[linux-dvb] Re: Another idea to enhance timed recordings.

[Christoph Ackermann <christophackermann@t-online.de>]

Hello Carsten,

this is of course a nice idea, but a little bit unrealistic. 
Eg. To solve a very simple "Shot Detection" for mpeg1 video with a
State-of-art algorithm, you need at least the power of an 200-300Mhz CPU
for each videostream. I think that a videoanalysis of this mpeg2 stream
with a four times higher resolution is more wastefully with your
"number-crunching-resources" and therefore not possible in realtime.
An other aspect is given by the transmission between videosources (eg.
BetaCam SP VTR), routing "in house" and broadcaster to the satellite
uplink station. These connections are shurely but rarely of an analoge
type (yes composite- or component video). 
Belive me - I am very familiar with these technologies on german
boadcaster and german Telekom. 
So you have a set of distortion (noise, ...) and different levels of
luma/chroma that donīt allow to recognize parts of video in realtime. 
And i donīt want to by a "Numbercruncher" for my VDR (AMDK62-266, 128MB,
40GB and two DVBīs - Yes, it works great).

Regards and always fine recordings

Christoph
-- 
"... and all the hippies work for IBM or take control ..."
Joe Jackson - Big World, 1987

Carsten Koch wrote:
> 
> Here is an idea that is quite bullet-proof, but
> a bit limited in scope:
> 
> For recordings of programs (like 3sat's "nano"), which
> have a well-defined intro, we could do the following:
> 
> Take two frames from a previous recording, extract a
> few raster lines from the middle of these frames, build
> a checksum from theses lines and store it with the timer.
> 
> At a certain time before the scheduled start of this program,
> VDR would switch to that channel and compare the checksums
> of the same raster lines of every frame with the stored
> checksum. As soon as the first frame is found this way,
> VDR checks whether the second frame follows in the correct
> distances. If yes, it starts the recording.
> 
> As a safety precaution, it could start the recording at
> the scheduled time in any event.
> 
> Carsten.


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