc41.x86_64
x265-libs-3.6-3.fc41.x86_64

What’s especially annoying is that Firefox gives absolutely no additional information about exactly what is wrong …

This is similar to the previous post: No video with supported format and MIME type found - #4 by Espionage724 but the suggestions there did not work.

3

firefox does not support HEVC videos on linux and only recently added support on Windows if supported by HW.

about:support

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4

Thanks. Having that error link to the support page would be a start.

5

Not really that recent :stuck_out_tongue: (reports with media.wmf.hevc.enabled from 2023)

6

But had it any effect?

officially announced in 134.0, that’s recentl;y :stuck_out_tongue_winking_eye:

Hardware-accelerated playback of HEVC video content is now supported on Windows.

7

On Windows 1 made about:support show HW for HEVC where the default 2 iirc didn’t (this is 135.0.1 Win11 Intel UHD 630 with HEVC extension and 1):

Codec Name Software Decoding Hardware Decoding
H264 Supported Supported
VP9 Supported Supported
VP8 Supported Supported
AV1 Supported Supported
HEVC Unsupported Supported
AAC Supported Unsupported
MP3 Supported Unsupported
Opus Supported Unsupported
Vorbis Supported Unsupported
FLAC Supported Unsupported
Wave Supported Unsupported

I was setting it since around Aug 2024.

8

this is 137.0b3 on Fedora 41

Support HEVC playback on Linux.

Name Firefox
Version 137.0b3
Build ID 20250307103915
Codec Name Software Decoding Hardware Decoding
H264 Supported Supported
VP9 Supported Supported
VP8 Supported Supported
AV1 Supported Unsupported
HEVC Supported Supported
AAC Supported Unsupported
MP3 Supported Unsupported
Opus Supported Unsupported
Vorbis Supported Unsupported
FLAC Supported Unsupported
Wave Supported Unsupported
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