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 E90DA49D90 for ; Mon, 11 Mar 2024 14:01:49 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 3F28568CD6D; Mon, 11 Mar 2024 16:01:38 +0200 (EET) 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 4745868CEE5 for ; Mon, 11 Mar 2024 16:01:31 +0200 (EET) Received: from cji.paris (unknown [172.16.3.159]) by srv-infra-1.infra.inf.glb.tvvideoms.com (Postfix) with ESMTP id 7F20220688; Mon, 11 Mar 2024 14:01:30 +0000 (UTC) From: Nicolas Gaullier To: ffmpeg-devel@ffmpeg.org Date: Mon, 11 Mar 2024 15:01:28 +0100 Message-Id: <20240311140128.1730332-2-nicolas.gaullier@cji.paris> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240311140128.1730332-1-nicolas.gaullier@cji.paris> References: <20240311140128.1730332-1-nicolas.gaullier@cji.paris> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 1/1] 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 must not be confused with data corruption. In standard conditions with certified products, it has been observed that 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 (923 is the minimum I have seen 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 9c3f6006c2..1f8442e2e9 100644 --- a/libavcodec/dolby_e.c +++ b/libavcodec/dolby_e.c @@ -845,6 +845,7 @@ static int parse_indices(DBEContext *s, DBEChannel *c) return 0; } +#define MIN_MANTISSAS 800 static int parse_mantissas(DBEContext *s, DBEChannel *c) { DBEGroup *g; @@ -885,6 +886,13 @@ 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; } -- 2.30.2 _______________________________________________ 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".