Difference between MP2 and MP3 and how much space each takes?

[BCinSC]

I've seen specs claim that a 4GB iPod can hold 1000 songs. I believe that's MP3s. I have someone else telling me 1GB per 10 hours of MP2 compressed audio at 44,100hz/16bit/stereo. Do those statements roughly equal each other?

 

[Spike]

Well, first off ipods don't play MP3's, they play AAC's which is a newer and supposedly better compression form over mpeg-3. AAC is actually mpeg-2 AAC or mpeg 4 AAC depending on it's quality. mpeg-4 AAC is supposed to be better than mpeg-2 AAC in terms of sound quality and file size. I believe mpeg-2 plain is video only, not an audio compression scheme.

In my opinion, AAC's don't sound any better than MP3's on your standard headphones, computer speakers, and lower-mid end home audio systems. Maybe when you get to the higher end it is better, but at my price range MP3 is the same.

I am not sure about the size comparisions as all formats have different quality levels that you can change. For example I rip audio at 192 Kbps MP3, which means that a 3 min song takes roughly 4.32 MB 1GB/4.32 = 231.5 songs per GB x 4 = 926 songs in 4GB.

If you record at a lower rate MP3 like 128Kbps, then you can fit 1389 songs in 4GB. The other formats such as AAC and WMA have quality levels that can be changed so space taken up per song would change as well. Hope that helps!

-spike

 

[BCinSC]

What kind of overhead does DRM add?

 

[ribbon13]

Are you considering an iPod or do you already have one?

If you want really quality the Rio Karma can play FLAC and Ogg

 

[Baked]

Originally posted by: Spike
Well, first off ipods don't play MP3's, they play AAC's which is a newer and supposedly better compression form over mpeg-3.

Bwhahahhahahahaha... *catches breath* Bwhahahahahhahaha... That's the funniest thing I've read today. Let's check iPod specs and see what they say -

Audio

* Up to 25 minutes of skip protection
* Frequency response: 20Hz to 20,000Hz
* Audio formats supported: AAC (16 to 320 Kbps), MP3 (32 to 320 Kbps), MP3 VBR, Audible, AIFF, Apple Lossless and WAV
* Upgradable firmware enables support for future audio formats

Originally posted by: BCinSC
What kind of overhead does DRM add?

Nothing. Apple iTunes Music store sells 128bit AAC w/ DRM.

 

[Jigglelicious]

Well, first off ipods don't play MP3's, they play AAC's

Uhh, what planet are you living on? iPods play mp3's just fine.

 

[Dennis Travis]

Baked, that is what I was going to say. Yes the Ipod will play MP3's just fine. MP2 I doubt it and even if it would the quality would not be that good.

 

[BCinSC]

But if MPEG-2 is primarily video, which includes audio, how could it not be that good for audio alone? I mean aren't 99% of DVD's recorded in MPEG-2? I thought MPEG-3 was higher compression, but lower quality?

 

[BCinSC]

Linear PCM / MP2 / MP3 / ADPCM

 

[RaiderJ]

We know at least one iTunes sucker!

 

[batmanuel]

Originally posted by: BCinSC
But if MPEG-2 is primarily video, which includes audio, how could it not be that good for audio alone? I mean aren't 99% of DVD's recorded in MPEG-2? I thought MPEG-3 was higher compression, but lower quality?

Hold on. You might be confusing a few terms. MPEG-2 is the compression standard for video files. MP3 is a audio compression format for the audio component of those files, hence the full name: MPEG Layer 3. The first people that started compressing music into MP3s just took the compression technology in the MPEG specs and built a stereo audio file format out of it, but the basic technology is the same as that used to store the audio compnents of the MPEG-2 files. (Which is why practically every DVD play out there can play MP3s on a CD as well as DVD movies).

Notice on the page how the term MP3 can become bit of a misnomer, since Layer 3 only corresponds to the lowest bitrate (around 128kpbs) and Layers 1 and 2 are defined as higher bitrates in the original spec. Thus a 192kbps-encoded MP3 file is technically an MP2, not an MP3. The term "MP3" has become so all-encompassing, though, that any bitrate of MPEG audio file is called an MP3 now, so there is no point to really use the MP1 and MP2 terminology anymore since it only confuses matters.

 

[Auric]

There is no MPEG-3. MP3 is MPEG-1 Layer 3, which is almost a decade old. The sooner MPEG-4 supplants 1 & 2 in both audio and video, the better. Actually, the latter has been in use for at least six years (pre-finalized) but has had little official raison d'etre while SD-DVD (MPEG-2) has reigned.

 

[BCinSC]

Thank you for those clarifications. That's why I love these boards so much. So, what do y'all think of these people and what they are offering for making my own radio station?: BSI and what about their audio cards - unclear if it's PCI, PCI-X or PCIe, since says PCIx, but Dell systems they use are PCIe

BTW, if there's no MPEG-3, then why is there MPEG-4?

 

[ribbon13]

no MPEG-3 so it wouldn't be confused with the rampant word 'mp3'?

 

[ViRGE]

Originally posted by: BCinSC
BTW, if there's no MPEG-3, then why is there MPEG-4?

MPEG-3 was going to be the original HDTV spec, but it was scrubbed when engineers realized MPEG-2 with modifications would work just as well.

 

[imported_CromsDog]

I am an the IT Director for a cluster of 6 radio stations in south carolina. All of our audio files are encoded in an mpeg layer2 format for storage. I'd have to check the bitrate to be sure but i think it is somewhere around 192 to 256 Kb/s. Audio quality at this rate is comperable to CD, trust me we have enough audiophiles in the building to let us know. The file names show up as .WAV's but that is becase of the wrapper on it. The only thing we are using the AAC format for right now is ISDN codec feeds. Please lord don't let anyone at corporate decide we need to start converting all files to a smaller "better" format to save space cause dude I ain't got the time.

 

[SickBeast]

Originally posted by: Spike
In my opinion, AAC's don't sound any better than MP3's on your standard headphones, computer speakers, and lower-mid end home audio systems. Maybe when you get to the higher end it is better, but at my price range MP3 is the same.

LAME alt-preset-standard MP3s sound better than AAC files encoded at 192kbps according to listening tests I've read. I can't say the same for MP2's, but your opinion is definately somewhat justfied.

To use lousy sound equipment as an excuse to encode poorly is silly. Chances are down the line you'll have better equipment, unless you're an eternal pessimist.

 

[BCinSC]

Originally posted by: CromsDog
I am an the IT Director for a cluster of 6 radio stations in south carolina. All of our audio files are encoded in an mpeg layer2 format for storage. I'd have to check the bitrate to be sure but i think it is somewhere around 192 to 256 Kb/s. Audio quality at this rate is comperable to CD, trust me we have enough audiophiles in the building to let us know. The file names show up as .WAV's but that is becase of the wrapper on it. The only thing we are using the AAC format for right now is ISDN codec feeds. Please lord don't let anyone at corporate decide we need to start converting all files to a smaller "better" format to save space cause dude I ain't got the time.

Why mpeg layer2 format and not layer3?