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avcodec/svq3: Factor out decoding extradata

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Reduces indentation and avoids an extra variable for whether
a sequence header has been found.
It also fixes potential undefined behaviour:
NULL + 0 is undefined and happens when no extradata is available.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-05-15 03:09:45 +02:00
parent 0b3dae6c63
commit 0468b866ca
1 changed files with 132 additions and 127 deletions
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149
libavcodec/svq3.c
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@ -1114,71 +1114,22 @@ static void init_dequant4_coeff_table(SVQ3Context *s)
}
}
static av_cold int svq3_decode_init(AVCodecContext *avctx)
static av_cold int svq3_decode_extradata(AVCodecContext *avctx, SVQ3Context *s,
int seqh_offset)
{
SVQ3Context *s = avctx->priv_data;
int m, x, y;
unsigned char *extradata;
unsigned char *extradata_end;
unsigned int size;
int marker_found = 0;
const uint8_t *extradata = avctx->extradata + seqh_offset;
unsigned int size = AV_RB32(extradata + 4);
GetBitContext gb;
int ret;
s->cur_pic = &s->frames[0];
s->last_pic = &s->frames[1];
s->next_pic = &s->frames[2];
s->cur_pic->f = av_frame_alloc();
s->last_pic->f = av_frame_alloc();
s->next_pic->f = av_frame_alloc();
if (!s->cur_pic->f || !s->last_pic->f || !s->next_pic->f)
return AVERROR(ENOMEM);
ff_h264dsp_init(&s->h264dsp, 8, 1);
ff_h264_pred_init(&s->hpc, AV_CODEC_ID_SVQ3, 8, 1);
ff_videodsp_init(&s->vdsp, 8);
avctx->bits_per_raw_sample = 8;
ff_hpeldsp_init(&s->hdsp, avctx->flags);
ff_tpeldsp_init(&s->tdsp);
avctx->pix_fmt = AV_PIX_FMT_YUVJ420P;
avctx->color_range = AVCOL_RANGE_JPEG;
s->avctx = avctx;
s->halfpel_flag = 1;
s->thirdpel_flag = 1;
s->has_watermark = 0;
/* prowl for the "SEQH" marker in the extradata */
extradata = (unsigned char *)avctx->extradata;
extradata_end = avctx->extradata + avctx->extradata_size;
if (extradata) {
for (m = 0; m + 8 < avctx->extradata_size; m++) {
if (!memcmp(extradata, "SEQH", 4)) {
marker_found = 1;
break;
}
extradata++;
}
}
/* if a match was found, parse the extra data */
if (marker_found) {
GetBitContext gb;
int frame_size_code;
int unk0, unk1, unk2, unk3, unk4;
int w,h;
size = AV_RB32(&extradata[4]);
if (size > extradata_end - extradata - 8)
if (size > avctx->extradata_size - seqh_offset - 8)
return AVERROR_INVALIDDATA;
init_get_bits(&gb, extradata + 8, size * 8);
extradata += 8;
init_get_bits(&gb, extradata, size * 8);
/* 'frame size code' and optional 'width, height' */
frame_size_code = get_bits(&gb, 3);
int frame_size_code = get_bits(&gb, 3);
int w, h;
switch (frame_size_code) {
case 0:
w = 160;
@ -1221,15 +1172,16 @@ static av_cold int svq3_decode_init(AVCodecContext *avctx)
s->thirdpel_flag = get_bits1(&gb);
/* unknown fields */
unk0 = get_bits1(&gb);
unk1 = get_bits1(&gb);
unk2 = get_bits1(&gb);
unk3 = get_bits1(&gb);
int unk0 = get_bits1(&gb);
int unk1 = get_bits1(&gb);
int unk2 = get_bits1(&gb);
int unk3 = get_bits1(&gb);
s->low_delay = get_bits1(&gb);
avctx->has_b_frames = !s->low_delay;
/* unknown field */
unk4 = get_bits1(&gb);
int unk4 = get_bits1(&gb);
av_log(avctx, AV_LOG_DEBUG, "Unknown fields %d %d %d %d %d\n",
unk0, unk1, unk2, unk3, unk4);
@ -1238,8 +1190,10 @@ static av_cold int svq3_decode_init(AVCodecContext *avctx)
return AVERROR_INVALIDDATA;
s->has_watermark = get_bits1(&gb);
avctx->has_b_frames = !s->low_delay;
if (s->has_watermark) {
if (!s->has_watermark)
return 0;
#if CONFIG_ZLIB
unsigned watermark_width = get_interleaved_ue_golomb(&gb);
unsigned watermark_height = get_interleaved_ue_golomb(&gb);
@ -1250,23 +1204,23 @@ static av_cold int svq3_decode_init(AVCodecContext *avctx)
unsigned long buf_len = watermark_width *
watermark_height * 4;
int offset = get_bits_count(&gb) + 7 >> 3;
uint8_t *buf;
if (watermark_height <= 0 ||
get_bits_left(&gb) <= 0 ||
(uint64_t)watermark_width * 4 > UINT_MAX / watermark_height)
return AVERROR_INVALIDDATA;
buf = av_malloc(buf_len);
if (!buf)
return AVERROR(ENOMEM);
av_log(avctx, AV_LOG_DEBUG, "watermark size: %ux%u\n",
watermark_width, watermark_height);
av_log(avctx, AV_LOG_DEBUG,
"u1: %x u2: %x u3: %x compressed data size: %d offset: %d\n",
u1, u2, u3, u4, offset);
if (uncompress(buf, &buf_len, extradata + 8 + offset,
uint8_t *buf = av_malloc(buf_len);
if (!buf)
return AVERROR(ENOMEM);
if (uncompress(buf, &buf_len, extradata + offset,
size - offset) != Z_OK) {
av_log(avctx, AV_LOG_ERROR,
"could not uncompress watermark logo\n");
@ -1279,12 +1233,63 @@ static av_cold int svq3_decode_init(AVCodecContext *avctx)
av_log(avctx, AV_LOG_DEBUG,
"watermark key %#"PRIx32"\n", s->watermark_key);
av_free(buf);
return 0;
#else
av_log(avctx, AV_LOG_ERROR,
"this svq3 file contains watermark which need zlib support compiled in\n");
return AVERROR(ENOSYS);
#endif
}
static av_cold int svq3_decode_init(AVCodecContext *avctx)
{
SVQ3Context *s = avctx->priv_data;
int m, x, y;
unsigned char *extradata;
int ret;
s->cur_pic = &s->frames[0];
s->last_pic = &s->frames[1];
s->next_pic = &s->frames[2];
s->cur_pic->f = av_frame_alloc();
s->last_pic->f = av_frame_alloc();
s->next_pic->f = av_frame_alloc();
if (!s->cur_pic->f || !s->last_pic->f || !s->next_pic->f)
return AVERROR(ENOMEM);
ff_h264dsp_init(&s->h264dsp, 8, 1);
ff_h264_pred_init(&s->hpc, AV_CODEC_ID_SVQ3, 8, 1);
ff_videodsp_init(&s->vdsp, 8);
avctx->bits_per_raw_sample = 8;
ff_hpeldsp_init(&s->hdsp, avctx->flags);
ff_tpeldsp_init(&s->tdsp);
avctx->pix_fmt = AV_PIX_FMT_YUVJ420P;
avctx->color_range = AVCOL_RANGE_JPEG;
s->avctx = avctx;
s->halfpel_flag = 1;
s->thirdpel_flag = 1;
s->has_watermark = 0;
/* prowl for the "SEQH" marker in the extradata */
extradata = (unsigned char *)avctx->extradata;
if (extradata) {
for (m = 0; m + 8 < avctx->extradata_size; m++) {
if (!memcmp(extradata, "SEQH", 4)) {
/* if a match was found, parse the extra data */
ret = svq3_decode_extradata(avctx, s, m);
if (ret < 0)
return ret;
break;
}
extradata++;
}
}
s->mb_width = (avctx->width + 15) / 16;