[mythtv-users] HD MPEG-2 to MPEG-4 transcoding

[Peter Ras]

Hi sorry to disturb you, do you know if the mpeg4 H.264 AVS , The Chinese 
one is still alive ? as i was told it is pretty good.

i saw Europe will use alternative for Dolby Difital surround based on 
amongst other Philips / Coding technologies and takes substantial less 
bitrates but further than that i have not seen anything of it.



Greetiings from South Africa



Peter

----- Original Message ----- 
From: "Yeechang Lee" <ylee at pobox.com>
To: "MythTV user mailing list" <mythtv-users at mythtv.org>
Sent: Sunday, July 16, 2006 11:18 PM
Subject: [mythtv-users] HD MPEG-2 to MPEG-4 transcoding


Joel Turner <jturner421 at aol.com> says:
> On another note, I've been experimenting with H.264 encoding as a
> way to preserve HD content and conserve space.

Me too, except I'm using mythtranscode to convert MPEG-2 HDTV to some
(non-H.264/x264) MPEG-4 format.

> My initial tests are not very promising.  The encoding times are
> horrendous. I've been converting MPEG content for several years now
> and x264 encoding is about an 11:1 time ratio for encoding one
> minute of 1080i content to 720p on my old XP based P4 2.66mhz.

My 3.0GHz Pentium 4 frontend/backend took 458 minutes to transcode,
without resizing and at a 5000Mbps bitrate, a 15.7GB 125-minute HDNet
(18000Mbps) Movies recording to a 5.7GB MPEG-4, a 3.67:1 time ratio
and a 64% space savings. (Both mythbackend and mytfrontend were active
at various times during the process.) I'd love to see mythtranscode be
able to use x264 for the better video quality at the same bitrate
(since User Jobs remains a mystery to me), but suspect that encoding
times would, as you note, become even more painful.

Despite the transcode time requirements, I nowadays have almost all
recordings set to transcode-without-resize and have been freeing up
room by rerecording old movies I haven't yet got around to see with
the transcode settings set to what I want. (This is where the lack of
a way from within mythfrontend to change trancode settings after
recording is most telling.) The quality is OK; sometimes the sky
appears a bit muddy due to compression blocks, as if the camera lens
needed a wipe with a clean cloth. But for the typical movie I record
without any particular expectation that I'll ever get around to
watching it, or have already seen before and want to keep around for
future viewings, it's quite acceptable.

-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US
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