[vdr] HDTV -> mpeg4

Joerg Knitter joerg.knitter at gmx.de
Wed Mar 30 01:59:23 CEST 2005

Reinhard Walter Buchner wrote:
> Hi Grégoire,
>> just done a small try to convert an Euro1080 FTA preview
>> to mpeg4, with a bitrate of 2500 with mencoder : quality
>> was very bad...
>> Anyone already converted (and keeping the resolution)
>> HDTV with a perfect quality to mpeg4 ?
> ROFL (sorry!). MPEG4 compression already sucks on
> normal TV. Doing that to a HDTV resolution should be
> outlawed ;o)))
> Please don't misunderstand, but re-compressing (mpeg4)
> something that is already compressed (mpeg2) is ALWAYS
> going to give you miserable results. Doing the same to a
> high resolution picture is only going to make things worse.
> A bitrate of 2500 isn't enough for standard quality TV. You'll
> need at least 3-5x that rate if you want to see the advantages
> of HDTV.


I think you all wrote about MPEG4 ASP. When talking about HDTV, we are 
talking about DVB-S2 (not receiveable with current cards) and MPEG4 AVC 
alias H.264 which is far better than MPEG4 ASP.
I made some tests by deinterlacing and downscaling an Euro1080 sequence 
to 1280x720 (720p) as this is a resolution a PC running at 3 GHz is able 
to play without interruptions. At 4 MBit/s encoded with Nero Digital 
AVC, the image is amazing and far better than with DivX 5.x, WMV 9 and 
even better than DivX 6.
IMHO, this time you can really say that you only need half the bitrate 
of MPEG-2. Read some more information on MPEG4 AVC (and a codec 
comparision) on Doom9.org (esp. the MPEG4 FAQ in the message board).


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