Computer audio discussion

[Cogito]

What is better about jPlay?

See page#4 in this tread.

[DaveR]

I don't buy the timing thing. If the PC couldn't keep up with the DAC you'd know it. From the PC's perspective music is slow, easy to keep up with it. My primary listening PC doesn't do anything except play music. The PC I listen to the most is in my work area. It usually has 10 plus programs running and is busy doing stuff all the time. I don't have any issues with bits not getting to the DAC in time. The music is being pulled of another computer over my network, no issues. In the end you're better off giving the DAC more than it needs and refreshing the buffer in time so it doesn't under run. I can't imagine a real time synchronous data stream to a DAC would work well. My guess is it really isn't doing anything real time, just like any other player.

[Cogito]

If the PC couldn't keep up with the DAC you'd know it.

Timing is/was never a consideration in regular operating systems. That is why people are talking about real-time Linux OSs. Programs like jPlay try to dedicate all resources to itself to get to as close to real-time operation as possible.

For example, in redbood, amplitude information has to reach the dac every 0.0226 milli-seconds precisely. About half that time for 24x96kHz PCM. If the info doesnt reach the DAC precisely in time, the resultant analog wave will be slightly different than what is represented in the digital data.

Anyways, you can try it out jPlay yourself and post your observations. It takes 10 mins to download and setup. Use "Hibernate" mode.

[Grover Gardner]

Okay, I got AP-Linux installed and running. I can't connect to it from the rest of my network but I was able to get some sample albums loaded and playing back through Cantata. It sounds brutally analytical in my system, to the extent that I wonder if I did something wrong. I've tried a dozen or more different players on Windows, Mac and Linux and none of them sound as harshly spotlit as this. I like the detail and the openness, but there's no bloom or sweetness to the music. I wish Snakeoil had a bit more of the precision I hear with AP-Linux but I find it far more analogue-like and engaging to listen to. I'll poke around in the forum and see if there's some way to get it to relax a bit.

[Cogito]

I dont have the harshness issue. I guess it is system dependent.


This from AP-Linux messages board:

If you want to configure mpd in mpd.conf – use Cantata standard configuration! This is very important, because if you use the “basic” configuration option – mpd.conf will not have any influence on Cantata.

AP V4 sound is very sharp, focused and detailed.
If you want to make it a little bit thicker and warmer – add format “*32:*” to your device configuration in mpd.conf. (if you have 32bit capable DAC) The difference is subtle, but noticeable.

[DaveR]

If the PC couldn't keep up with the DAC you'd know it.

For example, in redbood, amplitude information has to reach the dac every 0.0226 milli-seconds precisely. About half that time for 24x96kHz PCM. If the info doesnt reach the DAC precisely in time, the resultant analog wave will be slightly different than what is represented in the digital data.

USB audio, as with all USB data, is sent in packets - it is not synchronous. The requirement for precise timing on the source end is limited to ensuring the packets are sent in time for their arrival at the DAC before the DAC needs the data. You can dedicate all resources on the PC to delivering the audio data if you like, but there is no benefit if the PC can do whatever else it is doing and still deliver the audio data to the USB port in a timely manner.

[DaveR]

Okay, I got AP-Linux installed and running. I can't connect to it from the rest of my network but I was able to get some sample albums loaded and playing back through Cantata. It sounds brutally analytical in my system, to the extent that I wonder if I did something wrong. I've tried a dozen or more different players on Windows, Mac and Linux and none of them sound as harshly spotlit as this. I like the detail and the openness, but there's no bloom or sweetness to the music. I wish Snakeoil had a bit more of the precision I hear with AP-Linux but I find it far more analogue-like and engaging to listen to. I'll poke around in the forum and see if there's some way to get it to relax a bit.

Is AP-Linux using an ASIO, or other bit perfect, driver to deliver bit perfect data to the DAC? Does what you're comparing it to deliver bit perfect data? I'm assuming at least one does not or they would both sound the same.

[Grover Gardner]

They both use MPD as the player and ALSA as the driver. As far as I know it's bit perfect but I'll have to run some checks to see. But resampling wouldn't account for this, in my experience. Maybe it's more revealing of...something...in my system but if's that's the case, I'm not sure I want to know!

[Grover Gardner]

I dont have the harshness issue. I guess it is system dependent.


This from AP-Linux messages board:

If you want to configure mpd in mpd.conf – use Cantata standard configuration! This is very important, because if you use the “basic” configuration option – mpd.conf will not have any influence on Cantata.

AP V4 sound is very sharp, focused and detailed.
If you want to make it a little bit thicker and warmer – add format “*32:*” to your device configuration in mpd.conf. (if you have 32bit capable DAC) The difference is subtle, but noticeable.

Thanks, I'll try that, though I'm not sure if my DAC will take 32 bits. I'll check the MPD configuration as well.

[Cogito]

If it doesn't work, I can bring over the AK4497 DAC one day. Some CDs have harshness in the upper treble. With this DAC harshness is gone, with more details. Now, I am able enjoy "non-audiophile" sources.