MP3 file format

On May 2, 2006, at 11:16 AM, Udo Huth wrote:

> What the heck is going on with MP3 files on the Macintosh????

Are you saying that you tried and these same files work correctly on
a PC?

Regards,

Howard

On 5/2/06 10:16, "Udo Huth" <u.hutht-online.de> wrote:

> What the heck is going on with MP3 files on the Macintosh????

Nothing. That's an application issue, not an OS issue. You'd be better off
asking what is *SoundJam* doing to your MP3's

--
John C. Welch Writer/Analyst
Bynkii.com Mac and other opinions
jwelchbynkii.com

On 5/2/06 11:16 AM, "Udo Huth" <u.hutht-online.de> wrote:

> Can anyone enlighten me about the format of MP3 files on the Macintosh? I have
> hundreds of files, some created with SoundJam MP, some not.
>
> There are some anomalies I notice. As defined the tags of an MP3 file ought
> to be at the end of the file. I now find files with an "ID3" header at the
> top of the file. This seem to originate in SoundJam MP as "SoundJam" is
> written into this header at at least two places. Some of these files have an
> MP3 tag at the end of the file, too.

ID3 tags are not a part of the MP3 file format (actually I'm not sure there
really is an official "MP3" file format beyond saying its a file with audio
encoded using MPEG I Layer 3). ID3 tags are defined by an "informal
standard."

http://www.id3.org/history.html

Tag location within a file seems to more a matter of convention than
anything:

# Q: Where is an ID3v2 tag located in an MP3 file?

It is most likely located at the beginning of the file. Look for the marker
"ID3" in the first 3 bytes of the file.

If it's not there, it could be at the end of the file (if the tag is
ID3v2.4). Look for the marker "3DI" 10 bytes from the end of the file, or 10
bytes before the beginning of an ID3v1 tag.

Finally it is possible to embed ID3v2 tags in the actual MPEG stream, on an
MPEG frame boundry. Almost nobody does this.

http://www.id3.org/faq.html

The Wikipedia entry also supports putting tags at the beginning of files to
be the more common practice.

http://en.wikipedia.org/wiki/Id3

I think inconsistencies in tag support between different programs are still
a problem. Perhaps it has been resolved in later versions but a few years
ago I discovered that album art added to files by MusicMatch (a Windows MP3
player) would not display in iTunes and vice versa.

> Some of these files display the proper info for artist, title, and album in
> the corresponding fields inside the play lists of SoundJam MP. Those who
> don't display the proper info in the fields can't be changed permanently.
> The info is updated in the playlist, but the file doesn't appear as changed
> in the Finder. When those files are added to another play list, the changes
> are gone. Even with MP3Rage it isn't possible to change the tag info and
> have it displayd in SoundJam MP.
>
> What the heck is going on with MP3 files on the Macintosh????

This sounds more like a question of SoundJam MP support rather than a
general Mac issue.

>> What the heck is going on with MP3 files on the Macintosh????
> Are you saying that you tried and these same files work correctly on
> a PC?

No, my files are not usable on a PC, as they lack the ".mp3" ending which
is not needed on a Macintosh -- at least with OS prior to OS X...
>
> Tag location within a file seems to more a matter of convention than
> anything:
>
Well, thanks for this info.

> This sounds more like a question of SoundJam MP support rather than a
> general Mac issue.
>
I thought SoundJam MP was a mature product as Apple bought it to make it
into iTunes.

Thanks to all who responded to my questions.

Udo

On 5/4/06 13:47, "Udo Huth" <u.hutht-online.de> wrote:

> No, my files are not usable on a PC, as they lack the ".mp3" ending which
> is not needed on a Macintosh -- at least with OS prior to OS X...

They aren't needed on OS X either. OS X now has more ways to id a file than
OS 9 did, and only one requires an extension.

Lacking the .mp3 extension doesn't make them unusable on Windows. It makes
them more tedious to use.

>
>> This sounds more like a question of SoundJam MP support rather than a
>> general Mac issue.
>>
> I thought SoundJam MP was a mature product as Apple bought it to make it
> into iTunes.

That's a myth. They bought the developers. Soundjam remained a separate
product for a year or so following iTunes


--
John C. Welch Writer/Analyst
Bynkii.com Mac and other opinions
jwelchbynkii.com


[ IIRC, the SoundJam code became iTunes, the developers went to Apple *and* SoundJam contined as an aborted product for a short while. I remember well the first few releases of iTunes incrementally removing features which had been in SoundJam -- listening to and broadcasting MP3 streams among them. -Andrew ]

On May 4, 2006, at 11:47 AM, Udo Huth wrote:

> No, my files are not usable on a PC, as they lack the ".mp3"
> ending which
> is not needed on a Macintosh -- at least with OS prior to OS X...

The .mp3 extension isn't needed with Windows, either. Right-click
the file's icon, select Open with..., and pick one you suspect will
play the file (it's likely to be a moderately long list). [This was
an action which Mac copied from Windows, I believe.]

   --John

On May 4, 2006, at 11:47 AM, Udo Huth wrote:
> or to OS X...
>>
>> Tag location within a file seems to more a matter of convention than
>> anything:
>>
> Well, thanks for this info.
>
for more information about tags, check out http://id3.org

John in San Diego

Tag location within a file seems to more a matter of convention than anything:

# Q: Where is an ID3v2 tag located in an MP3 file?

It is most likely located at the beginning of the file. Look for the marker "ID3" in the first 3 bytes of the file.

If it's not there, it could be at the end of the file (if the tag is ID3v2.4). Look for the marker "3DI" 10 bytes from the end of the file, or 10 bytes before the beginning of an ID3v1 tag.

IIRC, the first version of the ID tag was stuck on the end of the file so as not to confuse the software which at the time did not know anything about them. At the end, it just got ignored. Later versions of the tag "standard" decided it was better at the front.

iTunes has an option to convert a file to any version of the ID tag standard. Advanced/Convert ID3 tags... So if it is an issue for you, convert all your files to whatever version of the standard suits you.

David