MPEG4

[tadam]

Please pardon my ignorance, but can someone explain the advantage of MPEG 4 vs. 2?

[Reggie3]

Please pardon my ignorance, but can someone explain the advantage of MPEG 4 vs. 2?

I believe it offers better compression algorithms for better performance over less bandwidth

[LameLefty]

Please pardon my ignorance, but can someone explain the advantage of MPEG 4 vs. 2?

It all comes down to bandwidth and how to use is - how much usable information can be crammed onto basically a fixed transponder size? If you use better compression (MPEG4 v. MPEG2), you can make better use of that transponder to carry more data.

[garoo]

Someone correct me if i'm wrong but it let's you record more HD stuff on your HD DVR.

[facmgr6569]

Someone correct me if i'm wrong but it let's you record more HD stuff on your HD DVR.

Yes more compression also = less space needed for recordings

[jburroughs]

Someone correct me if i'm wrong but it let's you record more HD stuff on your HD DVR.

That is true, MPEG-4 is a more efficient compression than MPEG-2, so you will receive higher quality video at a smaller size and a smaller size gives you more recording time.

[ghostdog]

That is true, MPEG-4 is a more efficient compression than MPEG-2, so you will receive higher quality video at a smaller size and a smaller size gives you more recording time.

Any idea on how much 'extra' recording time, if any, when compared to an MPEG 2, one hour recording?

[JDubbs413]

Any ideas on how much 'extra' recording time, if any, when compared to an MPEG 2,one hour recording?

I think it's 20 more hours of recording time with MPEG-4.

[cygnusloop]

Any idea on how much 'extra' recording time, if any, when compared to an MPEG 2, one hour recording?

It's about a 3:5 ratio. Of course this all depends on how compressed the MPEG2 is, and how compressed the MPEG4 is, and will vary depending on what the programming is (lots of static blue sky vs. a fast moving football game), but it's a pretty good rule of thumb. ~5 hours of MPEG4 will fit in the same space as ~3 hours of MPEG2. With the stock HR20 drive, ~30 hours of MPEG2 vs. ~50 hours of MPEG4.

[techrep]

Some proponents claim that mpeg-4 is lossles (spelling?) while mpeg-2 is lossy (again) but they use fuzzy math and there is no accepted standard for compression loss.

[cartrivision]

I think it's 20 more hours of recording time with MPEG-4.

That's what DirecTV implies in their estimated DVR recording capacities.... 50 Hrs MPEG4 vs. 30 hrs MPEG2, implying a 3/5 ratio, or in other words, MPEG4 requiring 40% less compressed data to represent the same HD picture, but I did some experiments a few weeks ago recording MPEG4 programs to see how much less disk space they took up on my DVR disk and I only saw about half that supposed 40% improvement…. about a 20% improvement. My experiments didn't include 24fps film based source material, just 60fps video source material, so now that we have some premium movie channels in MPEG4, I plan to see if those compress any more than the video based sources.

[cartrivision]

Some proponents claim that mpeg-4 is lossles (spelling?) while mpeg-2 is lossy (again) but they use fuzzy math and there is no accepted standard for compression loss.

Neither one is lossless, but MPEG4 requires less data (vs MPEG2) to achieve a similar level of quality.

[medic4jc7]

MPEG-4 comes with a few important improvements compared to the older and established video compression technologies like MPEG-1 and MPEG-2:

*independent encoding of pictures and video
*increased encoding efficiency, more efficient compression of pictures, video and textures
*very variable resolutions
*scalable complexity
*extended error correction
*increased flexibility for object-based encoding
*small buffer delay
*Global Motion Compensation (GMC)
*content-dependent scalability of textures

[cygnusloop]

Some proponents claim that mpeg-4 is lossles (spelling?) while mpeg-2 is lossy (again) but they use fuzzy math and there is no accepted standard for compression loss.

MPEG4 is absolutely a lossy compression scheme. What makes it "better" than MPEG2 is how it works, as in what the losses are. MPEG4 uses subjective algorithms. That is to say, quantitative testing (measured bit rates, resolution of individual frames, etc...) only tells part of the story.

MPEG4 takes into account how the human eye works, and depends on your brain to fill in missing bits, the idea being that you will never notice what isn't there. This assumes that you are looking at a stream of frames. When you look at individual frames of MPEG4, they really don't look that good, but it wasn't designed to look good that way. Objective analysis of MPEG4 will never correlate with how it looks empirically.

[medic4jc7]

In laymans terms.The MPEG decoding is done by a specialized chip. This chip has a built-in processor and decoding firmware. BOTH more horsepower, AND decoding firmware are required to git-r-done.

[ghostdog]

It's about a 3:5 ratio. Of course this all depends on how compressed the MPEG2 is, and how compressed the MPEG4 is, and will vary depending on what the programming is (lots of static blue sky vs. a fast moving football game), but it's a pretty good rule of thumb. ~5 hours of MPEG4 will fit in the same space as ~3 hours of MPEG2. With the stock HR20 drive, ~30 hours of MPEG2 vs. ~50 hours of MPEG4.

Nice added benefit, thanks for the info.

[Tom Robertson]

MPEG2 and MPEG4 are variable loss compression algorithms. At sufficient bandwidth both are as lossless as you can measure. My understanding is that at the same level of measured loss, MPEG4 will compress to 60% of the size of MPEG2 on HD material. I've also heard that SD does not quite compress as much, so switching MPEG2 SD streams to MPEG4 isn't a financially viable option.

Cheers,
Tom

[ChrisPC]

MPEG4 takes into account how the human eye works, and depends on your brain to fill in missing bits, the idea being that you will never notice what isn't there. This assumes that you are looking at a stream of frames. When you look at individual frames of MPEG4, they really don't look that good, but it wasn't designed to look good that way. Objective analysis of MPEG4 will never correlate with how it looks empirically.


I can tell MPEG4 from MPEG2 pretty easily because of that. MPEG4 just has a different look to its motion.