[FFmpeg-devel] [PATCHv2 2/3] avformat/utils: increase detected start_time with skip_samples

[Marton Balint]

On Tue, 8 Mar 2016, wm4 wrote:

> On Tue,  8 Mar 2016 21:29:52 +0100
> Marton Balint <cus at passwd.hu> wrote:
>
>> Signed-off-by: Marton Balint <cus at passwd.hu>
>> ---
>>  libavformat/utils.c               | 10 ++++--
>>  tests/ref/fate/gapless2-ipod-aac1 | 72 +++++++++++++++++++--------------------
>>  tests/ref/fate/gapless2-ipod-aac2 | 72 +++++++++++++++++++--------------------
>>  3 files changed, 80 insertions(+), 74 deletions(-)
>>

> I'm a probably bit late here, but what's the rationale of increasing the
> start time?
>

According to docs, start time is supposed to be the pts of the first
decoded frame, therefore skipped samples must be taken into account, when 
the start time is determined based on the first packet pts.

> Maybe it's like this: the first packet has a negative timestamp, so
> utils.c sets the start_time to something negative, so this has to be
> compensated again so that the start time is 0?

I am not sure I understand what you mean. In the gapless samples above, 
the first packet pts is 0, and not negative.

Regards,
Marton