[mythtv] What is the best way to implement overlapping recordings on one channel?

David Whyte david.whyte at gmail.com
Thu Mar 31 11:49:53 UTC 2005


I really like the idea of one and two.  

I like the idea of one, just as I hope that soon LiveTV will be
implemented like this so that it is a little more stable than the
current ring buffer implementation.  This will also allow you to
change channels and be able to rewind to where you were watching a
previous channel.

I think two is the best way of attacking this little problem though,
even if feature one did get implemented.  I think this would provide a
much more stable way of being sure that you only delete the correct
bits of recording when that time comes.  Also, you are actually
recording *two* shows so you should get two copies ;)

I tell you what though, being a fellow Aussie (from BNE), if you get
this implemented, let me know and I for one will buy you a carton of
XXXX (as in Castelmeine (sp?) for the non-Aussies) or two or whatever
your poison may be.  I am tired of only being able to record one
channel even though I have two tuners.

Thanks mate,
Dave


On Thu, 31 Mar 2005 20:09:05 +1000, Glenn Moloney
<glenn062 at optusnet.com.au> wrote:
> Hi All,
> 
> I have a "feature" (well - I call it a feature) I want to implement:
> 
>       Allow overlapping recordings on one tuner.
> 
> I am interested in feedback on how best to implement this feacture - in
> a manner acceptable to the mythtv powers that be.
> 
> I find that I need to allow at least 5 minutes (up to 15 for some
> networks in Australia) of "overrecording" on each program. If I want to
> record programs following each other on the same channel - I need to use
> two tuners. I would rather not use two tuners for this job - at least
> for the case where the same recording profile is used for both
> recordings.
> 
> As I see it, there are two approaches:
> 
> 1: The "high-level" approach: A "recording" may be fragmented across
> several fragments of files on disk. This means little change to the
> low-level recording code mythtv. Also permits constructing "virtual"
> recordings from existing recordings (eg. highlights), etc...
> 
> 2: The "low-level" approach: Allow the output from one tuner to be fed
> into two files during the overlap period. One approach would be to
> extend the RingBuffer class to allow two (or more) output files to be
> attached to each ringbuffer. There will also be some fiddling in
> tv_rec.h to "do the right thing" during the overlapping recordings, and
> some changes to how we test if a channel is available for recording,
> transferring ownership of the ringbuffer, etc...
> 
> 3: Copy data from the end of the previous recording into the next
> recording. In this case, we delay the start of the second recording, and
> copy the data from end of the previous recording file into the new
> recording file. Needs to happen seamlessly.
> 
> I am favouring Option 2 - and have started planning for it.
> 
> Obviously there is more to it than I describe here - but you get the
> idea. The scheduler will need to recognise that these recordings are NOT
> a conflict (given the first feature is working correctly).
> 
> Any suggestions or comments welcome.
> 
> cheers,
> glenn.
> 
> 
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> 
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