A Beginner's Guide to Computer Audio

[Lee]

Friends,

I recently gave a very basic (too much so for some of you I imagine) talk on computer audio to the AV Club of Atlanta. Here is a link to the slides:

http://www.mediafire.com/?3ecwdh8gaptjl1t

I hope this may be useful to some of you. For more advanced users the dCS Guide written by Chris Connaker is the best I have found so far.

Lee

P.S.

There is one change I need to make. You can do 24/192 over USB2.

 

[ted_b]

Lee, with proprietray USB drivers on USB2.0 you can do 32/384 (M2tech Young DAC inhouse) and up to 5.6Mhz (Playback Designs forthcoming MPS-3).

 

[Lee]

Lee, with proprietray USB drivers on USB2.0 you can do 32/384 (M2tech Young DAC inhouse) and up to 5.6Mhz (Playback Designs forthcoming MPS-3).

Thanks Ted. At that level you are at DSD quality in my opinion.

 

[ted_b]

Lee, well at least DXD (24/352). Some say DXD is equivalently as resolving as DSD128 (with 24/176 being equivalent to DSD64) but I'm not sure really. It sounds great, but the selections aren't exactly my cup oif tea all the time.

 

[Lee]

I have not had experience with DXD buit based on my recording I still think DSD is more natural than 24/176 although that is the rate I record at.

 

[Vincent Kars]

I do think dCs guide is not very clearly written concerning USB.

You can set USB to isochronous transfer.
This is a kind of 'soft' realtime mode used for AV streaming.
? Guaranteed access to USB bandwidth.
? Bounded latency.
? Stream Pipe - Unidirectional
? Error detection via CRC, but no retry or guarantee of delivery.
? Full & high speed modes only.
? No data toggling.
http://www.beyondlogic.org/usbnutshell/usb4.shtml

In this transfer mode you can have 3 types of endpoints
Synchronous
The clock is directly derived from the 1 kHz frame rate.
Adaptive
in this mode the clock comes from a separate clock generator (usually implemented as a PLL referenced by a crystal oscillator) that can have its frequency adjusted in small increments over a wide range. A control circuit (either hardware or firmware running on an embedded processor) measures the average rate of the DATA coming over the bus and adjusts the clock to match that. Since the clock is not directly derived from a bus signal it is far less sensitive to bus jitter than synchronous mode.
Asynchronous
In this mode an external clock is used to clock the data out of the buffer and a feedback stream is setup to tell the host how fast to send the data. A control circuit monitors the status of the buffer and tells the host to speed up if the buffer is getting too empty or slow down if its getting too full.
http://www.thewelltemperedcomputer.com/KB/USB.html

In your guide I should focus on adaptive and async only.
The guaranteed bandwidth is for the USB only. It is not guaranteed that the processor will feed the USB hub in time (drop outs)

Slide7: dbPoweramp for ripping? Faster and easier to configure then EAC
Slide 14: WASAPI? (automatic sample rate switching in Win)
Slide 17: You mean lossless Compression?
Slide 18: You say USB 2 & 3 but this are the general USB specs.
USB audio class 1= 24/96 (runs on USB1= 12 Mb/s)
USB audio class 2=24/192 (runs on USB2 in high-speed mode= 480 Mb/s)

Maybe a bit about Tagging?

Good guide.

 

[Lee]

Good points Vincent. I appreciate the feedback.

 

[Morbius]

For more advanced users the dCS Guide written by Chris Connaker is the best I have found so far.

Lee,

Thanks. The dCS Guide is very well written. I can see where people who are not familiar with
computer communication protocols might have a hard time with this guide. Therefore, the
admonishment, "for more advanced users" is appropriate.

Greg

 

[microstrip]

This is really a beginner question: how can I convert a track from a CD in a .wav file? I have the free version of MediaMonkey.

 

[amirm]

This is really a beginner question: how can I convert a track from a CD in a .wav file? I have the free version of MediaMonkey.

Use Windows Media Player. Go into Tools->Options->Rip Music and under Format, select "WAV(lossless)."

 

[Vincent Kars]

This is really a beginner question: how can I convert a track from a CD in a .wav file? I have the free version of MediaMonkey.

Probably something like Tools > Rip CD and choose the format in the dialog.
Do observe that due to a lack of standards tags in WAV have a very poor portability
http://www.thewelltemperedcomputer.com/KB/WAV_KB.htm

If you plan to rip you're entire collection, I recommend dbPoweramp
http://www.thewelltemperedcomputer.com/SW/ripping.html

A bit more about ripping: http://www.thewelltemperedcomputer.com/KB/Ripping.htm

 

[Johnny Vinyl]

I use MediaMonkey Gold and rip my CD's as FLAC files directly. Am I missing something by not using EAC as a ripper?

 

[Vincent Kars]

I’m inclined to say probably not.
Today’s ripping programs when set to secure do a good job most of the time.
Rippers like EAC or dbPoweramp offers AccurateRip as an extra.
The result of your rip is compared with those of others.
An additional safeguard.
My personal preference is dbPoweramp
- Fast
- Easy to configure
- Multiple tag sources
- AccurateRip

http://thewelltemperedcomputer.com/KB/Ripping.htm

 

[Johnny Vinyl]

Thank you Vincent! I am not the most literate when it comes to computers, so I think I'll stick with the easier route and continue using MediaMonkey Gold. I can always explore other options if I ever become more digitally educated.

PS: I love your site by the way. I'm always recommending it to others. Well done!

 

[FrantzM]

John

EAC and dbPoweramp are eminently easy to use... While I am not sure that a few bits of difference between the ripped files and the CD are audible, the perfectionnist in all audiophiles would be very happy to have a confirmation that the ripped fies are identical to those in the CD .. AccurateRip provides you with that confidence and EAC is free with dbPoweramp about the same price as media Monkey (I think) ... Vincent's site is mandatory education for anyone interested in Computer AUdio so go there often .. Clean simple and truly informative with no pretense ... whats's set this site apart is the no-nonsense approach ...No quackery there ...

 

[Johnny Vinyl]

Hi Frantz,

I suspect that once I have everything in place (mid-June) I'll be messing around with various programs, and now that you've confirmed the ease-of-use with EAC and dbPoweramp, I'll likely try them out. In fact, I do believe I have the EAC program already. What media player are you using? I want to try J-River Media, as I've heard good things about them. Any comment?

 

[garylkoh]

I use MediaMonkey Gold and rip my CD's as FLAC files directly. Am I missing something by not using EAC as a ripper?

John, as long as it works for you, MediaMonkey and FLAC will get you there. I don't think that with currently available implementations, there is any difference in sound between FLAC and WAV. I used to think so when I first started using a music server 8 years ago, but no longer. Rippers also made a lot of difference then, but IMO no longer.

I do hear some differences between J.River, MediaMonkey and Foobar but it may be due to some secondary effect and/or optimization. If you're not an expert, sticking to what you have gives you far more time to listen to music. No need to monkey around with computer hardware/software

 

[amirm]

I recently did an ad-hoc test for reliability of rips. I ripped on multiple machines, including a nearly 10 year old box. I tested new discs and old. I ripped multiple times and did a binary compare. I could not find one instant of rips being different.

I also spent many hours searching online trying to find anyone who had shown rips to not be the same using standard techniques. That also left me empty handed.

So while a rip that is not accurate can have serious issues, the probability of it happening seems exceedingly small based my research above.

BTW, I did my testing in "non-secure" mode. And per above, still couldn't get it hiccup.

 

[Johnny Vinyl]

John, as long as it works for you, MediaMonkey and FLAC will get you there. I don't think that with currently available implementations, there is any difference in sound between FLAC and WAV. I used to think so when I first started using a music server 8 years ago, but no longer. Rippers also made a lot of difference then, but IMO no longer.

I do hear some differences between J.River, MediaMonkey and Foobar but it may be due to some secondary effect and/or optimization. If you're not an expert, sticking to what you have gives you far more time to listen to music. No need to monkey around with computer hardware/software

Thanks Gary! That saves me a few bucks as well, which I can use for music instead!

 

[garylkoh]

Amir, try the same thing using different CDs. If you used a high-quality CD (may be one from FIM) and there are no scratches, there will be no difference. C1 errors are corrected by reconstruction. I no longer have the files, but when I first started doing this in 2004, I had copies of the same disc ripped from various CD-ROM drives that had different results. When I published the first copy of the Black CD White Paper, some readers called me out on that, and I sent them the files. There were less than a dozen samples different on those tracks.

One of the discs which I showed these errors on was so badly pressed that you can see right through the disc (the reflective aluminum layer was far too thin). Another had scratches.

With dBPowerAmp and AccurateRip, I find that most of the CDs I buy these days rip quickly and accurately, there are very few CD which require a second or third pass. If it doesn't clear the second or third pass, the disc is probably unreadable.