[mythtv-users] Stutter/pause and pixel debris when the programme moves from one to the next (Live TV)

Raymond Wagner raymond at wagnerrp.com
Wed Aug 10 22:57:56 UTC 2011

On Wed, 10 Aug 2011 23:22:37 +0100, Ben Lancaster
<mail at benlancaster.co.uk> wrote:
> Now the problem I have is that when the programme changes when watching
> live TV (and the backend starts writing to a new file), I get a stutter
> pause of a second or two, followed by pixel debris for a few more

LiveTV is nothing more than another recording.  One show records to one
file, and when a new show starts, it opens a new file and the existing
player is shifted over to it.  This can cause momentary stuttering during
the transition, although some users seem affected more than others.  Of
course many more don't even use LiveTV and sidestep the entire issue... :)

Recently reported by another English user are some strange encoding issues
with digital broadcasts.  Typically, MythTV must wait for the first I-frame
in a transmission.  An I-frame is one that is completely independent, and
stands on its own.  Other types of frames index changes between themselves
and the last I-frame.  Normally, once you hit an I-frame, all subsequent
frames do not reference further back than that.  The encoding strangeness
reported was that the reference frames do refer back behind the I-frame. 
Since you opened a new file, those old frames before the transition may no
longer be available for reference, resulting in the 'debris' as the player
simply has nothing to display there.

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