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Support CRA random access decoding #98

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Merged
mpeg5 merged 2 commits into from
Sep 17, 2026
Merged

Support CRA random access decoding #98

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47ebea4
Support CRA random access decoding
kpchoi Sep 17, 2026
cf7cfce
Support CRA random access decoding in the base profile build
kpchoi Sep 17, 2026
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34 changes: 33 additions & 1 deletion src_base/xevd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ static XEVD_CTX * ctx_alloc(void)

/* set default value */
ctx->pic_cnt = 0;
ctx->cra_start_poc = -1;

return ctx;
}
Expand Down Expand Up @@ -1860,6 +1861,29 @@ int xevd_dec_nalu(XEVD_CTX * ctx, XEVD_BITB * bitb, XEVD_STAT * stat)
sh->poc_lsb = ctx->poc.poc_val;
}

/* A CRA picture (a non-IDR picture with an I slice) as the first
* picture of the stream means decoding starts at a clean random
* access point. Leading pictures following it reference pictures
* preceding the CRA, which are not available, so skip them. */
if (ctx->nalu.nal_unit_type_plus1 - 1 != XEVD_NUT_IDR &&
sh->slice_type == SLICE_I && ctx->pic_cnt == 0)
{
ctx->cra_start_poc = ctx->poc.poc_val;
}
else if (ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR)
{
ctx->cra_start_poc = -1;
}
if (ctx->cra_start_poc >= 0 && ctx->poc.poc_val < ctx->cra_start_poc &&
ctx->nalu.nal_unit_type_plus1 - 1 != XEVD_NUT_IDR && sh->slice_type != SLICE_I)
{
/* leading picture after CRA random access - skip decoding */
stat->nalu_type = ctx->nalu.nal_unit_type_plus1 - 1;
stat->fnum = -1;
stat->read += XEVD_BSR_GET_READ_BYTE(&ctx->bs);
return XEVD_OK;
}

s32 pic_delay = (ctx->poc.poc_val - (s32)ctx->poc.prev_pic_max_poc_val - 1);
if (ctx->max_coding_delay < pic_delay)
{
Expand Down Expand Up @@ -1980,8 +2004,16 @@ int xevd_dec_nalu(XEVD_CTX * ctx, XEVD_BITB * bitb, XEVD_STAT * stat)
ctx->fn_picbuf_expand(ctx, ctx->pic);

/* put decoded picture to DPB */
ret = xevd_picman_put_pic(&ctx->dpm, ctx->pic, ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR, ctx->poc.poc_val, ctx->nalu.nuh_temporal_id, 1, ctx->refp, ctx->slice_ref_flag, ctx->ref_pic_gap_length);
ret = xevd_picman_put_pic(&ctx->dpm, ctx->pic, ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR ||
ctx->cra_start_poc == ctx->poc.poc_val, ctx->poc.poc_val, ctx->nalu.nuh_temporal_id, 1, ctx->refp, ctx->slice_ref_flag, ctx->ref_pic_gap_length);
xevd_assert_rv(XEVD_SUCCEEDED(ret), ret);

/* A CRA random access point resets output ordering like an IDR,
* but output starts from the CRA picture itself. */
if (ctx->cra_start_poc == ctx->poc.poc_val)
{
ctx->dpm.poc_next_output = ctx->poc.poc_val;
}
}

if(ctx->pic_cnt == 0) {
Expand Down
4 changes: 4 additions & 0 deletions src_base/xevd_def.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1398,6 +1398,10 @@ struct _XEVD_CTX
u32 prev_doc_offset;
/* the number of currently decoded pictures */
u32 pic_cnt;
/* POC of a Cra picture at which decoding started (random access), or -1.
* Leading pictures that follow such a CRA reference pictures preceding
* the CRA and cannot be decoded, so they are skipped. */
int cra_start_poc;
/* flag whether current picture is refecened picture or not */
u8 slice_ref_flag;
/* distance between ref pics in addition to closest ref ref pic in LD*/
Expand Down
34 changes: 33 additions & 1 deletion src_main/xevdm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ static XEVDM_CTX * xevdm_ctx_alloc(void)

xevd_assert_rv(ctx != NULL, NULL);
xevd_mset_x64a(ctx, 0, sizeof(XEVDM_CTX));
ctx->cra_start_poc = -1;

ctx->aps_gen_array = (XEVD_APS_GEN *)xevd_malloc(2 * sizeof(XEVD_APS_GEN));
//xevd_assert_rv(ctx->aps_gen_array != NULL, NULL);
Expand Down Expand Up @@ -3079,6 +3080,29 @@ int xevd_dec_nalu(XEVD_CTX * ctx, XEVD_BITB * bitb, XEVD_STAT * stat)
ctx->slice_ref_flag = 1;
}

/* A CRA picture (a non-IDR picture with an I slice) as the first
* picture of the stream means decoding starts at a clean random
* access point. Leading pictures following it reference pictures
* preceding the CRA, which are not available, so skip them. */
if (ctx->nalu.nal_unit_type_plus1 - 1 != XEVD_NUT_IDR &&
sh->slice_type == SLICE_I && ctx->pic_cnt == 0)
{
mctx->cra_start_poc = ctx->poc.poc_val;
}
else if (ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR)
{
mctx->cra_start_poc = -1;
}
if (mctx->cra_start_poc >= 0 && ctx->poc.poc_val < mctx->cra_start_poc &&
ctx->nalu.nal_unit_type_plus1 - 1 != XEVD_NUT_IDR && sh->slice_type != SLICE_I)
{
/* leading picture after CRA random access - skip decoding */
stat->nalu_type = ctx->nalu.nal_unit_type_plus1 - 1;
stat->fnum = -1;
stat->read += XEVD_BSR_GET_READ_BYTE(&ctx->bs);
return XEVD_OK;
}

s32 pic_delay = (ctx->poc.poc_val - (s32)ctx->poc.prev_pic_max_poc_val - 1);
if (ctx->max_coding_delay < pic_delay)
{
Expand Down Expand Up @@ -3220,8 +3244,16 @@ int xevd_dec_nalu(XEVD_CTX * ctx, XEVD_BITB * bitb, XEVD_STAT * stat)
ctx->fn_picbuf_expand(ctx, ctx->pic);

/* put decoded picture to DPB */
ret = xevdm_picman_put_pic(&mctx->dpm, ctx->pic, ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR, ctx->poc.poc_val, ctx->nalu.nuh_temporal_id, 1, ctx->refp, ctx->slice_ref_flag, sps->tool_rpl, ctx->ref_pic_gap_length);
ret = xevdm_picman_put_pic(&mctx->dpm, ctx->pic, ctx->nalu.nal_unit_type_plus1 - 1 == XEVD_NUT_IDR ||
mctx->cra_start_poc == ctx->poc.poc_val, ctx->poc.poc_val, ctx->nalu.nuh_temporal_id, 1, ctx->refp, ctx->slice_ref_flag, sps->tool_rpl, ctx->ref_pic_gap_length);
xevd_assert_rv(XEVD_SUCCEEDED(ret), ret);

/* A CRA random access point resets output ordering like an IDR,
* but output starts from the CRA picture itself. */
if (mctx->cra_start_poc == ctx->poc.poc_val)
{
mctx->dpm.poc_next_output = ctx->poc.poc_val;
}
}

if(ctx->pic_cnt == 0) {
Expand Down
5 changes: 5 additions & 0 deletions src_main/xevdm_def.h
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Original file line number Diff line number Diff line change
Expand Up @@ -588,6 +588,11 @@ struct _XEVDM_CTX
/* ats_inter info map */
u8 * map_ats_inter;

/* POC of a CRA picture at which decoding started (random access), or -1.
* Leading pictures that follow such a CRA reference pictures preceding
* the CRA and cannot be decoded, so they are skipped. */
int cra_start_poc;

/* function address of ALF */
int(*fn_alf)(XEVD_CTX * ctx, XEVD_PIC * pic);
};
Expand Down
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