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lavc/h2645_parse: Don't automatically remove nuh_layer_id > 0 packets

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HEVC standard supports multi-layer streams (ITU-T H.265 02/2018 Annex
F). Each NAL unit belongs to a particular layer defined by nuh_layer_id
in the header.

Currently, all NAL units that do not belong to a base layer are
automatically removed in ff_h2645_packet_split(). Some data may
therefore be lost when future filters/decoders are designed to support
multi-layer streams.

A better approach is to forward nuh_layer_id > 0 packets and let blocks
down the chain decide how to process them. The condition to remove
packets has been moved to hevcdec and cbs.

Found-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>
This commit is contained in:
Andriy Gelman 2019-12-05 22:15:41 -05:00 committed by James Almer
parent 5b7e90b252
commit ad326379c6
6 changed files with 17 additions and 5 deletions
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3
libavcodec/cbs_h2645.c
View File

@ -565,6 +565,9 @@ static int cbs_h2645_fragment_add_nals(CodedBitstreamContext *ctx,
AVBufferRef *ref;
size_t size = nal->size;
if (nal->nuh_layer_id > 0)
continue;
// Remove trailing zeroes.
while (size > 0 && nal->data[size - 1] == 0)
--size;

7
libavcodec/h2645_parse.c
View File

@ -292,23 +292,22 @@ static int get_bit_length(H2645NAL *nal, int skip_trailing_zeros)
static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)
{
GetBitContext *gb = &nal->gb;
int nuh_layer_id;
if (get_bits1(gb) != 0)
return AVERROR_INVALIDDATA;
nal->type = get_bits(gb, 6);
nuh_layer_id = get_bits(gb, 6);
nal->nuh_layer_id = get_bits(gb, 6);
nal->temporal_id = get_bits(gb, 3) - 1;
if (nal->temporal_id < 0)
return AVERROR_INVALIDDATA;
av_log(logctx, AV_LOG_DEBUG,
"nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
nal->type, hevc_nal_unit_name(nal->type), nuh_layer_id, nal->temporal_id);
nal->type, hevc_nal_unit_name(nal->type), nal->nuh_layer_id, nal->temporal_id);
return nuh_layer_id == 0;
return 1;
}
static int h264_parse_nal_header(H2645NAL *nal, void *logctx)

5
libavcodec/h2645_parse.h
View File

@ -56,6 +56,11 @@ typedef struct H2645NAL {
*/
int temporal_id;
/*
* HEVC only, identifier of layer to which nal unit belongs
*/
int nuh_layer_id;
int skipped_bytes;
int skipped_bytes_pos_size;
int *skipped_bytes_pos;

2
libavcodec/hevc_parse.c
View File

@ -37,6 +37,8 @@ static int hevc_decode_nal_units(const uint8_t *buf, int buf_size, HEVCParamSets
for (i = 0; i < pkt.nb_nals; i++) {
H2645NAL *nal = &pkt.nals[i];
if (nal->nuh_layer_id > 0)
continue;
/* ignore everything except parameter sets and VCL NALUs */
switch (nal->type) {

3
libavcodec/hevc_parser.c
View File

@ -202,6 +202,9 @@ static int parse_nal_units(AVCodecParserContext *s, const uint8_t *buf,
H2645NAL *nal = &ctx->pkt.nals[i];
GetBitContext *gb = &nal->gb;
if (nal->nuh_layer_id > 0)
continue;
switch (nal->type) {
case HEVC_NAL_VPS:
ff_hevc_decode_nal_vps(gb, avctx, ps);

2
libavcodec/hevcdec.c
View File

@ -3077,7 +3077,7 @@ static int decode_nal_units(HEVCContext *s, const uint8_t *buf, int length)
if (s->avctx->skip_frame >= AVDISCARD_ALL ||
(s->avctx->skip_frame >= AVDISCARD_NONREF
&& ff_hevc_nal_is_nonref(nal->type)))
&& ff_hevc_nal_is_nonref(nal->type)) || nal->nuh_layer_id > 0)
continue;
ret = decode_nal_unit(s, nal);