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Old 20th July 2014, 10:50 AM   #61
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Question MPD tinny audio with 16-bit files

I've been investigating the 'MPD tinny sound with 16-bit files' issue. I think it comes down to period_size being too low.

When MPD plays a 16-bit FLAC file the following hw_params are used:
Code:
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 90
buffer_size: 22050
When the same file is played with aplay using:
Code:
flac -d <16bit-flac-file> -c | aplay -
I get:
Code:
access: RW_INTERLEAVED
format: S16_LE
subformat: STD
channels: 2
rate: 44100 (44100/1)
period_size: 2048
buffer_size: 32768
With mpd (both mainline and my version) the music sounds tinny, with aplay it sounds good.

Any thoughts?
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Old 29th July 2014, 11:57 AM   #62
miero is offline miero  Czech Republic
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lintweaker: sorry, I've missed your post...

in the mpd.conf there is following line:

# BOTIC fixup: request the lowest period time
period_time "1"

you can try to increase it for increasing period size

but I think the easier solution (for now) is to force 32 bit output using

format "*:32:*"
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Old 2nd August 2014, 12:04 PM   #63
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Exclamation alsa patches for mainline

Hi Miero,

ALSA tools/libs etc 1.0.28 are out but are still limited to 384kHz. I think it would be a good idea to post your patches for 768000 support. There is now a even a affordable mainstream DAC/headamp combo (iFi micro iDSD) available which supports PCM 768k and DSD512.

If you do not have the time, I won't mind picking this up.
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Old 3rd August 2014, 04:14 AM   #64
miero is offline miero  Czech Republic
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Lintweaker, the patch for ALSA requires also kernel support. I'll write to alsa-devel next week.
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Old 4th August 2014, 11:15 AM   #65
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Having taken delivery of a BBB I installed from meiro's website the 'as is' Botic distribution yesterday - no problems encountered so thanks for the efforts there.

Over the last few weeks, in anticipation of the Botic cape appearing I've been thinking about how I will control the solution. My preference is a UPnP/DLNA solution and I've been happily using BubbleUPnP as a control point for a while now.

On a couple of Raspberry Pi based renderers I use I've recently switched to Volumio 1.4 as it includes a UPnP/DLNA capability that routes music through to the mpd-based Volumio player. This works very well. I reasoned that conceptually the Botic and Volumio solutions are similar, being customised/optimised Debian distributions so I investigated the Volumio UPnP module;

An UPnP Audio Media Renderer based on MPD

I installed upmpdcli on my BBB by following the install instructions for the Raspberry Pi on the Downloads page and, hey presto, I appear to have a functioning BBB with Botic software and UPnP functionality; I say appear to have because I haven't actually got any audio output kit hooked up to the BBB so I can't hear the ouput but BubbleUPnP sees the device, serves flac files to it and reports playback progress and on the BBB the activity LEDs suggest things are happening.

As UPnP/DLNA is an obvious and established approach to controlling the Botic I thought this might be of interest to others; perhaps someone can give it a listen too?

If there is sufficient interest in this approach it might even be worth including it, or something similar, in the Botic distribution to provide 'out of the box' control functionality as with the Volumio solution?

Cheers

Ray
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Old 4th August 2014, 12:20 PM   #66
twluke is offline twluke  Japan
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Quote:
Originally Posted by nautibuoy View Post
Having taken delivery of a BBB I installed from meiro's website the 'as is' Botic distribution yesterday - no problems encountered so thanks for the efforts there.
Just off-topic but sorry to say that I've been just wondering why you are calling miero as meiro. Respect for the author might include writing his handle name correctly.
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Old 4th August 2014, 12:31 PM   #67
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Quote:
Originally Posted by twluke View Post
Just off-topic but sorry to say that I've been just wondering why you are calling miero as meiro. Respect for the author might include writing his handle name correctly.
Thanks for pointing out my typographic errors; I have always had a 'blind spot' for some letter combinations and I will try to proof read more carefully in future. There certainly wasn't any disrespect intended and, hopefully, none taken?

Apologies again.

Ray
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Old 4th August 2014, 12:50 PM   #68
twluke is offline twluke  Japan
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Quote:
Originally Posted by nautibuoy View Post
Thanks for pointing out my typographic errors;
Ray
Glad to see your kind response. Thank you. Now let's wait for the new botic driver by the author, probably coming up soon, I believe.

twluke
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Old 13th August 2014, 11:35 AM   #69
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I've been following this for some time with interest. I want to interface the BBB to a WM8741 DAC rather than the ESS you're targeting. Are your driver/modifications open source? If so can you please post a link so I can adapt your work as I need?

Thanks
Simon
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Old 13th August 2014, 06:49 PM   #70
miero is offline miero  Czech Republic
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komri: Everything that has been published has also source code included in the /sources directory of the SD card image.

However, in the latest published version there is no I2C control enabled, so it might work without changes with your WM8741 if it is set in the autodetect mode. Just connect needed signals.

I do not have Opus DAC, so I cannot test this.
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