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DAC+ DSP Toslink input to RPI

Mikesz

November 25, 2019 22:52

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I'm trying to get Toslink PCM audio into the RPI.  This is the entire reason I purchased two of these cards.  This is for capturing TV audio for distribution using snapcast and/or Linux based audio filters run outside of the DSP.

I have Sigma Studio up and running and have successfully written a profile to the DSP using it.

Responses to the second question of this post mentions a 'hifiberry-dacplusdsp' dtoverlay which supports reading data from the DSP to the RPI, but does not expand further. https://support.hifiberry.com/hc/en-us/community/posts/360006995438-HifiBerry-DAC-DSP-192k-Processing-Path-and-SPDIF-input

I'm guessing perhaps I need ASRCout, but don't know much beyond that.  I'm an electrical engineer by degree, took some DSP classes in school, have been studying ALSA, but I2S is foreign to me.

A kick in the right direction would be very helpful here.  What outputs in the DSP must I route the signal to?  Where am I looking for the data in the RPI?  Approximate steps to get the data into a named pipe/mkfifo appreciated.

Thanks,

Mike

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36 comments

• 0
  
  HiFiBerry team November 26, 2019 18:46

  Hi,

  there are 2 things you have to do:

  1. use the hifiberry-dacdsp overlay to load the DAC+ DSP driver that supports input. This will give you an ALSA input that you can ready data from.

  2. Create a DSP profile, that sends data out on the last output of the DSP (3 or 4 depending on numbering from 0 or 1). The output has to be configured to use the ASRC and be clock slave.
  
  Maybe this part of the circuit diagram helps to understand this:

  
  
  Unfortunately I don't have a DSP profile ready that can just be used for this, but I'll see if we can add this to our generic profile soon.
  
  Best regards,
  Daniel

• 0
  
  Mikesz November 27, 2019 05:28

  Thanks Daniel.  That and some head scratching got me there.  Is there some reason documentation such as this isn't made available to purchasers of these boards?

  For anyone else who wants the SPDIF as an input to the PI you can do this with the standard DSP profile, you only need to modify register settings.  It wasn't too bad.  The hardest part was putting together enough little crumbs of information to get my bearings enough to start to understand what's going on.

  1- in /boot/config.txt change your existing dtoverlay=hifiberrydac to dtoverlay=hifiberrydacplusdsp

  2- open Sigma Studio and get connected.  Directions here:  https://github.com/hifiberry/hifiberry-dsp/blob/master/doc/dspprofiles.md  Stop at the 'open connection' part.

  3- right click the IC and select "Register Window"

  4- Go to the routing matrix tab.  At the bottom right click 'SOUT SOURCE 20'.  Chance the source to "From ASRC".  Select ASRC7 as ASRC7 is configured by default to read from SPDIF

  5- Go to the serial ports tab.  At the bottom right under OUT3 change LRCLK Source and BCLK Source to Slave from CLK domain 3.  Change word Length to 32 bits.

  That's it.  At this point it should work.  Go into the pi at the terminal and run 'arecord -f dat test.wav' to record some sound that you can then play back or look at with a program like Audacity.

  Optional:

  I didn't want the SPDIF input routed directly to the analog output.  By default ASRC7 reads from the analog input and is routed to the analog output.  Preventing ASRC7 from writing to the analog output would require a new DSP program, so instead I removed the SPDIF from the input of ASRC7.  Do this from the routing matrix tab by clicking on ASRC 7 and changing the ASRC source from SPDIF to "not used".  You still need ASRC to get the audio into the PI.  ASRC6 isn't used for anything, so I used that.  Go into ASRC6 and select SPDIF as the source, then modify step 4 above to select ASRC6 instead of 7.  As a simple test run arecord -f dat | aplay -f dat and you should hear the SPDIF input on the analog output.
  
  

  Mike

• 0
  
  HiFiBerry team November 27, 2019 07:18

  > Is there some reason documentation such as this isn't made available to purchasers of these boards?
  
  Sure, there is ;-) The DAC+ DSP and the Beocreate 4CA are products that are extremely flexible and we could create hundreds of guides. However, our resources are limited. Therefore there might not be documentation available for every feature. We'll try to update and improve the documentation for stuff that users are looking for. We put this on our Todo list!

  It's also planned to include this in the Generic DSP profile.

  Best regards,
  Daniel

• 0
  
  Matthew Martin January 14, 2020 12:27

  Hi - I also purchased the card to use the Toslink input.

  I've followed Mikesz's instructions and I'm getting audio into the pi fine apart from one thing. The incoming sample rate as reported by Audacity etc is 44100 Hz. I would really like this to be 48000 Hz.

  Can you advise how I can change this?

  Thanks

  Matt

• 0
  
  HiFiBerry team January 14, 2020 12:32

  Sorry, ignore my last post (that I have removed already). As the connection is always via the sample rate converter, you should be able to use any sample rate from 44.1 to 192kHz, the ASRC will just convert the sample rate to what you request. 

• 0
  
  Matthew Martin January 14, 2020 15:54

  Hi,

  Could you clarify what you mean? From a software/programming point of view I can only open an input stream from the board if I set the sample rate to 44100. PortAudio reports that all other sample rates are not-supported.

  From SigmaStudio I've tried changing the System Sample Rate to 48kHz and also other clock settings. None of these have any effect.

  Thanks

• 0
  
  HiFiBerry team January 14, 2020 15:56

  This might be a problem of your ALSA and/or Portaudio configuration. The board supports sample rates from 44.1-196kHz. You should be able to see these sample rates as supported rates.
  Check if you have resampling or DMIX enabled somewhere.

• 0
  
  Matthew Martin January 15, 2020 09:06

  Thanks - I ended up re-imaging with a vanilla Raspbian build and after reinstalling dsptoolkit etc managed to get everything working as expected with full control of all the sample rates. Looks like a brilliant bit of kit.

• 0
  
  case January 25, 2020 15:22

  Hi,

  thanks Mikesz and the hifiberry team for the description. I can now record the toslink audio. What do i need to do, to record the audio played from the raspberry (for example with aplay some.wav) as well? 

• 0
  
  HiFiBerry team January 25, 2020 16:03

  The snoop module might work, but I never tested this:
  https://superuser.com/questions/1248439/can-i-pipe-input-from-a-linux-soundcard-into-2-different-applications
  
  Best regards,
  Daniel

• 0
  
  case January 25, 2020 22:22

  Hi Daniel,

  thank you for your quick response. I tried to record the audio with the dsnoop module, but it records only the toslink audio. When my TV runs i can record the audio with 'arecord -d 10 -c 2 -D dsnoop:0,0 -f S32_LE -r 48000 snoop.wav', when only spotify (raspotify) runs, it complains that the only supported format is S16_LE and the rate 44100, but issuing 'arecord -d 10 -c 2 -D dsnoop:0,0 -f S16_LE -r 44100 snoop.wav' than records only silence. I also tried to create a custom snoop pcm device like in the link you provided. It does not work either and recording from this device additionally mutes everything (as long as arecord runs). My alsa knowledge is quite limited, so i might do something wrong here, but any further help would be greatly appreciated.

• 2
  
  Mikesz January 26, 2020 02:39

  Hello Daniel,

  On the question of releasing information, I'm not asking for you to provide step by step instructions for every possible use case of your product.  That would be very time consuming to impossible.  I'm more asking about the information specific to the Hifiberry implementation of the DSP board that we can't get anywhere else.  Information we need to be able to help ourselves.  Information like the circuit diagram you provided above or the "hifiberry-dacplusdsp" overlay which I happened to find in a different thread on this forum.  Is there any other information about this specific board that you think would be helpful for us to help ourselves?

  Now to directly contradict the above... :)  I'm trying to understand what the "hifiberry-dacplusdsp" overlay actually does for no other reason than to understand how it works.  I tried to find the source for this but only came up with what looked like binary files to me.  I'm guessing I need more of an education on device tree overlays, modules, alsa, drivers, etc.  A link, search term, something to point me in the right direction would be most helpful.  I'm currently trying to figure alsa timestamps.  Part of that is querying the hardware to find out what it's capable of.  I'm at the point where I really just want to understand as much as I can about the whole process to make better decisions about how to proceed with various projects.

  Also to give contribute some, below are some command line options that do everything I listed listed in the third post of this thread including the "optional" stuff.  I had varied success on getting these changes to survive a reboot, so a script which executes the below commands is my solution. 

  dsptoolkit set-volume 0%
  dsptoolkit set-limit 0db

  dsptoolkit write-mem 0xF106 0x0003
  dsptoolkit write-mem 0xF146 0x0004
  dsptoolkit write-mem 0xF107 0x0000
  dsptoolkit write-mem 0xF195 0x0000
  dsptoolkit write-mem 0xF194 0x0033
  dsptoolkit write-mem 0xF21C 0x6C40

  dsptoolkit write-reg 0xF106 0x0003
  dsptoolkit write-reg 0xF146 0x0004
  dsptoolkit write-reg 0xF107 0x0000
  dsptoolkit write-reg 0xF195 0x0000
  dsptoolkit write-reg 0xF194 0x0033
  dsptoolkit write-reg 0xF21C 0x6C40

   

  Thanks,

  Mike

   

   

• 0
  
  ctburne January 28, 2020 23:17

  Hi Mike

  Those dsptoolkit instructions you gave above will replace the need to use Sigma Studio entirely?  I'm looking for something similar, but i'm not a sound engineer so everything inside Sigma Studio seems very overwhelming.  I have a Pi4 and the DAC+DSP hifiberry card.

  The two scenarios I need are:

  1. TOSLINK Input -> TOSLINK Output (which is there by default and currently works
  2. TOSLINK Input -> PI audio input such that it can be used for arecord (eventually to be streamed over my Pi WIFI using darkice and icecast2)

  I'm not super clear how to proceed.

  Thanks for any assistance to point me in the right direction.

  Chris

• 0
  
  HiFiBerry team January 29, 2020 14:20

  Mikesz: Most DSP-related stuff can be found on Github:
  https://github.com/hifiberry/hifiberry-dsp/tree/master/doc
  
  You might still miss something, just ask! I'll try to help as much as possible. I will also try to add more documentation where it helps.
  
  The new overlay just makes sure, the DAC+ DSP driver is being loaded. It is basically a "dump" driver that doesn't care about the DAC+ DSP at all (therefore it will even load if no DAC+ DSP is connected). It just connects an input and output to the Raspberry Pi's sound interface to allow playback and recording. The driver normally used (hifiberry-dac) only has output functionality. 
  
  ctburne
  With the new HiFiBerryOS release, there is a profile that should work:
  https://raw.githubusercontent.com/hifiberry/hifiberry-os/master/buildroot/package/dspprofiles/dspdac-10.xml
  
  Note that the recording functionality has been implemented, but not tested as we're not using any recording functionality on HiFiBerryOS.
  
  It is quite a complex profile. Playback of SPDIF input to the output is disabled by default, but you can enable it using

  dsptoolkit write-mem 4840 1

  Note that this is a bit experimental as usually the HiFiBerryOS UI is handling this stuff and the profile is created by our partner from B&O

   

• 0
  
  case January 29, 2020 20:53

  Hi,

  Is there any documentation about the profiles, regarding their features, differences, use cases, supported hardware, etc?

  i just tested the new profile you mentioned. Recording does not work. It just records a static noise, no matter if the input comes from the raspberry or toslink. Even with no input, it records the static noise. You mentioned the new profile is quite complex, why is that, mixing was removed, what was added?

• 0
  
  HiFiBerry team January 30, 2020 06:10

  Hi,

  The documentation is the SigmaProfile file. You can download the SigmaProfile projects and open them to see what a the flow is doing.
  https://github.com/bang-olufsen/create/blob/master/BeocreateUniversal-v10.dspproj
  We can't simply describe a complex DSP flow with lots of parameters with a few sentences.
  
  Nothing has been "added" or "removed" on the Beocreate profile. It's a profile that's used on HiFiBerryOS  to handle 1-8 channel setups with all kinds of equalisations and functions.This comes with some complexity. I recommend to have a look at the DSP project file to get an idea.
  
  I'll look into the recording functionality with this profile. However, this requires a test setup that I don't have at the moment. Therefore, this will take some time.

  Best regards,
  Daniel

• 0
  
  ctburne March 18, 2020 05:20

  Hi Daniel;

  I did the following:

  1.  Added dtoverlay=hifiberrydacplusdsp to /boot/config.txt

  2.  dsptoolkit install-profile https://raw.githubusercontent.com/hifiberry/hifiberry-os/master/buildroot/package/dspprofiles/dspdac-10.xml

  3.  dsptoolkit write-mem 4840 1

  The audio still goes through the SPDIF input -> SPDIF output, however, my arecord -l still shows no Capture devices.  I see no PCM devices that can capture audio either:

  arecord -L
  null
      Discard all samples (playback) or generate zero samples (capture)
  jack
      JACK Audio Connection Kit
  pulse
      PulseAudio Sound Server
  equal
  plugequal
      Equalizer for plughw:0,0
  usbstream:CARD=ALSA
      bcm2835 ALSA
      USB Stream Output

  I suspect I do not have the sound driver on my system as i'm getting an error in my vcdbg log: Failed to load overlay 'hifiberrydacplusdsp'.  I updated my kernel and did apt update and apt upgrade with no luck

  Thanks for any help you can give me.

  Chris

  Edited by ctburne March 18, 2020 05:47
• 0
  
  ctburne March 18, 2020 15:30

  I am looking for instructions for installing the sound card driver for DAC+DSP and I don't see instructions for DAC+DSP here: https://www.hifiberry.com/docs/software/configuring-linux-3-18-x/

  I have nothing in my blacklist file and I'm using Buster version 4.19.108-v8+

  Is there a location I can download the driver from?

  I have followed the installation instructions for dsptoolkit here: https://github.com/hifiberry/hifiberry-dsp/blob/master/README.md

  AndI don't see the driver getting installed from this repo or any of these python scripts.

  Thanks for your assistance. This is my COVID-19 at home project.

• 0
  
  HiFiBerry team March 18, 2020 15:37

  The driver is part of the Linux kernel. You don't need to download it. Check that you have the file
  

  /boot/overlays/hifiberry-dacplusdsp.dtbo
  
  Due to the current situation, our access to lab equipment is limited at the moment, therefore we cannot test any SPDIF functionality of any DSP profile at the moment.
• 0
  
  ctburne March 18, 2020 15:47

  Yes, it is present:
  -rwxr-xr-x 1 root root 699 Mar 17 22:36 hifiberry-dacplusdsp.dtbo

  Okay, typo in my config.txt.  I see it.

  I see it now.  Thank you, I'm unblocked. 

  Stay safe.

  Edited by ctburne March 18, 2020 15:51
• 0
  
  HiFiBerry team March 18, 2020 15:48

  Looking at your previous postz, you might have a typo:

  
   dtoverlay=hifiberrydacplusdsp
  
  should be

   dtoverlay=hifiberry-dacplusdsp

   

• 0
  
  ctburne March 18, 2020 15:52

  Yes, that is what I just saw as well. My capture device is showing up now. Thank you for your help.

• 0
  
  ctburne March 19, 2020 05:20

  Hi Daniel

  I've not made it much farther after a few hours of trying different ways to record the audio from the DSP.  I've got the card showign up properly in:

  arecord -l
  **** List of CAPTURE Hardware Devices ****
  card 0: sndrpihifiberry [snd_rpi_hifiberrydacplusdsp_sou], device 0: Hifiberry DAC+DSP SoundCard HiFi dacplusdsp-codec-0 [Hifiberry DAC+DSP SoundCard HiFi dacplusdsp-codec-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

  I've verified I can get sound OUT of the card by playing a sample wave file:

  aplay -Dplughw:0,0 CantinaBand60.wav
  Playing WAVE 'CantinaBand60.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono

  (i hear sound out of the card as expected)

  I know i'm getting sound IN the card b/c I can hear sound coming from the SPDIF input going to the SPDIF output (i am guessing this is some sort of hardware bypass though).

  I've applied the DSP profile above along with the additional memory register:

  dsptoolkit install-profile https://raw.githubusercontent.com/hifiberry/hifiberry-os/master/buildroot/package/dspprofiles/dspdac-10.xml

  dsptoolkit write-mem 4840 1

  The only thing I can conclude is that the DSP profile is not routing sound from the SPDIF to the capture device on the PI.  Is that possible based on what you know of the profile?  

  I'm not using any of the analog input/output of the DAC+DSP, only the SPDIF Input and SPDIF Output, plus I want the audio coming from the SPDIF Input to go to the pi so I can stream it over my network.

  What i'm using to test is the following:

  Variations of this to record:  arecord -f dat -r 60000 -Dplughw:0,0 -d 5 test3.wav

  And then testing using:  aplay -Dplughw:0,0 test3.wav

  It's possible my test case is flawed as well.

  Thanks for any assistance.  I know probably I will need to crack open Sigma Studio, but I have opened a profile in that before and watched a few videos and it seems quite daunting to attempt to figure out.

• 0
  
  case March 28, 2020 10:30

  Hi Daniel,

  did you found some time to look into the recording issue or is there something i can do, to help you to debug it?

• 0
  
  HiFiBerry team March 28, 2020 16:51

  There isn't an "issue", but simply no profile from us that supports this out-of-the-box. As we have limited access to our lab, there won't be probably anything from us for the next time. 
  You can check the post from Mikesz at the top to see what to do to create your own DSP program for this.

  Best regards,
  Daniel

• 0
  
  case March 28, 2020 19:59

  Hi again,

  I don't agree with your assessment that there isn't an issue.

  Daniel wrote: "Nothing has been "added" or "removed" on the Beocreate profile. It's a profile that's used on HiFiBerryOS to handle 1-8 channel setups with all kinds of equalisations and functions.This comes with some complexity. I recommend to have a look at the DSP project file to get an idea.

  Note that the recording functionality has been implemented, but not tested as we're not using any recording functionality on HiFiBerryOS."

  So the issue is, that recording is enabled, but not working.

  I understand that you can't create a profile for every use case, but recording from toslink input or/and sound that is directly created on the rpi, is probably a very basic use case. So it would be very kind of you guys to help us to get these basic use cases work, especially as the documentation is very thin.

  Also, Daniel wrote he wants to look into this. Now you write there isn't even an issue. That is kinda confusing...

• 0
  
  Dr Nick August 04, 2020 16:14

  I too am trying to get recording working having purchased one, but so far have not suceeded despite hours of wasted time. I agree that this is a basic feature that should be implemented by default - indeed it is an advertised feature and there is a whole page all about it: https://www.hifiberry.com/docs/hardware/comparison-of-hifiberry-cards-for-audio-recording/ which clearly directs potential customers to the DAC+DSP. I suspect that efforts have been made to implement this as this has been an issue for some time, but for some reason it does not work. Has anyone managed to get this working?

• 0
  
  HiFiBerry team August 04, 2020 16:54

  Sure, just check post 2 and 3 in this topic. These explain what you have to do to route SPDIF to the Pi.

• 0
  
  HiFiBerry team August 05, 2020 13:16

  Dr Nick: I have compiled the important information from this topic to a separate document:
  https://www.hifiberry.com/docs/software/using-the-dac-dsp-to-record-audio-from-s-pdif/

• 0
  
  Dr Nick August 06, 2020 10:30

  Excellent, this is exactly what I needed! I have just tested it and can confirm that it works!

  Many thanks!