[linux-dvb] saa7134_dvb / digital glitches: Status

Hartmut Hackmann hartmut.hackmann at t-online.de
Wed Nov 9 22:43:08 CET 2005


Hi,

Rainer Menzner wrote:
> A few days ago I have asked for some help on Audio / Video
> dropouts with saa7134.
> 
> After updating to the latest sources I have played some time
> with the ts_nr_packets and tsbuf parameters of saa7134. I found
> these in some note by Hartmut Hackmann, who recommended to use
> ts_nr_packets=128 and tsbuf=16.
> 
> When using exactly these values, the occurence of those glitches is
> definitely reduced best, but not removed completely. When setting
> up certain other values, this might cause much more and in
> particular more serious glitches (larger regions, ...)
> 
> I conclude that the DMA transfer is still an issue, and I don't know
> why it works on some machines and why it doesn't on other machines.
> The only points I know are:
> 
> - It is not related to CPU load
> - It does not depend on where the DVB data is written to (disk or
>    memory for display purpose)
> 
> Let me know if I can do something more ...
> 
> Keep up the great work and thanks,
> -Rainer
> 
Please see my previous reply.
By the way: the parameters ts_nr_packets and tsbuf no longer have a
meaning in dvb mode (this caused one of the bugs in the DMA code).

Good luck
   Hartmut



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