[linux-dvb] Re: [OT] Reality

[Jerico Webmail <jerico@jerico.demon.co.uk>]

Yea, I think there are a few factors holding back MPEG-4 at the moment, cost of
hardware: at the moment the hardware for MPEG-2 is really relatively very cheap
(because of the volume) and also MPEG-4 has struggled with standardisation
despite being implemented for sometime. I am seeing more newsgathering people
using MPEG-4 and interestingly we will be testing MPEG-4 multicasted over IP
encapsulated in DVB very soon. If demand for HDTV grows the money people may
demand MPEG-4 to save bandwidth but more likely just higher modulation schemes
(8PSK).

I'm also interested to see how many broadcasters make the transition to 8PSK
over satellite for DTH. I must say, we've tried using 16QAM over satellite (for
DVB-IP) and even with a 2.4m antenna and stressing the satellite transponder
the reliability is quite poor. I wouldn't hope for 16QAM anytime soon over
satellite, but 8PSK is more than ready for deployment when the receivers can be
deployed. Alot of outside broadcast sporting events are using 8PSK and where a
decent setup can be deployed and demand is high the occasional 16QAM is used.

For a channel 15Mbps is very nice bandwidth, but if thats being sat muxed then
that could take a big hit. The biggest problem with DVB broadcasting is that no
one will pay for pre-processing of the media, and when you put film media
filmed in the 70's into an MPEG-2 encoder it looks appauling compared to the
uncompressed version. MPEG coders don't know what to do with simple analogue
noise and get all confused wasting bandwidth on that. Snell & Wilcox provide
some lovely processing hardware that claim to be able to save significant
bandwidth by preprocessing analogue noise out.

Bob


 ----- Message from gdh@acentral.co.uk ---------
     Date: Sat, 15 May 2004 01:08:16 +0100
     From: Gavin Hamill <gdh@acentral.co.uk>
 Reply-To: Gavin Hamill <gdh@acentral.co.uk>
  Subject: [linux-dvb] Re: [OT] Reality
       To: linux-dvb@linuxtv.org

 On Friday 14 May 2004 23:45, Jerico Webmail wrote:
 > Well, I can tell you we don't get any metadata for that here. :)

 Not yet... ;)

 > People controling the money seem to have not spoken to those who actually
 > use this compression hardware. Can't wait to see the customer response when
 > the new system goes on air...

 Oh dear :) When management and reality collide... sure if MPEG-4 was used, no
 probs... but alas next-to-nothing supports it yet.

 Our cableco does squeeze 10 or so TV channels per 8MHz multiplex, but there's
 a lot of QAM64 squishiness going on, so I guess the usable bitrate is higher
 that with sateliite's QPSK, hence the quality is OK.

 A lot of digital TV still annoys me - especially as you point out the problems
 with smooth colour gradients, and whilst I don't see pure colour blocks, I do
 see a lot of blockiness on the FTA channels who get lowest priority on the
 statmuxing, but I also see it on national broadcasters (BBC ONE on DVB-T is
 supposedly allocated 15Mbps if you believe the headers....) and it's a bit
 saddening :/

 At least the advantage is pure digital recordings that always replay at
 precisely the same quality as they were received at.

 So much for progress :)

 Cheers,
 Gavin


 --
 Info:
 To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb"
 as subject.



 ----- End message from gdh@acentral.co.uk -----



-- 
Info:
To unsubscribe send a mail to ecartis@linuxtv.org with "unsubscribe linux-dvb" as subject.