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image: fully populate VAImageFormat per VAAPI spec for NV12

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QueryImageFormats and DeriveImage previously set only .fourcc and
left byte_order, bits_per_pixel, depth, and color masks zero
(uninitialized in the caller's buffer). VAAPI consumers that read
these fields (FFmpeg's hwcontext_vaapi.c::vaapi_init_pixfmt,
intel-vaapi-driver test paths) inherit caller-stack garbage with
non-deterministic behavior.

Cross-reference: Mesa's gallium/frontends/va/image.c and
intel-vaapi-driver's i965_drv_video.c both publish NV12 with
byte_order=VA_LSB_FIRST and bits_per_pixel=12. We now match.

For YUV formats, depth/red_mask/green_mask/blue_mask/alpha_mask
are not meaningful (RGB-bitlayout-only fields); leave them zeroed
via memset.

Audit context: 2026-05-04 cross-reference of all libva entry
points Firefox 150 calls vs our backend implementations. The
SEPARATE_LAYERS fix (commit ac891a0) cleared the load-bearing
bug; this fixes a latent uninitialized-field issue that was
masked by mpv's tolerance.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Markus Fritsche
2026-05-04 18:34:50 +00:00
parent ac891a01fa
commit c036a44f98
1 changed files with 22 additions and 0 deletions
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src/image.c
+22
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@@ -198,7 +198,11 @@ VAStatus RequestDeriveImage(VADriverContextP context, VASurfaceID surface_id,
return status;
}
/* Fully populate VAImageFormat to match QueryImageFormats output. */
memset(&format, 0, sizeof(format));
format.fourcc = VA_FOURCC_NV12;
format.byte_order = VA_LSB_FIRST;
format.bits_per_pixel = 12;
status = RequestCreateImage(context, &format, surface_object->width,
surface_object->height, image);
@@ -221,7 +225,25 @@ VAStatus RequestQueryImageFormats(VADriverContextP context,
VAImageFormat *formats, int *formats_count)
{
request_log("ENTER RequestQueryImageFormats\n");
/*
* Populate the VAImageFormat fully per VAAPI spec for NV12 —
* not just .fourcc. Consumers (FFmpeg's hwcontext_vaapi, mpv,
* Firefox) read .byte_order and .bits_per_pixel; leaving them
* uninitialized inherits whatever caller-stack garbage is in
* the buffer and produces non-deterministic behavior. Reference:
* Mesa's gallium/frontends/va/image.c::vlVaQueryImageFormats and
* intel-vaapi-driver's i965_drv_video.c — both publish NV12
* with byte_order=VA_LSB_FIRST and bits_per_pixel=12.
*
* For YUV formats, depth/red_mask/green_mask/blue_mask/alpha_mask
* are not meaningful (those describe RGB bit layouts); leave them
* zeroed via memset before populating.
*/
memset(&formats[0], 0, sizeof(formats[0]));
formats[0].fourcc = VA_FOURCC_NV12;
formats[0].byte_order = VA_LSB_FIRST;
formats[0].bits_per_pixel = 12;
*formats_count = 1;
return VA_STATUS_SUCCESS;