[mythtvnz] Channel change stability issues with MythTV and VDPAU in NZ

[Steven Ellis]

On 7/06/2009, at 7:56 PM, Jean-Yves Avenard wrote:

> Hi
>
> 2009/6/7 Steven Ellis <steven at openmedia.co.nz>:
>> I still get the occasional "Error was encountered" while changing  
>> channels,
>> but I haven't had a crash yet..
>
> I think I've identified what the problem could be.
>
> Haven't looked in that code there, but from some error messages I saw,
> I wouldn't be surprised if that was the reason.
>
> So, a mythfrontend tries to watch LiveTV
> mythbackend kicks the capture card and start a recording
> mythfrontend now waits for that recording to be available for a set
> period of time
> once the recording has buffered enough and is available, mythfrontend
> starts playback
>
> Now when you change channel quickly: it goes on like this:
> mythfrontend tries to watch LiveTV
> mythbackend kicks the capture card and start a recording
> mythfrontend now waits for that recording to be available for a set
> period of time
> mythfrontend change channel
> wait time above lapsed start to try watching the new recordings which
> doesn't exist yet: failure
>
> When changing channel very fast, a few times I saw in the log that
> buffering time had lapsed and then an error that a given recording
> didn't exist.
>
> As the mythtv developers do not use LiveTV, I'm guessing they never
> really looked at this issue.
>

I'll reply on list this time..

You have described the extreme case which I usually include in my  
stress tests, but at the moment I'm doing the following.

1. Start Live TV

2. Make sure I'm on a freeview|HD only channel - I have freeview's SD  
DTH service and their DTT freeview|HD service on the same box.

3. Wait for video playback

4. Change to another channel - could be HD or SD

5. Goto 3

So on every channel change I wait, sometimes upto 10 seconds, for the  
video playback to start.

Steve



Steven Ellis - Technical Director
OpenMedia Limited
email   - steven at openmedia.co.nz
website - http://www.openmedia.co.nz

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