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MPEG-4 anybody watched or made any movies on it? Need advice.

The quality is rather good but it sucks compared to DVD, and the Cpu util. is rather huge. The advantages is by no comparison the small size of the files, and the ability to put'em on a ordinary cd.

Just IMHO

AoD 😉
 
Mp4 is besically a really advanced compression codec. in theory it can take what MPeg2 does currently (quality wise) and reduce the size of the file a bit more, whilst not changing the quality.. in theory. I don't know of anyone reputable who's done a side by side comparison.

I personally have downloaded a few DivX (an 'illegal' version of Mp4) movies (yes on my lowly old 56k modem, I get about 1 movie in a night), which were Star Trek TNG episodes. they were all about 40 minutes long. the bad quality ones were about 80 megs each, but the ones with more acceptable quality were about 160 megs each. that would be between 2 and 4 megs a minute.
 


<< The quality is rather good but it sucks compared to DVD >>

You have to remember that DVDs are encoded with a bitrate of 6-9 mbit/sec, whereas most DivX/MPEG-4 files distributed over the net are encoded at 900 kbit/sec. The quality is obviously going to be inferior, but the file size is much smaller. Setting the DVD/MPEG-2 bitrate to 900 kbit/sec would result in the same video quality. If you turn the DivX bitrate up past 2-3 mbit/sec (it can go up to 6 mbit/sec), you'll have a video that is nearly identical to the DVD, yet is still 1/2 to 1/3 the size.
 
I started off before I asked this question by downloading in the divx and decss codecs (or whatever). I had to cross check I had the real DecSS BTW. I'd seen the Tom's Hardware article already and what I really wanted was other peoples' experiences of the quality. I mean, could you watch it? Is it as good as VHS? Maybe it isn't so smart compared to a TVout and a good VCR. But I wanted to make a little presentation disk of some movie clips and some other files to a movie buff friend of mine. I have a TV in too.
The main problem with VHS from my point of view is the hissy sound quality on your common-or-garden recorder, and the poor speaker on the average telly.
 
It really depends on what bitrate you make the conversion at. If you d/l a movie from the net that is 2*160MB then it´s obviously gonna be pretty crappy quality. But if you make an own rip from a DVD to two CD´s you´ll get pretty darn good quality. So if you want near DVD quality you should make it at around 2000Kbit/s and use the Low-motion codec, the Fast-motion codec looks like sh!t (except in high action scenes). Then you´ll be able to get around an hour (maybe less with 2000KBit/s) of video (640*480) with 128KBit/s MP3 sound on one CD.
 
Using windows media encoder I record directly to mpeg4 in real time. I cant get much higher than 320x240 in real time, but at 1mbps its pretty sweet, and fairly hard to tell the difference between the mpeg and the source at 320x240. Mostly music videos and the like. Doubling the video window will show some obvious differences, but hell, south park looks pretty sweet even at 300kbps. I would imagine recording from digital video in non real time will present even better quality.
 
For those interested in some of the more advanced topics dealing with MPEG4 encoding, I strongly suggest joining the DivX-Digest forums at Delphi and also Doom9's outstanding MPEG Palace.

There are some very promising developments which have emerged over the last couple of months, most notably low- and high-motion merging and adaptive (scene-change) algorithms. I have been experimenting with an AviUtl plugin called Lotus m4c. This algorithm examines the video and inserts keyframes only when necessary, particularly at scene changes or during lots of on-screen motion. The results are an order of magnitude better than conventional methods which rely on fixed keyframe intervals. I just finished a single-CD version of The Matrix last night and the quality is considerably better than a prior 2-CD version with the DivX low motion codec.

Best regards,
Floyd
 
Does the hardware motion compensation, etc, on ATi cards for instance come into play with MPEG4? CPU utilisation can be rather high I see.
 
hmm.. if anyone is wondering where I got my videos, it's at this place it's actually a pretty good place for DivX and MP4.

I have a question about hardware acceleration of MP4. does it exist? could my H+ help somewhat in decoding Mpeg4?
 
I'm not aware of any MPEG4 hardware-based accelerators, however judging by the popularity of the format, it probably won't be long before we see them. I'm speaking a little outside of my area of experience, so there may already be some fringe hardware decoders on the market. I do know some are in the works. The only difficulty, I presume, is the variety of MPEG4 formats...software can deal with them readily but it's a little more complicated when designing hardware. [edit] Then there's the consideration that MPEG4 is under a constant state of flux, many people are working on improving the codecs and introducing new variants. Assuming any of these become successful, it could instantly render hardware decoders obsolete. If hardware designers are smart (and they most certainly are), they'll make some sort of provision for firmware updating to keep with the state-of-the-art. [/edit] But with clock rates steadily growing as they are, I'm not sure if the CPU utilization is a real issue.

If you're encoding MPEG4 from an MPEG2 source such as DVD, hardware decoding can help assuming you can integrate it into the encoding chain.

Best regards,
Floyd
 
I encode DIVX movies all of the time. I don't like they way most people encode their movies. I have them on my FTP site which is on the profile on my AOL IM sn.
 


<< You have to remember that DVDs are encoded with a bitrate of 6-9 mbit/sec, whereas most DivX/MPEG-4 files distributed over the net are encoded at 900 kbit/sec >>

Sohcan: I'm well aware of that but Rigoletto asked for my opinion on the subject which I did then 🙂.

AoD 😉
 
thats even lower 112KB/s. 1 byte = 8 bits. Personally i don't like divx until it hits around 1800kbit/s.. course only 30 show episodes are practical at that resolution because of the size.
 
Thanks for whipping your calculator out Zucchini. They say you can fit a 110 minute movie on to 700Mb. That's like 2/3 Mb per minute which is... um... 0.106 Mb/s. Hey, that's really slow actually. Sounds like sucky quality to me, is the sound very clear on that?
 
DivX is no DVD, but if you back away from your monitor as though it were a TV instead of staring at it from like a foot or two like usual, it's better than VHS by a long shot, and pretty damn close to DVD. I have 30 movies already.

It's on it's way to becoming the MP3 of video.
 
> &quot;thats even lower 112KB/s. 1 byte = 8 bits&quot;

...and 1024 bytes = 1kB, so it's 109.86kB/sec 😀

Ok, so I'm pedantic.

Best regards,
Floyd
 
Well, watching Divx on your monitor is generally crap... but if you can tv-out to a tv, quality is nice, about VCR quality or so.
 
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