uploading regular md audio: transcoding losses?

[fishbpm]

Hi,

I refer to the administrator (kurisu)'s posted digital/analogue soundcard input solution to "how to upload regular md audio" below

It's all covered here: http://forums.minidisc.org/index.php?showtopic=7070

But doesn't this, by defacto, mean the ATRAC3 is transcoded to whatever codec is used by the software associated with the soundcard (which is very likely not atrac3?). Or is there software available that can avoid transcoding using a digital I/O soundcard?

I had come to believe that transcoding should be avoided at all costs, but now I;m not sure

Would it be better to digi-copy the older md content over to a hi-MD and then upload via the built-in hiMD functionality?

This would definitely retain the native ATRAC3 format. Plus there would be no need to manually set recording gain thus removing the risk of clipping and gain loss.

I;m not sure about comparative costs/logistics between digital I/O soundcards and hi-MD recorders.

What does everyone else think?

cheers

[greenmachine]

For a (close to) bit-perfect decoded copy you'd need a recording device without level control or with defeatable l.c. at the digital-in. I use(d) a NJB3 for this job to record the decoded 44.1khz 16bit Windows pcm (*.wav), upload to the 'puter and encode to *.flac for storage.

[fishbpm]

ok I think I get it...

youve replicated the source by recompressing with a lossless codec

Which means the resultant file size [flac] must be much larger than the source file size [atrac3]?

Which isn't what I had in mind - obviously the larger file contains a pile of effectively useless data (ie. data additional to the original atrac3 encoding)

I wanted a bit-perfect copy by keeping native atrac3 (I have a LOT of data!)

So therefore Im trying to avoiding any transcoding and was wondering whether using soundcard made this possible....

or whether it necessitated uploading by creating an intermediate hiMD copy.

again this is on the assumption that "transoding is BAD"? Now Im not even sure about this...

so now Ive probably totally confused everyone!

For a (close to) bit-perfect decoded copy you'd need a recording device without level control or with defeatable l.c. at the digital-in. I use(d) a NJB3 for this job to record the decoded 44.1khz 16bit Windows pcm (*.wav), upload to the 'puter and encode to *.flac for storage.

[greenmachine]

Upload in its compressed form ain't possible with MDs in standard mode (SP, MONO, LP 2/3/4). All you can currently do is a realtime re-recording of the decoded data.

[dex Otaku]

Any methods of copying from SP / LP2 / LP4 recordings on legacy MDs involves decoding the audio to PCM.

If you copy the analogue route - your player convert ATRAC or ATRAC3 audio to PCM, then to analogue, then recording on your computer converts analogue back to PCM.

If you copy using a deck with optical output, it still converts to PCM, and whatever you record with records -that- PCM directly.

As greenmachine said, there is no way to copy from legacy MD without the audio being decoded.

[Sparky191]

AFAIK any transfer of a lossy source file, you can do to another format will involve passing it through a decoder/encoder, or transcoding it at some point. You can't avoid it.

[fishbpm]

AFAIK any transfer of a lossy source file, you can do to another format will involve passing it through a decoder/encoder, or transcoding it at some point. You can't avoid it.

Hmmm.

atrac --------------(realtime)----> PCM -----------------(codec compress)----> atrac/atrac3

[legacy MD] ----(soundcard)----> [pooter or hiMD] -------(sonicstage?)-----> [pooter]

I am wondering why the above is not possible?

Firstly, to be clear I assume the PCM file is effectively the atrac file "padded out" with redundant data (ie. meaningless or at best replicate bits inserted into the atrac data stream)

Therefore I would have thought that REcompressing the resultant PCM file would not involve transcoding to any noticeable degree since the compression algorithm is very close to the original (atrac) algorithm.

I;m making some assumptions here about current sonicstage (or similar?) sony encoding software. ie. do the latest atrac codecs differ markedly from the original atrac codecs on legacy MDs?

At the end of the day I just want my trax to sound like they do now, but reside on my PC in compressed format (ie. comparable to MP3 filesize)

ok where's my mistake??

newfish

[dex Otaku]

Hmmm.

atrac --------------(realtime)----> PCM -----------------(codec compress)----> atrac/atrac3

[legacy MD] ----(soundcard)----> [pooter or hiMD] -------(sonicstage?)-----> [pooter]

I am wondering why the above is not possible?

Firstly, to be clear I assume the PCM file is effectively the atrac file "padded out" with redundant data (ie. meaningless or at best replicate bits inserted into the atrac data stream)

Therefore I would have thought that REcompressing the resultant PCM file would not involve transcoding to any noticeable degree since the compression algorithm is very close to the original (atrac) algorithm.

...

ok where's my mistake??

Your mistake is in your assumptions about "padding out". When ATRAC [or atrac3 or atrac3plus] audio is played back, first it's converted back to PCM, then it's put through D/A conversion.

Data does not just get "padded out" to fit over the SP/DIF pipe. It gets decoded to PCM. That means any loss from the first pass of compression is part of that PCM.

Any further encoding incurs a further loss.

I just wrote about this is another thread [also by you], so see there:

http://forums.minidisc.org/index.php?showtopic=13231

To clarify one thing: to my knowledge, only 3 lossily-compressed formats are regularly used over SP/DIF [coax or optical digital connections]: DTS [which can be as high in bitrate as full 16-bit 48kHz PCM], AC3 [aka dolby digital], and MP2 [common on European DVDs]. All of the above are transmitted over SP/DIF by setting a flag which denotes the data as other than standard PCM; decoders that don't understand the data will either decode as silence or as pseudo-random noise.

I have never heard of ATRAC of any form being transmitted over SP/DIF, though there were at one point professional MD drives that could copy data directly to computers. These cost several thousand dollars per drive, and AFAIK no longer exist.

[fishbpm]

Thanks Dex,

I just wrote about this is another thread [also by you], so see there:

Yeah sorry bout that. Dropped the ball on that other thread a bit... but I did believe you both times!

The reason Im asking all these (difficult?) questions is:

My objective is to move my entire MD collection onto a harddisk player for my daily use - preferably in a uniform format (I would also retain a hard-drive archive copy but thats just incidental).

This is just so much easier than having to handle hundreds of MDs and offers much greater functionality..

Hence my desire to use a compression codec (maximise portable capacity).

So based on your other useful comments (below).......>

Recompressing the PCM it into *any* lossy format will incur another generation of loss; basically, you're taking the first lossy compression pass and applying more lossy compression to it.

While the loss in quality isn't that significantly noticeable by the majority of people until several generations of loss have been applied [the original patents for ATRAC refer to something like, 'high-quality data reduction that can survive several passes without losing quality']

......I am keen to try recompressing the PCM file.

Which brings me to my final problem:

Choice of (recompression) codec directly impacts my choice of hard-disk player. If I recompress using Sony's atrac codec I MUST buy a Sony player.

To be honest I would rather not be 'forcibly devoted' to SOny in this way. There at least 10 or 15 other excellent hard-disk players that I would least like the opportunity to consider

So here is the crux (well crux #2 it seems!)..

Is it reasonable for me to assume that recompression using Mp3 (or other "industry standard" (ie. not Sony) codec) will give me noticeably worse results than recompressing with atrac?

Since you;ve said (see below) that the first PCM pass "reconstructs" the whole bitstream, is the choice of recompression codec really that important? Or does my original concern about "avoiding transcoding" still apply?

Decoding ATRAC to PCM converts the lossy data into an uncompressed format by reconstructing the whole original signal - minus the parts that lossily compressing it in the first place threw away.

All this info is determining my fate with respect to Sony (the one and only, but preferably not under duress! )

newFish

[Sparky191]

I think this such all be qualified by saying transcoding can give you poor results. But if you can't hear the difference does it really matter. (it would to be me I wouldn't do it) However a lot of opinions on SQ are subjective, so it really up to you to decide whats acceptable to you.

However its important to note that in the future you may be come more demanding and transcoded, or low bitrates may no longer be acceptable. So it a form of future proofing to try and achieve the best SQ from the start. However if in the future you decide you need to recode your library, to improve SQ, perhaps for a favorite album etc. You can always keep the original files on MD as a backup.

Personally I think and MP3 encoded with LAME and high quality preset settings (theres many different possible settings - all hotly debated) can equal the quality of ATRAC. But perhaps create slightly larger files to achive the same SQ. While ATRAC has it advantages, its a proprietary format like Apples' iPod only ACC format. MP3 is much more widely supported, and is a good compromise between SQ and size. Many people choose to archive from the original source as lossless, FLAC or WAV as this allows you recode without transcoding. But it does means you need a huge amount of disk space.

Another point to note is that on a modern computer it doesn't take long to rencode a CD. So you could easily do 100+ in an afternoon. Retagging is a pain, but it would only take a few hours. The effort required to record in realtime 100+ MD's, split the tracks, recode them, and tag them is huge. You'd be literally months doing that. When you consider you could pick up 2nd hand CD's for very little. You have to compare the time + cost of both methods. Of couse if your MD's are primarily live recordings, then you've no other option. But the quality encoding from CD is excellent, and you have the CD's as backup.

I started recording and encoding my cassettes and the time and effort involved just wasn't worth the results. Now I'm picking up 2nd CD's when I can, and only recording the best and/or the rarest of the cassettes.

Edited November 24, 2005 by Sparky191

[fishbpm]

MP3 encoded with LAME and high quality preset settings (theres many different possible settings - all hotly debated) can equal the quality of ATRAC.

Yes thanks I understand but my situation is slightly different since my source recordings are all atrac, NOT wav (albeit they will be "decompressed" to PCM as necessitated to enable upload).

While I have also read volumes on the relative merits of atrac vs mp3 etc, I am trying to establish whether the fact that my recordings originated as atrac3 therefore strongly favours the use of atrac for recompression.

The effort required to record in realtime 100+ MD's, split the tracks, recode them, and tag them is huge. You'd be literally months doing that.

Yes Ive been there!

That's why I am considering the hi-MD option (ie. copying over to hi-MD then using hiMD built-in upload). But Im not sure whether any metadata (ie. track markings) will be transferred this way either. Even tho they are both MD players and both made by Sony Ive been lead to believe the legacy MD output can only be received as a purely analogue signal.

I'm still not conviced as to what is or is not possible with hi-MD in this regard

fish

[A440]

Just forget about "uploading" anything off your MDs or "copying" to Hi-MD. Can't be done. Not with Hi-MD, not with anything else. The Sony brand doesn't help you here.

The best you can do, if you get a Hi-MD unit, is to put your original discs in the Hi-MD and record the tracks onto your hard drive in real time. You can find a NH600D for under $100 that will have the USB connection.

Marcnet's Hi-MDRenderer--and I'm so happy to know about this! Marcnet continues to rock!--will let you connect via USB to control the unit and get metadata, and to separately record each track into your computer via soundcard-in as an analog input. It's automated and a time-saver. It is realtime, it is analog, and your computer will need a line-in input. Griffin iMic, M-Audio Transit, whatever.

That's the solution I would use.

If you want the slight quality improvement of all-digital, you can record from the optical-out of your deck and in through the M-Audio transit (or other optical input). No Hi-MD unit necessary. But you won't get metadata and you'll have to edit.

Those are your choices.

To get every bit of information off the disc, record in PCM. A 74-minute disc will give you a full CD's worth of audio files, so you could just burn the files to a CD that would be playable or rippable to MP3. Alternatively, you could convert to a lossless format (.flac) and burn two MDs to one CD. It won't play in a CD player, but you could do computer playback or rip to your hard drive or portable player.

Dbpoweramp, available in Downloads, converts just about everything back and forth.

It doesn't matter that the originals were recorded in Atrac. The originals are now just source material, and they could just as well be LPs or cassettes or answering-machine recordings.

To compress again, I'd suggest mp3 with Alt-Preset-Extreme so you get good quality but escape from Sony's alternate universe. ATRAC won't be any better. Once you have mp3 files, whatever player you eventually get will be compatible.

Edited November 24, 2005 by A440

[Sparky191]

Yes thanks I understand but my situation is slightly different since my source recordings are all atrac, NOT wav (albeit they will be "decompressed" to PCM as necessitated to enable upload).

Yes but you're recording them to WAV. (ATRAC >>>WAV) So it doesn't matter that they were once ATRAC. Unless you some technical information that proves otherwise. You're still transcoding it once you encode the WAV to something else.

While I have also read volumes on the relative merits of atrac vs mp3 etc, I am trying to establish whether the fact that my recordings originated as atrac3 therefore strongly favours the use of atrac for recompression.

It doesn't make any difference. Other than you'll be putting them back into a proprieterty format again, and likely have the same problem again in a year or so. Which doesn't make sense. Also you're missing my point. I was replying on this post.

Is it reasonable for me to assume that recompression using Mp3 (or other "industry standard" (ie. not Sony) codec) will give me noticeably worse results than recompressing with atrac?

If its done right there shouldn't be any difference.

Yes Ive been there!

That's why I am considering the hi-MD option (ie. copying over to hi-MD then using hiMD built-in upload). But Im not sure whether any metadata (ie. track markings) will be transferred this way either. Even tho they are both MD players and both made by Sony Ive been lead to believe the legacy MD output can only be received as a purely analogue signal.

I'm still not conviced as to what is or is not possible with hi-MD in this regard

You've answered your own question. You can only record them back in real time, regardless of which player you use. The HiMD have the advantage of USB playback though. I guess it depends on how important SQ and the cost of your time is.

Edited November 24, 2005 by Sparky191