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h264: derive the delay from the level when it's not present

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Fall back to maximum DPB size if the level is unknown.

This should be more spec-compliant and does not depend on the caller
setting has_b_frames before opening the decoder.

The old behaviour, when the delay is supplied by the caller setting
has_b_frames, can still be obtained by setting strict_std_compliance
below normal.
This commit is contained in:
Anton Khirnov 2015-10-20 19:04:57 +02:00
parent 792b9c9dfc
commit b09ad37c83
2 changed files with 37 additions and 11 deletions
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15
libavcodec/h264.c
View File

@ -851,18 +851,11 @@ static void decode_postinit(H264Context *h, int setup_finished)
// FIXME do something with unavailable reference frames
/* Sort B-frames into display order */
if (h->sps.bitstream_restriction_flag &&
h->avctx->has_b_frames < h->sps.num_reorder_frames) {
h->avctx->has_b_frames = h->sps.num_reorder_frames;
h->low_delay = 0;
}
if (h->avctx->strict_std_compliance >= FF_COMPLIANCE_STRICT &&
!h->sps.bitstream_restriction_flag) {
h->avctx->has_b_frames = MAX_DELAYED_PIC_COUNT - 1;
h->low_delay = 0;
if (h->sps.bitstream_restriction_flag ||
h->avctx->strict_std_compliance >= FF_COMPLIANCE_NORMAL) {
h->avctx->has_b_frames = FFMAX(h->avctx->has_b_frames, h->sps.num_reorder_frames);
}
h->low_delay = !h->avctx->has_b_frames;
pics = 0;
while (h->delayed_pic[pics])

33
libavcodec/h264_ps.c
View File

@ -105,6 +105,26 @@ static const uint8_t default_scaling8[2][64] = {
24, 25, 27, 28, 30, 32, 33, 35 }
};
/* maximum number of MBs in the DPB for a given level */
static const int level_max_dpb_mbs[][2] = {
{ 10, 396 },
{ 11, 900 },
{ 12, 2376 },
{ 13, 2376 },
{ 20, 2376 },
{ 21, 4752 },
{ 22, 8100 },
{ 30, 8100 },
{ 31, 18000 },
{ 32, 20480 },
{ 40, 32768 },
{ 41, 32768 },
{ 42, 34816 },
{ 50, 110400 },
{ 51, 184320 },
{ 52, 184320 },
};
static inline int decode_hrd_parameters(H264Context *h, SPS *sps)
{
int cpb_count, i;
@ -501,6 +521,19 @@ int ff_h264_decode_seq_parameter_set(H264Context *h)
goto fail;
}
/* if the maximum delay is not stored in the SPS, derive it based on the
* level */
if (!sps->bitstream_restriction_flag) {
sps->num_reorder_frames = MAX_DELAYED_PIC_COUNT - 1;
for (i = 0; i < FF_ARRAY_ELEMS(level_max_dpb_mbs); i++) {
if (level_max_dpb_mbs[i][0] == sps->level_idc) {
sps->num_reorder_frames = FFMIN(level_max_dpb_mbs[i][1] / (sps->mb_width * sps->mb_height),
sps->num_reorder_frames);
break;
}
}
}
if (!sps->sar.den)
sps->sar.den = 1;