[mythtvnz] Cutting H.264 DVB-T files with ffmpeg without transcoding

[David Moore]

Ross and Jemima Knudsen wrote:
> David Moore wrote:
>> I get the picture now. I also am new to anything in linux really but I'm 
>> prepared to give it a go. With my minimal experience I believe you can 
>> do pretty much anything in a bash script although the built-in script 
>> features are not as flash as something like perl.
>>
>> I like your ideas. I'll get started but it will probably take me a while 
>> so don't hold your breath. :-)
>>
> Yeah, as with any FOSS can't expect anyone to do anything.
> 
> Only other option I thought of just now is whether writing it in VB.net
> (or C#.net) would be worthwhile as mono have pretty good libraries now.
> I know VB fairly well but last time I tried using a mono based IDE on
> Ubuntu I couldn't get it to work.
> 

I've used VB a fair bit also but I don't think it's a good idea to rely 
on something which isn't pretty standard in Ubuntu for portability 
reasons. Turns out sql in bash is really simple. Just echo the sql 
commands through a pipe to mysql and catch the results. Dead easy. :-) 
Hardest thing will be understanding which tables need updating. 
Recordedseek and recordedmarkup are the ones I know of so far.

Actually looks like the trickiest thing is handling the cuts. Myth cuts 
in recordedmarkup table are in frames whereas ffmpeg uses times so need 
to do some maths to convert frame to time. Bash doesn't do floating 
point maths but there is a linux utility called bc to do this so that's 
no problem. Could be a problem with cut accuracy however. I had a look 
at one of my recordings last night and it seems that the time myth shows 
for the cut points is not exactly equal to the cut point frame number x 
25 (fps). I'm guessing there might be some issue with the start time for 
the recording but not sure yet.