[mythtv-users] Terrible LiveTV performance

[Curtis Stanford]

I'm glad other people are having this "changing channels" problem. I've had 
this for a while but thought it was my ivtv driver. You don't even have a 
PVR-250 and have the same problem. Interesting...

On August 14, 2003 10:22 am, Paul Jara wrote:
> I used to be able to watch live TV with MythTV without much issue. I've
> got a P4 2.2 with 512MB RAM, and MPEG-4 480x480 live TV was quite
> smooth. However, for the best part of 4 months, I've been using MythTV
> solely to record shows and have been watching these recordings later.
> I've been upgrading MythTV in this time period. This past week I just
> got into using the live TV functionality again, and the performance is
> just terrible on my machine. There are a couple of issues. I've been
> using the RPMs but 3 times I've compiled from source and the problems
> still remain. Interestingly enough, they are often worse when compiling
> from source.
>
> 1) Slow-motion video after changing channels. When switching to live
> TV, the first channel is quite viewable and performance is great - the
> video is fluid with no dropped frames. Changing channels though causes
> the audio to drop out, and the video to continue in slow-motion. The
> only workaround is to exit out of live TV and restart it, at which
> point the cycle continues with the initial channel working as expected
> and subsequent channels not working properly.
>
> 2) Jerky video after changing channels. I've cleaned out and
> re-installed MythTV about half a dozen times. More often than not, this
> issue is the consistent one with issue 1) happening consistently with
> only 2 of those installs (1 being an RPM install and the other a build
> from source). Watching live TV is quite viewable with the initial
> channel, but changing the channel immediately results in a consistent
> dropping of frames. Consequently, the video appears jerky and the audio
> periodically pops. I can workaround this issue by pausing the video,
> building up a 5 second buffer, and resuming watching, at which point
> the video is as smooth as that produced by the initial channel.
>
> I'm using RH9 with the latest kernel. I've got the ALSA drivers
> installed for my SBLive! Value. ALSA support is not compiled into the
> RPMs, but when building from source, I have compiled it in and as I
> said, the problems are actually worse (similar behaviour, but they are
> more exaggerated). Not sure if this is because of the ALSA support or
> some other variables in the build process that vary from the RPMs. I'm
> using an Nvidia GeForce 3 and have tried the two latest binary releases
> and the XFree86 open source drivers without resolving this issue. This
> problem happens when using MPEG-4 and RTjpeg as the live TV codec.
> Ditto with using uncompressed audio and MP3 audio. I've tried with
> Jitter reduction on/off, experimental AV sync on/off, aggressive
> soundcard buffering on/off, and the commercial skipping and flagging
> features on/off. None resolve the problem.
>
> I'm sure lots has changed since April, but at one time I was able to
> watch live TV and it was great. I'm not sure where along the lines the
> problems started but I've also built a recent CVS version and the
> problems remain.
>
> -Paul