[FFmpeg-cvslog] avcodec/h261dec: Stop using MpegEncContext.gb
Andreas Rheinhardt
git at videolan.org
Thu Jul 3 21:55:26 EEST 2025
ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Sun Jun 15 22:44:56 2025 +0200| [80ed8682967e09439cc84f5c6dea6333304fdb43] | committer: Andreas Rheinhardt
avcodec/h261dec: Stop using MpegEncContext.gb
This is in preparation for removing said field from MpegEncContext.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=80ed8682967e09439cc84f5c6dea6333304fdb43
---
libavcodec/h261dec.c | 80 +++++++++++++++++++++++++++-------------------------
1 file changed, 41 insertions(+), 39 deletions(-)
diff --git a/libavcodec/h261dec.c b/libavcodec/h261dec.c
index 146f979a5e..50fc375c26 100644
--- a/libavcodec/h261dec.c
+++ b/libavcodec/h261dec.c
@@ -29,6 +29,7 @@
#include "avcodec.h"
#include "codec_internal.h"
#include "decode.h"
+#include "get_bits.h"
#include "mpeg_er.h"
#include "mpegutils.h"
#include "mpegvideo.h"
@@ -51,6 +52,8 @@ static VLCElem h261_cbp_vlc[512];
typedef struct H261DecContext {
MpegEncContext s;
+ GetBitContext gb;
+
H261Context common;
int current_mba;
@@ -129,18 +132,18 @@ static int h261_decode_gob_header(H261DecContext *h)
if (!h->gob_start_code_skipped) {
/* Check for GOB Start Code */
- val = show_bits(&s->gb, 15);
+ val = show_bits(&h->gb, 15);
if (val)
return -1;
/* We have a GBSC */
- skip_bits(&s->gb, 16);
+ skip_bits(&h->gb, 16);
}
h->gob_start_code_skipped = 0;
- h->gob_number = get_bits(&s->gb, 4); /* GN */
- s->qscale = get_bits(&s->gb, 5); /* GQUANT */
+ h->gob_number = get_bits(&h->gb, 4); /* GN */
+ s->qscale = get_bits(&h->gb, 5); /* GQUANT */
/* Check if gob_number is valid */
if (s->mb_height == 18) { // CIF
@@ -153,7 +156,7 @@ static int h261_decode_gob_header(H261DecContext *h)
}
/* GEI */
- if (skip_1stop_8data_bits(&s->gb) < 0)
+ if (skip_1stop_8data_bits(&h->gb) < 0)
return AVERROR_INVALIDDATA;
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;
if (s->mb_intra) {
/* DC coef */
- level = get_bits(&s->gb, 8);
+ level = get_bits(&h->gb, 8);
// 0 (00000000b) and -128 (10000000b) are FORBIDDEN
if ((level & 0x7F) == 0) {
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)
// 0 1 1s
// * * 0*
- int check = show_bits(&s->gb, 2);
+ int check = show_bits(&h->gb, 2);
i = 0;
if (check & 0x2) {
- skip_bits(&s->gb, 2);
+ skip_bits(&h->gb, 2);
block[0] = qmul + qadd;
block[0] *= (check & 0x1) ? -1 : 1;
i = 1;
@@ -291,14 +294,14 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
return 0;
}
{
- OPEN_READER(re, &s->gb);
+ OPEN_READER(re, &h->gb);
i--; // offset by -1 to allow direct indexing of scan_table
for (;;) {
- UPDATE_CACHE(re, &s->gb);
- GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
+ UPDATE_CACHE(re, &h->gb);
+ GET_RL_VLC(level, run, re, &h->gb, rl->rl_vlc[0], TCOEFF_VLC_BITS, 2, 0);
if (run == 66) {
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",
s->mb_x, s->mb_y);
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
* 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits
* level. */
- run = SHOW_UBITS(re, &s->gb, 6) + 1;
- SKIP_CACHE(re, &s->gb, 6);
- level = SHOW_SBITS(re, &s->gb, 8);
+ run = SHOW_UBITS(re, &h->gb, 6) + 1;
+ SKIP_CACHE(re, &h->gb, 6);
+ level = SHOW_SBITS(re, &h->gb, 8);
if (level > 0)
level = level * qmul + qadd;
else if (level < 0)
level = level * qmul - qadd;
- SKIP_COUNTER(re, &s->gb, 6 + 8);
+ SKIP_COUNTER(re, &h->gb, 6 + 8);
} else if (level == 0) {
break;
} else {
level = level * qmul + qadd;
- if (SHOW_UBITS(re, &s->gb, 1))
+ if (SHOW_UBITS(re, &h->gb, 1))
level = -level;
- SKIP_COUNTER(re, &s->gb, 1);
+ SKIP_COUNTER(re, &h->gb, 1);
}
i += run;
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",
s->mb_x, s->mb_y);
return -1;
@@ -333,7 +336,7 @@ static int h261_decode_block(H261DecContext *h, int16_t *block, int n, int coded
j = scan_table[i];
block[j] = level;
}
- CLOSE_READER(re, &s->gb);
+ CLOSE_READER(re, &h->gb);
}
s->block_last_index[n] = i;
return 0;
@@ -348,7 +351,7 @@ static int h261_decode_mb(H261DecContext *h)
cbp = 63;
// Read mba
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);
/* Check for slice end */
@@ -360,7 +363,7 @@ static int h261_decode_mb(H261DecContext *h)
} while (h->mba_diff == MBA_STUFFING); // stuffing
if (h->mba_diff < 0) {
- if (get_bits_left(&s->gb) <= 7)
+ if (get_bits_left(&h->gb) <= 7)
return SLICE_END;
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);
// 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) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid mtype index\n");
return SLICE_ERROR;
@@ -387,7 +390,7 @@ static int h261_decode_mb(H261DecContext *h)
// Read mquant
if (IS_QUANT(com->mtype)) {
- s->qscale = get_bits(&s->gb, 5);
+ s->qscale = get_bits(&h->gb, 5);
if (!s->qscale)
s->qscale = 1;
}
@@ -410,8 +413,8 @@ static int h261_decode_mb(H261DecContext *h)
h->current_mv_y = 0;
}
- h->current_mv_x = decode_mv_component(&s->gb, h->current_mv_x);
- h->current_mv_y = decode_mv_component(&s->gb, h->current_mv_y);
+ h->current_mv_x = decode_mv_component(&h->gb, h->current_mv_x);
+ h->current_mv_y = decode_mv_component(&h->gb, h->current_mv_y);
} else {
h->current_mv_x = 0;
h->current_mv_y = 0;
@@ -419,7 +422,7 @@ static int h261_decode_mb(H261DecContext *h)
// Read cbp
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) {
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)
{
MpegEncContext *const s = &h->s;
- int format, i;
uint32_t startcode = 0;
- for (i = get_bits_left(&s->gb); i > 24; i -= 1) {
- startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
+ for (int i = get_bits_left(&h->gb); i > 24; i -= 1) {
+ startcode = ((startcode << 1) | get_bits(&h->gb, 1)) & 0x000FFFFF;
if (startcode == 0x10)
break;
@@ -482,14 +484,14 @@ static int h261_decode_picture_header(H261DecContext *h, int *is_key)
}
/* temporal reference */
- skip_bits(&s->gb, 5); /* picture timestamp */
+ skip_bits(&h->gb, 5); /* picture timestamp */
/* PTYPE starts here */
- skip_bits1(&s->gb); /* split screen off */
- skip_bits1(&s->gb); /* camera off */
- *is_key = get_bits1(&s->gb); /* freeze picture release off */
+ skip_bits1(&h->gb); /* split screen off */
+ skip_bits1(&h->gb); /* camera 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
if (format == 0) { // QCIF
@@ -500,11 +502,11 @@ static int h261_decode_picture_header(H261DecContext *h, int *is_key)
s->height = 288;
}
- skip_bits1(&s->gb); /* still image mode off */
- skip_bits1(&s->gb); /* Reserved */
+ skip_bits1(&h->gb); /* still image mode off */
+ skip_bits1(&h->gb); /* Reserved */
/* PEI */
- if (skip_1stop_8data_bits(&s->gb) < 0)
+ if (skip_1stop_8data_bits(&h->gb) < 0)
return AVERROR_INVALIDDATA;
h->gob_number = 0;
@@ -552,7 +554,7 @@ static int h261_decode_frame(AVCodecContext *avctx, AVFrame *pict,
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);
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