[linux-dvb] How high a bitrate can the cards take?

[Sebastian Kemper <sebastian_ml@gmx.net>]

Hello list!

I ran a few tests with mplayer to sort out the problem with skipping 
playback on my box. I'm a mplayer.sh user :)
There are two options to choose from: Either you take fixed quality 
scale or fixed bitrate. The mplayer man says this:

lavc[=quality:fps]
Fast software YV12 to MPEG1 conversion with libavcodec for use with 
DVB/DXR3.
Faster and of better quality than -vf fame.

          quality
                  1-31: fixed qscale
                  32-:  fixed bitrate in kBits

My experience is that you get the eventual skip with lavc <=4 and 
lavc>=6000. My first thought was it happened because by VDR couldn't 
handle the CPU load (AMD 1700+). So I checked that: I used a part of a 
movie that had skips before with lavc=2 but instead of piping the output 
to the dvb card I piped it into a file. Then I playbacked that file with 
mplayer. CPU usage went no higher then 2% (usually mplayer uses 30-40% 
playing divx on the dvb). So I think mplayer didn't process anything and 
just piped the file to the dvb card. Interstingly, the skips still 
occured. So I think there may be a bootleneck somewhere else. Maybe it's 
the pci bus, maybe it's the dvb card.

Can you guys tell me if the dvb card has any boundaries concerning MPEG1 
playback? Also, are there differences concerning this issue between the 
different dvb card revisions?

Btw, I thought quality scale means variable bitrates. Why can they still 
call it MPEG1. MPEG1 is constant bitrate, right?

Thanks!

Sebastian