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Old 22nd January 2012, 01:08 PM   #961
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The "momentary" frequency says what it means :-)

Based in the rate feedback, the host (PC) changes its freq momentarily to keep feeding the samples to the widget accordingly to the widget's clock.

So the PC will be sending samples NOT exactly at 44100 but near it and will vary from moment to moment :-)

Alex
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Old 22nd January 2012, 03:17 PM   #962
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Quote:
Originally Posted by alexlee188 View Post
The "momentary" frequency says what it means :-)

Based in the rate feedback, the host (PC) changes its freq momentarily to keep feeding the samples to the widget accordingly to the widget's clock.

So the PC will be sending samples NOT exactly at 44100 but near it and will vary from moment to moment :-)

Alex
fine, something like that was what I thought it should be...
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Old 23rd January 2012, 02:37 PM   #963
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Quote:
Originally Posted by oneoclock View Post
I do not know, in Linux MPD server, how to configure a resamplig and a memory playback from a WAV file.
192000 resampling is even better. Playing the file from memory may be better.
resampling should be easy, check the config file. I guess you just need to set:

Code:
audio_output_format            "192000:24:2"
samplerate_converter           "Best Sinc Interpolator"
for what regards playing from memory, I'm afraid that can't be done without modifying the MPD source code.

On the other end, the easiest way to do some test to verify whether doing so would really be useful, is to play directly from the command line, using a simple script. Some time ago I had prepared a few ones exactly for this purpose. Check here:

www.audiofaidate.org - Con Linux sulla via del cMP²

the relevant script is this one:

Code:
#!/bin/bash

# copy specified files into the RAM-disk
#
declare -a playlist
i=1
for file in "$@"; do
   cp -v "$file"  /dev/shm/
   playlist[$i]="/dev/shm/`basename "$file"`"
   let i++
done

# play files from RAM-disk (with online upsampling)
#
schedtool -a 0,1 -R -p 10 -e \
sox -S -V3 --single-threaded --combine sequence "${playlist[@]}" \
 -t alsa -b 32 hw:0,0 \
 gain -3 \
 rate -v -I 192000

# clean-up the RAM-disk
#
rm -vf "${playlist[@]}"
save it as "mplay.sh" (or whatever you like), make it executable (chmod +x mplay.sh), and use it as follows:

./mplay.sh /path/to/some/audio_files/*.ext

edit: of course, the script supports all of the file formats supported by "sox" (thus usually including flac, wv, wav, etc). The use of "schedtool" to apply real time scheduling to the play process is optional (it can safely be omitted). You may want to play with schedtool options to see whether that makes any difference. And of course you may want to play with SOX options too.
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Last edited by UnixMan; 23rd January 2012 at 02:58 PM.
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Old 23rd January 2012, 03:17 PM   #964
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Quote:
Originally Posted by UnixMan View Post
resampling should be easy, check the config file. I guess you just need to set:

Code:
audio_output_format            "192000:24:2"
samplerate_converter           "Best Sinc Interpolator"
Thanks Unixman. I'll try.

I do not know whether Linux resampling will improve the sound, depends on the quality of the resampler. With most card and Windows programs is often worse with resampler.

The resampler Pure Music is excellent, but the Mac's own resampler is almost as good with changes in OSX and iTunes at the beginning of last year.

Several DAC with Hiface on MAC I have measured better background noise: 1.5 dB from 44 to 48 and another 1.5 dB to 92, does not improve to 192.

With Audio Widget on MAC I think have a progressive improvement up to 192 . In WindowsXP I could only test 44 to 48 with Foobar2000 and SoX and also seems to improve slightly.
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Old 23rd January 2012, 03:51 PM   #965
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Resampling in MPD is done using libsrc (that is the famous "Secret Rabbit Code", one of the best available algorithms).

On the other end, using the suggested script you'll be using SOX, thus you can use any of the several algorithms (and settings) supported by that powerful software. With the suggested options (rate -v -I) you'll be using the best sox algorithm (which is one of the absolute best ever) using "Intermediate phase" settings (which is what I subjectively like most for listening). You can change options to use whatever setting you like. From the command line sox offers way more options than using the limited Foobar SOX plugin.
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Old 23rd January 2012, 04:11 PM   #966
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Thanks unixman!
I checked recently if ramplayback sounds better on my machine with the widget, and yes, unfortunatly it does. Someone has to talk the programmers into building it in mpd!
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Old 23rd January 2012, 10:10 PM   #967
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With MPD an option to try could be "live stream" mode, that is receiving the data stream through the network instead of having MPD read it from a disk file. That way the stream may also be upsampled on the stream source (if so desired), off-loading the local CPU from that heavy task. I have never tried that though, not even well checked the required setup details.
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Old 23rd January 2012, 10:16 PM   #968
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Quote:
Originally Posted by UnixMan View Post
With MPD an option to try could be "live stream" mode, that is receiving the data stream through the network instead of having MPD read it from a disk file. That way the stream may also be upsampled on the stream source (if so desired), off-loading the local CPU from that heavy task. I have never tried that though, not even well checked the required setup details.
What I tried is having the music-dir on an external server (via nfs) and copying the music-dir on a ramdisk. Both options sound better, but need some scripting or a 2nd computer.

Rüdiger
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Old 24th January 2012, 12:14 PM   #969
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Quote:
Originally Posted by Onvinyl View Post
What I tried is having the music-dir on an external server (via nfs) and copying the music-dir on a ramdisk. Both options sound better, but need some scripting or a 2nd computer.
interesting. Thus it looks like direct HDD access is a possible source of problems. Either the noise produced by the HDD and/or the IRQ processing are possible suspect.

Have you tried reading from an external (USB/FW/eSATA) HDD powered from its own, external PSU?
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Old 24th January 2012, 12:26 PM   #970
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No, I didn't. I plan to test SSD's in the future, though.

Since the client/server model is the one i will implement on a permanent base, I will eventually test network vs. ram-playback, but I believe the differences will be to small to notice (at least to me).

Rüdiger
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