[vdr] Re: Bad compression on Pro7

[Daniel Schneider <d.r.schneider@gmx.ch>]

>It is 100% and totaly normal.
>
>Every 12 Frames (0.5 Seconds) is a Key frames. The 11 frames between
>each Key-Frame are Delta-Frames. Too much changes/movement result in the
>picture getting block-artefacts. It's a weakness in the system that
>can't be resolved.(*)

That's not true at all. With a significant higher datarate you can
avoid almost all MPEG typical artefacts. Also better encoding can
help. You can see the proof for that on DVDs, there not much DVDs
with that bad artefacts you have on DVB. DVDs typically use datarates
around 7 MBit/s (up to approximately 10 MBit/s). The MPEG-2 encoding
for DVDs is also much better, mostly because there you can run
multiple pass encoding (which is hard to do with realtime encoding as
used for digital tv) and optimize complex scenes.

Most private TV stations aren't interested in good video quality,
they want to squeeze as many channels on one transponder as possible.
3sat and other "Öffentlich-Rechtliche Sender" have higher datarates
and better video quality.

Another possibility to improve digital tv quality would be HDTV. With
a resolution of 1920x1080 pixels as used in the USA you don't see
much MPEG-2 artefacts, because the 8x8/16x16 macro blocks are very
small. But European TV stations don't want to invest in new HDTV
equipment and in quality in general (of cause you can't have so many
HDTV channels on a satellite as DVB PAL crap stations with different
ads for each country...)

Dany


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