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Mp4? (1 Viewer)

DavidBelis

Agent
Joined
Jan 15, 2003
Messages
47
I know this might be an very ignorant question, but do mp4s exist?

Because I've heard this name mentioned before. I know that there are MP2 and MP3s (obviously), but I had never heard of MP4s.

If so, then how's their sound quality? How do they differe from MP3s? Also, are there any MP4 players in existence (software or hardware).

I'd appreciate some information regarding MP4 files (assuming they're not just some sort of hoax)

Thanks.
 

Ken Chan

Senior HTF Member
Joined
Apr 11, 1999
Messages
3,301
MPEG-1 uses the same three Layers, so it's probably safer to call it just "MPEG Layer-3 audio". The MPEG-2 flavors add really low bitrate and multi-channel support, but that's not what most people are using. So:

MPEG-1: video and audio, VCDs. VCDs use Layer-2 audio, not Layer-3.
MPEG-2: video and audio, DVDs, SVCDs, and HDTV. Note that DVDs are HDTV do not use MPEG audio! DVDs use PCM, Dolby Digital, and DTS, HDTV uses DD. (And SVCD uses Layer-2.)
MPEG-3: originally MPEG for HD, but turned out to be unnecessary, folded into MPEG-2; no such thing
MPEG-4: video and audio, even better compression, but requires more horsepower to encode/decode. DivX (the codec, not the Circuit City thing; the guys that come up with these names should be slapped around) is a variant.

Next is... MPEG-7 (dunno what happened to 5 and 6).

MP1: no such thing
MP2: no such thing
MP3: MPEG Layer-3 audio
AAC: Advanced Audio Coding, different and better than MP3; used by satellite radio, and can be used with MPEG-2 and MPEG-4.
MP4: There is an MPEG-4 Audio standard, a progression from AAC, but I dunno if people have started calling it "MP4" -- or whether they should. Don't you think it's confusing enough? :)

//Ken
 

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