DVD v/s DVB

[Shahid]

Which is giving the better picture. Say for example I watched 'MISSION IMPOSSIBLE 2' currenly on Multivision on DVB (Digital satellite). Then watched it on DVD.
Out of watching the two, which is giving a better picture.
I do not have a DVD, for those who have, what are your findings.

I hope that DVB comes out on top or the same in this debate.

Thank you in advance for your findings for those who have DVD.

Shahid

 

[noddyo1]

I would have thought it was academic why cough up 15 quid for the dvd when you can watch it on dvb for nowt, there is not going to be 15 quids diference either way, save your money and get down the walkabout for a drink with your money saved.Thats what I do ,lol.

 

[BarMoo]

Dear All,

DVD.

Non technically speaking, think of five seconds worth of movie time.

During that time span, the DVD will give you that one movie - D-SAT will happily deliver 10 times five seconds worth of movie during the same time span (or, put simply, ten movies).

What do you think ? There can only be ten times more movie by losing something somewhere ;-)

Mark.

 

[Channel Hopper]

The DVD disc will have a fixed format for data rate per second up to the maximum space available on the disc (currently about 700 M

The DVB standard is not fixed so the broadcaster can comperss the signal as much as they like (usually until somebody complains, and then some), so you may find the transmission is either jumpy, the sound is lacking, or worse still it makes you sick trying to watch it

Major broadcasters will be the worst culprits, believing that the masses will put up with poor quality ad infinitum, and unfortunately the lack of choice to us living in the UK in choosing exactly who we subscibe willingly to, further prevents the 'voting with your feet' succeeding

Those in this forum with less than official cards at least have a way of checking who is and who is not giving the viewer the better quality picture

I still go to the cinema if I feel that the film is worth seeing

 

[Doodler]

One thing for sure, the sound is going to be way better from a DVD if you have a Dolby Digital decoder or amp, so give me the DVD any day!

As for picture quality, (what follows is based on my very limited understanding) basically it's down to the amount of bandwidth applied. As ChannelHopper pointed out, this can be variable in the case of DVB, and although there is a limitation I don't know what it is.

In the case of DVD there is a maximum of about 4GB (700MB is for CDs). Most DVDs include a lot of extra material, so let's say 3GB and if the average movie is 1.5 hours that equates to an average of 33MB per minute or 550K (bytes) per second. Anyone know how this compares to DVB bandwidth?

I guess for either DVB or DVD a given level of quality is going to require more for action scenes (with lots of movement onscreen).

 

[Channel Hopper]

Capacity of disc - my mistake, I am still recovering from yesterdays partying

In satellite use, packing more and more data into each transponder for more services - makes the broadcaster more money, as is using less bandwidth (saving money on transponder leasing).

The main question over quality from any datastream would not be the capacity of the storage device, but the bitrate the information is sent out at.

An average viewer will notice a bitrate of 4 Mbits/s gives rise under scenes of complexity / high movement (ie in an action film) to faults in the playback, regardless of how good the equipment is. In tests it has been shown few people will pick up faults on a stream playing at 6.5 to 7 Mbits/s, so this is set as the maximum required for quality reproduction on the MPEG-2 standard.

The amount of data capacity on the DVD disc and the time it has to run will determine the bitrate supplied. The quality of the reproduction will therefore be fixed by how long it has to run.

Standard DVDs for a two hour mass pressed film (plus features) will run at a bitrate of between 3.7 and 4.5 Mbit/s.

DVB on satellite, however, can be set to almost any type of bitrate the broadcaster wishes, and with a 27.5 Mbits/s transponder symbol rate on the more common satellites (Including Hotbird and Astra 2), there would be enough for four perfect 7 Mbits/s streams.

If a DVD played back at the rate of 7Mbit/s you would get only one hour of programme, - half a film.

Back to the question - DVD v Multivision

Transponder 11662MHz V on Hotbird transmitting seven streams at 27.5 Mbits/s gives a bitrate per film of just under 4Mbit/s (ignoring other factors). Chances then that it would be on par to the better DVDs on todays shelves.

By comparison - the Astra 2 transponder, 11.469 MHz Horizontal, symbol rate 27.5 Mbits/s showing at present 11 BSkyB Box Office Movies would mean each stream is delivered at under 2.5 MBits/s per programme stream (not good).

The simple comparison between watching a film on Multivision and a DVD therefore would not really be noticeable, however once you start looking at BSKYB transmissions packed like sardines one would have to ask if you are getting what you pay for.

Then again to answer the original question from Shahid, present quality of his eyesight and the resultant blur that is 'Emission Impossible' on the screen will have far more impact on the viewing pleasure than the various bitrates between the two mediums.