From: Michael Niedermayer <michael@niedermayer.cc> To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> Subject: Re: [FFmpeg-devel] [PATCH v3] avformat/mov: add option max_stts_delta Date: Mon, 27 Dec 2021 00:51:17 +0100 Message-ID: <20211226235117.GV2829255@pb2> (raw) In-Reply-To: <20211226160044.5913-1-ffmpeg@gyani.pro> [-- Attachment #1.1: Type: text/plain, Size: 2644 bytes --] On Sun, Dec 26, 2021 at 09:30:44PM +0530, 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. > --- > v3 changes: > > factored out loop > simplified correction logic this looks more sane now i guess this cannot be easily split into a seperate patch ? [...] > @@ -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)/sample_count; division by 0 thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB It is a danger to trust the dream we wish for rather than the science we have, -- Dr. Kenneth Brown [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 195 bytes --] [-- Attachment #2: Type: text/plain, Size: 251 bytes --] _______________________________________________ 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".
next prev parent reply other threads:[~2021-12-26 23:51 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-12-26 16:00 Gyan Doshi 2021-12-26 17:39 ` "zhilizhao(赵志立)" 2021-12-26 23:51 ` Michael Niedermayer [this message] 2021-12-27 5:59 ` Gyan Doshi
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