[mythtv-users] Pause in image after switch channels...

Nicolas Riendeau knightr at istop.com
Mon Jul 9 00:35:20 UTC 2007


Bruce Markey wrote:
> Nicolas Riendeau wrote:

>>The pause is not immaediate, it can take something like 5-10 after I

Oops, I meant to say 5-10 seconds... Your reply suggest that you understood what I
meant however...

>>upgraded the pc it doesn`t seem to have happened... If I look at the
>>same passage again (ie I rewind) the pause is not present...

> Of course.

I initially thought it could be a glitch in the recording which it was not...

>>The tuner is a PVR-150 MCE and the pc itself if a P5B-Plus with a
>>E6600 and the hard disk is a Seagate 7200.10 320 Mb SATA drive...
> Irrelevant.

Since I did not know the reason of the problem I thought it would be best to give as
much info as possible...

>>Please help...
> Sure. Record the shows you like and spend your time in front
> of the TV watching what you like rather than flipping through
> channels hoping to find something 'good'.

I thought the problem could also happen when using the program guide (which is not
"flipping through channels" but I guess I was wrong...

> For live TV, the signal is digitized, compressed, blocks sent
> to the disk, blocks read from disk, uncompressed, queued then
> displayed. it takes about 50 (30-70) frames worth data to fill
> the pipeline (regardless of how much you've spent on any piece
> of hardware, it's the amount of data not the speed of any device).

I kind of realized that when upgrading the pc did not get rid of the "pause" (it did
correct other problems though so it's not a loss).

> New users often complain of the 2-3 sec of delay (until they
> figure out what they really want to do instead) and therefore
> we cut it as close as possible. However, when the scene becomes
> static or dark. the video can be compressed more efficiently
> and therefore less data is being created and blocks are moved
> less frequently until the playback runs out of frames and has
> to pause until there are more frames available.

Gee, I would have never thought this was related to that (which I had read about...).

> So, after you change channels there is about half a chance that
> it will pause at least once in the first few seconds or minute
> until you hit pause or rewind. We could increase the delay (number
> of decoded frames queued) before playback starts after a channel
> change to reduce this effect but people complain much more about
> slow channel changes so it is a compromise to start as soon as
> possible without causing too many pauses.

Could it be made configurable? As somebody else said too I wouldn't mind waiting a 
tad longer if it means getting rid of the slight "glitch"...

The default could be the current behavior and buffer size with the possiblity to 
change it (by adding a switch or maybe by a configuration parameter).

There's something else I could see that could be done (though I don't know how doable 
  it is)... Could it be possible to show a (paused) frame of the captured info as 
soon as possible while the buffer keeps filling up and once it's filled up "unpause" 
automatically... That could make the people who want to get go from one channels to 
the next (ie "zap") happy has they could see what's on that channels and if they 
don't like it they could change to the next...

Would that make sense?

Thank you very much for your help (and for the great program as I believe you are one 
of the developers)!


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