Loss of AAC/H.264 support on Linux since Waterfox 6.6.x (system FFmpeg removed)

[NeonGOD78]

What happened?

Hi Alex and team,

First off, thank you for continuing to maintain Waterfox — it’s one of the few browsers that still respects user choice and performance on Linux.

However, I’ve noticed a serious regression since version 6.6.x: media playback using AAC and H.264 no longer works on Linux systems. It used to work perfectly in 6.5.x, but after the 6.6.x rebuild, about:support now reports both “AAC: Unsupported” and “H.264: Unsupported”.

This means that sites like TV2 Play, Bitmovin demos, and various news portals no longer have sound or video, even though YouTube (Opus/Vorbis) still works fine.

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🧩 Technical details

• In 6.5.x, Waterfox properly detected and used the system’s FFmpeg libraries for decoding AAC and H.264.
• In 6.6.x, that integration appears to have been removed (likely due to build-system or ESR toolchain changes).
• Setting media.libavcodec.allow-obsolete or adjusting LD_LIBRARY_PATH no longer makes a difference.
• FFmpeg (libavcodec.so.62) is installed system-wide and works fine with Firefox and LibreWolf.

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⚙️ Expected behavior

Waterfox should detect and use system FFmpeg libraries on Linux, as Firefox and LibreWolf do.
This ensures support for AAC/H.264 playback without bundling proprietary codecs directly.

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🧪 Environment

• OS: Arch Linux (fully up to date)
• Waterfox build: 6.6.4 (AUR / binary)
• FFmpeg installed: yes (/usr/lib/libavcodec.so.62)
• DRM: enabled (Widevine functional)
• about:support: AAC/H.264 = Unsupported

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🔁 Steps to reproduce

1. Visit https://bitmovin.com/demos/drm
2. Observe: video plays, but no sound
3. Open about:support → “AAC: Unsupported”

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✅ Suggested fix

Please restore or re-enable system FFmpeg integration (--enable-ffmpeg) in the Linux builds.
If licensing concerns are the reason it was disabled, perhaps offer a “Full Codec” Linux build for users who already have FFmpeg installed system-wide.

This small change would restore full functionality for legitimate streaming services and align Waterfox with how Firefox handles codec support.

Thank you for considering this!

Reproducible?

• [x] I have checked that this issue cannot be reproduced on Mozilla Firefox.

Version

6.6.4-1

What platform are you seeing the problem on?

Linux

[NeonGOD78]

Just adding a quick follow-up for visibility 👋

If anyone else on Linux is experiencing the same issue (no sound on DRM sites like TV2 Play, Bitmovin, or other H.264/AAC content), please comment or react here.
This regression affects all 6.6.x builds on Linux due to FFmpeg support being removed from the toolchain.

The more confirmations we gather, the easier it is for Alex and the team to prioritize re-enabling system FFmpeg support or offering a “Full Codec” Linux build.

Thanks in advance to anyone who can confirm their environment and share logs from about:support → “Media” section.

[Nearataa]

I have a similar issue, as i cant watch Livestreams on youtube/twitch. On youtube it says "Your browser cant play this video" Normal videos work fine.

I'm on arch linux (up to date) Waterfox (6.6.4)

From about:support :

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

[NeonGOD78]

Try removing all from waterfox install: sudo pacman -Rns waterfox-bin reboot and install it again using yay -S waterfox-bin and choose to cleanbuild all

[Nearataa]

well thanks that did the trick

[Kreevoz]

I have the same problem - the suggested workaround of removing and reinstalling waterfox-bin doesn't work for me though. Same OS and other system parameters as the OP.

You can also get more information out of waterfox if you run it from a terminal with MOZ_LOG="PlatformDecoderModule:5" waterfox

[...]
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFMPEG: version: 0x100, macro: 61, micro: 100, isFFMpeg: yes
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFVPX: Link result: Success
[...]
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder rejects requested type 'audio/mp4a-latm'
[Utility 22533: Main Thread]: D/PlatformDecoderModule Agnostic decoder rejects requested type 'audio/mp4a-latm'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/mpeg'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/mpeg'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/opus'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/opus'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/vorbis'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/vorbis'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/flac'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/flac'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/x-wav'
[Utility 22533: Main Thread]: D/PlatformDecoderModule FFmpeg decoder supports requested type 'audio/x-wav'

[NeonGOD78]

try installing ffmpeg4.4

[Fifthdread]

Try removing all from waterfox install: sudo pacman -Rns waterfox-bin reboot and install it again using yay -S waterfox-bin and choose to cleanbuild all

Had this same issue, and this fixed it for me. The cleanbuild was absolutely required.

[arisumag]

I'm experiencing the same issue, the reinstall with cleanbuild did not work. it works with ffmpeg4.4 but i notice that it breaks on some websites like Instagram when you scroll reels for too long (and the browser needs to be restarted) it's been like this for weeks.

[you-oops-dev]

@arisumag @NeonGOD78 Installing fmpeg2.1 ffmpeg3.4 from AUR helped me.

[ArcherFlesk]

Facing the same issue myself, though on my other machine I haven't updated anything prior to 6.5.x~ compared to my current machine. Already tried previously mentioned troubleshooting fixes (cleanbuild of Waterfox, installing different versions of ffmpeg (2.1, 3.4, and 4.4). Did noticed something weird (aside from the current issue) and that is whenever the audio is muted for a livestream or certain videos, it plays fine. However, if I turn the audio back on, it immediately pauses the video / stream.