[mythtv] Using an external program for scheduled recordings

Joe Venzon mythtv-dev@snowman.net
Sat Jan 11 12:20:34 EST 2003


I really like MythTV, with its slick interface and well-made database 
structures.  I've only started to look over the code a bit, but it looks 
like it's very well done (albiet comments aren't quite as plentiful as I 
would hope).  Anyway, I recently switched my home theater PC over from 
Windows 2000 (where I was running a PVR program which called a 
command-line capture program, both of which I wrote) to Linux, mainly 
because MythTV sounded great (and also because I recently switched over 
from dualbooting windows and linux to using Linux on my desktop 
exclusively).  I've been much happier with MythTV than with my shoddy, 
scrapped together PVR program in many ways, not the least of which is 
the ability to use two capture cards (and that beautiful program guide).

Unfortunately, though, the modified NuppelVideo capture format isn't 
really living up to my expectations -- not only is it nearly impossible 
to find programs to read it (only the patched MPlayer) it also has very 
slow seeking within the file for some reason, and the fact that there 
are no windows players leave my roommates out in the cold, since they 
also like to watch the files it generates.  I don't use MythTV's live tv 
pausing features at all (although they are pretty neat) and I don't use 
MythTV to watch normal TV or to playback any of the videos it records (I 
play them back on my computer).  I'm guessing that the reason the NUV 
format was modified was to allow for the ringbuffer playing which is key 
to viewing and pausing live TV, and since I don't really care about 
these, I really would like to modify MythTV to be able to use an 
external command-line capture program such as nvrec 
(http://nvrec.sourceforge.net) to do all of the capturing, so I can 
generate nice run-of-the-mill DivX-encoded AVI files with mp3 audio. 
Using nvrec seems to also have the benefit of slightly reduced CPU usage 
(compared to mpeg4 nuv).

So, now that my longwinded explanations are over, I'll get to my 
question:  can anyone give me an idea of how difficult this would be to 
do?  I've only looked at the code a bit so far, and the NuppelVideo 
encoding seems to be done in source for MythTV (the libNuppelVideo 
library it compiles).  I've looked at the source for the front-end a bit 
(I'm using 0.7, by the way) and I can't find where the code to begin 
capturing is.  I'll look at it some more, but if anyone can give me some 
quick insight, it would be much appreciated.

Thanks,
Joe Venzon




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