[vdr] Re: vdr cuts recordings with ugly artifacts at cutting-points

[Oliver Endriss <o.endriss@gmx.de>]

Stefan Huelswitt wrote:
> On 16 Apr 2003 "Dr. Werner Fink" <werner@suse.de> wrote:
> > ... whats about the audio/dd frames between cutOut mark
> > upto the point where the video PTS at cutOut reach the
> > audio/dd PTS?  Shouldn't those ones be included or
> > replaced with silence:
> >
> >                            commercial
> >   video  ----------------%************%-----------------
> >   audio  ----------------%--|*********%**|--------------
> >                          ^            ^
> >                        cutOut       cutIn
> >                          ^^^^
> >                          audio PTS delay
> >
> > ?
>
> Any packets behind cutOut are removed anyways (just as in plain
> vdr). I can only guess that the driver will replace the missing
> packets with silence.
>
> For a completely correct cut, these packets have to be recovered
> and must be muxed into the packets after cutIn. This is not easy.

What about a simplified approach: Audio cutting could be based on the 
PTS of the video, i.e.
- delay audio cutOut until audio_PTS > video_PTS(CutOut)
- delay audio cutIn until audio_PTS > video_PTS(cutIn)
Maybe this would work *without* remuxing.

> In my test a typical audio delay was 36000 pts-ticks. It seems to
> be a 90 kHz clock, so this would be around 400ms delay. So the last
> 400ms video before cutOut are silent.
>
> Can say if this is noticeable. Let's see first is the removal of
> the the excess cutIn packets gives improvement.

Silence is bad[tm]. With the old solution, you could very often find a 
good cutting point, because some channels repeat a some seconds of a 
movie after the commercial break. If you simply discard audio frames 
this will not work anymore.

Oliver


-- 
Info:
To unsubscribe send a mail to listar@linuxtv.org with "unsubscribe vdr" as subject.