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avcodec/hevcdec: Avoid allocation of common CABAC state

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It used to be allocated separately, so that the pointer to it
is copied to all HEVCContexts, so that all slice-threads
use the same. This is completely unnecessary now that there
is only one HEVCContext any more. There is just one minor
complication left: The slice-threads only get a pointer to
const HEVCContext, but they need to modify the common CABAC
state. Fix this by adding a pointer to the common CABAC state
to HEVCLocalContext and document why it exists.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-07-22 03:04:02 +02:00
parent 5bf4ac9113
commit 247d513beb
3 changed files with 21 additions and 12 deletions
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8
libavcodec/hevc_cabac.c
View File

@ -455,18 +455,18 @@ void ff_hevc_save_states(HEVCLocalContext *lc, int ctb_addr_ts)
(ctb_addr_ts % s->ps.sps->ctb_width == 2 ||
(s->ps.sps->ctb_width == 2 &&
ctb_addr_ts % s->ps.sps->ctb_width == 0))) {
memcpy(s->cabac->state, lc->cabac_state, HEVC_CONTEXTS);
memcpy(lc->common_cabac_state->state, lc->cabac_state, HEVC_CONTEXTS);
if (s->ps.sps->persistent_rice_adaptation_enabled_flag) {
memcpy(s->cabac->stat_coeff, lc->stat_coeff, HEVC_STAT_COEFFS);
memcpy(lc->common_cabac_state->stat_coeff, lc->stat_coeff, HEVC_STAT_COEFFS);
}
}
}
static void load_states(HEVCLocalContext *lc, const HEVCContext *s)
{
memcpy(lc->cabac_state, s->cabac->state, HEVC_CONTEXTS);
memcpy(lc->cabac_state, lc->common_cabac_state->state, HEVC_CONTEXTS);
if (s->ps.sps->persistent_rice_adaptation_enabled_flag) {
memcpy(lc->stat_coeff, s->cabac->stat_coeff, HEVC_STAT_COEFFS);
memcpy(lc->stat_coeff, lc->common_cabac_state->stat_coeff, HEVC_STAT_COEFFS);
}
}

8
libavcodec/hevcdec.c
View File

@ -2653,6 +2653,7 @@ static int hls_slice_data_wpp(HEVCContext *s, const H2645NAL *nal)
return AVERROR(ENOMEM);
s->HEVClcList[i]->logctx = s->avctx;
s->HEVClcList[i]->parent = s;
s->HEVClcList[i]->common_cabac_state = &s->cabac;
}
offset = (lc->gb.index >> 3);
@ -3582,8 +3583,6 @@ static av_cold int hevc_decode_free(AVCodecContext *avctx)
av_freep(&s->md5_ctx);
av_freep(&s->cabac);
for (i = 0; i < 3; i++) {
av_freep(&s->sao_pixel_buffer_h[i]);
av_freep(&s->sao_pixel_buffer_v[i]);
@ -3630,12 +3629,9 @@ static av_cold int hevc_init_context(AVCodecContext *avctx)
return AVERROR(ENOMEM);
s->HEVClc->parent = s;
s->HEVClc->logctx = avctx;
s->HEVClc->common_cabac_state = &s->cabac;
s->HEVClcList[0] = s->HEVClc;
s->cabac = av_malloc(sizeof(*s->cabac));
if (!s->cabac)
return AVERROR(ENOMEM);
s->output_frame = av_frame_alloc();
if (!s->output_frame)
return AVERROR(ENOMEM);

17
libavcodec/hevcdec.h
View File

@ -439,6 +439,18 @@ typedef struct HEVCLocalContext {
GetBitContext gb;
CABACContext cc;
/**
* This is a pointer to the common CABAC state.
* In case entropy_coding_sync_enabled_flag is set,
* the CABAC state after decoding the second CTU in a row is
* stored here and used to initialize the CABAC state before
* decoding the first CTU in the next row.
* This is the basis for WPP and in case slice-threading is used,
* the next row is decoded by another thread making this state
* shared between threads.
*/
HEVCCABACState *common_cabac_state;
int8_t qp_y;
int8_t curr_qp_y;
@ -485,8 +497,6 @@ typedef struct HEVCContext {
int width;
int height;
HEVCCABACState *cabac;
/** 1 if the independent slice segment header was successfully parsed */
uint8_t slice_initialized;
@ -559,6 +569,9 @@ typedef struct HEVCContext {
uint16_t seq_decode;
uint16_t seq_output;
/** The target for the common_cabac_state of the local contexts. */
HEVCCABACState cabac;
int enable_parallel_tiles;
atomic_int wpp_err;