[linux-dvb] Re: VDR Playback not smooth ?

[Peter Funk <pf@artcom-gmbh.de>]

Hi,

Emil Naepflein:
> Sorry Klaus, this should go to the list only. :(

off topic: You (and Klaus) might want to have a look into the tool
'procmail'.  If you are subscribed to mailing lists and people use
"Group reply" in their MUA to reply to your post you will always
receive the answers to your post twice:  one directly mailed to you
and one through the list exploder.  With procmail you can automatically
filter these duplicates out using the unique message id.  This is common 
use since at least the mid 90es.

> On Sat, 21 Apr 2001 23:13:29 +0200, Klaus Schmidinger
> <Klaus.Schmidinger@cadsoft.de> wrote:
> 
> > The problem ist in the bad multiplexing of the data delivered from the driver.
> > VDR merely stores what the driver delivers.
> 
> I don't agree fully with you here, because I found out that if you
> increase buffersize the intervall between the stutter increases
> correspondingly. In my opinion the reason for the problem is the buffer
> code in VDR. During replay you have to feed the card constantly and fast
> enough with frames. As I understood the buffering code the next data
> from the file is read just then when you have to feed the data into the
> driver. As reading may cause disk I/O and therefor additional delay, you
> may not be able to feed the driver fast enough and cause the stutter. 
[...]

If Emils analysis is right, it might make sense to use the select
system call and a simple ring buffer of some size.  This allows to 
handle this situation within the same thread, which simplifies the design 
considerably compared to having to use two threads or processes.

Regards, Peter
-- 
Peter Funk, Oldenburger Str.86, D-27777 Ganderkesee, Germany, Fax:+49 4222950260
office: +49 421 20419-0 (ArtCom GmbH, Grazer Str.8, D-28359 Bremen, Germany)



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