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pretorious
(Just popping in)


Joined: 2006/10/12
Posts: 6

Posted on: 2006/10/12 5:19

AAC, MPEG-4/m4a, and YamiPod
I am completely confused!

The AudioCoding.com wiki entry for faac states that the iPod...

Quote:
...only reads MPEG-4 AAC LC bitstreams in the MP4 container with the file extensions *.m4a, *.m4b and *.m4p (but not the standard *.mp4 extension).

...and AudioCoding.com wiki entry for mp4 describes the .mp4 file extension:

Quote:
This is the global file extension for the MPEG-4 container format including all kinds of multimedia content...
In the context of audio compression MP4 normally means "MPEG-4 AAC" audio files that do not differ in sound quality from "older" MPEG-2 AAC files, because the raw bitstream is exactly the same, only the file headers are different (i.e. if they have been encoded with the same codec and the same settings)...But being a container format, an MP4 file can also contain an MPEG-2 AAC or even an MP3 bitstream.

The feature list on the YamiPod homepage states that...

Quote:
# mp3 and AAC files can be copied to/from iPod.

...but In the forum post "Cannot copy 1 or more .m4a files to ipod" - (2006/6/3) Tomas states ...

Quote:
m4a isn't fully supported.

Is AudioCoding.com wrong (i.e., Can the iPod play MPEG-2 AAC files?) or is the YamiPod feature list wrong?
yamipod
(Webmaster)


Joined: 2005/1/18
Posts: 793

Posted on: 2006/10/12 12:13

Re: AAC, MP4/m4a, and YamiPod
m4a are fully support by iPod but not by YamiPod.


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pretorious
(Just popping in)


Joined: 2006/10/12
Posts: 6

Posted on: 2006/10/12 22:02

Re: AAC, MP4/m4a, and YamiPod
The feature list on the YamiPod homepage states that...

Quote:
# mp3 and AAC files can be copied to/from iPod.


Quote:
yamipod wrote:
m4a are fully support by iPod but not by YamiPod.

So is the feature list wrong or does the iPod support MPEG-2 AAC?
yamipod
(Webmaster)


Joined: 2005/1/18
Posts: 793

Posted on: 2006/10/12 23:27

Re: AAC, MP4/m4a, and YamiPod
As long as I know AAC files aren't the same as M4A.


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pretorious
(Just popping in)


Joined: 2006/10/12
Posts: 6

Posted on: 2006/10/14 0:11

Moved
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pretorious
(Just popping in)


Joined: 2006/10/12
Posts: 6

Posted on: 2006/10/14 2:37

Re: AAC, MP4/m4a, and YamiPod
From the AudioCoding.com wiki entry for mp4:

Quote:
This is the global file extension for the MPEG-4 container format including all kinds of multimedia content... In the context of audio compression MP4 normally means "MPEG-4 AAC" audio files that do not differ... from "older" MPEG-2 AAC files, because the raw bitstream is exactly the same, only the file headers are different.
pretorious
(Just popping in)


Joined: 2006/10/12
Posts: 6

Posted on: 2006/10/14 12:35

Re: AAC, MP4/m4a, and YamiPod
From the AudioCoding.com wiki entry for AAC:

Quote:
AAC means "Advanced Audio Coding", and in the beginning it was also called MPEG-2 NBC for "Non-Backwards Compatible" as opposed to the MPEG-1 and MPEG-2 BC standards. It is considered to be the actual "state of the art" in general audio coding and the natural successor of MPEG-1/2 Layer III / MP3 in the multimedia standard MPEG-4 that uses MP4 as the container format for all kinds of content.

Profiles

Actually AAC comes in different "flavours" called Profiles (in MPEG-2) or Object Types (in MPEG-4) which make up a whole family of compressors that are not necessarily compatible to each other, especially for different players. See also the MP4 and FAAC pages in this Wiki for more informations on this:...

File formats

Several packaging methods exist for AAC/MP4 files that use different headers in the bitstream.

* MPEG-4 Systems audio stream, i.e. the MP4 container format.

So it might seem logical that one would interpret AAC to mean MPEG-4 AAC, no?
Ardwych
(Just popping in)


Joined: 2007/1/5
Posts: 7

Posted on: 2007/1/5 19:45

Re: AAC, MP4/m4a, and YamiPod
..Only three months since your syllogism, pretor.
Maybe the people in charge will help soon....

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