ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinha...@outlook.com> | Thu May 15 03:09:45 2025 +0200| [0468b866ca3eb97647b4d506c44cd79aba3659dd] | committer: Andreas Rheinhardt
avcodec/svq3: Factor out decoding extradata 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.rheinha...@outlook.com> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=0468b866ca3eb97647b4d506c44cd79aba3659dd --- libavcodec/svq3.c | 259 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 132 insertions(+), 127 deletions(-) diff --git a/libavcodec/svq3.c b/libavcodec/svq3.c index 6319e9b021..f264140dbc 100644 --- a/libavcodec/svq3.c +++ b/libavcodec/svq3.c @@ -1114,14 +1114,139 @@ static void init_dequant4_coeff_table(SVQ3Context *s) } } +static av_cold int svq3_decode_extradata(AVCodecContext *avctx, SVQ3Context *s, + int seqh_offset) +{ + const uint8_t *extradata = avctx->extradata + seqh_offset; + unsigned int size = AV_RB32(extradata + 4); + GetBitContext gb; + int ret; + + if (size > avctx->extradata_size - seqh_offset - 8) + return AVERROR_INVALIDDATA; + extradata += 8; + init_get_bits(&gb, extradata, size * 8); + + /* 'frame size code' and optional 'width, height' */ + int frame_size_code = get_bits(&gb, 3); + int w, h; + switch (frame_size_code) { + case 0: + w = 160; + h = 120; + break; + case 1: + w = 128; + h = 96; + break; + case 2: + w = 176; + h = 144; + break; + case 3: + w = 352; + h = 288; + break; + case 4: + w = 704; + h = 576; + break; + case 5: + w = 240; + h = 180; + break; + case 6: + w = 320; + h = 240; + break; + case 7: + w = get_bits(&gb, 12); + h = get_bits(&gb, 12); + break; + } + ret = ff_set_dimensions(avctx, w, h); + if (ret < 0) + return ret; + + s->halfpel_flag = get_bits1(&gb); + s->thirdpel_flag = get_bits1(&gb); + + /* unknown fields */ + 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 */ + int unk4 = get_bits1(&gb); + + av_log(avctx, AV_LOG_DEBUG, "Unknown fields %d %d %d %d %d\n", + unk0, unk1, unk2, unk3, unk4); + + if (skip_1stop_8data_bits(&gb) < 0) + return AVERROR_INVALIDDATA; + + s->has_watermark = get_bits1(&gb); + + 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); + int u1 = get_interleaved_ue_golomb(&gb); + int u2 = get_bits(&gb, 8); + int u3 = get_bits(&gb, 2); + int u4 = get_interleaved_ue_golomb(&gb); + unsigned long buf_len = watermark_width * + watermark_height * 4; + int offset = get_bits_count(&gb) + 7 >> 3; + + if (watermark_height <= 0 || + get_bits_left(&gb) <= 0 || + (uint64_t)watermark_width * 4 > UINT_MAX / watermark_height) + return AVERROR_INVALIDDATA; + + 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); + + 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"); + av_free(buf); + return -1; + } + s->watermark_key = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0, buf, buf_len)); + + s->watermark_key = s->watermark_key << 16 | s->watermark_key; + 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; - unsigned char *extradata_end; - unsigned int size; - int marker_found = 0; int ret; s->cur_pic = &s->frames[0]; @@ -1154,139 +1279,19 @@ static av_cold int svq3_decode_init(AVCodecContext *avctx) /* 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; + /* if a match was found, parse the extra data */ + ret = svq3_decode_extradata(avctx, s, m); + if (ret < 0) + return ret; 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) - return AVERROR_INVALIDDATA; - init_get_bits(&gb, extradata + 8, size * 8); - - /* 'frame size code' and optional 'width, height' */ - frame_size_code = get_bits(&gb, 3); - switch (frame_size_code) { - case 0: - w = 160; - h = 120; - break; - case 1: - w = 128; - h = 96; - break; - case 2: - w = 176; - h = 144; - break; - case 3: - w = 352; - h = 288; - break; - case 4: - w = 704; - h = 576; - break; - case 5: - w = 240; - h = 180; - break; - case 6: - w = 320; - h = 240; - break; - case 7: - w = get_bits(&gb, 12); - h = get_bits(&gb, 12); - break; - } - ret = ff_set_dimensions(avctx, w, h); - if (ret < 0) - return ret; - - s->halfpel_flag = get_bits1(&gb); - s->thirdpel_flag = get_bits1(&gb); - - /* unknown fields */ - unk0 = get_bits1(&gb); - unk1 = get_bits1(&gb); - unk2 = get_bits1(&gb); - unk3 = get_bits1(&gb); - - s->low_delay = get_bits1(&gb); - - /* unknown field */ - unk4 = get_bits1(&gb); - - av_log(avctx, AV_LOG_DEBUG, "Unknown fields %d %d %d %d %d\n", - unk0, unk1, unk2, unk3, unk4); - - if (skip_1stop_8data_bits(&gb) < 0) - return AVERROR_INVALIDDATA; - - s->has_watermark = get_bits1(&gb); - avctx->has_b_frames = !s->low_delay; - if (s->has_watermark) { -#if CONFIG_ZLIB - unsigned watermark_width = get_interleaved_ue_golomb(&gb); - unsigned watermark_height = get_interleaved_ue_golomb(&gb); - int u1 = get_interleaved_ue_golomb(&gb); - int u2 = get_bits(&gb, 8); - int u3 = get_bits(&gb, 2); - int u4 = get_interleaved_ue_golomb(&gb); - 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, - size - offset) != Z_OK) { - av_log(avctx, AV_LOG_ERROR, - "could not uncompress watermark logo\n"); - av_free(buf); - return -1; - } - s->watermark_key = av_bswap16(av_crc(av_crc_get_table(AV_CRC_16_CCITT), 0, buf, buf_len)); - - s->watermark_key = s->watermark_key << 16 | s->watermark_key; - av_log(avctx, AV_LOG_DEBUG, - "watermark key %#"PRIx32"\n", s->watermark_key); - av_free(buf); -#else - av_log(avctx, AV_LOG_ERROR, - "this svq3 file contains watermark which need zlib support compiled in\n"); - return AVERROR(ENOSYS); -#endif - } - } - s->mb_width = (avctx->width + 15) / 16; s->mb_height = (avctx->height + 15) / 16; s->mb_stride = s->mb_width + 1; _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog To unsubscribe, visit link above, or email ffmpeg-cvslog-requ...@ffmpeg.org with subject "unsubscribe".
