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No sound with flac 24bits/176Khz - Raspbian / DAC+

Stéphane Plantard

December 11, 2014 15:55

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Hello,

I just received my HifiBerry DAC+ and configured my Raspbian installation to support it (I had a usb sound-card before)
I use mpd 0.19.5 to play music from web radios and from a USB key.

It reads very well all MP3 from 44.1Khz/128kbits to 48Khz/320kbits without problem and the following command reports the proper frequency.
cat /proc/asound/card0/pcm0p/sub0/hw_params

But when I try to read a FLAC 176Khz/~6000kbits there is no sound and time is progressing faster than normal.

The above command reports properly 176Khz use by the DAC+.

Here is my soft configuration.
cat /etc/modules

# snd-bcm2835
snd_soc_core
snd_soc_bcm2708_i2s
bcm2708_dmaengine
snd_soc_hifiberry_dacplus

cat /etc/modprobe.d/raspi-blacklist.conf

blacklist spi-bcm2708
# blacklist i2c-bcm2708

alsa part of mpd.conf

audio_output {
        type "alsa"
        name "HifiBerry DAC+"
        device "hw:0,0"
        mixer_control "Playback Digital"
        mixer_device "hw:0"
        mixer_index "0"
        dsd_usb "yes"
}

cat /etc/asound.conf

pcm.!default  {
 type hw card 0
}
ctl.!default {
 type hw card 0
}

cat /proc/version
Linux version 3.12.34+ (dc4@dc4-XPS13-9333) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) ) #725 PREEMPT Sun Dec 7 13:14:11 GMT 2014

Can you tell what I made wrong?
These FLAC were playing with no problem on the USB sound-card, but probably down-sampled, I did not check since I was waiting for the DAC+ to have the full 176Khz support.

Note: I power the Pi+ with a stabilized high quality 5V/3A power-supply by GPIO pins and the Pi+ is not over-clocked.

Regards

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7 comments

• 0
  
  HiFiBerry team December 11, 2014 17:31

  Dear Stéphane,
  
  we heard about similar issues with MPD in Volumio and RuneAudio. Unfortunately I can't say what they did to fix this, but you might ask the developers what they changed.
  
  Best regards
  Daniel
• 0
  
  Stéphane Plantard December 12, 2014 09:48

  Hello Daniel,
  
  I made a bit more tests, and it seams like a problem of bandwidth.
  I create these FLAC file using 1977 - The Eagles - Hotel California - Hotel California - 6.33 from DSD64 source 24 bits / 282Khz
  
  24bits / 88Khz: play with sound but too fast and clipping
  24bits / 176Khz: no sound and raspberry goes to 100% CPU and the full system do not respond after 10 secs, by this time I see the file is playing far to fast.
  16bits / 88KHz: play properly
  16bits / 176Khz: play with sound but too fast and clipping
  
  At first I thought about a 24bits problem, but 16bits/176KHz leads to same problem as 24bits/88KHz
  - 16/88 is 1370kbps and play properly
  - 16/176 is 1836kbps and play too fast/clipping
  - 24/88 is 2750kbps and play too fast/clipping
  - 24/176 is 6457kbps and play too fast with no sound and hangs the system
  
  Just a thought: Is there is setting somewhere about the transfer speed of the i2s bus or a buffer size?
  
  Regards,
  Stéphane
• 0
  
  Stéphane Plantard December 12, 2014 12:36

  Found a solution, now I can play FLAC 24bits / 176KHz with HiFiBerry DAC+ :)
  
  Instead of upgrading kernel, downgraded it like found on Volumio forum.
  sudo rpi-update e38850519c56b835dbd1c81e04d9307e154c36ed
  
  cat /proc/version
  Linux version 3.12.26+ (dc4@dc4-Latitude-E6510) (gcc version 4.8.3 20140303 (prerelease) (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) ) #702 PREEMPT Wed Aug 6 17:43:49 BST 2014
  
  I will make a thread on Raspberry Pi forum about this issue.
  
  Regards,
  Stéphane
• 0
  
  HiFiBerry team December 12, 2014 14:16

  This is interesting as playback via sox (this is our standard test) works without problems also on new kernels. Have you tested other playback software, e.g. "mplayer"?
  
  Best regards
  Daniel
• 0
  
  Stéphane Plantard December 12, 2014 15:10

  Unfortunately I did not test other player, I did not even think about it :/
  
  I wanted to make MPD work since I use this Pi as a web radio + mp3 + flac from USB key player and I wrote 2 years ago a complete Mpc front-end for it to fit a 4.3" screen connected via composite video.
• 0
  
  Stéphane Plantard December 12, 2014 16:36

  I am currently in "talk" with popcornmix via the kernel issue tracker to identify the issue in latest kernels. It seams it's not gpu firmware (dma stuffs) related but kernel related.
• 0
  
  Stéphane Plantard December 12, 2014 18:42

  The final answer: With latest kernel add
  dma.dmachans=0x0035
  to /boot/cmdline.txt
  And it works.
  
  From popcornmix "use the cmdline.txt fix for now, but there will be a firmware update that will fix it soon."
  
  Have fun, this DAC is fantastic and it's fantastic how we can get support for all around Raspberry PI stuffs when we do enough effort to report properly ;)
  
  Stéphane