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(AI written summary of troubleshooting steps taken before making this support thread)

Firefox version: - 152.0.1 Release - 153.0 Nightly

OS: - Windows 11 build 26200

GPU: - NVIDIA GeForce RTX 4070 SUPER

Codec package: - Microsoft HEVC Video Extensions installed from Microsoft Store

Problem

Firefox does not expose HEVC playback support, causing Twitch to disable 1440p streams encoded with HEVC.

The same machine can play the same HEVC Twitch streams in Chrome immediately after installing HEVC Video Extensions.

Expected result

Firefox should report HEVC playback support and allow playback of HEVC streams, as Chrome does on the same system.

Actual result

Firefox reports HEVC as unsupported.

about:support:

codecSupportInfo: H264 SWDEC HWDEC VP9 SWDEC HWDEC VP8 SWDEC HWDEC AV1 SWDEC HWDEC HEVC NONE

Troubleshooting already performed

- Installed Microsoft HEVC Video Extensions - Rebooted Windows - Updated NVIDIA drivers - Verified hardware acceleration is enabled - Tested with a brand new Firefox profile - Tested with Firefox Nightly - Confirmed Chrome can play the same HEVC streams

Additional observations

Chrome: - Twitch 1440p becomes available immediately after installing HEVC Video Extensions - Twitch Stats for Nerds reports:

 hev1.1.6.L150.90.0.0.0.0.0

Firefox: - Twitch reports that the browser does not support the required resolution - 1440p remains greyed out - about:support continues to report HEVC NONE

Reproducible tests

Firefox console:

MediaSource.isTypeSupported('video/mp4; codecs="hev1.1.6.L150.90"')

Result: false

MediaSource.isTypeSupported('video/mp4; codecs="hvc1.1.6.L150.90"')

Result: false

navigator.mediaCapabilities.decodingInfo({

 type: "media-source",
 video: {
   contentType: 'video/mp4; codecs="hev1.1.6.L150.90"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: false,
 smooth: false,
 powerEfficient: false

}

For comparison:

MediaSource.isTypeSupported('video/mp4; codecs="av01.0.08M.08"')

Result: true

navigator.mediaCapabilities.decodingInfo({

 type: "file",
 video: {
   contentType: 'video/mp4; codecs="av01.0.08M.08"',
   width: 2560,
   height: 1440,
   bitrate: 8000000,
   framerate: 60
 }

})

Result: {

 supported: true,
 smooth: true,
 powerEfficient: true

}

Additional note

Setting:

dom.media.webcodecs.h265.enabled = true

causes HTML5 codec test (https://html5test.co/) to report H.265 support, but does not change:

- about:support - MediaSource.isTypeSupported() - MediaCapabilities.decodingInfo() - Twitch HEVC playback availability

Question

Is this a known issue with HEVC Media Source Extensions support on Windows 11 build 26200, or is there another requirement for Firefox to expose HEVC playback capability through MediaSource and MediaCapabilities when the Windows HEVC codec is installed and functioning in Chromium-based browsers?

Basically every time i play a livestream on YouTube, it lags a lot/constantly buffers and when i play it, when i press the live button to go to the livesteam's current time i guess. It just goes back to the previous time in the stream and idk how to fix it. Basically i disabled ublock origin & it still has issues on mobile =( also it sometimes happens on PC but mostly with ublock on. Unfortunately i can't screen record on mobile

Hello All,

I have a somewhat confusing issue that I've only found two posts on Reddit mentioning previously, but there were no responses.

A short summary: On Discord's website, in an audio call, audio will progressively move from stereo/both ears to mono/only the right ear after anywhere from five to sixty seconds. This only occurs on Firefox, it does not occur on Chrome or Edge (with the same extensions, when applicable.) For the record - this also only occurs with the one headset. I've tried with a second headset and don't have the same issue, but I don't believe the Headset is solely to blame since the issue only happens on Firefox.

I have also tested on Firefox Nightly as a fresh install - no extensions, no settings changed, just install and login to Discord.

Specs:

ASUS TUF Dash F15 FX517ZR HP USB-C G5 Essential Dock (Monitors are connected through it) Windows 11 (August update/build 26200.9168) Razer Blackshark V2 Pro RZ04-0453 headset (Connects via USB-A Dongle plugged in to the laptop) Firefox (x64) (154.0.1)

Troubleshooting steps I've taken:

Removing the Audio driver for my computer and re-installing it. Removing/re-installing the drivers for the Headset. Verified all audio related drivers for my device are up to date. Verified the BIOS is up to date (it's solved unusual problems before) Toggling the "media.latency_preference" toggle in about:config (recommendation from a friend) Disabling all extensions on Discord. Disabling Firefox's strict mode on Discord. Verifying all audio related drivers for my device are up to date. Tested on a Firefox Nightly install (the first time it's been installed on my device). A separate browser (Chrome/Edge - the issue is not present) A separate headset (Issue is not present) Downloading Razer Synapse and disabling any "extra" features, and testing with various options on/off. Disabling any and all other Audio devices (speakers and microphones) while using the headset. Charging the Headset to full.

Things I haven't tested, but thought of:

Resetting Firefox in any capacity - I can, but hopefully testing with Nightly is sufficient. A different computer entirely - on my list, when I can next. A new User profile. Testing with no headset at all, and just utilizing the built-in speakers/microphone for the laptop.

Oddities:

Changing audio settings in Windows will "fix" the issue momentarily - for instance the "Spatial sound" option. Changing from one setting to "Off" (or vice versa) fixes the issue for the same ~5-60 seconds until it slowly goes back to the right ear. These options are present for every device, even ones not experiencing this issue.

It's very odd to me because on one hand it may be the headset, but then the issue is only present in Firefox.

Any help or things to test would be greatly appreciated!

Thank you.

Firefox for Android 150.0 Build 2016155439 OS Android 16 Autoplay set to "Block audio and video" but audio and video still autoplay from NPR.org website started happening a few weeks ago Is there a way to fix this please?

thank you

I can't seem to get microphone and video to work I've checked the permissions and still it's not working. I need to sign a docusign with a notary and time is of the essence . I am about to throw the phone at the wall. please help

When I try to watch youtube, firefox will repeatedly rotate from portait to landscape. This is not what I want and there are no settings I can find to stop this. I cannot find a solution anywhere. I would like to view content the way I want, not landscape just because it is youtube.

My Youtube video stutters every 6-10 seconds. When I turn off my HW acc off, this issue happened. Turning the HW acc on solve it, but the thing is if I have my HW acc on another problem came up, which is my Firefox will starts to blink. Anyone has a solution for this?

'how to cast videos from my phone to my TV if I got android phone, and I have i basic Sylvania TV without wifi or Bluetooth connection, hmi and a softwaode with fire fox app.

For the past.. month I would say, any time I try to use Youtube on my Firefox Browser it nearly always switches over to landscape mode after watching a video. It doesn't matter whether my phone screen's auto rotate is on or off it still does it. Yes. I already tried to turn my auto rotate on to switch it back to potrait mode, it still won't work. The only solution I currently have is closing Youtube all together from my Browser, which really REALLY sucks!!

Can someone PLEASE look into the glitch?!

It was working fine until the day before yesterday. The volume of the speaker got low before it stopped working. The PodCast and Vimeo are working fine. So it is not the problem of my computer speaker.

After a Windows 11 update my Firefox browser no longer has any audio. The sound is turned all the way up in the Sound Mixer and I have no Bluetooth devices connected. After it initially happened I connected my Bluetooth earbuds and it worked for a few minutes before it too lost audio.

I have audio on all my other applications.

Hello Firefox Support Team/Forum

I am writing to request guidance on a hardware video acceleration issue that I have been unable to resolve despite extensive troubleshooting. Firefox appears to be blocking VA-API hardware decoding on my system even though the VA-API stack is confirmed working at the system level. — SYSTEM SPECIFICATIONS — OS: Arch Linux (rolling), kernel 7.0.13-arch1-1 Desktop: Hyprland 0.55.4 (Wayland, DRM backend) CPU: AMD A9-9425 (2 cores, 3.1GHz, Excavator architecture) RAM: 8GB Firefox: installed via pacman (native, not Flatpak) Mesa: 26.1.3-arch1.2 GPU setup (dual): • card0 / renderD128: AMD Stoney R5 Graphics (iGPU) — VA-API confirmed working here • card1 / renderD129: AMD Hainan R5 M435 (dGPU) — used by Hyprland for display output — CONFIRMED WORKING AT SYSTEM LEVEL — Running ‘vainfo’ on the integrated GPU (renderD128) confirms the following profiles are available: VAProfileH264ConstrainedBaseline, VAProfileH264Main, VAProfileH264High (VLD + EncSlice) VAProfileHEVCMain, VAProfileHEVCMain10 (VLD) VAProfileMPEG2Simple, VAProfileMPEG2Main, VAProfileVC1 (VLD) VAProfileJPEGBaseline (VLD) MPV with ‘–hwdec=vaapi-copy’ successfully hardware-decodes H264 locally, confirmed by ‘nv12’ pixel format output and reduced CPU usage. radeontop monitoring card0 (stoney, bus 00) during Firefox video playback shows: • Graphics pipe: ~53% (compositing activity) • UVD row: absent / 0% (no hardware video decode activity) • Memory clock: near 0.00G This confirms Firefox is NOT using the hardware decoder despite VA-API being functional. — FIREFOX DECISION LOG (from about:support) — HARDWARE_VIDEO_DECODING: default available / user force_enabled H264_HW_DECODE: default available (no blocklist) HEVC_HW_DECODE: default available VP8_HW_DECODE: env blocklisted — FEATURE_FAILURE_VIDEO_DECODING_MISSING VP9_HW_DECODE: env blocklisted — FEATURE_FAILURE_VIDEO_DECODING_MISSING AV1_HW_DECODE: env blocklisted — FEATURE_FAILURE_VIDEO_DECODING_MISSING DMABUF_SURFACE_EXPORT: env blocked — FEATURE_FAILURE_BROKEN_DRIVER WEBRENDER_COMPOSITOR: env blocklisted — FEATURE_FAILURE_WEBRENDER_COMPOSITOR_DISABLED Note: VP8/VP9/AV1 being missing is expected and correct for this GPU generation. The concern is that H264, which IS in the vainfo profile list and shows as ‘available’ in the decision log, is still not being routed to the hardware decoder in practice. — ENVIRONMENT VARIABLES IN USE — MOZ_ENABLE_WAYLAND=1 LIBVA_DRIVER_NAME=radeonsi LIBVA_DRM_DEVICE=/dev/dri/renderD128 MOZ_DISABLE_RDD_SANDBOX=1 — about:config SETTINGS CURRENTLY SET — media.ffmpeg.vaapi.enabled = true media.hardware-video-decoding.force-enabled = true media.hardware-video-decoding-vulkan.enabled = false media.rdd-process.enabled = true — WHAT WAS TRIED — 1. Installed full Mesa stack: mesa, libva-mesa-driver, libva-utils, ffmpeg, vulkan-radeon (64-bit and 32-bit variants via multilib). 2. Set LIBVA_DRM_DEVICE=/dev/dri/renderD128 to hardcode VA-API to the stoney iGPU and prevent it from accidentally targeting the hainan dGPU (which fails Firefox’s internal VA-API test with FEATURE_FAILURE_VIDEO_DECODING_TEST_FAILED). 3. Enabled media.ffmpeg.vaapi.enabled and media.hardware-video-decoding.force-enabled in about:config. 4. Disabled MOZ_DISABLE_RDD_SANDBOX via both ~/.bash_profile and hl.env() in the Hyprland Lua config to allow Firefox’s RDD process to access /dev/dri/renderD128. 5. Installed enhancedH264ify extension with VP9 and AV1 blocking enabled. YouTube confirms H264 (avc1.64002a) is being served. Despite this, over 1100 frames out of ~4200 are dropped during 1080p60 playback. 6. Verified with radeontop -b 0 (stoney, bus 00) during active 1080p H264 playback: the UVD block shows no activity whatsoever, confirming the CPU is doing all decoding. 7. Tested with and without gfx.webrender.all = true. Enabling it caused severe visual corruption (texture artifacts, split UI elements), so it was reset to default. 8. Did NOT disable media.rdd-process.enabled (correctly kept at true, as RDD is the process Firefox uses for VA-API decoding). 9. Confirmed Firefox is installed via pacman (not Flatpak), so there is no Flatpak sandbox layer involved. — THE CORE QUESTION — Given that: • vainfo confirms H264 hardware decode is available on renderD128 • H264_HW_DECODE shows as ‘default available’ in Firefox’s own decision log with no blocklist entry • media.hardware-video-decoding.force-enabled is set to true • MOZ_DISABLE_RDD_SANDBOX=1 is set • LIBVA_DRM_DEVICE explicitly points to the correct render node • MPV successfully uses vaapi on the same system …why is Firefox’s RDD process still not routing H264 decoding through VA-API, and what additional steps or logs would help identify the specific internal failure point?

Any guidance on enabling verbose VA-API logging within Firefox’s RDD process, or any known issues with AMD Stoney + Hainan dual-GPU setups on Wayland that might explain the DMABUF_SURFACE_EXPORT FEATURE_FAILURE_BROKEN_DRIVER blocklist, would be greatly appreciated.

Thank you.

Yesterday I updated Firefox to version 115.22.0esr this morning when it was released. Have never had any problems viewing video on Netflix but now I am getting Netflix error message F7702-1003. Yesterday I asked "what can I do? I've rebooted computer as Netflix says and it didn't help."

Today, to see if the issue was a bug with version 115.22.0 esr I logged onto both Peacock and Hoopla to try to stream video. On both sites the same thing happened that happened on Netflix. I log into the site, select a video, and when I try to play it I get a message that "widevineCdm plugin has crashed" and video won't play.

Since this problem just appeared after I updated to version 115.22.0 esr it seems likely that there is a bug in this version which is crashing the plugin and preventing streaming video. I note that I can stream some video having checked both YouTube and an online television station.

Hello Team, I am having issues with Mozilla Firefox and Nightly Browser sound. If I use another browser, the sound is perfect. I have been using Firefox for years now and am accustomed to it, as well as Nighty, for all browsing needs.

Regards, Roopesh