[mythtv-users] is mythtv smart enough to do this (overlap/back-to-back) with recordings?

[Steve Hodge]

On 7/27/06, Paul Wheeler <paulrwheeler at gmail.com> wrote:
> I have for a long time wanted something like this. However i think the
> difficulty comes in 'splicing' the overlapping time. From my
> understanding of the various formats this would be difficult on all
> non mpg2 recordings and even on mpg2 recordings (where i believe you
> can join together by literally 'cat'ing the files together) you then
> have issues about how much of the file do you 'paste' on to the end of
> the first recording as this will be a variable size (iirc mpg2 uses
> variable bitrates).

I can see this being a problem for mpeg2 recordings, but for capture
cards which don't encode it shouldn't be difficult. You have a stream
comming from the card that you are compressing and writing to a file.
At the appropriate time you start duplicating the stream (or at least
treating it as if it were two separate streams) and you start writing
the second stream to the second file. No "pasting" pieces of file
around at all. It could even be done with a v4l driver, at least for
capture cards with no tuner.

One issue no one seems to have mentioned is the work required in the
scheduler. That's probably non-trivial.

> It is these problems that unfortunately make a very simple idea
> extremely non trivial as such i have never looked into it at all or
> asked others about it as it is extremely unlikely anyone will have the
> time/effort to code it up for what is a minor 'defect'.

It's not a minor defect, it's a major issue for people with one card.
It means carefully monitoring schedules and overriding your usual
default start early and end late times.

Steve