[mythtv-users] Video is behind audio, dropping frames to catch up (VDPAU, HD content)

[Thomas Börkel]

HI!

On 25.02.2013 23:34, Joseph Fry wrote:

> Because the duration between skips is so great, I don't think it's your
> playback profile.  It could be any number of things inside or outside of
> Mythtv.
> 
> Keep in mind that, because you are running a diskless frontend, any disk
> IO on your frontend could impact playback.  Because you have no issues
> in mplayer, I would look to other things besides just playback that
> mythtv may be doing.  For example, mythtv may access the seek table in
> the database during playback... if the database is busy updating EIT
> data or scheduling, you may get a hiccup.
> 
> The fact that it seems to occur more at the ends of recordings, and
> because it came up in another thread, makes me wonder about disk
> fragmentation.  When starting a recording, a certain amount of disk
> space is preallocated (not sure how much), and once that block is filled
> it will allocate another block that may or may not be contiguous.
>  I believe it will typically it will start writing an area with a lot
> of contiguous blocks free... then once it runs out it starts to write in
> another location on the disk.  Perhaps playback is ok when on
> the contiguous part of the file, but once it has to start seeking your
> playback degrades?

When the data does not come fast enough, wouldn't the log message then
"prebuffering pause"?

BTW, after further investigation, I found that the case, where it was
more at the end of the recording also was at the same time mythfrontend
was trying to contact mythlcdserver over and over.

I have now disabled usage of the LCD in mythfrontend, but still got the
message about every 10 minutes.

But I will also test the same recording on another remote (but not
diskless) frontend to rule out disk problems.

Thomas