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 2D6A540DD7 for ; Fri, 31 Dec 2021 09:21:25 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 0172E68AEF7; Fri, 31 Dec 2021 11:21:23 +0200 (EET) Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 0E34E6800E0 for ; Fri, 31 Dec 2021 11:21:17 +0200 (EET) Received: from smtp202.mailbox.org (smtp202.mailbox.org [IPv6:2001:67c:2050:105:465:1:4:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4JQKQ419k7zQk4J for ; Fri, 31 Dec 2021 10:21:16 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Message-ID: Date: Fri, 31 Dec 2021 14:51:00 +0530 MIME-Version: 1.0 Content-Language: en-US To: ffmpeg-devel@ffmpeg.org References: <20211228164203.617-1-ffmpeg@gyani.pro> From: Gyan Doshi In-Reply-To: <20211228164203.617-1-ffmpeg@gyani.pro> Subject: Re: [FFmpeg-devel] [PATCH v4] avformat/mov: add option max_stts_delta 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: Pushed as 9cfc7a244052dced520776ff0ecc6f0a9390f62b On 2021-12-28 10:12 pm, Gyan Doshi wrote: > Very high stts sample deltas may occasionally be intended but usually > they are written in error or used to store a negative value for dts correction > when treated as signed 32-bit integers. > > This option lets the user set an upper limit, beyond which the delta is clamped to 1. > Values greater than the limit if negative when cast to int32 are used to adjust onward dts. > > Unit is the track time scale. Default is UINT_MAX - 48000*10 which > allows upto a 10 second dts correction for 48 kHz audio streams while > accommodating 99.9% of uint32 range. > --- > v4 change: > avoid division by 0 > > doc/demuxers.texi | 9 ++++++++ > libavformat/isom.h | 1 + > libavformat/mov.c | 55 +++++++++++++++++++++++++--------------------- > 3 files changed, 40 insertions(+), 25 deletions(-) > > diff --git a/doc/demuxers.texi b/doc/demuxers.texi > index cab8a7072c..99d4ab7bc5 100644 > --- a/doc/demuxers.texi > +++ b/doc/demuxers.texi > @@ -713,6 +713,15 @@ specify. > > @item decryption_key > 16-byte key, in hex, to decrypt files encrypted using ISO Common Encryption (CENC/AES-128 CTR; ISO/IEC 23001-7). > + > +@item max_stts_delta > +Very high sample deltas written in a trak's stts box may occasionally be intended but usually they are written in > +error or used to store a negative value for dts correction when treated as signed 32-bit integers. This option lets > +the user set an upper limit, beyond which the delta is clamped to 1. Values greater than the limit if negative when > +cast to int32 are used to adjust onward dts. > + > +Unit is the track time scale. Range is 0 to UINT_MAX. Default is @code{UINT_MAX - 48000*10} which allows upto > +a 10 second dts correction for 48 kHz audio streams while accommodating 99.9% of @code{uint32} range. > @end table > > @subsection Audible AAX > diff --git a/libavformat/isom.h b/libavformat/isom.h > index ef8f19b18c..625dea8421 100644 > --- a/libavformat/isom.h > +++ b/libavformat/isom.h > @@ -305,6 +305,7 @@ typedef struct MOVContext { > int32_t movie_display_matrix[3][3]; ///< display matrix from mvhd > int have_read_mfra_size; > uint32_t mfra_size; > + uint32_t max_stts_delta; > } MOVContext; > > int ff_mp4_read_descr_len(AVIOContext *pb); > diff --git a/libavformat/mov.c b/libavformat/mov.c > index 2aed6e80ef..351ecde770 100644 > --- a/libavformat/mov.c > +++ b/libavformat/mov.c > @@ -2925,6 +2925,8 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom) > unsigned int i, entries, alloc_size = 0; > int64_t duration = 0; > int64_t total_sample_count = 0; > + int64_t current_dts = 0; > + int64_t corrected_dts = 0; > > if (c->fc->nb_streams < 1) > return 0; > @@ -2965,11 +2967,34 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom) > sc->stts_data[i].count= sample_count; > sc->stts_data[i].duration= sample_duration; > > - av_log(c->fc, AV_LOG_TRACE, "sample_count=%d, sample_duration=%d\n", > + av_log(c->fc, AV_LOG_TRACE, "sample_count=%u, sample_duration=%u\n", > sample_count, sample_duration); > > - duration+=(int64_t)sample_duration*(uint64_t)sample_count; > - total_sample_count+=sample_count; > + /* STTS sample offsets are uint32 but some files store it as int32 > + * with negative values used to correct DTS delays. > + There may be abnormally large values as well. */ > + if (sample_duration > c->max_stts_delta) { > + // assume high delta is a correction if negative when cast as int32 > + int32_t delta_magnitude = (int32_t)sample_duration; > + av_log(c->fc, AV_LOG_WARNING, "Too large sample offset %u in stts entry %u with count %u in st:%d. Clipping to 1.\n", > + sample_duration, i, sample_count, st->index); > + sc->stts_data[i].duration = 1; > + corrected_dts += (delta_magnitude < 0 ? (int64_t)delta_magnitude : 1) * sample_count; > + } else { > + corrected_dts += sample_duration * sample_count; > + } > + > + current_dts += sc->stts_data[i].duration * sample_count; > + > + if (current_dts > corrected_dts) { > + int64_t drift = (current_dts - corrected_dts)/FFMAX(sample_count, 1); > + uint32_t correction = (sc->stts_data[i].duration > drift) ? drift : sc->stts_data[i].duration - 1; > + current_dts -= correction * sample_count; > + sc->stts_data[i].duration -= correction; > + } > + > + duration+=(int64_t)sc->stts_data[i].duration*(uint64_t)sc->stts_data[i].count; > + total_sample_count+=sc->stts_data[i].count; > } > > sc->stts_count = i; > @@ -3856,13 +3881,10 @@ static void mov_build_index(MOVContext *mov, AVStream *st) > unsigned int distance = 0; > unsigned int rap_group_index = 0; > unsigned int rap_group_sample = 0; > - int64_t last_dts = 0; > - int64_t dts_correction = 0; > int rap_group_present = sc->rap_group_count && sc->rap_group; > int key_off = (sc->keyframe_count && sc->keyframes[0] > 0) || (sc->stps_count && sc->stps_data[0] > 0); > > current_dts -= sc->dts_shift; > - last_dts = current_dts; > > if (!sc->sample_count || sti->nb_index_entries) > return; > @@ -3973,26 +3995,8 @@ static void mov_build_index(MOVContext *mov, AVStream *st) > current_offset += sample_size; > stream_size += sample_size; > > - /* A negative sample duration is invalid based on the spec, > - * but some samples need it to correct the DTS. */ > - if (sc->stts_data[stts_index].duration < 0) { > - av_log(mov->fc, AV_LOG_WARNING, > - "Invalid SampleDelta %d in STTS, at %d st:%d\n", > - sc->stts_data[stts_index].duration, stts_index, > - st->index); > - dts_correction += sc->stts_data[stts_index].duration - 1; > - sc->stts_data[stts_index].duration = 1; > - } > current_dts += sc->stts_data[stts_index].duration; > - if (!dts_correction || current_dts + dts_correction > last_dts) { > - current_dts += dts_correction; > - dts_correction = 0; > - } else { > - /* Avoid creating non-monotonous DTS */ > - dts_correction += current_dts - last_dts - 1; > - current_dts = last_dts + 1; > - } > - last_dts = current_dts; > + > distance++; > stts_sample++; > current_sample++; > @@ -8577,6 +8581,7 @@ static const AVOption mov_options[] = { > { "decryption_key", "The media decryption key (hex)", OFFSET(decryption_key), AV_OPT_TYPE_BINARY, .flags = AV_OPT_FLAG_DECODING_PARAM }, > { "enable_drefs", "Enable external track support.", OFFSET(enable_drefs), AV_OPT_TYPE_BOOL, > {.i64 = 0}, 0, 1, FLAGS }, > + { "max_stts_delta", "treat offsets above this value as invalid", OFFSET(max_stts_delta), AV_OPT_TYPE_INT, {.i64 = UINT_MAX-48000*10 }, 0, UINT_MAX, .flags = AV_OPT_FLAG_DECODING_PARAM }, > > { NULL }, > }; _______________________________________________ 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".