From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id CC4AB44519 for ; Tue, 13 Sep 2022 21:31:39 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 0C37068BAB0; Wed, 14 Sep 2022 00:31:36 +0300 (EEST) Received: from srv-infra-1.infra.inf.glb.tvvideoms.com (www.inf.tvvideoms.com [213.205.126.156]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 2255868B32D for ; Wed, 14 Sep 2022 00:31:29 +0300 (EEST) Received: from cji.paris (unknown [172.16.3.159]) by srv-infra-1.infra.inf.glb.tvvideoms.com (Postfix) with ESMTP id 1C9D229D55; Tue, 13 Sep 2022 21:31:29 +0000 (UTC) From: Nicolas Gaullier To: ffmpeg-devel@ffmpeg.org Date: Tue, 13 Sep 2022 23:31:27 +0200 Message-Id: <20220913213127.1756-1-nicolas.gaullier@cji.paris> X-Mailer: git-send-email 2.37.2.windows.2 MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH] avcodec/dolby_e: Add error recovery when parse_mantissas run out of bits 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 Cc: Nicolas Gaullier 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: Mantissas are the last data in the channel subsegment and it appears it is sometimes missing a very few bits for the parsing to complete. This should not be confused with data corruption. For 5.1+2@25fps, the occurence of this issue is pretty steady and about once every 2 hours. The truncation is at about 950 out of the 1024 values (never seen below 923 so far). The current code raises a severe 'Read past end' error and all data is lost resulting in 20ms(@25fps) of silence for the affected channel. This patch introduces a tolerance: if 800 out of the 1024 mantissas have been parsed, a simple warning is raised and the data is preserved. Signed-off-by: Nicolas Gaullier --- libavcodec/dolby_e.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libavcodec/dolby_e.c b/libavcodec/dolby_e.c index 06f4fdd44f..0ec7b5e318 100644 --- a/libavcodec/dolby_e.c +++ b/libavcodec/dolby_e.c @@ -844,6 +844,7 @@ static int parse_indices(DBEContext *s, DBEChannel *c) return 0; } +#define MIN_MANTISSAS 800 static int parse_mantissas(DBEContext *s, DBEChannel *c) { DBEGroup *g; @@ -884,6 +885,13 @@ static int parse_mantissas(DBEContext *s, DBEChannel *c) } } } else { + if (i == c->nb_groups - 1 + && count * size1 > get_bits_left(&s->gb) + && get_bits_left(&s->gb) >= 0 + && (int)(mnt - c->mantissas) >= MIN_MANTISSAS) { + av_log(s->avctx, AV_LOG_WARNING, "Truncated mantissas @%d, highest frequencies not recoverable\n", (int)(mnt - c->mantissas)); + break; + } for (k = 0; k < count; k++) mnt[k] = get_sbits(&s->gb, size1) * scale; } -- 2.11.0 _______________________________________________ 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".