`vaapi-copy` is unavailable when `vaapi` support is enabled

I see a rather contradictory behavior: when vaapi feature is enabled, mpv for some reason loses ability to fall back to vaapi-copy.

The thing is, I have some newer AMD GPUs which can use vaapi, but also have older GPUs which don't support drm modifiers and only able to use vaapi-copy. So I want to use vaapi when possible and fall back to vaapi-copy, but I can't make them both working in the same mpv build.

When vaapi feature is disabled, vaapi-copy works just fine:

[   0.018][v][vd] Looking at hwdec h264-vaapi-copy...
[   0.018][d][ffmpeg] VAAPI: Trying to use DRM render node for device 0.
[   0.019][d][ffmpeg] VAAPI: libva: VA-API version 1.23.0
[   0.019][d][ffmpeg] VAAPI: libva: Trying to open /usr/lib/dri/radeonsi_drv_video.so
[   0.019][d][ffmpeg] VAAPI: libva: Found init function __vaDriverInit_1_23
[   0.020][d][ffmpeg] VAAPI: libva: va_openDriver() returns 0
[   0.020][d][ffmpeg] VAAPI: Initialised VAAPI connection: version 1.23
[   0.020][d][ffmpeg] VAAPI: VAAPI driver: Mesa Gallium driver 26.0.3 for AMD Radeon RX 7700 XT (radeonsi, navi32, ACO, DRM 3.64, 7.0.0-rc6).
[   0.020][d][ffmpeg] VAAPI: Driver not found in known nonstandard list, using standard behaviour.
[   0.020][v][vd] Trying hardware decoding via h264-vaapi-copy.

But when when vaapi feature is enabled, vaapi-copy fails:

[   0.018][v][vd] Looking at hwdec h264-vaapi-copy...
[   0.018][v][vd] Could not create device.
[   0.018][v][vd] Using software decoding.

Attached both full logs below.

mpv Information

mpv v0.41.0 Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
libplacebo version: v7.360.1
FFmpeg version: 8.1
FFmpeg library versions:
   libavcodec      62.28.100
   libavfilter     11.14.100
   libavformat     62.12.100
   libavutil       60.26.100
   libswresample   6.3.100
   libswscale      9.5.100

Reproduction Steps

Build mpv with vaapi support enabled.

Expected Behavior

vaapi-copy should work.

Actual Behavior

vaapi-copy doesn't work.

Log File

vaapi-disabled.log
vaapi-enabled.log

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested and confirmed that the issue exists with the latest release version or newer.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

Start by comparing the vaapi-disabled.log and vaapi-enabled.log outputs and tracing the build-time vaapi and vaapi-copy hardware-decoding paths. Reproduce the issue by building mpv with vaapi support enabled; the fix is complete when vaapi-copy works while vaapi remains available for compatible GPUs.