Overview

Who am I? Just a regular guy who loves watching movies. I also tend to dig into the technical side of everyday problems — but I’m usually too lazy to actually solve them. A few months ago, I ran into an issue while trying to play a media file. That’s when I realized my system wasn’t too friendly with AV1-encoded videos.

So, what did I do? Well, since I have a dual-boot setup, I simply switched over to Windows to play it. (Don’t judge!) But honestly, how long could I keep doing that? It was incredibly inconvenient to switch OSes just to watch a movie.

A few days ago, I finally decided to dig deeper. At first, I looked online to see if others had the same issue. I had tried that before — back when the problem first appeared — but didn’t find any promising solutions. That’s why I kept relying on my quick “boot to Windows” workaround.

This time, though, I was serious. My inner engineer refused to stay quiet. And that’s how this debugging journey began. In this article, I’ll take you along with me — step by step — through how I diagnosed and finally solved what seemed like a complex issue that turned out to be surprisingly tricky but simple af.

Introduction

Problem Statement

I had this .mkv video file encoded with the shiny new AV1 codec, and for some reason, it just refused to play on my Ubuntu machine — even though I already had mpv and ffmpeg installed. The player would either crash or refuse to open the file. Was it a codec issue, a player quirk, or something weird going on with GPU hardware decoding behind the scenes?

System Overview

Here’s a brief summary of my setup:

Investigation Process - The Journey

Check MPV & FFmepeg Build Info

Some Ubuntu systems, especially if using older media players or missing certain libraries — don’t support AV1 playback natively. Although I had done basic installation of both the software and as my OS and Kernel not that old, I knew there must be support for AV1.

ffmpeg -codecs | grep av1
---Notable OUTPUT---
WARNING: library configuration mismatch
...
DEV.L. av1         Alliance for Open Media AV1 (decoders: libdav1d libaom-av1 av1 av1_cuvid av1_qsv) (encoders: libaom-av1 librav1e libsvtav1 av1_nvenc av1_qsv av1_vaapi)
DEAIL. wmav1       Windows Media Audio 1

FFmpeg build does include AV1 decoding support, thus FFmpeg and MPV can handle AV1 — at least from a codec capability perspective.

As for the WARNING message, initially I thought MPV might be loading mismatched libraries but this message is common to have after upgrades. Trust me, I did the clean re-installation, the warning was gone for a new start. However, it recurred after few reboots.

Just in case if you would like to perform clean re-install:

sudo apt purge ffmpeg mpv -y
sudo apt autoremove -y
sudo apt update
sudo apt install ffmpeg mpv -v
ffmpeg --version && mpv --version

Check if FFmpeg can Decode it Manually

ffmpeg -v error -i yourfile.mkv -f null -

This will attempt to decode the entire video to /dev/null. If you see no errors, FFmpeg can decode it fine — the issue is purely in playback. If there’s a decoding error at this step its because the file is corrupted or encoded with an unsupported AV1 profile like 10-bit.

Inspect Video Stream Details:

ffprobe -v error -select_streams v:0 -show_entries stream=codec_name,profile,pix_fmt,width,height,bit_rate -of default=nw=1 yourfile.mkv

Therefore, my media file is a 10-bit AV1 video (pix_fmt=yuv420p10le), so software decoders like libdav1d libaom-av1 should easily handle it. I did this step out of curiosity as I read somewhere that some GPU-accelerated pipelines can’t handle 10-bit AV1 video file yet. So I just wanted to check that it.

Check MPV logs

mpv -v yourfile.mkv | tee mpv.log
---Notable OUTPUT---
[vo/gpu/wayland] GL_VENDOR='Intel'
[vo/gpu/wayland] GL_RENDERER='Mesa Intel(R) Graphics (ADL GT2)'
...
[vd] Opening decoder libdav1d
[vd] Looking at hwdec av1-vaapi...
[vo/gpu] Loading hwdec drivers for format: 'vaapi'
[vo/gpu] Loading hwdec driver 'vaapi'
...
[vd] Pixel formats supported by decoder: cuda vaapi vdpau vulkan yuv420p10le
...
[ffmpeg/video] av1: Failed to end picture decode issue: 23 (internal decoding error).
[ffmpeg/video] av1: HW accel end frame fail.
[vd] Error while decoding frame (hardware decoding)!

Well this log was full of informational details I needed. Lets see what did I find out:

• Intel integrated graphic was used as renderer. While Alder Lake does support AV1 hardware decoding, it depends on:

  • The driver stack, VAAPI version, Wayland/X11 compositor setup

  • Many systems with Intel iGPUs hit issues like black screen, freeze, or no output when AV1 VAAPI decoding is attempted — especially under Wayland.

• My guess, MPV loads VAAPI → Wayland → EGL → dmabuf interop → hardware AV1 decoder. This is where it likely stops showing video — the FPU driver fails silently.

• Hence, problem = VAAPI hardware docoding of AV1 under Intel-iGPU + Wayland combo.

This is where the problem statement got real clear.

Switch to NVIDIA

Confirm which GPU is active:

glxinfo | grep "OpenGL renderer"

If it says something like OpenGL renderer string: Mesa Intel(R) Graphics … then your session (wayland or X) is currently using the Intel GPU, not NVIDIA.

Lets check GPU and Driver Stack

vainfo | grep -i av1
ffmpeg -hwaccels
ffmpeg -decoders | grep av1

If vainfo lists only Intel devices, it means the NVIDIA VAAPI driver (rarely used) isn’t active. That’s expected;

If you see cuda, vulkan, or vaapi in the list, good — the driver stack is okay.

Lastly, check that ffmpeg recognizes the NVIDIA AV1 decoder.

Test playback directly via NVIDIA

DRI_PRIME=1 mpv --hwdec=cuda --vo=gpu-next --gpu-api=opengl --gpu-context=waylandvk "censored-name.mkv"

This means mpv found the NVIDIA GPU (via DRI_PRIME=1) but couldn’t create a rendering context under Wayland — because Wayland + NVIDIA is still finicky with OpenGL/Vulkan interop.

Test with the safer X11 EGL path

DRI_PRIME=1 mpv --hwdec=cuda --vo=gpu-next --gpu-context=x11egl "censored-name.mkv"

This forces mpv to use an XWayland bridge to talk to the NVIDIA GPU.

• mpv successfully detects the video, audio, and subtitle tracks.

• The libEGL warning (failed to create dri2 screen) and CUDA_ERROR_INVALID_GRAPHICS_CONTEXT indicate a context mismatch — CUDA tried to access OpenGL through the wrong display backend (likely Wayland instead of X11).

• The note CUDA hwdec only works with OpenGL or Vulkan backends explains the failure reason.

• Despite that, mpv still falls back to software rendering

Now, I am sure its a context mismatch issue.

Fixing GPU context mismatch

__GLX_VENDOR_LIBRARY_NAME=nvidia mpv --hwdec=cuda --vo=gpu-next --gpu-context=waylandvk "censored-name.mkv"

Finally It worked !! This plays the video with now errors or warnings.

Wayland sessions and NVIDIA drivers don’t always automatically set the correct OpenGL vendor path.
The variable __GLX_VENDOR_LIBRARY_NAME=nvidia forces MPV (and the GLX stack) to use the NVIDIA OpenGL library instead of Mesa (Intel/AMD). This fixed the “invalid OpenGL or DirectX context” errors.

---

Final Solution

For convenience you can make this your default MPV configuration so you don’t have to type it each time.

vi ~/.config/mpv/mpv.conf
---Add below configurations---
hwdec=cuda
vo=gpu-next
gpu-context=waylandvk

vi ~/.config/environment.d/99-nvidia.conf
---Add below configurations---
__GLX_VENDOR_LIBRARY_NAME=nvidia

---REBOOT System---
Enjoy your media file.

What ~/.config/environment.d/ is — This directory is part of systemd’s user environment mechanism.
Anything you put as .conf files here (with KEY=value pairs) gets automatically loaded into your user session environment, before applications start.

---

Conclusion

What started as “why won’t this stupid file play” turned into a journey through drivers, GPU contexts, and environment tweaks — and I learned more about the Linux graphics stack in one evening than I had in months.

References

• https://ffmpeg.org/documentation.html

• https://github.com/mpv-player/mpv/issues/15980

• https://github.com/mpv-player/mpv/issues/10854

• https://github.com/mpv-player/mpv/issues/372

• https://wiki.archlinux.org/title/Hardware_video_acceleration

• https://developer.nvidia.com/video-codec-sdk

Lesson Learned

• Try to step out of the comfort box, being lazy dosen’t solve things.

• Problems seems hard until its well understood.

• Data Flow : MPV → FFmpeg → CUDA/NVDEC → NVIDIA GPU → Display (Wayland

• Logs are the goto debugging checkpoints.

• PS: This is my 1st time writing a technical article, thus open to take suggestion to improve the structure and writing.