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lavc/hevcdec: move handling of byte alignment at the end of slice header

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Do it in hls_slice_header() rather than cabac_init_decoder() - the
former is a more logical place as according the spec the byte alignment
is a part of the slice header, not slice data. Avoids a second instance
of alignment handling in vaapi_hevc.

Also, check that alignment_bit_equal_to_one is, in fact, equal to one.
This commit is contained in:
Anton Khirnov 2024-05-28 16:59:23 +02:00
parent a14440867c
commit 74159cbfc3
4 changed files with 9 additions and 5 deletions
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2
libavcodec/hevc_cabac.c
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@ -430,8 +430,6 @@ static int cabac_reinit(HEVCLocalContext *lc)
static int cabac_init_decoder(HEVCLocalContext *lc)
{
GetBitContext *gb = &lc->gb;
skip_bits(gb, 1);
align_get_bits(gb);
return ff_init_cabac_decoder(&lc->cc,
gb->buffer + get_bits_count(gb) / 8,
(get_bits_left(gb) + 7) / 8);

7
libavcodec/hevcdec.c
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@ -1005,6 +1005,13 @@ static int hls_slice_header(HEVCContext *s)
skip_bits(gb, 8); // slice_header_extension_data_byte
}
ret = get_bits1(gb);
if (!ret) {
av_log(s->avctx, AV_LOG_ERROR, "alignment_bit_equal_to_one=0\n");
return AVERROR_INVALIDDATA;
}
sh->data_offset = align_get_bits(gb) - gb->buffer;
// Inferred parameters
sh->slice_qp = 26U + s->ps.pps->pic_init_qp_minus26 + sh->slice_qp_delta;
if (sh->slice_qp > 51 ||

1
libavcodec/hevcdec.h
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@ -277,6 +277,7 @@ typedef struct SliceHeader {
int16_t chroma_offset_l1[16][2];
int slice_ctb_addr_rs;
unsigned data_offset;
} SliceHeader;
typedef struct CodingUnit {

4
libavcodec/vaapi_hevc.c
View File

@ -485,9 +485,7 @@ static int vaapi_hevc_decode_slice(AVCodecContext *avctx,
.slice_data_size = size,
.slice_data_offset = 0,
.slice_data_flag = VA_SLICE_DATA_FLAG_ALL,
/* Add 1 to the bits count here to account for the byte_alignment bit, which
* always is at least one bit and not accounted for otherwise. */
.slice_data_byte_offset = (get_bits_count(&h->HEVClc->gb) + 1 + 7) / 8,
.slice_data_byte_offset = sh->data_offset,
.slice_segment_address = sh->slice_segment_addr,
.slice_qp_delta = sh->slice_qp_delta,
.slice_cb_qp_offset = sh->slice_cb_qp_offset,