[opendtv] Re: BBC Demonstrates HDTV Broadcasts over SD Channels
- From: "Gary Hughes" <ghughes@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 23 Jun 2005 09:48:58 -0400
> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx=20
> [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of John Willkie
> Last sunday evening, I saw an episode of the new Dr. Who in a=20
> San Francisco living room; it was the episode shown on=20
> Saturday evening. I don't know the source channel, but it=20
> did mention that a repeat would be available on Sunday on BBC=20
> three. I suspect that in short order this technology --=20
> after a bit of hacking -- will enable folks in San Francisco=20
> and other places to watch Dr. Who at higher quality than=20
> today, simultaneously or in advance of the BBC "premiere." =20
> In TV engineering terms, the picture was horrible: tremendous=20
> macroblocking in the reds (seen on an analog set.) I asked=20
> the "media host" in this "diverse" household about the tx=20
> path. MPEG-4 via Bit torrent to him, (about 8 mbytes for=20
> each of the 42 minutes) transcoding to something he called=20
> Avid-X, then transcoding to MPEG-1 for burining to a Video=20
> CD, with the resulting file about 10 mbytes/minute.
>=20
Amateurs :-) A direct copy of the BBC1 broadcast bitstream=20
(720x576 25Hz @4.35mbit/sec) hit the 'net about the same time.=20
So what you watched had gone through at least 3, possibly 6,=20
transcodes (it seems common practice to record to a DVD recorder and
convert the result) and possibly a frame rate conversion.=20
I've also seen some of the BT MPEG-4 (Xvid encoder at about
2mbit/sec in an AVI wrapper, IIRC) versions and they aren't far
behind the MPEG-2 capture in quality. A bit stressed during the
titles and effects sequences. Perhaps your friend
should invest in a Divx DVD player (e.g. Philips DVP642) and
just watch the MPEG-4, skipping all that transcoding.
BTW, the BBC have quite sensibly released the series on DVD
already. Selling quite well apparently, despite the prolific
net copying. Or is it because of...?
gary
(former owner of tardis.com)
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