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Code Issues Releases Activity

avcodec/h261dec: Stop using MpegEncContext.gb

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This is in preparation for removing said field from MpegEncContext.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-06-15 22:44:56 +02:00
parent fabbe79170
commit 80ed868296
1 changed files with 41 additions and 39 deletions
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80
libavcodec/h261dec.c
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@ -29,6 +29,7 @@
#include "avcodec.h" #include "avcodec.h"
#include "codec_internal.h" #include "codec_internal.h"
#include "decode.h" #include "decode.h"
#include "get_bits.h"
#include "mpeg_er.h" #include "mpeg_er.h"
#include "mpegutils.h" #include "mpegutils.h"
#include "mpegvideo.h" #include "mpegvideo.h"
@ -51,6 +52,8 @@ static VLCElem h261_cbp_vlc[512];
typedef struct H261DecContext { typedef struct H261DecContext {
MpegEncContext s; MpegEncContext s;
GetBitContext gb;
H261Context common; H261Context common;
int current_mba; int current_mba;
@ -129,18 +132,18 @@ static int h261_decode_gob_header(H261DecContext *h)
if (!h->gob_start_code_skipped) { if (!h->gob_start_code_skipped) {
/* Check for GOB Start Code */ /* Check for GOB Start Code */
val = show_bits(&s->gb, 15); val = show_bits(&h->gb, 15);
if (val) if (val)
return -1; return -1;
/* We have a GBSC */ /* We have a GBSC */
skip_bits(&s->gb, 16); skip_bits(&h->gb, 16);
} }
h->gob_start_code_skipped = 0; h->gob_start_code_skipped = 0;
h->gob_number = get_bits(&s->gb, 4); /* GN */ h->gob_number = get_bits(&h->gb, 4); /* GN */
s->qscale = get_bits(&s->gb, 5); /* GQUANT */ s->qscale = get_bits(&h->gb, 5); /* GQUANT */
/* Check if gob_number is valid */ /* Check if gob_number is valid */
if (s->mb_height == 18) { // CIF if (s->mb_height == 18) { // CIF
@ -153,7 +156,7 @@ static int h261_decode_gob_header(H261DecContext *h)
} }
/* GEI */ /* GEI */
if (skip_1stop_8data_bits(&s->gb) < 0) if (skip_1stop_8data_bits(&h->gb) < 0)
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
if (s->qscale == 0) { if (s->qscale == 0) {
@ -257,7 +260,7 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
scan_table = s->intra_scantable.permutated; scan_table = s->intra_scantable.permutated;
if (s->mb_intra) { if (s->mb_intra) {
/* DC coef */ /* DC coef */
level = get_bits(&s->gb, 8); level = get_bits(&h->gb, 8);
// 0 (00000000b) and -128 (10000000b) are FORBIDDEN // 0 (00000000b) and -128 (10000000b) are FORBIDDEN
if ((level & 0x7F) == 0) { if ((level & 0x7F) == 0) {
av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n",
@ -275,10 +278,10 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
// EOB Not possible for first level when cbp is available (that's why the table is different) // EOB Not possible for first level when cbp is available (that's why the table is different)
// 0 1 1s // 0 1 1s
// * * 0* // * * 0*
int check = show_bits(&s->gb, 2); int check = show_bits(&h->gb, 2);
i = 0; i = 0;
if (check & 0x2) { if (check & 0x2) {
skip_bits(&s->gb, 2); skip_bits(&h->gb, 2);
block[0] = qmul + qadd; block[0] = qmul + qadd;
block[0] *= (check & 0x1) ? -1 : 1; block[0] *= (check & 0x1) ? -1 : 1;
i = 1; i = 1;
@ -291,14 +294,14 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
return 0; return 0;
} }
{ {
OPEN_READER(re, &s->gb); OPEN_READER(re, &h->gb);
i--; // offset by -1 to allow direct indexing of scan_table i--; // offset by -1 to allow direct indexing of scan_table
for (;;) { for (;;) {
UPDATE_CACHE(re, &s->gb); UPDATE_CACHE(re, &h->gb);
GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0); GET_RL_VLC(level, run, re, &h->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
if (run == 66) { if (run == 66) {
if (level) { if (level) {
CLOSE_READER(re, &s->gb); CLOSE_READER(re, &h->gb);
av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n",
s->mb_x, s->mb_y); s->mb_x, s->mb_y);
return -1; return -1;
@ -307,25 +310,25 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
/* The remaining combinations of (run, level) are encoded with a /* The remaining combinations of (run, level) are encoded with a
* 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits * 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits
* level. */ * level. */
run = SHOW_UBITS(re, &s->gb, 6) + 1; run = SHOW_UBITS(re, &h->gb, 6) + 1;
SKIP_CACHE(re, &s->gb, 6); SKIP_CACHE(re, &h->gb, 6);
level = SHOW_SBITS(re, &s->gb, 8); level = SHOW_SBITS(re, &h->gb, 8);
if (level > 0) if (level > 0)
level = level * qmul + qadd; level = level * qmul + qadd;
else if (level < 0) else if (level < 0)
level = level * qmul - qadd; level = level * qmul - qadd;
SKIP_COUNTER(re, &s->gb, 6 + 8); SKIP_COUNTER(re, &h->gb, 6 + 8);
} else if (level == 0) { } else if (level == 0) {
break; break;
} else { } else {
level = level * qmul + qadd; level = level * qmul + qadd;
if (SHOW_UBITS(re, &s->gb, 1)) if (SHOW_UBITS(re, &h->gb, 1))
level = -level; level = -level;
SKIP_COUNTER(re, &s->gb, 1); SKIP_COUNTER(re, &h->gb, 1);
} }
i += run; i += run;
if (i >= 64) { if (i >= 64) {
CLOSE_READER(re, &s->gb); CLOSE_READER(re, &h->gb);
av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n",
s->mb_x, s->mb_y); s->mb_x, s->mb_y);
return -1; return -1;
@ -333,7 +336,7 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
j = scan_table[i]; j = scan_table[i];
block[j] = level; block[j] = level;
} }
CLOSE_READER(re, &s->gb); CLOSE_READER(re, &h->gb);
} }
s->block_last_index[n] = i; s->block_last_index[n] = i;
return 0; return 0;
@ -348,7 +351,7 @@ static int h261_decode_mb(H261DecContext *h)
cbp = 63; cbp = 63;
// Read mba // Read mba
do { do {
h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc, h->mba_diff = get_vlc2(&h->gb, h261_mba_vlc,
H261_MBA_VLC_BITS, 2); H261_MBA_VLC_BITS, 2);
/* Check for slice end */ /* Check for slice end */
@ -360,7 +363,7 @@ static int h261_decode_mb(H261DecContext *h)
} while (h->mba_diff == MBA_STUFFING); // stuffing } while (h->mba_diff == MBA_STUFFING); // stuffing
if (h->mba_diff < 0) { if (h->mba_diff < 0) {
if (get_bits_left(&s->gb) <= 7) if (get_bits_left(&h->gb) <= 7)
return SLICE_END; return SLICE_END;
av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y); av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
@ -379,7 +382,7 @@ static int h261_decode_mb(H261DecContext *h)
h261_init_dest(s); h261_init_dest(s);
// Read mtype // Read mtype
com->mtype = get_vlc2(&s->gb, h261_mtype_vlc, H261_MTYPE_VLC_BITS, 2); com->mtype = get_vlc2(&h->gb, h261_mtype_vlc, H261_MTYPE_VLC_BITS, 2);
if (com->mtype < 0) { if (com->mtype < 0) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index\n"); av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index\n");
return SLICE_ERROR; return SLICE_ERROR;
@ -387,7 +390,7 @@ static int h261_decode_mb(H261DecContext *h)
// Read mquant // Read mquant
if (IS_QUANT(com->mtype)) { if (IS_QUANT(com->mtype)) {
s->qscale = get_bits(&s->gb, 5); s->qscale = get_bits(&h->gb, 5);
if (!s->qscale) if (!s->qscale)
s->qscale = 1; s->qscale = 1;
} }
@ -410,8 +413,8 @@ static int h261_decode_mb(H261DecContext *h)
h->current_mv_y = 0; h->current_mv_y = 0;
} }
h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x); h->current_mv_x = decode_mv_component(&h->gb, h->current_mv_x);
h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y); h->current_mv_y = decode_mv_component(&h->gb, h->current_mv_y);
} else { } else {
h->current_mv_x = 0; h->current_mv_x = 0;
h->current_mv_y = 0; h->current_mv_y = 0;
@ -419,7 +422,7 @@ static int h261_decode_mb(H261DecContext *h)
// Read cbp // Read cbp
if (HAS_CBP(com->mtype)) if (HAS_CBP(com->mtype))
cbp = get_vlc2(&s->gb, h261_cbp_vlc, H261_CBP_VLC_BITS, 1) + 1; cbp = get_vlc2(&h->gb, h261_cbp_vlc, H261_CBP_VLC_BITS, 1) + 1;
if (s->mb_intra) { if (s->mb_intra) {
s->cur_pic.mb_type[xy] = MB_TYPE_INTRA; s->cur_pic.mb_type[xy] = MB_TYPE_INTRA;
@ -466,11 +469,10 @@ intra:
static int h261_decode_picture_header(H261DecContext *h, int *is_key) static int h261_decode_picture_header(H261DecContext *h, int *is_key)
{ {
MpegEncContext *const s = &h->s; MpegEncContext *const s = &h->s;
int format, i;
uint32_t startcode = 0; uint32_t startcode = 0;
for (i = get_bits_left(&s->gb); i > 24; i -= 1) { for (int i = get_bits_left(&h->gb); i > 24; i -= 1) {
startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF; startcode = ((startcode << 1) | get_bits(&h->gb, 1)) & 0x000FFFFF;
if (startcode == 0x10) if (startcode == 0x10)
break; break;
@ -482,14 +484,14 @@ static int h261_decode_picture_header(H261DecContext *h, int *is_key)
} }
/* temporal reference */ /* temporal reference */
skip_bits(&s->gb, 5); /* picture timestamp */ skip_bits(&h->gb, 5); /* picture timestamp */
/* PTYPE starts here */ /* PTYPE starts here */
skip_bits1(&s->gb); /* split screen off */ skip_bits1(&h->gb); /* split screen off */
skip_bits1(&s->gb); /* camera off */ skip_bits1(&h->gb); /* camera off */
*is_key = get_bits1(&s->gb); /* freeze picture release off */ *is_key = get_bits1(&h->gb); /* freeze picture release off */
format = get_bits1(&s->gb); int format = get_bits1(&h->gb);
// only 2 formats possible // only 2 formats possible
if (format == 0) { // QCIF if (format == 0) { // QCIF
@ -500,11 +502,11 @@ static int h261_decode_picture_header(H261DecContext *h, int *is_key)
s->height = 288; s->height = 288;
} }
skip_bits1(&s->gb); /* still image mode off */ skip_bits1(&h->gb); /* still image mode off */
skip_bits1(&s->gb); /* Reserved */ skip_bits1(&h->gb); /* Reserved */
/* PEI */ /* PEI */
if (skip_1stop_8data_bits(&s->gb) < 0) if (skip_1stop_8data_bits(&h->gb) < 0)
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
h->gob_number = 0; h->gob_number = 0;
@ -552,7 +554,7 @@ static int h261_decode_frame(AVCodecContext *avctx, AVFrame *pict,
h->gob_start_code_skipped = 0; h->gob_start_code_skipped = 0;
init_get_bits(&s->gb, buf, buf_size * 8); init_get_bits(&h->gb, buf, buf_size * 8);
ret = h261_decode_picture_header(h, &is_key); ret = h261_decode_picture_header(h, &is_key);