Ultimate sound quality in MPD

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Ultimate sound quality in MPD

Postby bbest » February 12th, 2017, 4:34 pm

Hello!

Wanted to maximize sound quality from MPD. It sounds really good, but not equal to wtfplayer (uwtfplayer). Last one sounds more delicate with nice vocal.
For maximize quality I read several articals like this:
http://www.symphonic-net.com/kubotayo/a ... .html#need
http://mubox.voyage.hk/realtime_kernel
1) my config includes rows:
audio_output {
type "alsa"
auto_resample "no"
auto_format "no"
auto_channels "no"
replay_gain_handler "none"
mixer_type "none"
priority "FIFO:99"
...
}
realtime_option {
memlock "yes"
stack_reserve "1024"
heap_reserve "10240"
main_priority "OTHER:0"
player_priority "FIFO:50"
decoder_priority "FIFO:47"
update_priority "OTHER:0"
}

2) used Debian stretch branch with kernel 4.8.15
3) kernel with RT patch, Fully Preemptible Kernel (RT)
4) MPD also patched with RT patch
5) installed rtirq-init script to turn IRQ latency
6) used tsc clock
7) used command "chrt -f -p 80 `pgrep irq/27-xhci_hcd`" for USB 3.0 card, which connected to Amanero on my DAC

MPD work in terminal mode on HTPC + used Ethernet interface. All control used from remote PC, from Cantata client.
Could I do something else to be close to uwtfplayer in sound quality? May be patch MPD for cut-off some useless features for my purpose?
bbest
 
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Joined: February 12th, 2017, 2:42 pm

Re: Ultimate sound quality in MPD

Postby max » February 13th, 2017, 8:09 am

Your configuration suggests that you're not using MPD, but some weird fork. I can only help you if you use the official MPD.

After you've switched to official MPD, follow the instructions on https://www.musicpd.org/help/ and read the manual section on bit-perfect playback.

Once you have achieved bit-perfect playback, it is impossible to improve sound quality further. If you then still believe another software has better quality, that's just superstition. There's a lot of superstition and charlatanery involved with self-proclaimed "audiophiles", so that wouldn't be a suprise to me.
max
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Re: Ultimate sound quality in MPD

Postby bbest » February 13th, 2017, 4:55 pm

Thanks for answer max!

Of cause I know about bit-perfect. But wanted to make one step after bit-perfect. I have high level sound equipment: HiFiman HE-6 + balanced beta22, DAC END-R ES9018 v2.With this could hear difference between cheap USB cable and AudioQuest Diamond USB.
Used 20.4 version of MPD (latest one). As described here http://www.symphonic-net.com/kubotayo/a ... .html#need , used RT kernel and RT mode of MPD (https://onedrive.live.com/?cid=CE384832 ... 8DA832!105) .
As I see there are 4 process:
- main
- update
- player
- decoder
First two don't need any attention, so RT priority could be 0. But last two very important: player, decoder. Don't want to share priority between each of them. Could MPD decode portion of audio file to memory and after that send with RT priority=99 (player thread) to irq FIFO of USB device (in my case Amanero)?
bbest
 
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Joined: February 12th, 2017, 2:42 pm

Re: Ultimate sound quality in MPD

Postby max » February 13th, 2017, 5:24 pm

bbest wrote:With this could hear difference between cheap USB cable and AudioQuest Diamond USB.

We can stop the conversation here. Because I consider this superstitious bullshit.

Bit-perfect is bit-perfect, and unless you have unrecoverable transmission errors (which would lead to larger problems), any USB cable has the exact same quality.

Sorry, go somewhere else to ask for help. I can't help with your superstition. But maybe I'm wrong - and in any case I'm the wrong guy to ask.
max
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Re: Ultimate sound quality in MPD

Postby bbest » February 14th, 2017, 7:42 am

Thats ok, nothing wrong.
Only one question. Let suppose one scenario:
1) decoder unzip portion of audio file, for example 100Mb to memory
2) decoder thread sleep until output buffer is not empty
3) player send raw data to FIFO USB -> Amanero
4) when buffer of raw data near empty size, decoder awake and decode next portion of data from audio file
For decoder and player threads resposnsible src codes in
mpd-0.20.4\src\decoder
mpd-0.20.4\src\player
directories.
Could you suggest which files must be changed for increasing/decreasing size of buffer raw data (before sending to FIFO of USB devices) ?
bbest
 
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Joined: February 12th, 2017, 2:42 pm


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