Mpeg4
 

Earlier tonight I was fast searching 5HD and it seemed faster than before, so i checked the system info diagnostics and it appears that they have
switched to H.264(Mpeg4) Video. I checked some other channels and BBC 2hd, Universal hd, itvBe hd, Film 4hd and BT Sport 3 have switched also. While this is a good thing I have found the 2x search or 30 sec skip is now too fast !.:confused:

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I use subtitles, and the 2x speed allows me to watch a programme in half the time. We seem to have lost 2x speed. It goes from play(1x) to 1x(again) to 6x.

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Same here going much quicker than normal.

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It's so fast it's almost as if it's an error in frame handling and counting.

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Wait until they swap to H.265, the compression is insane with that codec.

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Not sure the DVB-C standards include H.265 yet?

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I wasn't talking about imminently :)

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Playing back H264 & H265 videos on my PC doesn't have these problems, so it must be fixable.

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Indeed it is :D

I have x265 (HEVC) copies of many of my TV episodes, and the 1280 x 720 files are smaller than the older 720 x 404 [x264] copies.

(and way smaller than the older xvid format).

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My V6 is unaffected so far. Fast forward was at the usual speed.

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Yep, looking at the file sizes on some of this weeks recordings - some channels (BBC1HD) are around 7-8Gb for an hour's HD, others (BBC2 HD) around 2Gb. I'm guessing the 7-8Gb are still MPEG2 currently, perhaps a staggered change maybe.

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

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Watching KIRI on Channel 4 last night and FFding through the adverts it went much faster than normal. Is this the H264 malarky?

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It does seem a bit wrong at the moment, pressing the 30sec forward button to 4 minutes to bypass the adverts goes way past 4 minutes, to more like 8 minutes then jumps backwards to correct itself. I hope they sort it out and slow it down a tad.

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The important piece of info would be the GOP setting.

H264 and H265 are capable of being fast forwarded at a reasonable rate.

Is it a problem of handling the situation where MPEG2 and MPEG4 versions of the channel are available and the decoding settings for MPEG2 are used on MPEG4?

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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.

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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.

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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.

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

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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

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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.

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

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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

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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.

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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.

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Hopefully this extra compression will not reduce the quality.

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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.

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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.

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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.

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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.

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Thats the progress of video compression.

MPEG2 is the dinosaur of its world, MP4 (x264) gives the same quality for less space.
Even thats out of date now, HEVC (x265) gives the same quality for even less space (up to 50% less in many cases).
The problem with HEVC is that many devices are not capable of decoding it properly yet.

Re: Mpeg4
 

Was looking for this, having noticed a massive speed blast at 3rd step of FF (Tivo, not V6)

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It needs the hardware to support it so you can't just download a firmware upgrade for most devices. Unfortunately our smart TV has no upgrade so we're stuck with x264 for playing downloaded content.

The file size reduction is quite impressive.

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Compression is getting better and better all the time
https://www.broadbandtvnews.com/2017...perseus-codec/
http://www.bbc.co.uk/news/av/technol...worth-watching

Re: Mpeg4
 

Looks like there are a few issues cropping up on the Community forum.

Some VHD & V+HD customers reporting their HD channels at reverting to 4:3 aspect & they cant change it.

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Maybe it's a ploy to get them to change over to a V6? ;)

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The only issue with those codecs, i assume, is the broadcaster would have to buy a license to use it.

No such problems with an open source codec.

Aren't broadcasters moving away from the Dolby sound codec for TruSurround for options that don't require a license?

Re: Mpeg4
 

Sky bought a minority stake in V-Nova and uses it in Italy wonder whether that's why the dishless Sky Q option will firstly roll out in Italy.

6-10 Mbps for UHD is impressive.

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V6 rollout will most likely be partly in order to shift everything to MPEG4 (and maybe HEVC) so that there's capacity for more channels per MUX, freeing up MUXes for higher bandwidth broadband offerings.

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Probably a very basic question (so apologies in advance) but this format change only applies to recorded files, not "live" broadcasts. In other words, nothing has changed on live tv...

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It's the encoding of the actual streams from the headend. That's why they're keen to swap out all the boxes that will not support it.

That more efficient encoding will allow for better bit rates on some channels if they choose and more overall capacity elsewhere.

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Hope the fix this fast forward bug, and it is a bug. There is no good reason why it couldn't be 2x speed as before with MPEG2.

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The transmission is encoded in MPEG4. The box records the transmission as recieved (bitrate, encoding etc).

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Ah ha... thanks guys. I wonder if this is why I have noticed a slight change in picture quality on Standard Definition channels recently. Do we know when these changes took effect?

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SD channels haven't changed - it's only on the HD channels

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Curiouser and curiouser...

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Yes, it'll be fixed by the next software update

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Am I reading the bitrates incorrectly or does the move to MPEG4 look a little underwhelming?

From digitalbitrates, Virgin MPEG2 is showing an average of 16.6Mbps for BBC One HD, Virgin MPEG4 is 11.9Mbps and Freeview MPEG4 is 4.7Mbps.

Would we expect Virgin's MPEG4 to be at a lower bitrate?

Unscientifically recordings HD recordings on a V6 seem to eat up less % of disk space now but it's not a very granular measurement.

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Yes you should expect much lower rates as it's a far more efficient codec so can produce the same results as mpeg2 with a smaller file size/bit rate.

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Do you know when this is due?

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Coming soon...........:D

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Probably. It's currently on pilot, and will be rolled out nationally if the pilot is successful.

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Until Virgin come up with other uses for the space it is likely they will use high bitrate MPEG4. When they squeeze in more channels, or reallocate it for broadband, we will see lower bitrates.

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Thanks, that makes sense. Virgin can't win really, high bit rate and I'll moan about the space taken up for recordings, once they lower it I'll moan about any degradation in picture quality. I'll bask in the high bit rates for now. ;)

Re: Mpeg4
 

Could the V6 do h.265 if it ever materialises onto VM?

---------- Post added at 01:39 ---------- Previous post was at 01:36 ----------

I'm getting that on BBC News HD. Not noticed it on other channels, not that I watch many others.

---------- Post added at 01:43 ---------- Previous post was at 01:39 ----------

Interesting links, thanks.

Begs the question, why the need for ever faster broadband connections, when the compression technology is leaping ahead so far?

If a UHD film can be streamed at 6mb, what is the point of my current 200mb connection, let alone 300mb or a future 1gb service?

Re: Mpeg4
 

No idea, it could be automatically part of the chipset being used, or not.

The faster connections allow for multiple devices to be used at the same time.

We've gone from a time where you'd use one device with your connection, to basically everything being connected.

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I hope they don't fix it, means you can FF through the ads twice as quick. Best bug ever ! ;)

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You could before by pressing FF again.

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You can't go faster than 3 fast forward arrows, and the bug makes that speed twice as quick. It's brilliant, keep it.

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Netflix and Amazon say you need at least 15Mpbs for their highly compressed UHD streams. BT will not offer their UHD service on a line which can not constantly achive 44Mbps.

If on your network you are not going to have several users taken up a lot of bandwidth then you don't need more than 200mb.

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Agreed but then Netflix don't use the compression in the article that Horizon was referring to.

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Netflix does use h265 on UHD content.

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He was referring to this technology V-Nova
https://www.broadbandtvnews.com/2017...perseus-codec/