[mythtv-users] RTJPEG, MPEG4 and analog TV

[Jesse Burt]

Kevin Bailey wrote:
> When I first tried making analog recordings (HD3000 on 0.20),
> they wouldn't play correctly. As far as I could tell, they were
> playing double-time. You could tell what was going on, but it
> was painful.

> Under Settings//Recording Profiles/V4L based/Default, I noticed
> that the format was set to RTJPEG. I had never heard of this
> format and so gave the alternative, MPEG4, a try. It worked.
> 
> The trouble is, this doesn't help for live TV. It captures a
> second or so of data, plays it quickly, and then pauses for a
> half-second.
> 
> Since MPEG4 is probably harder on the CPU to play (I have an AMD
> 3400+), and even harder to generate, and so I can play live TV,
> I'd like to get this RTJPEG (if that's what the live TV process
> is generating) working.

> Anyone with this kind of set-up had this problem and gotten
> it to work ?

Kevin,
I have a 3400+ (1st gen Athlon64) as well with an HD5500 and HD3000 and 
it is able to record two MPEG4 or RTJpeg simultaneously while watching 
one of them (with MPEG4 it is definitely tight on processor time...no 
commercial flagging :)) so as far as raw processor time (unless it's a 
Sempron64, AthlonXP/MP...I can't vouch for those personally) you should 
be okay, even though things may be tight.

If I understand your symptom correctly (the double-time) I have had the 
same thing happen before. If it is the same thing I have seen, I believe 
it is more a driver issue with the pcHDTV cards than MythTV (check the 
output of dmesg when it happens...usually the cx88 driver says IRQ loop 
detected, disabling interrupts). I can't remember exactly which kernel 
version I was using when I first starting seeing the problem; it might 
have been 2.6.22 or something even earlier. I started using 2.6.23 when 
it came out and didn't have the problem any more. I now use a 32bit 
installation of Myth on 2.6.24 and the problem has reappeared, though 
not very often. You might want to experiment trying different kernel 
versions to see if that fixes it for you.

 > I have the audio rate set to 48kHz everywhere I could find
 > and I have "sync to video" set under Settings/Playback.

48kHz is the correct sample rate if you're using the cx88-alsa module 
for audio. I would however try disabling the sync to video option to see 
if it helps. I think several people on the list have reported it causes 
them problems.

Best of luck,
Jesse Burt