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Fri, 21 Oct 2022 05:56:31 -0700 (PDT) From: James Almer To: ffmpeg-devel@ffmpeg.org Date: Fri, 21 Oct 2022 09:56:03 -0300 Message-Id: <20221021125604.1107-1-jamrial@gmail.com> X-Mailer: git-send-email 2.37.3 MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 1/2] avcodec/ac3dec: split off code discarding garbage at the beginning of a packet X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Signed-off-by: James Almer --- libavcodec/ac3_parser.c | 19 +++++++++++++++++++ libavcodec/ac3_parser_internal.h | 2 ++ libavcodec/ac3dec.c | 15 ++------------- 3 files changed, 23 insertions(+), 13 deletions(-) diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c index 4f154bb7c4..425e1b4742 100644 --- a/libavcodec/ac3_parser.c +++ b/libavcodec/ac3_parser.c @@ -53,6 +53,25 @@ static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; */ 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; -- 2.37.3 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".