ATRAC Advanced Lossless?

[Abby Normal]

I know Wikipedia isn't the end all of references, but it's handy--so I'll quote it here (emphasis is mine):

ATRAC Advanced Lossless (AAL) is the latest update to the codec family. It can provide compression for a CD music source at approximately 30-80% that of the original size without any quality loss.

ATRAC Advanced Lossless is one of the very few audio codecs in the market that can provide scalable compression. It records both the information of ATRAC3 and ATRAC3plus, the residual information that ATRAC3 or ATRAC3plus eliminated from original signal. The ATRAC3 or ATRAC3plus data can be extracted just as it is, or the eliminated information can be added to perfectly reproduce the information on the original CD. In other words, ATRAC Advanced Lossless only requires storing one type of data, eliminating the need of data recompression and allowing the file size to be smaller than uncompressed or compressed versions of the same file. Benefits of scalable compression include providing excellent backward compatibility as well as faster transfer speed between portable audio devices and PC.

If I convert some tracks to AAL 352kb, how far the does backwards compatibility go? Does making the encoding rate that high make it less backwards compatible or is the format layered such that older units would still be able to play a version of it?

Please don't speculate--answer only if you know. Preferably, I'd like to hear from people who have a wide enough range of units to try (or have already tried) this. Don't forget to format your disc as MD.

Thanks.

Edited July 3, 2009 by narp

[sfbp]

So far I'm very impressed with AAL. In addition, SS rips to AAL much much better than it rips to PCM, which I can hardly believe is an accident. I reported all this a couple of weeks back.

Another thing, it's never encrypted. So you can go from AAL to almost any format you can think of and the result will be good. It's very close to ATRAC (though I am not as au fait as I would wish with the mechanics of the transformation, but I am learning slowly as I basically watch the guys on the linux-minidisc effort), so seems to have many of ATRAC's benefits.

(added: the point about non-encrypted is that it is a better candidate for an archival format than any other SONY codec).

[Abby Normal]

Okay, so I've done some tests. Apparently it is layered with an LP2 track. So, to answer my own question is that the unit must at least support MDLP. Am I missing anything? Keep in mind that my question is where can you play an AAL disc with any particular MD unit and not whether you can convert it to anything else via Sonic Stage.

Okay--so I'm a little slow. Let me know if I have this right. There is no minidisc device that can play AAL, only the LP2 layer it encapsulates. However, the information is still present and if you chose to you could take that disc and import it into SonicStage and jump to other low-loss or lossless formats (such as PCM, high-bit-encoded mp3, ogg, etc) and end up with a higher quality result than if you were to only transport a strictly LP2 recording.

Am I catching up?

Edited July 4, 2009 by narp

[sfbp]

Okay, so I've done some tests. Apparently it is layered with an LP2 track. So, to answer my own question is that the unit must at least support MDLP. Am I missing anything? Keep in mind that my question is where can you play an AAL disc with any particular MD unit and not whether you can convert it to anything else via Sonic Stage.

I think you can go from AAL to almost any Atrac3 or Atrac3+ bitrate and the result will be as good as if you went straight from CD and SimpleBurner to the same destination.

Clearly there is a problem with making SP disks, however 256k and 352k are much better than LP2, so should sound great (however you seem to want LP2 as the compatibility base, and I agree with you, LP2 is "good enough" most of the time). However the linux-minidisc crowd now have an SP codec for ffmpeg, and this will make it possible to generate *real* SP disks from the PC. Not sure how soon, but soon, I think.

In addition, I bet if you burn a regular CD from the AAL file (or from wave files that you regenerated from AAL) that you won't be able to tell the difference from the original CD (that's kindof what Sony and Wikipedia both claim in the description). I haven't tried this, and I cannot try it right now. Sounds like a test.....

LP2 is mentioned because it is the "first" lossy format (SP is just about non-lossy, that is you can go from SP back to CD - I have been doing this for the last 7 years and is why I got into all this to start with). Because it saves all the information it threw away then the 3+ formats are covered too. Clear as mud? (I have been struggling with this, and it's only since my discovery about the bad PCM ripping that I have ?realised the true benefits of AAL).

[Abby Normal]

It's not that I want LP2 as a compatibility base, it's just that is what SonicStage seems to be layering with the lossless track. Maybe I'm doing something wrong. I have an idea what the problem might be though. I wanted this disc to be playable on a non-HiMD unit. Maybe SonicStage will only use LP2 when importing a CD into AAL while in NetMD (vs. HiMD) mode.

Edited July 4, 2009 by narp

[sfbp]

I don't think it cares what mode the MD is in when it's ripping from CD.

[Abby Normal]

I wouldn't have thought so either (I felt kinda funny posting that when I posted it, too). I am doing some more experiments.

I don't think it cares what mode the MD is in when it's ripping from CD.

[pata2001]

There are 2 components of AAL, the lossless part, and the lossy part.

When you rip to AAL, Sonicstage will compress the audio into AAL, AND an Atrac version based on the bitrate you choose.

When you transcode the AAL audio file into another format, Sonicstage does NOT transcode the lossless version, but the Atrac lossy version. This can be easily observed when you rip from CD to AAL and picked the lowest Atrac bitrate (eg. 48kbps). Any subsequent transcoding done to any Atrac bitrate will only sound as good as the lossy part (in this case, 48kbps).

This made AAL pretty much useless for an intermediate lossless source, unless you have devices that can play AAL natively.

If your target is LP2, for best result, is to rip in AAL + 132kbps.

Or simply rip the CD to WAV, encode them to LP2, backup the WAV somewhere and delete it from your machine to save space. Anytime you need re-encoding, simply encode from the backup WAV file.

Edited July 4, 2009 by pata2001

[sfbp]

That makes perfect sense. Of course the file is much much smaller. In my comments I was assuming the largest file size, ie 352kbps bit rate.

So in your experience, if you rip at the highest rate will it transcode ok to the lower ones? Or not.....

However "simply rip the CD to WAV" absolutely doesn't work, on my system. You can tell - it takes so little time to grab the CD track there must be a catch. Avrin says there's some stuff you can detect with VLC and configure when using EAC, but I am very suspicious of the fact that Sony doesn't give you a quality option on CD->WAV but does give one for AAL and other lossy formats.

If I go CD->PCM 1411 (using SonicStage) and then try to generate LP2, I get a mushy mess, consistently. I almost gave up on compressed formats the first week I owned the RH1 (my first portable), and it was almost a year before I figured out that LP2 was decent in its own right.

[Abby Normal]

So, the bottom line is there is no such animal, correct? AAL isn't nearly as neat as I thought it was. What I'm observing is when doing the transfer to MD, SonicStage is consistently exercising its "second-option"--to convert to LP2 rather than transfer the AAL. The description would have you believe that the AAL file will be accepted by the MDLP compatible device and it ignores the lossless component of the file. I understand now, though--they intended it to be a convenient way to store two different qualities in the same file--on your computer, not your media player. With today's processing power and low storage costs that's become largely irrelevant. You can store everything in PCM and convert when you need to.

This made AAL pretty much useless for an intermediate lossless source, unless you have devices that can play AAL natively.

Edited July 4, 2009 by narp

[sfbp]

You can store everything in PCM and convert when you need to.

Except for one small thing... don't use SonicStage to import the PCM from your CD disk.

But it should still work pretty well to go from 352 to 132, n'est-ce pas? I have done that, and it sounds just great, way better than SonicStage-imported PCM, and as good as SimpleBurner or direct Optical In recording at LP2. So if you can afford the space, rip to 352. Then you can transfer to HiMD or MD as you choose.

Or rip to 256k AAL, maybe? That's something I haven't yet tried.

Also I don't hear someone definitively saying that the special information is discarded when you transcode from the saved AAL to a lower bitrate format.

Sorry for belabouring this point, as it is something I would like clarity on myself, and as you say the given explanation is far from clear.

[pata2001]

However "simply rip the CD to WAV" absolutely doesn't work, on my system.

Anybody who is concerned about quality will use a secure CD ripper like EAC. It has a quite steep learning curve to configure, but it's the gold standard of quality CD ripper. Rip the CD to WAV using EAC, and simply have Sonicstage encode the WAV to whatever Atrac bitrate you want as needed.

I understand now, though--they intended it to be a a convenient way to store two different qualities in the same file--on your computer, not your media player.

Pretty much, although I can argue whether it is really convenient or not.. I think any recent NW series Walkman (Japan only models, as usual) do support playback of AAL natively.

[kino170878]

Clearly there is a problem with making SP disks, however 256k and 352k are much better than LP2, so should sound great (however you seem to want LP2 as the compatibility base, and I agree with you, LP2 is "good enough" most of the time). However the linux-minidisc crowd now have an SP codec for ffmpeg, and this will make it possible to generate *real* SP disks from the PC. Not sure how soon, but soon, I think.

This sounds great, so will we be able to transfer SP tracks from the PC to 1GB Hi-MD discs thereby getting 5 hours of SP audio on one disc?

[sfbp]

This sounds great, so will we be able to transfer SP tracks from the PC to 1GB Hi-MD discs thereby getting 5 hours of SP audio on one disc?

Sure, you can get them there. But you won't be able to play them back

[kino170878]

Sure, you can get them there. But you won't be able to play them back

But the Hi-MD unit can play SP if it is recorded by the unit itself. I thought cbmuser said that if the hardware side can support it then the software will be able to do it too. So why can't it work?

Edited July 19, 2009 by kino170878

[sfbp]

For the same reason that if you put a DVD with MP3's on it into a DVD player that recognises CD's with MP3's on them, the player won't play it. Silly (I have one DVD player that it works with and another make that doesnt do it), but a matter of the player's own firmware. Here, you have a codec that Sony had no intention of supporting under HiMD formats, namely - SP -

[Abby Normal]

It's a shame that the firmware in HiMD devices aren't flash upgradeable. Imagine having something akin to Rockbox on an RH10 or RH910 (for their larger displays).