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HiFiBerryOS Room Correction

Clive

June 27, 2021 11:01

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Having now got my DIGI2 Pro and DSP board working, I want to set up room correction. After reading your "Implementing Room acoustics correction using REW" guide, it looked as if using the built-in facilities in HiFiBerryOS would be easier, so that's where I've started.

The first thing that puzzles me is the measurement phase. After connecting the mic (a Behringer ECM8000 + UMC22 preamp), HiFiBerryOS does indeed detect it. After clicking "Microphone Positioned", the system plays what sounds like pink noise at a high level in order to set levels. But when I click "Start Room Measurement" (and the page shows "Measuring room"), there is no audio output to the speakers. This surprises me. I would have expected some kind of frequency sweep (or maybe white/pink noise). I can't see how the the room can be measured without sending a signal to the speakers!

(In case it's relevant, one thing that I observed was that during the level setting process, adjusting the volume made no difference to the level; I had to adjust levels using the amp powering the speakers and the UMC22 input gain control. I'm guessing that this is because I'm using a DIGI2 Pro card, and the volume adjustment in HiFiBerryOS only works with cards that have a DAC?)

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34 comments

• 0
  
  HiFiBerry team June 28, 2021 06:26

  It should play a sweep. Unfortunately I can't say why it doesn't in your installation. You can try starting the measurement from command line:
  
  cd /opt/hifiberry/bin
  ./run-measurement

   

• 0
  
  Clive June 28, 2021 15:06

  I tried running the measurement from the command line as you suggested, but again there was no audio output. It also seemed to just keep going and I couldn't stop it with Ctrl-C; had to start another SSH session to kill it.

  Can I ask you to confirm that the sound that is played after clicking "microphone positioned" is supposed to be a kind of rough sounding static, sort of like distorted pink noise? It sounds a bit like a digital signal that's being incorrectly interpreted. Perhaps the DAC I'm using for tests (an old QED Digit) can't handle the format being output. Can you tell me what sample rate and bit depth is used?

• 0
  
  Clive June 28, 2021 17:10

  Update: given my suspicions about the QED DAC (I think it may only support 44.1kHz/16bit), I tried putting some test tones at various bit depths and sample rates on a USB stick to see which of them would play using HiFiBerryOS. Only the 44.1/16 did; others eimitted that characteristic rought static you get from an incorrectly decoded digital signal. So on the assumption that the room correction system uses some other format, I moved the whole setup over to my Meridian 218 (which supports anything you care to mention). Now, after clicking "microphone positioned", the signal was an obvious clean white noise rather than the distorted one I got through the QED.

  However, clicking on "start room measurement" still resulted in silence. This was using a Pi2. I'll try again with a Pi4 when I get the chance.

• 0
  
  HiFiBerry team June 29, 2021 05:58

  We haven't seen this here yet. Let's see how a Pi4 works.

• 0
  
  Clive June 30, 2021 09:17

  Just tried a Pi4 with exactly the same results: clean white noise during the level setting phase, then silence during the "measuring room" phase.

  Two things that may or may not be relevant:

  1. I'm using a DIGI2 Pro + DSP board rather than a board with a DAC. Have you tested this particular combination?

  2. Since the HiFiBerry USB mic is currently unobtainable, I'm using a Behringer ECM8000 with a UMC22 preamp. I presume the HiFiBerryOS room correction feature should work with that? It certainly registered a signal from it while the white noise was playing, because adjusting the volume changed the reported dB level.

  Looks like I may need to resort to using REW.

• 0
  
  HiFiBerry team July 01, 2021 06:44

  Unfortunately I can't say what's the problem in your setup. Is "normal" music playback working correctly?

• 0
  
  Clive July 01, 2021 09:01

  Is "normal" music playback working correctly?

  Yes, normal music playback works fine from FLAC files on a USB stick, and also via Squeezelite (when it works, which as you already know is a bit troublesome at times).

  As I said in my previous post, I'll try using REW. In the meantime, perhaps you could test with a combination of DIGI2 Pro + DSP board to see what happens. (The Pi4 I was using is a 4GB version).

• 0
  
  HiFiBerry team July 02, 2021 05:56

  We'll look into this. Due to vacation time, this will take some weeks.

• 0
  
  Clive July 04, 2021 17:03

  A final follow-up.

  I used REW with a Behringer ECM8000 to calculate the required filters, exported them to a text file, transferred the file to HiFiBerryOS and tried loading them using the dsptoolkit. But that didn't work (probably operator error with the toolkit), so I just manually added the filters on the parametric EQ page. Stored the settings in the card, then rebooted into piCorePlayer. I now have a working Squeezelite player with room correction. The bass humps are tamed and the sound is much less lumpy.

  It even all works just fine on the old RPi2, so no need to buy another RPi4 :-)

  So I'm a happy bunny.

  I do however urge you, when you have the time, to check out (a) whether the room correction in HiFiBerryOS works with a DIGI2Pro+DSP card, and (b) upgrade to the latest Squeezelite to see if that improves its behaviour.

• 0
  
  HiFiBerry team July 05, 2021 06:44

  We'll look into this.

• 0
  
  Shagmuf August 13, 2021 01:53

  I just posted regarding the same issue.

  RPi4, DIGI2 Pro + DSP. 4Gb.

  On a side note; Music plays correctly when it gets going, however, often the stream from Roon will stop and needs multiple starts (play/pause/play pause etc). This is only happens when streaming to the HiFiBerry DIGI2Pro+DSP. No idea what the cause of that issue is as Roon streams fine and unbroken to my Chromecast and to Apple Airplay devices.

• 0
  
  Shagmuf August 13, 2021 02:09

  I've found that switching for coax out put to optical has fixed the issue.

• 0
  
  Shagmuf August 13, 2021 02:26

  Maybe i spoke too early. 

  Something odd is going on.

  I went to take another measurement and same issue - set level on slider to blue area ok, but when recording test commences - no sound to record.

• 0
  
  HiFiBerry team August 16, 2021 06:34

  What happens if you run the run-measurement (see above) from command line?

• 0
  
  Shagmuf August 16, 2021 08:10

  it runs and i can change output level but no audio is heard. 

• 0
  
  Jacco August 17, 2021 09:09

  I have exactly the same issue pi 4, hifiberry digi2 DSP

• 0
  
  HiFiBerry team August 17, 2021 11:42

  We need to look into this. It'll help if you could create a bug report here:
  https://github.com/hifiberry/hifiberry-os/issues

• 0
  
  Jacco August 18, 2021 09:56

  Bug report created.

• 0
  
  Clive August 19, 2021 10:15

  I checked the bug report created by Jacco and saw the responses, so decided to give it another try. I don't have a GitHub account and didn't feel inclined to register just to add a comment there, so I'll post my findings here...

  First, I upgraded to the latest HiFiBerryOS release to make sure all was up to date - am now running release 20210804

  The room correction mechanism behaves exactly as it did before: white noise during level setting, then silence during the sweeps. So I tried connecting via SSH and ran /opt/hifiberry/bin/pause-all, and got this response:

  # /opt/hifiberry/bin/pause-all
  python3
  don't know how to pause python3
  
  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
  <html>
  <head>
  <title>Error: 404 Not Found</title>
  <style type="text/css">
  html {background-color: #eee; font-family: sans;}
  body {background-color: #fff; border: 1px solid #ddd;
  padding: 15px; margin: 15px;}
  pre {background-color: #eee; border: 1px solid #ddd; padding: 5px;}
  </style>
  </head>
  <body>
  <h1>Error: 404 Not Found</h1>
  <p>Sorry, the requested URL <tt>&#039;http://localhost:81/api/player/pause/&#039;</tt>
  caused an error:</p>
  <pre>Not found: &#039;/api/player/pause/&#039;</pre>
  </body>
  </html>
  
  pgrep: no matching criteria specified
  Try `pgrep --help' for more information.
  #

  Looks to me as if there should be an HTTP server running on port 81, but netstat didn't show anything listening on port 81.

  I also checked the entire file system looking for a directory called api with a subdirectory called player. There are three directories named api:

  # find / -name api -print
  /usr/lib/python3.9/site-packages/docker/api
  /usr/lib/node_modules/mpd-api/lib/api
  /usr/share/upmpdcli/cdplugins/qobuz/api
  #

  But there is no directory called player anywhere on the system:

  # find / -name player -print
  #

  After that, attempting to run /opt/hifiberry/bin/run-measurement via SSH, or using the GUI, again resulted in silence during the sweeps.

  So for me, the suggested fix hasn't worked.

  NB. I am using a Pi2, and I know you'll ask me to try again with a Pi4, but everything I have ever tried in HiFiBerry has behaved identically on a Pi2 and Pi4, so I don't think this is the issue.

  PS. The upgrade process said that it was going to update Squeezelite, but after the upgrade it's still running Squeezelite 1.9.1

• 0
  
  Jacco August 19, 2021 12:27

  Clive,

  I have seen that too. What I did is power down and up you PI, if it is running.

  When your PI is started it seems that you have to wait a bit before MPD becomes responsive, 5 minutes or so.

  I ran pause-all successfully , ran the run-measurement, which went well too. Then through the GUI, gave me 4 sweeps and done.

  When I wanted to implement a filter based on the measurements I found out that my DSP board was disappeared.

  Power down, power up solved that.

  Some other attempts gave me the same issues as you described, it's bit unpredictable at this stage. Sometimes it works and sometimes it doesn't, it's a bit of a hassle. I hope it will be improved in the next release.

• 0
  
  Clive August 19, 2021 12:45

  Jacco: what is MPD?

  My Pi had been up for way longer than 5 minutes when I tried running pause-all. I got the impression that there was nothing listening on port 81 (although I can't be certain of that), and that the HTML file being requested didn't exist.

  Looking at the source of pause-all (a bash script), it appears to be expecting a command line parameter, but what should be supplied is a mystery to me.

• 0
  
  Jacco August 19, 2021 12:56

  Clive 

  Music Player Daemon (musicpd.org) comes standard with HifiBerryOS and that's what I am using for playback for years now, on another system. 

  The pause script worked (couple of times) for me without any parameters. I also have disabled all the non used sources, except Bluetooth, Music (MPD) and Radio. 

• 0
  
  HiFiBerry team August 19, 2021 20:24

  @Clive: Looks like something is wrong in your setup in general. On port 81, there should be audiocontrol2 running that handles all player control in HiFiBerryOS:
  https://github.com/hifiberry/hifiberry-os/blob/master/doc/architecture.md

• 0
  
  Clive August 20, 2021 16:48

  @Clive: Looks like something is wrong in your setup in general. On port 81, there should be audiocontrol2 running that handles all player control in HiFiBerryOS

  I guess it's possible there is something wrong, although it's difficult to guess what, since all I did was download & install HiFiBerryOS and boot it up.

  It could well be that there is a service running on port 81, although netstat didn't show it.

  What is absolutely certain is that there is no directory called api with a subdirectory called player, because I was logged in as root and find / -name player -print found nothing. So the pause-all bash script that attempts to curl that file must inevitably fail.

  But this really isn't an issue for me. I was just curious whether the reported fix would work and decided to report what I found in case it is of value to you. For my actual daily use I run piCorePlayer, and was able to use REW to calculate the filters, set them up in HiFiBerryOS, then reboot into piCorePlayer.

• 0
  
  Shagmuf August 20, 2021 21:57

  I've had the exact same results as Clive when running those commands on a

  RPi4, DIGI2 Pro + DSP. 4Gb.

  /opt/hifiberry/bin/pause-all

  find / -name api -print

  find / -name player -print

• 0
  
  HiFiBerry team August 22, 2021 05:55

  You won't find any api or player files. There are no such files on the file system. That's perfectly fine.

• 0
  
  Clive August 22, 2021 17:26

  You won't find any api or player files. There are no such files on the file system.

  OK, but am confused...

  The bash script pause-all attempts to execute this command:

   curl http://localhost:81/api/player/plause/$PLAYER

  What is that meant to do?

• 0
  
  HiFiBerry team August 22, 2021 17:38

  It simply sends an HTTP request to the given URL. This triggers the pause functionality.

  Edited by HiFiBerry team August 22, 2021 17:38
• 0
  
  Clive August 23, 2021 08:55

  It simply sends an HTTP request to the given URL. This triggers the pause functionality.

  OK. So the only conclusion I can draw from this is that there is a service running on port 81 which uses the HTTP protocol, but it's not a traditional web server and instead interprets the supplied URL to decide what to do to the playback subsystem?

  This doesn't alter the fact that when I ran pause-all it returned the error message I posted earlier.

  But no matter - it doesn't affect my use of the hardware. I was simply reporting my experiences in case it might help you in your development/debugging.

• 0
  
  hashkey September 29, 2021 14:55

  Same story here- DIGI2 Pro + DSP, no sweep being output.

  Any vague timescale on the next release?