forums.ps2dev.org

Zak · Joined: 16 Aug 2005 Posts: 3

Hi there,
as far as I can tell nobody has figured out yet how to create AT3 files with atrac3+ inside.
Is it off-limits to discuss the file structure of those files here?
I've made some observations and only need a little help but if AT3 reverse engineering isn't wanted here I'll respect that.

Thanhda · Joined: 09 Apr 2005 Posts: 331 Location: Canada

what do you mean? you want to create at3 files. or convert at3 files to playable audio on the pc? creating it has been done already. you just need sound forge and the at3 codec.

http://forums.ps2dev.org/viewtopic.php?t=2178&highlight=at3
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PspPet · Joined: 30 Mar 2005 Posts: 210

Sony ATRAC3 music play includes two parts,

The ATRAC3/ATRAC3Plus audio codec. This is ok to talk about. There are limited technical resources that can be found on the net. Also the PC codec which can be used to decode and create .AT3 files.
Apparently AT3 format files needed by some games are not so easy to convert.

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The other part of "ATRAC" is the Sony DRM for copy protected songs.
Talking about how to use Sonic Stage to copy the DRM protected files is ok [although not a developer question - so don't ask here ;-]
Talk about the file format details and how the DRM works is not ok.

Zak · Joined: 16 Aug 2005 Posts: 3

There is no atrac3+ codec available. What Thanhda refered me to is the atrac3 codec which has a much lower quality.

I'll let you know what I know about AT3 files (with atrac3+):
They have the usual WAV-header (Riff, fact, ...) and they come in two different versions: on has the SMPL chunk, the other doesn't.
What's interesting is that - unlike any other codec embedded in WAV - they use a FACT chunk of 8 bytes instead of 4. This chunk can be used for codec specific information, in this case it's apparently a code for the number of samples that were in the original file.

I managed to play a few files by injecting their data section into an OMA file created with SonicStage. There is also a converter that renders them to normal WAV files.

I believe it would be interesting to figure out how to play them on PSP without libatrac3plus. And how to make those files. Don't forget that they are the PSP's native format like SID is for C64. However given that the only sample files we have are from the ripped games or the sample disk, I guess discussing it further is against the rules of this forum.

If anyone could point me to a place where I can find help on this matter, please let me know.

zabbyh · Joined: 15 Jul 2005 Posts: 13

i used a program called goldwave to convert any mp3/wma i had to wav and encoded using the Atrac3 codec, then renamed to.at3 and put it into a game to test it and it worked. I uploaded the tutorial on www.alucard.cc i think. Check it out if you want

PspPet · Joined: 30 Mar 2005 Posts: 210

> Don't forget that they are the PSP's native format like SID is for C64
Hopefully regular ATRAC3 (not plus) is good enough for the game previews and other things that require .AT3 files.
For cases where you want higher quality (like listening to music), the PSP does play back MP3 files.

My general advice for people exploring ATRAC3 for their music is that the hassles aren't worth it (dealing with DRM, SonicStage, stick incompatibilities etc). Encode a slightly larger MP3 will get you similar audio quality for listening.
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If interested in the details of the ATRAC3/ATRAC3Plus codecs, quality of the compression etc, that's getting beyond the scope of this BBS
http://www.minidisc.org, http://www.minidisc.org/aes_atrac.html

Because of the narrow focus (a Sony proprietary file format), and the fact there is a free codec (ATRAC3 not plus) I don't believe anybody has bothered to go any further to reverse engineer the format. If you want to continue down that path, you may be the first.
BTW: I've seen some comparisons of audio quality in testing, and ATRAC3/Plus is certainly better bit-for-bit than MP3, but not as good as OGG and other more recent codecs. Take it with a grain of salt, like any of these tests

Stellar · Joined: 12 Dec 2005 Posts: 48

i dunno if this has been posted somewhere else on these forums, but i had a hard time finding it. I just wanted custom splash music and found the second post from this page. i built it into my eboot and it works. converted an mp3 to atrac3 :D. tho i wouldnt use that format in a game, its good to make it look polished.
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Torch · Joined: 28 May 2008 Posts: 842

Reviving an OLD topic but...
Can't you extract the Atrac3Plus data from a file that has been made using SonicStage?

There is an OMA/OMG source filter installed which allows other applications to open these files. The data is then decoded to PCM by a filter called OMG TRANSFER.

You can use SonicStage to create AT3+ OMA files, and dump the data from the OMA and put it in a WAV-AT3.