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avcodec/vc1dec: Split VC-1 decoders from msmpeg4 

The only msmpeg4 code that is ever executed by the VC-1 based
decoders is ff_msmpeg4_decode_init() and what is directly
reachable from it. This is:
a) A call to av_image_check_size(), then ff_h263_decode_init(),
b) followed by setting [yc]_dc_scale_table and initializing
scantable/permutations.
c) Afterwards, some static tables are initialized.
d) Finally, slice_height is set.

The replacement for ff_msmpeg4_decode_init() performs a)
just like now; it also sets [yc]_dc_scale_table,
but it only initializes inter_scantable and intra_scantable
and not permutated_intra_[hv]_scantable: The latter are only
used inside decode_mb callbacks which are only called
in ff_h263_decode_frame() which is unused for VC-1.*

The static tables initialized in c) are not used at all by
VC-1 (the ones that are used have been factored out in
previous commits); this avoids touching 327KiB of .bss.

slice_height is also not used by the VC-1 decoder (setting
it in ff_msmpeg4_decode_init() is probably redundant after
b34397b4cd).

*: It follows from this that the VC-1 decoder is not really
based upon the H.263 decoder either; changing this will
be done in a future commit.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-10-30 18:22:16 +01:00
parent d1d30edf42
commit cbe6ef1031
4 changed files with 19 additions and 18 deletions
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2
configure vendored
View File

@ -2970,7 +2970,7 @@ utvideo_encoder_select="bswapdsp huffman llvidencdsp"
vble_decoder_select="llviddsp"
vbn_decoder_select="texturedsp"
vbn_encoder_select="texturedspenc"
vc1_decoder_select="blockdsp h264qpel intrax8 mpegvideodec msmpeg4dec vc1dsp"
vc1_decoder_select="blockdsp h263_decoder h264qpel intrax8 mpegvideodec vc1dsp"
vc1image_decoder_select="vc1_decoder"
vorbis_encoder_select="audio_frame_queue"
vp3_decoder_select="hpeldsp vp3dsp videodsp"

12
libavcodec/msmpeg4.c
View File

@ -27,8 +27,6 @@
* MSMPEG4 backend for encoder and decoder
*/
#include "config_components.h"
#include "libavutil/thread.h"
#include "avcodec.h"
@ -40,8 +38,6 @@
#include "msmpeg4data.h"
#include "msmpeg4_vc1_data.h"
#include "mpegvideodata.h"
#include "vc1data.h"
#include "libavutil/imgutils.h"
/*
* You can also call this codec: MPEG-4 with a twist!
@ -139,16 +135,8 @@ av_cold void ff_msmpeg4_common_init(MpegEncContext *s)
s->y_dc_scale_table= ff_wmv1_y_dc_scale_table;
s->c_dc_scale_table= ff_wmv1_c_dc_scale_table;
break;
#if CONFIG_VC1_DECODER
case 6:
s->y_dc_scale_table= ff_wmv3_dc_scale_table;
s->c_dc_scale_table= ff_wmv3_dc_scale_table;
break;
#endif
}
if(s->msmpeg4_version>=4){
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable, ff_wmv1_scantable[1]);
ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable, ff_wmv1_scantable[0]);

3
libavcodec/msmpeg4dec.c
View File

@ -373,9 +373,6 @@ av_cold int ff_msmpeg4_decode_init(AVCodecContext *avctx)
break;
case 5:
break;
case 6:
//FIXME + TODO VC1 decode mb
break;
}
s->slice_height= s->mb_height; //to avoid 1/0 if the first frame is not a keyframe

20
libavcodec/vc1dec.c
View File

@ -33,12 +33,12 @@
#include "codec_internal.h"
#include "decode.h"
#include "get_bits.h"
#include "h263dec.h"
#include "hwconfig.h"
#include "mpeg_er.h"
#include "mpegvideo.h"
#include "mpegvideodec.h"
#include "msmpeg4_vc1_data.h"
#include "msmpeg4dec.h"
#include "profiles.h"
#include "simple_idct.h"
#include "vc1.h"
@ -46,6 +46,7 @@
#include "vc1_vlc_data.h"
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/imgutils.h"
#include "libavutil/thread.h"
@ -406,11 +407,26 @@ static av_cold int vc1_decode_init_alloc_tables(VC1Context *v)
av_cold int ff_vc1_decode_init(AVCodecContext *avctx)
{
int ret = ff_msmpeg4_decode_init(avctx);
VC1Context *const v = avctx->priv_data;
MpegEncContext *const s = &v->s;
int ret;
ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
if (ret < 0)
return ret;
ret = ff_h263_decode_init(avctx);
if (ret < 0)
return ret;
s->y_dc_scale_table = ff_wmv3_dc_scale_table;
s->c_dc_scale_table = ff_wmv3_dc_scale_table;
ff_init_scantable(s->idsp.idct_permutation, &s->inter_scantable,
ff_wmv1_scantable[0]);
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable,
ff_wmv1_scantable[1]);
ret = vc1_decode_init_alloc_tables(v);
if (ret < 0) {
ff_vc1_decode_end(avctx);