whats the difference between MPEG2 and 4?

ftaok

macrumors 603
Jan 23, 2002
6,199
1,220
East Coast
wirelessimports said:
Im loooking to get EyeTV. Anyone know the difference between MPEG2 and MPEG4?
mpeg2 is the format used on DVDs. mpeg4 is a newer format that is used on various devices from web video to cell phones.

Properly encoded mpeg4 will yield better quality than mpeg2 at the same file size.
 

sandman42

macrumors 6502a
Oct 23, 2003
957
59
Seattle
macstudent said:
MPEG4
-MPEG2
_______
2

The diference is 2. :D
Check your algebra: the answer to your problem would be MPEG2!

But the question was, "what's the difference between MPEG2 and 4?"

I think that would be more like:

4-MPEG2 = 2*(2-MPEG)​

But without knowing the value of MPEG (which is much more valuable to some than others) we can't solve for a specific value.
 

Studawg7

macrumors regular
May 15, 2004
213
0
Cville, VA
for the value....

ask the music and motion picture industries, they seem to know lol

but anyway... think of it as an update, a version 2 or 3 or 4 etc, like ftaok said, one is currently used for dvds and the other is gaining ground b/c of its encoding abilities. or to put in in other terms, most people have mp3, but many are moving towards the mp4 (especially if they are ripping cds to itunes and have left the default). its a slightly better way of encoding, more quality same size.
 

revenuee

macrumors 68020
Sep 13, 2003
2,251
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umm isn't mpeg4 mean mpeg 1 layer 4?

just like mp3 is mpeg 1 layer 3

mpeg 2 is a different breed of compression used for DVD authoring

while the mpeg 1 standards are used for internet distripution
 

sandman42

macrumors 6502a
Oct 23, 2003
957
59
Seattle
revenuee said:
umm isn't mpeg4 mean mpeg 1 layer 4?

just like mp3 is mpeg 1 layer 3
No, MPEG4 is a new compression algorithm that is different from MPEG1 and MPEG2. You're right about MP3 -- it usually means MPEG1 layer 3 (though it can also be MPEG2, layer 3), but the MPEG4 standard is for audio and video. AAC is the audio portion of MPEG4, so you sometimes see AAC files with the extension .mp4, which makes it confusing.

See: http://www.apple.com/mpeg4/
 

revenuee

macrumors 68020
Sep 13, 2003
2,251
1
sandman42 said:
No, MPEG4 is a new compression algorithm that is different from MPEG1 and MPEG2. You're right about MP3 -- it usually means MPEG1 layer 3 (though it can also be MPEG2, layer 3), but the MPEG4 standard is for audio and video. AAC is the audio portion of MPEG4, so you sometimes see AAC files with the extension .mp4, which makes it confusing.

See: http://www.apple.com/mpeg4/
good call ... thanks for that

interesting ... i've been doing a lot more short video -- but i haven't been putting them to the web ... looks like i need to get back into the codec game ... it was always such a pain though
 

vouder17

macrumors 6502a
Apr 30, 2003
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Now where does AVI fall into..is that also mpeg 4 just a different breed. And another question will Quicktime 7 support more formats.. i have been looking for a link and apple's page but it is not to be found.
 

Lacero

macrumors 604
Jan 20, 2005
6,639
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vouder17 said:
Now where does AVI fall into..is that also mpeg 4 just a different breed. And another question will Quicktime 7 support more formats.. i have been looking for a link and apple's page but it is not to be found.
Holy Cow! I just finished encoding a 640x480 DV video to H.264 and the quality is unbelievable! This is at full frame and full 30 fps, at 500Kbps. At the same settings with Sorenson 3, it came out into chunky bits.
 

vouder17

macrumors 6502a
Apr 30, 2003
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Lacero said:
Holy Cow! I just finished encoding a 640x480 DV video to H.264 and the quality is unbelievable! This is at full frame and full 30 fps, at 500Kbps. At the same settings with Sorenson 3, it came out into chunky bits.
Great Info!! But why did u quote me.. I think you did it by mistake.. :p
 

James Philp

macrumors 65816
Mar 5, 2005
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0
Oxford/London
ftaok said:
mpeg2 is the format used on DVDs. mpeg4 is a newer format that is used on various devices from web video to cell phones.

Properly encoded mpeg4 will yield better quality than mpeg2 at the same file size.
What he said.
But I'm not sure of the second statement.
mpeg2 is used on DVD's because it compresses the file less, meaning you get better picture quality, but a much larger data rate. Mpeg4 uses a lot more compression, allowing for small data rates but a reduction in volume. (FYI: mpeg2 is the standard for digital TV bradcasting in the UK)

skubish said:
MPEG4 downloads twice as fast on bitTorrent than MPEG2
No not really! Mpeg 4 is scaleable (just try exporting using mpeg4 in iMovie).
H.264 is like the next level - a codec that not only supplys good image quality at high data rates and high resolution, but is also scaleable to provide good image quality at low data rates.(usually codecs can either do one (compress a lot) or the other (compress less).
mpeg3 was a codec that only really lent itself to audio.
mpeg4 also lends itself to audio (under the guise of AAC)
dunno 'bout H.264
mpeg1 (i think) is fully uncompressed or summit and has an extemely high data rate that maybe only the BluRay discs will be able to hold!

These standards were all ratified a while ago by the developers, but the more recent ones (4 & 3) were only "recently" implemented.
This was done (along with other compression techniques) to work out required bandwidth for things like digital TV, Radio and esp. Cell Phones. This was a legal requirement so governments could put a price on a frequency range for broadcasters and telephone servive providers (BTW the govenments made a TON of money selling this "airspace" - wierd to sell something that never really existed until it's sold!)

Sorry for all the extra info!
 

BornAgainMac

macrumors 603
Feb 4, 2004
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Lacero said:
Holy Cow! I just finished encoding a 640x480 DV video to H.264 and the quality is unbelievable! This is at full frame and full 30 fps, at 500Kbps. At the same settings with Sorenson 3, it came out into chunky bits.
Excellent! I purchased Sorenson 3 Pro and get terrible quality at 500Kbps at 30 fps. H.264 is way over due. Finally, a stock codec can deliver quality and a decent file size. I might even re-encode all my video clips to H.264 just to get back some free disk space even with the risk of losing some quality with the 2nd encoding pass.

I wonder how the speed of encoding H.264 compares to MPEG-2. Is it much slower?
 

AtHomeBoy_2000

macrumors 6502a
Feb 3, 2005
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anyone know how large a file would be using H.264 if the video was 20 minutes long at 180x120 with Mono audio?
 

Lacero

macrumors 604
Jan 20, 2005
6,639
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BornAgainMac said:
I wonder how the speed of encoding H.264 compares to MPEG-2. Is it much slower?
It's really slow. About 3-4 times slower than Sorenson 3 on a dual G5. On my PB 1.33Ghz G4, it is really, really slow. When Apple says you need a G5 to encode H.264, they weren't kidding.
 

sandman42

macrumors 6502a
Oct 23, 2003
957
59
Seattle
James Philp said:
What he said.
But I'm not sure of the second statement.
The statement: "Properly encoded mpeg4 will yield better quality than mpeg2 at the same file size" is true.

MPEG4 is a more advanced compression method than MPEG2, and gives you a better trade off of file size vs quality loss. If you were to compress your source video using the two standards down to files of the same size, MPEG4 would have better quality. If you compress both to comparable video quality, the MPEG4 file will be smaller. Make sense?
 

wirelessimports

macrumors member
Original poster
Mar 24, 2005
88
0
sandman42 said:
The statement: "Properly encoded mpeg4 will yield better quality than mpeg2 at the same file size" is true.

MPEG4 is a more advanced compression method than MPEG2, and gives you a better trade off of file size vs quality loss. If you were to compress your source video using the two standards down to files of the same size, MPEG4 would have better quality. If you compress both to comparable video quality, the MPEG4 file will be smaller. Make sense?

Does anyone know the ratio of what the compression rate is in comparison to the MPEG2? Like for example if a video file was 100MB in MPEG2 Format how many Megs would it be in MPEG4 if the quality was the same?
 

Catfish_Man

macrumors 68030
Sep 13, 2001
2,579
1
Portland, OR
wirelessimports said:
Does anyone know the ratio of what the compression rate is in comparison to the MPEG2? Like for example if a video file was 100MB in MPEG2 Format how many Megs would it be in MPEG4 if the quality was the same?
It's somewhat software dependent. Apple's MPEG4 implementation is really quite bad, from what I've read. Better encoders would get a better quality to bitrate ratio.
 

Fukui

macrumors 68000
Jul 19, 2002
1,615
6
vouder17 said:
Now where does AVI fall into..is that also mpeg 4 just a different breed. And another question will Quicktime 7 support more formats.. i have been looking for a link and apple's page but it is not to be found.
AVI is just a wrapper format. Just like Quicktime .mov.
Some quicktime files have MotionJPEG or some have sorenson or MP4,
in the same way AVI can have a MP4 or a WMV track too.
AVI is not as flexible as .mov or .mp4 formats, but it can carry MP4 video
and audio streams just like .mp4. If you see a .m4a or .m4v file then its the
pure stream without the wrapper format.

Quicktime can play .AVI just fine, but most DIVX (MPEG4) .avi files either use
WMA for the audio or VBRMP3 which AVI does not in its standard form
handle very well (VBR audio), which is why you see MS using .wmv files instead of AVI anymore.
 

petej

macrumors regular
Jun 9, 2004
132
0
MPEG2 is an encoding standard, there are a few different ways to package the encoded data.

MPEG4 defines a new type of file packaging that is very similar to the QuickTime file format. Like QuickTime and .avi's you have a choice of codecs you can use for the data within the MPEG4 container. Apple hyped up MPEG4 when it was released with QuickTime but you don't find too much video content encoded with the default codec. H.264 is the new high performance video codec that is part of the MPEG4 - Layer 10 specification (IIRC). AAC and HE-AAC are both audio codecs that are listed in parts of the MPEG4 specification.

What will lead to massive confusion in the future is media playback devices that claim support for MPEG4 such as eyeHome. Support for the container file is one thing but consumers will also have to know which codecs the device supports.
 

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