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*/ static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; +int ff_ac3_find_syncword(const uint8_t *buf, int buf_size) +{ + int i; + + for (i = 1; i < buf_size; i += 2) { + if (buf[i] == 0x77 || buf[i] == 0x0B) { + if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) { + i--; + break; + } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) { + break; + } + } + } + if (i >= buf_size) + return AVERROR_INVALIDDATA; + + return i; +} int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { diff --git a/libavcodec/ac3_parser_internal.h b/libavcodec/ac3_parser_internal.h index bd4e1bbffb..2ac0e67ec2 100644 --- a/libavcodec/ac3_parser_internal.h +++ b/libavcodec/ac3_parser_internal.h @@ -79,4 +79,6 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr); int avpriv_ac3_parse_header(AC3HeaderInfo **hdr, const uint8_t *buf, size_t size); +int ff_ac3_find_syncword(const uint8_t *buf, int buf_size); + #endif /* AVCODEC_AC3_PARSER_INTERNAL_H */ diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index 340f6e1e37..8e40587ff1 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -1508,19 +1508,8 @@ static int ac3_decode_frame(AVCodecContext *avctx, AVFrame *frame, s->superframe_size = 0; buf_size = full_buf_size; - for (i = 1; i < buf_size; i += 2) { - if (buf[i] == 0x77 || buf[i] == 0x0B) { - if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) { - i--; - break; - } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) { - break; - } - } - } - if (i >= buf_size) - return AVERROR_INVALIDDATA; - if (i > 10) + i = ff_ac3_find_syncword(buf, buf_size); + if (i < 0 || i > 10) return i; buf += i; buf_size -= i;