[mythtv-users] mpeg merging?

John Veness John.Veness.myth at pelago.org.uk
Tue Dec 18 18:28:16 UTC 2007


Andrew Gallatin wrote:
> My local PBS digital station is sometimes difficult to receive,
> however they typically broadcast the same show multiple times in a
> week.  I currently check the recording of a show, and if it shows
> glitches, schedule it to be re-recorded.  I was wondering if there
> might be something smarter that I could do.
> 
> Since it seems unlikely that reception glitches will occur at exactly
> the same time in all recordings,  I was wondering if there was any
> software which can take two or more mpeg files which should be
> identical, and "merge" them.  Eg, if file A has damage at a particular
> point, it consults file B to repair the damage, if B is also damaged,
> it consults file C, etc.  It seems that given enough samples, one
> should always be able to reconstruct a perfect copy of a digital
> broadcast. 

I like the idea, as I also have that problem sometimes. However, I think 
it would be very hard to do what you suggest automatically. I don't 
think the digital stream from two different broadcasts of the same 
program, even if both received perfectly, will be the same. The MPEG 
encoding is done in real-time by the broadcaster, and any variations in 
adverts or on-screen graphics, or a change in bitrate from one broadcast 
to another, would cause the stream to be different. It would be very 
hard for an automatic process to synchronise the two streams. I'd be 
happy to be proven wrong, though.

Cheers,

John

-- 
John Veness, MythTV user, UK, DVB-T


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