[linux-dvb] Re: VDR 0.80pre8

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Ralph Metzler wrote:
> 
> See my reply in my last mail (a few minutes ago).
> 
>  > 2. Audio loss during normal replay
>  >
>  > 3. Audio "chopped" during replay
> 
> These will be fixed in the next version.
> Some channels really seem to have a big offset between audio and
> video and if the video buffer is too small, the audio for the video
> data at the buffer exit sometimes has not arrived yet -> audio underflow.
> This works fine during normal TV watching since the
> hardware/firmware ROM can use the overflow buffer in DRAM.
> During playback I cannot (don't know how to) do this and thus need
> more of the original video buffer space.
> 
> This will probably be bad for VDR because there is now about 30KB less
> OSD memory and I don't know yet if I need more.
> I checked for audio buffer underflows in a longer recording of ZDF
> during this "music awards thing" (lots of motion and sound) and
> adjusted the buffer until the dropouts went away. If they still occur
> I will have to reclaim more memory.

Arghh, that's too bad. The OSD is already quite a compromise as it is.
Making it even smaller will hurt VDR quite a bit.

I know you at convergence have no need for the OSD, but I wouldn't want
to miss it because I want to use the DVB card's own A/V-out. So I would
really appreciate if there were an other solution to this problem...

>  > 4. A/V disturbances while recording
>  >
> 
> I cannot reproduce this problem. I recorded hours of ZDF and 3Sat and
> had no problems. I did not use VDR but "ntuxzap -e" +
> "dd if=/dev/ost/dvr ...". So, I can only assume ... :-)

I am setting the VPID and APID and reading the TS from the /dev/ost/dvr
device. While recording I unpack the TS and write out multiplexed PES
(see remux.c for details). It would appear that the error strongly depends
on what is currently broadcast. When I tested it yesterday on ZDF at around
13:10, the result was a total mess. Later in the afternoon (I believe it was
an episode of "Traumschiff") there was no such problem. I'll try to make
notes when this happens and when it is ok. Maybe others can also report
any recordings that cause this problem (with channel, date and time, so that
maybe we can figure out whether it occurs only with special kinds of broadcasts).

>  > 5. No smooth "Fast Forward/Back"
>  >
>  >    When replaying a recording that was done with the new driver and VDR,
>  >    the "fast forward/back" function doesn't result in a "smooth" display
>  >    as it used to in the old system. Interestingly, when replaying an old
>  >    recording on the new system, this function works fine. And it also works
>  >    when replaying a new recording on the old system.
>  >    I'm not sure what to make of this, whether to assume a problem in the
>  >    driver or in VDR.
> 
> I assume you extract I-frames from the stream and send them to the
> card? As long as the actual ES from which they come is alright, I
> also cannot see the difference the old and the new streams should
> make.

The actual data must be ok, since it play fine in normal replay.
Meanwhile I have an idea what might cause this: in the old VDR version (0.72)
I explicitly removed the audio packets before sending the data to the driver
in fast forward/back mode. In the new version there are the AV_SYNC and AUDIO_MUTE
calls, which I though would make the driver ignore any incoming audio packets,
so I no longer remove any audio packets in fast forward/back modes. I'll try to
remove them again tonight and will let you know if that helped.

> Can you make examples of the "I-frame-streams" which you send to the
> card for each of the cases (old driver's file+new VDR/driver, new driver's
> file+new VDR/driver, etc.)?

Will do so if the above test doesn't help.

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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