[mythtv-users] Frame rate problem when watching live TV

Mark Smit mark at miracle-online.nl
Fri Jan 4 15:33:11 UTC 2008

Hi Robin,

>> I have installed MythBuntu, i.e. Ubuntu Gutsy 7.10 with a pre-installed
>> stable MythTV version. I am using fglrx 8.42.3.
>> Now I have the problem that the frame rate is low when watching live TV. 
>> I
>> can watch recordings however at full frame frame rate. It makes no
>> difference if it is an HD or SD channel.
>> I am aware that my driver does not support XV, which can cause slowdowns.
>> For this reason, I have tried the following to no avail:
> What is your basis for this statement? Fglrx definitely does support
> xv as far as I am aware. Does it not support your graphics chip
> properly?

Flgrx has a problem with xv support for R600. When I configure for xv with 
"aticonfig --ovt=Xv" and reboot, and run xvinfo, I get the result "no 
adapters present".

>> I have the following questions:
>> - Given the fact that it is possible for me to view recordings or DVD's 
>> with
>> no frame rate problems, is the lack of XV support from any currently
>> available drivers still a likely cause?
> Possible.
>> - Since Myth always records live TV, could the problem be caused by a
>> possible problem in the Linux support for SATA?
> Try an hdparm -t /dev/whatever and check the value is sensible. It
> should be at least 30MB/sec.

It's 80.13 MB/sec, but that's just reading, which I don't have any problems 
with. The problem is it refuses to go into DMA mode, when I attempt this, I 
get the message it reverts to PIO. Other postings I read suggested to set 
this directly in the bios (for which I have no option), or that SATA can't 
be configured for DMA at all.

> Have you tried scheduling a recording and then watching the recording
> while it is in progress? This should be exactly the same as watching
> LiveTV.
>> - Can the above possibility be checked by turning off the recordinfg when
>> watching live TV?
> No, try another program such as tvtime, mplayer, vlc etc to view the
> stream directly.

Tvtime terminates immediately with the message that it requires XV support. 
Mplayer hangs when I try to tune to a channel. On VLC, I get "No suitable 
access module for 'dvb:'". Any suggestions?

>> - Is mythtv-vid still a branch? Has there ever been a stable version? I 
>> have
>> read somewhere in this list that part of the code has been merged to the
>> trunk. Would it make sense to try an SVN version of MythTV (trunk)?
> I think it has mostly been merged. I think your problems are more to
> do with the configuration of your system than MythTV.

The reason I tried mythtv-vid was the ability to configure alternatives to 



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