diff options
author | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2022-06-30 15:01:22 +0200 |
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committer | Andreas Rheinhardt <andreas.rheinhardt@outlook.com> | 2022-07-25 23:31:37 +0200 |
commit | 72d5ce9fa6cd67497fbfffc97031cb6b7ab23c6d (patch) | |
tree | a3c4c3b1c2a9c7b1e462cf229a6022e7e8e6664e /libavcodec/hevc_cabac.c | |
parent | 8c4f95e1e1488bbbaca19bc6c6214393136e1b51 (diff) |
avcodec/hevcdec: Add stat_coeffs to HEVCABACState
The HEVC decoder has both HEVCContext and HEVCLocalContext
structures. The latter is supposed to be the structure
containing the per-slicethread state.
Yet that is not how it is handled in practice: Each HEVCLocalContext
has a unique HEVCContext allocated for it and each of these
coincides with the main HEVCContext except in exactly one field:
The corresponding HEVCLocalContext.
This makes it possible to pass the HEVCContext everywhere where
logically a HEVCLocalContext should be used.
This led to confusion in the first version of what eventually became
commit c8bc0f66a875bc3708d8dc11b757f2198606ffd7:
Before said commit, the initialization of the Rice parameter derivation
state was incorrect; the fix for single-threaded as well as
frame-threaded decoding was to add backup stats to HEVCContext
that are used when the cabac state is updated*, see
https://ffmpeg.org/pipermail/ffmpeg-devel/2020-August/268861.html
Yet due to what has been said above, this does not work for
slice-threading, because the each HEVCLocalContext has its own
HEVCContext, so the Rice parameter state would not be transferred
between threads.
This is fixed in c8bc0f66a875bc3708d8dc11b757f2198606ffd7
by a hack: It rederives what the previous thread was and accesses
the corresponding HEVCContext.
Fix this by treating the Rice parameter state the same way
the ordinary CABAC parameters are shared between threads:
Make them part of the same struct that is shared between
slice threads. This does not cause races, because
the parts of the code that access these Rice parameters
are a subset of the parts of code that access the CABAC parameters.
*: And if the persistent_rice_adaptation_enabled_flag is set.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Diffstat (limited to 'libavcodec/hevc_cabac.c')
-rw-r--r-- | libavcodec/hevc_cabac.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/libavcodec/hevc_cabac.c b/libavcodec/hevc_cabac.c index a194f8a02a..985c97ef2a 100644 --- a/libavcodec/hevc_cabac.c +++ b/libavcodec/hevc_cabac.c @@ -453,19 +453,18 @@ void ff_hevc_save_states(HEVCContext *s, 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, s->HEVClc->cabac_state, HEVC_CONTEXTS); + memcpy(s->cabac->state, s->HEVClc->cabac_state, HEVC_CONTEXTS); if (s->ps.sps->persistent_rice_adaptation_enabled_flag) { - memcpy(s->stat_coeff, s->HEVClc->stat_coeff, HEVC_STAT_COEFFS); + memcpy(s->cabac->stat_coeff, s->HEVClc->stat_coeff, HEVC_STAT_COEFFS); } } } -static void load_states(HEVCContext *s, int thread) +static void load_states(HEVCContext *s) { - memcpy(s->HEVClc->cabac_state, s->cabac_state, HEVC_CONTEXTS); + memcpy(s->HEVClc->cabac_state, s->cabac->state, HEVC_CONTEXTS); if (s->ps.sps->persistent_rice_adaptation_enabled_flag) { - const HEVCContext *prev = s->sList[(thread + s->threads_number - 1) % s->threads_number]; - memcpy(s->HEVClc->stat_coeff, prev->stat_coeff, HEVC_STAT_COEFFS); + memcpy(s->HEVClc->stat_coeff, s->cabac->stat_coeff, HEVC_STAT_COEFFS); } } @@ -508,7 +507,7 @@ static void cabac_init_state(HEVCContext *s) s->HEVClc->stat_coeff[i] = 0; } -int ff_hevc_cabac_init(HEVCContext *s, int ctb_addr_ts, int thread) +int ff_hevc_cabac_init(HEVCContext *s, int ctb_addr_ts) { if (ctb_addr_ts == s->ps.pps->ctb_addr_rs_to_ts[s->sh.slice_ctb_addr_rs]) { int ret = cabac_init_decoder(s); @@ -525,7 +524,7 @@ int ff_hevc_cabac_init(HEVCContext *s, int ctb_addr_ts, int thread) if (s->ps.sps->ctb_width == 1) cabac_init_state(s); else if (s->sh.dependent_slice_segment_flag == 1) - load_states(s, thread); + load_states(s); } } } else { @@ -556,7 +555,7 @@ int ff_hevc_cabac_init(HEVCContext *s, int ctb_addr_ts, int thread) if (s->ps.sps->ctb_width == 1) cabac_init_state(s); else - load_states(s, thread); + load_states(s); } } } |