Tivo V6 : Mpeg4

[japitts]

Originally Posted by nodrogd

This might be helpful:
http://www.en.digitalbitrate.com/dtv...ve=209&lang=en

Yeah I'd had a little play with that last night before seeing the post on here. I could see the HD channels were coming up as MPEG4, but it looked like each HD channel was being carried twice - once in MPEG2 and once in MPEG4. Or is that how the site displays pre & post changeover detail.

Certainly setting a few dummy recordings of SD & HD, on some channels there is very little difference in file size now. But on others (Nat Geo & BBC1 I'm not wholly convinced of yet) there still is.

[nodrogd]

Originally Posted by japitts

Yeah I'd had a little play with that last night before seeing the post on here. I could see the HD channels were coming up as MPEG4, but it looked like each HD channel was being carried twice - once in MPEG2 and once in MPEG4. Or is that how the site displays pre & post changeover detail.

Certainly setting a few dummy recordings of SD & HD, on some channels there is very little difference in file size now. But on others (Nat Geo & BBC1 I'm not wholly convinced of yet) there still is.

With jj20x no longer around interpreting all this info is a little more difficult. It may be that some parts of the network are still MPEG2 while others have moved to MPEG4.

[BenMcr]

Originally Posted by nodrogd

With jj20x no longer around interpreting all this info is a little more difficult. It may be that some parts of the network are still MPEG2 while others have moved to MPEG4.

Or it's possible that Virgin Media are running the channels in both MPEG2 and MPEG4 until they confident that the change hasn't caused any major issues, and there isn't a need to revert back to MPEG 2.

[alwaysabear]

Originally Posted by BenMcr

Or it's possible that Virgin Media are running the channels in both MPEG2 and MPEG4 until they confident that the change hasn't caused any major issues, and there isn't a need to revert back to MPEG 2.

That would be the sensible thing to do!
Cudos to VM if this is indeed what is happening.

[nodrogd]

Originally Posted by BenMcr

Or it's possible that Virgin Media are running the channels in both MPEG2 and MPEG4 until they confident that the change hasn't caused any major issues, and there isn't a need to revert back to MPEG 2.

Look s like you may be right.

Check the third graph down on the BBC2 HD analysis:

http://www.en.digitalbitrate.com/dtv...9&lang=en&af=1

[spiderplant]

Running both in parallel is part of the process. The MPEG-4 encoders have been already set up and tested, so the actual changeover is almost as simple as flicking a switch. It's much easier and safer than trying to reconfigure the encoders on the night, and means there is almost no loss of service for the changeover. It also makes it easy to change back if anything goes wrong.

[devilincarnate]

simple question for Spiderplant does this mean we will get recording space ?

[trickytree]

The potential of this to suddenly boost the number of recordings the box can hold is great.

The past 2 days definitely got speedy in the fast forward department.
Will look tonight at how much an old hour of recordings v a new hour is as i'm told it says in the info page

[OLD BOY]

Originally Posted by trickytree

The potential of this to suddenly boost the number of recordings the box can hold is great.

The past 2 days definitely got speedy in the fast forward department.
Will look tonight at how much an old hour of recordings v a new hour is as i'm told it says in the info page

Now, that would be really interesting. I'm dying to know that because I struggle to find sufficient room for all my HD recordings at the moment.

[spiderplant]

Originally Posted by devilincarnate

simple question for Spiderplant does this mean we will get recording space ?

You'll get almost twice as many HD recordings on your hard drive from now on. Recordings made before the switch will remain the same size of course, as will SD ones.

[Raider999]

Originally Posted by spiderplant

You'll get almost twice as many HD recordings on your hard drive from now on. Recordings made before the switch will remain the same size of course, as will SD ones.

Hopefully this extra compression will not reduce the quality.

[nodrogd]

Originally Posted by Raider999

Hopefully this extra compression will not reduce the quality.

As far as VM are concered I shouldn't think it would. There is no lack of space in the cable RF spectrum & AFAIK VM don't charge channels for the amount of bandwidth they use, unlike other providers.

[Raider999]

Originally Posted by nodrogd

As far as VM are concered I shouldn't think it would. There is no lack of space in the cable RF spectrum & AFAIK VM don't charge channels for the amount of bandwidth they use, unlike other providers.

Thanks for the reply - however I am now confused as other posts have suggested that Mpeg4 recordings will use considerably less space. This is what makes me think quality may be compromised.

[nodrogd]

Originally Posted by Raider999

Thanks for the reply - however I am now confused as other posts have suggested that Mpeg4 recordings will use considerably less space. This is what makes me think quality may be compromised.

There is no reason to think what you see will be any different to what you see now. Sky & Freeview HD have always used MPEG4 for HD. I can't see any reason VM would reduce quality.

[spiderplant]

Originally Posted by Raider999

Hopefully this extra compression will not reduce the quality.

If VM had wanted to save bandwidth by reducing picture quality, they could have done it years ago, just by increasing the compression on MPEG-2. Switching to MPEG-4 allows bandwidth to be saved without compromising quality.