marfrit/libva-v4l2-request-fourier
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Revert iter28b DIAG: trim=40 universal-trim breaks IDR frame 1

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iter28b tested LIBVA_HEVC_TRIM_TRAILING=40 on HEVC. Result: hash
differed at byte 899745 (inside frame 1, NOT just frame 2 boundary at
byte 1382401). Trimming 40 bytes off the IDR slice (96890→96850)
corrupted frame 1. The 40-byte inflation is not uniform per slice;
requires dynamic detection (e.g., scan for rbsp_stop_one_bit) or
per-slice-type logic.
This commit is contained in:
Claude (noether)
2026-05-14 14:42:24 +00:00
parent c5557882aa
commit 6646b1635e
1 changed files with 4 additions and 23 deletions
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src/picture.c
+4 -23
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@@ -61,32 +61,13 @@ static VAStatus codec_store_buffer(struct request_data *driver_data,
struct object_buffer *buffer_object)
{
switch (buffer_object->type) {
case VASliceDataBufferType: {
case VASliceDataBufferType:
/*
* Since there is no guarantee that the allocation
* order is the same as the submission order (via
* RenderPicture), we can't use a V4L2 buffer directly
* and have to copy from a regular buffer.
*/
size_t slice_bytes = buffer_object->size * buffer_object->count;
/*
* iter28b DIAG (env-gated): trim trailing N bytes from
* VAAPI's slice_data buffer for HEVC. Tests the hypothesis
* that ffmpeg-vaapi inflates slice_data_size vs
* ffmpeg-v4l2request. Set LIBVA_HEVC_TRIM_TRAILING=N to
* trim. For BBB frame 2 with libva 5549 vs kdirect 5509:
* try N=40.
*/
if (profile == VAProfileHEVCMain) {
const char *trim_env = getenv("LIBVA_HEVC_TRIM_TRAILING");
if (trim_env) {
unsigned long t = strtoul(trim_env, NULL, 0);
if (t < slice_bytes)
slice_bytes -= t;
}
}
if (context->h264_start_code) {
static const char start_code[3] = { 0x00, 0x00, 0x01 };
@@ -98,11 +79,11 @@ static VAStatus codec_store_buffer(struct request_data *driver_data,
memcpy(surface_object->source_data +
surface_object->slices_size,
buffer_object->data,
slice_bytes);
surface_object->slices_size += slice_bytes;
buffer_object->size * buffer_object->count);
surface_object->slices_size +=
buffer_object->size * buffer_object->count;
surface_object->slices_count++;
break;
}
case VAPictureParameterBufferType:
switch (profile) {