[linux-dvb] saa7134_dvb / digital glitches: Status

Rainer Menzner rmenzner at viisage.com
Wed Nov 9 09:58:54 CET 2005

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,

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