[Telynau]

I play music using an Apple MacBook (Intel Core 2 Duo Processor) with 2 gigs of memory, Wavelength Audio Cosecant Version 2.0 USB Tube DAC and a 250 gig LaCie hard drive (I don't use the MacBook hard drive for music). I rip my CD's onto the hard drive using Apple Lossless Compression (ALC) and a high end Plextor drive. I don't use the Apple for anything else other than playing music.

As I understand it, this setup allows me to read my CD's onto the hard drive in a "read until right" mode -- i.e., my Plextor drive reads the information on each CD as slowly as it needs to and as many times as it needs to in order to make a "perfect," error corrected copy of the CD on the LaCie hard drive. This is supposed to be a fundamentally different process than playing a CD on a CD player, where the player has to do error correction in real time (literally on the fly, as the read head flies over the CD) and where the error correction algorithms in the player (really the drive electronics) typically end up at least partially screwing up the music by adding information (subsequently processed by the DAC) which isn't right.

When I play a song on my rig, the iTunes player in my MacBook accesses the song on the LaCie hard drive and transmits it via the USB port to the Cosecant (with the USB controller and the Cosecant doing their own handshake and error correction). During playback, therefore, the song is subject to corruption by (among other things) uncorrected hard disk read errors.

All this is a long lead up to my question, which is whether performance can be further improved by playing songs out of the MacBook's 2 gig main memory rather than off the hard drive. This appears to be what the Rega Apollo and a few other players now do -- read the CD (Apollo) or hard drive (CD server) data into memory, do whatever error correction is necessary and then play the song out of memory.

Can this be done with the Apple or with a PC? I read somewhere that there is a setting in Foobar that will cause the PC to play the song out of memory rather than the hard disk. Is this so? Is there anything comparable for iTunes and/or Apple?

I am a music lover rather than a techie, so I am not stating any of the above as fact -- it is just my understanding and I state it only in order to pose my question. I welcome corrections.

It just seems to me that it would be better if music could be loaded into solid state memory from the hard drive, error corrected and then played out of memory rather than played directly out of a complicated electro-mechanical device such as a disk drive. I would also think that 2 gigs of memory would be plenty for this purpose -- certainly if nothing else was running on the Apple or the PC.

Regards, James

 

[wnmnkh]

There would be little..... well, let's say..... no difference.

 

[spongezone]

If I'm not mistaken, most if not all audio players will buffer a set time period into RAM before playing. If there are enough hard drive errors, you would likely hear a pause as the player trys to refill its buffer, rather than hearing errored audio. Another option if you're worried about errors is to use a codec with built in error checking, like FLAC. Then you'll know if you have hard drive errors significant enough to change your music (an unlikely scenario, unless your drive or filesystem is seriously messed up).

 

[werdwerdus]

yeah by defualt computers buffer the data to RAM before it's actually used by the application

 

[HFat]

Quote:

Originally Posted by Telynau /img/forum/go_quote.gif I read somewhere that there is a setting in Foobar that will cause the PC to play the song out of memory rather than the hard disk. Is this so?

Yes.

It's not going to improve audio quality with error correction or some such because this stuff is already taken care of by the hard drive.
However, it is useful in at least two cases:
-you have a laptop whose drive sometimes briefly stops working when you move it (and causes audio hiccups)
-your drive is mostly/only used to load music into memory in which case making it work less often might reduce noise (I'm not talking about noise in the signal but noise coming directly out of the drive)

You have a lot of RAM so you might want to try a more radical solution: loading the music in a RAM (virtual) drive. This might or might not be practical depending on your listening habits but there's no reason to use it all the time anyway. At least it'd work for all players. Most likely you'll have to ask a techie for help to automate the process (doing it manually is probably going to be too much busywork).

 

[jiiteepee]

If not mentioned already, just set the pre-buffer size big enough in your playback software to get undisturbed audio playback.

If you like to try RAMDrive/Disk software, there seem to be available these for both O/S (I'm using SuperDisk's RAMDisk Desktop System with success in W2k Pro system).

jiitee

 

[brokensound]

There should be no difference in sound quality. Anything you play on your computer will be buffered and stored on the RAM before use. If you want to try storing your music on ram, they have solid state hard drives. These drives are usually 2.5" form for the laptop, but should work fine with your desktop too. However the pricing makes it very expensive.

 

[thomaspf]

As the previous posters mention all audio is buffered in memory from the hard drive before it is played.

But here is a minor addition. Standard USB audio devices do not perform error correction on the link. They use a real time streaming connection with no error correction or retransmits over the USB bus. However, the error rate is low.

Cheers

Thomas

 

[diego]

Yes, foobar has a setting that lets you do that. However, I have tried and I can't hear any significant difference. I still use a 40 mb buffer just in case it helps prevent pauses in the audio stream because I use a USB transport. The truth is that hard drives are simply much better storage and play back devices than cd players.

Regards,
Diego

 

[jiiteepee]

Quote:

Originally Posted by thomaspf /img/forum/go_quote.gif ... But here is a minor addition. Standard USB audio devices do not perform error correction on the link. They use a real time streaming connection with no error correction or retransmits over the USB bus. However, the error rate is low. Cheers Thomas

I've read the error rate to be low especially in MAC/Linux systems. When the played data format is std wave, it should be quite harmless in any system. Even AC-3 format files might/should play well despite of error checkings done in decoder part (there are two CRC words used in data frames) but, I suppose that this is related to the selected property of the decoder implementation):

Quote:

Originally Posted by Digital Audio Compression Standard (AC-3, E-AC-3), Ch 7.3.x ... In some implementations it may be important that the decoder be able to benignly deal with (these) errors. Specifically, decoders may wish to ensure that (these) errors do not cause reserved memory to be overwritten with invalid data, and do not cause processing delays by looping with illegal loop counts. Invalid audio reproduction may be allowable, so long as system stability is preserved.

jiitee

 

[Telynau]

Thanks to all for the advice. Ever onward! Regards, James

 

[ted_b]

Telynua,
Great subject. I don't know, there are many new players and devices, like the ridiculously priced Nova Physics Memory Player ($10k to start), that espouse reading music off of flash drives rather than spinning HD's. Seems to be some merit, or at least worth investigating further. Those folks who've commented that they can't hear it....where did you hear "it"...pc speakers, internal soundcard source, where?

I am also looking at Mac (never touched one yet in my life) to be my music server, even though I currently really like Foobar, SSRC at 24/96 and FLAC with Cue files (all Windows proprietary). The MAc environment has been proven to be significantly quieter, less cluttered and less, well, kludgy than the Windows world. Since I'll be sending this precious signal to my very hi-end music room, I think these subtle changes really add up. i'll be borrowing one of Gordon's USB Bricks for my eval, but will likely end up with a Cosecant (or Crimson if I my will gets too weak).

Keep on asking and investigating....lemme know what you find, and I'll do the same.

Ted

 

[Mr00000]

When I first saw this thread, I got a little worried that we'd have another Patrick82 on our hands. *whew*

Please don't take this as an insult, Telynau; memories from Patrick82 still disturb my nightmares.

But, on topic, I don't believe that human ears would be able to discern a difference between playing from ram or HD. Actually, in most cases, I believe that the HD would buffer to ram before a song plays.

The only thing that any settings would have an effect on are what HFat mentioned.

 

[ted_b]

Quote:

Originally Posted by Mr00000 /img/forum/go_quote.gif But, on topic, I don't believe that human ears would be able to discern a difference between playing from ram or HD. Actually, in most cases, I believe that the HD would buffer to ram before a song plays. The only thing that any settings would have an effect on are what HFat mentioned.

You state this likes it a well-known fact. Several audio companies out there are looking at flash-loaded music servers due to the investigations that hard drives may have significantly more jitter than flash memory. Not that THAT's a fact either, but it's clearly being investigated. The Nova MP claims that it accounts for a large part of their $10k value prop (excessive case scenario). Anyway, I'm not dismissing it like so many here on this thread are. I can't believe you've all a/b'd it. That would be very unusual, all these very early adopter/pioneering types on one thread at the same time.

 

[Febs]

Quote:

Originally Posted by ted_b /img/forum/go_quote.gif You state this likes it a well-known fact. Several audio companies out there are looking at flash-loaded music servers due to the investigations that hard drives may have significantly more jitter than flash memory.

How could "hard drives have significantly more jitter than flash memory"? At what point in the process of transferring data from either a hard drive or flash memory into a RAM buffer is there the opportunity for introduction of "jitter"?