On Fri, May 29, 2015 at 03:27:36PM +0200, Andreas Cadhalpun wrote:
> On 29.05.2015 05:03, Michael Niedermayer wrote:
> > On Thu, May 28, 2015 at 06:49:02PM +0200, Andreas Cadhalpun wrote:
> >> @@ -2522,7 +2519,27 @@ 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 (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;
> >
> > this would enfore strict monotonicity not just monotoicity
> > dts[i-1] == dts[i] was previously left as is
> > is there a reason to change this ?
>
> If the dts doesn't change, the packet duration is passed through. This
> leads to a wrong packet duration, when dts_correction is in effect.
>
> > Ive not checked what the spec says about it but i suspect there are
> > files which have such dts
>
> I haven't found an explicit mentioning of duration 0 in the spec, but
> if you think it's better not to change how this was handled previously
> for samples which didn't have a negative duration, one can simply
> add '!dts_correction ||' before the 'current_dts + dts_correction > last_dts'
> check. Attached patch includes this change.
>
> Best regards,
> Andreas
> > mov.c | 29 +++++++++++++++++++++++------ > 1 file changed, 23 insertions(+), 6 deletions(-) > d6041f950d69f7b2717d4df347cf0f6db4ccdd58 > 0001-mov-fix-DTS-calculation-for-samples-with-negative-st.patch > From 266bb402dcc6c53200637c8c37572239192bb0d3 Mon Sep 17 00:00:00 2001 > From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com> > Date: Wed, 27 May 2015 23:57:50 +0200 > Subject: [PATCH] mov: fix DTS calculation for samples with negative stts > duration > > A negative sample duration is invalid according to the spec, but there > are samples that use it for the DTS calculation, e.g.: > http://files.1f0.de/samples/mp4-negative-stts-problem.mp4 > > These currently get out of A/V sync. > > Also change the logging type to AV_LOG_WARNING, because decoding the > sample can continue. LGTM thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB it is not once nor twice but times without number that the same ideas make their appearance in the world. -- Aristotle
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