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Topic: What is the difference between these audio formats?

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Old 12-15-2004, 12:38 PM
#1
 
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What is the difference between these audio formats?

Hello,

What is the difference between these audio formats?
.mp4 (MPEG-4/AAC)
.m4a (MPEG-4/AAC)
.aac (MPEG-2/AAC)

Which one should i use?

I found some extra information about them but i am new to this so i can't really take any conclusions about it.

.mp4 (MPEG-4/AAC)
MPEG-4/AAC encoded audio written to MP4 container.
Metadata is written in ISO 8859-1 character set.

.m4a (MPEG-4/AAC)
Same as MP4 (MPEG-4/AAC), except the metadata is written in UTF-8 character set.

.aac (MPEG-2/AAC)
Raw MPEG-2/AAC audio file format.
Metadata is written to ID3 and ID3V2 tags.

Can you explain to me and advice me which one should i use?

Thanks,
Miguel
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Old 12-15-2004, 01:53 PM
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I don't know about the technical differences but if it's for an iPod you need to use the .m4a files that are produced by iTunes.




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Old 12-15-2004, 03:58 PM
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I think it's like this (I threw in some extras in case you're curious):

.mp3 - MPEG Audio Stream, Layer III
.mp4 - MPEG-4 Video File
.m4a - MPEG-4 Audio Layer of MPEG 4 video files
.m4p - Protected AAC File (purchased from iTMS)
.aac - MPEG-2 Advanced Audio Coding File

On the subject of .aac, I found this tidbit here:

http://www.m4a.com/
Quote:
What are .AAC files? Should I save files with the .AAC file extension or .M4A?
AAC stands for Advanced Audio Coding and is the "backbone" behind both the MPEG 2 and MPEG 4 audio file formats. MPEG 4 Audio files contain (have encapsulated in them) AAC audio streams. Basically .AAC files are audio files that are not contained in a MPEG 4 Audio container file. They are the raw "building blocks" that are used to make up M4A/MP4 files. The use or distribution to others of .AAC files is not recommended as there is not a "tagging standard" for them. Based on the opinions of audio professionals we have received, you should always save your MPEG 4 Audio files in a container file and use either the .m4a or .mp4 file extension. Plain audio .AAC files are not designed to contain song/album information like .m4a files can. Many players (such as Nero, Apple iTunes, iPods) will refuse to play .AAC files. To avoid these problems, always save your audio files to .m4a or .mp4 format instead.
Interesting.

Cheers.



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Old 12-15-2004, 04:05 PM
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Strange thing.

So when in iTunes i rip to AAC i am actually ripping to m4a?

So why is the file extension aac?

And what files are used in iPod?

Know i am getting confused. LOL

Cheers,
Miguel
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Old 12-15-2004, 04:26 PM
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Well,

i just ripped a music in 3 formats using the most complete rip program i know:

Easy CD-DA (www.poikosoft.com)

I used 3 file tipes:
.mp4 (MPEG-4/AAC)
.m4a (MPEG-4/AAC)
.aac (MPEG-2/AAC)

The last one didn't read in iTunes. Only the first two ones.
See what i mean?

So iTunes calls AAC to m4a?

This is very strange.

Cheers,
Miguel
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Old 12-15-2004, 04:36 PM
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The MP4/M4A dual file extension thing is confusing. The thing to remember is that M4A files will always contain only MPEG 4 Audio. MP4 files can be used for MPEG 4 video files, combined video and audio files, or just plain MPEG 4 audio.

It is recommended that you use the .m4a file extension rather than .mp4 on your audio files.

.aac files are raw building blocks and will not be readable by iTunes/iPod devices. This extension should not be used at all.

Think of M4A as a nice wrapper that contains an AAC file in it as well as other details such as standard ID3 tag info etc...

Hope that helps.

So - bottom line - use the M4A file extension for your audio files.



[shabbs]

iPods: 4G [40GB, 20GB] + 2G iPod Touch [16GB]
iPod audio: Sony MDR-EX71SL + MDR-V600 headphones, h/k go + play
MP3: EAC 0.99pb4 [secure] w/ Lame v3.98 [-V 0]
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Old 09-21-2011, 11:29 PM
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