In a world where almost all HD channels are distributed with
MPEG-2,
HBO has just announced that
all 26 of their new HD channels will be
MPEG-4. The stream will be 8 Mbps, and HBO has mandated that the provider not reduce the bit-rate. What they didn't say is, what the minimum will be for all those MPEG-2 networks that will no doubt transcode the signal rather than upgrade their entire network (including all the STBs). This is an obvious advantage to satellite providers who are already planning on deploying their
new HD channels with MPEG-4; and for HBO who won't have to spend as much cash on bandwidth to distribute their feeds.
Reader Comments (Page 1 of 1)
mistermister @ Jun 22nd 2007 4:23PM
Newbie here: isn't Mpeg4 for adding more compression to the video than mpeg2? in other words, smaller file, but less quality?
Jean @ Jun 22nd 2007 4:34PM
http://en.wikipedia.org/wiki/MPEG_4
Eric M @ Jun 22nd 2007 4:35PM
Bahhaa, MPEG4 HDTV in Europe is around 16-20 MBs, but now we get 8... WHOOOOO.
mistermister @ Jun 22nd 2007 4:44PM
Jean: Thanks for the link, but it did everything but answer my question.
riverside_guy @ Jun 22nd 2007 4:50PM
I think a good part of the purpose of MPEG4(h.264) is to have equal or better quality at lower bit rates.
Cable Labs has already specified 15Mb/s as an "acceptable" rate.
Transcoding gives me the willies.
I had a feeling another show would drop... here it is!
mistermister @ Jun 22nd 2007 5:29PM
see I thought lower bitrates meant lower quality. That's whats confusing because Blu-ray uses Mpeg2-TS, which uses a higher bitrate of 40Mbps.
Ben @ Jun 22nd 2007 5:42PM
MPEG-4 is better quality than MPEG-2 at the same bit-rate. Although Blu-ray does use MPEG-2 sometimes, many discs are MPEG4. So an acceptable bit-rate with MPEG-2 is between 16-20 depending on the content, where MEPG-4 is between 6-10.
Brian Hoyt @ Jun 22nd 2007 5:43PM
MPEG-4 is much more efficient than MPEG-2, so at a given bit rate MPEG-4 should look better than MPEG-2. That said the more bits the better the quality, until you get to lossless rate that is. MPEG-4 encodes on HD-DVD / Blu-Ray I think average about 15 MB/s so what HBO is doing is still only going to 50% of the quality of those discs. The optical formats can go much higher though.
mistermister @ Jun 22nd 2007 5:49PM
This is sort of a domino effect, but why do some movie industries choose Mpeg2 vs. Mpeg4 if Mpeg 4 is better quality? curious to know what the determining factor is.
Michael @ Jun 22nd 2007 6:09PM
Cost is probably the main factor. You need new equipment at all stages to use MPEG4 if you are using an MPEG2 system. You will need to get new STBs, as well as new equipment to broadcast the MPEG4. Cable companies won't like either.
MegaZone @ Jun 22nd 2007 8:24PM
mistermister - It gets confusing. Speaking in general, for a given bitrate MPEG-4 will look better than MPEG-2. But this isn't a constant. The way the two systems do their encoding and compression is very different. Many people feel that MPEG-2 may be better than MPEG-4 on some types of content - depending on the bitrate. If you have the space and bandwidth to use a very high bitrate, MPEG-2 may provide a better end result. As you get diminishing returns as you increase the bitrate past a certain point.
MPEG-4 also requires new hardware and software. Studios have invested in MPEG-2 production system for many years, and the people doing the encoding have a lot of experience tweaking MPEG-2 and getting great results. (Look at early DVDs compared to new DVDs - and how much difference experience makes.) Switching to MPEG-4 (or VC-1) means an investment in new authoring tools. And it means a steep learning curve for the technicians to get good results. Most of the tricks they learned for MPEG-2 don't apply, so it is back to the early-DVD days of learning the gotchas and the optimizations to get the best encoding.
If you have the space and bandwidth, like with Blu-ray, it may not be worth making the switch to MPEG-4 because of the other factors. Studios may use MPEG-4 on lesser titles first, to get over the learning hump, before risking their big titles on the new encoding.
The problem for cable and satellite are all of the installed STBs. Almost none of them have MPEG-4 decoders. That's why DirecTV is only moving to MPEG-4 on their new HD channels - the didn't have that many HD receivers in the field, compared to all the SD receivers, and only those people who want the new channels need to upgrade their receiver. They plan to keep SD MPEG-2 because there are over ten million SD receivers in the field that would need to be replaced.
Cable has far more STBs in the field, and almost all of them would need to be replaced to handle MPEG-4. Newer cable boxes may be equipped for it, but it will be many years before there is any kind of general cut over. And then there will also be issues from people using CableCARD TVs, etc - as nearly all of them are MPEG-2 only too.
GhostDoggy @ Jun 23rd 2007 5:54AM
This will do nothiong if someone like directv accepts the mpeg4, converts it to mpeg2, reduces the quality therein, and recodes it for their flavor of mpeg4.
Also keep in mind they could just as easily not reduce the mpeg4 bitrate but chop a third of the horizontal resolution, transmit the reset, and have the STB extrapolate the missing data. They already do this.
L @ Jun 23rd 2007 10:58AM
Is it H.264 (MPEG-4 Part 10, a/k/a MPEG-4 AVC) or MPEG-4 Part 2? Big difference.
Siva @ Jun 23rd 2007 1:03PM
Nobody really uses part2. MPEG4 really means MPEG4 Part 10. AVC or H.264. BTW, most new titles on bluray are AVC and not MPEG2.
JQ Public @ Jun 23rd 2007 1:54PM
We all have to be compression and bitrate watchdogs. There are some things it seems you cannot see on video anymore:
Take Discovery HD's recent Planet Earth series. Ah, beautiful, crisp, colorful... until they did the flight through the Grand Canyon, when the coding could not keep up and the canyon walls and background all turned to mush. What a waste. (Maybe it's better on Blu-Ray.) Happens everywhere now.
One wonders if jittery / mushy backgrounds might cause seizures. 'Couple of lawsuits... and Bingo! great PQ.