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DAC+ DSP - Change sample rate of DSP programm to 44.1khz instead of 48khz

Andreas W.

October 30, 2022 22:00

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Hi Hifi-Berry-Community,

I created an own profile according to the guideline from the git repo.

https://github.com/hifiberry/hifiberry-dsp/blob/master/doc/adaptexistingprofiles.md 

I planned to adapt the profile coming from this sigma project: 

https://github.com/hifiberry/hifiberry-dsp/blob/master/sample_files/dspproj/dacdsp-v12-1.dspproj 

Loaded existing project into sigma studio and just applied the project sample rate from all blocks to 44.1khz. (strange was that before 96khz were set, thought that default is 48khz, anyhow)

I could also already get it visible in HBOS.

 

I changed the meta xml statements according to my board also set the sampleRate to 44100. Install process were succesfully but under SSH connection with following command:

# dsptoolkit get-samplerate
48000Hz

the result is still 48khz. SPDIF output to my av receiver didnt find any signal at SPDIF input. What also makes me struggeling is that the checksum didnt changed after writing latest compilation though DSP successfully. Just changing pojects sample rate seems not affect the checksum, hmm.

It seems not to be easy like that to adjust sample rate of dsp programs by just changing project sample rate and applying it to all blocks isnt it? 

Br Andreas

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9 comments

• 0
  
  HiFiBerry team October 31, 2022 06:18

  There is a bug in "get_samplerate" that we will fix in the next HiFIBerryOS release. 
  
  Yes, changing the sample rate won't affect the checksum. The program is still the same, but filters use different paramatrisation that's not part of the checksum process.
  
  Unfortunately I can't say why your SPDIF output isn't working anymore. Without an analyzer that's really hard to say as fliping one of the many bits in the SPDIF or power management settings might cause this.

• 0
  
  Andreas W. October 31, 2022 09:19

  Good Morning, 

  thanks for your quick response. All right, happy to hear that this is under investigation.

  Hmm, power management. Indeed yesterday with universal profile 12 from your side I paused the playback for some hours. After trying replaying some songs from Spotify I experienced no signal anymore from SPDIF. If run it that issue again I will note it under git issues. (if that helps)

  So I assume the procedure I have done is the way to go if you want to change the sample rate? 

  Maybe HBOS is confused because two profiles does have the same checksum?

  I reinstalled the universal profile 12 from your side and now output is working fine again. 

  Maybe something is wrong with the sigma studio project you provided? I just changed the sample rate as  described above. What I also noticed: the pre setted sample rate of the project is 96khz not 48khz. So I assume that this might not the same project that you used to provide customers with the Universal v12, please correct me if I am wrong.

  Any other suggestions to identitfy where the issue is coming from? 

  Br Andreas

• 0
  
  HiFiBerry team October 31, 2022 09:27

  HiFiBerryOS will definitely be confused if there are multiple profiles with the same checksum. You need to change something in the DSP program (e.g. add a simple block that does nothing) to get another checksum.

  Unfortunately I can't help with your SPDIF problem. As I wrote before, to debug this, the first thing would be to connect an SPDIF protocol analyser and check if something's wrong with the output.

• 0
  
  Andreas W. October 31, 2022 09:38

  Hi again,

  it might be relevant that in the param reader after loading my systems param file I found some warning.(non-sequential-adresses)

  Br Andreas

• 0
  
  HiFiBerry team October 31, 2022 11:41

  With these blocks, not sequential addresses are no problem. This is only a problem for IIR blocks

• 0
  
  Andreas W. October 31, 2022 16:34

  Hi again, 

  I just delete the reduncancy of checksums but unfortuatly there is still no output coming from the card. I dont think that the output is damaged or something because with your provided profile is working well. 

  Can you please confirm, like I wrote and ask before, that my way to archiev a sample rate from 44.1khz is the right way to do it in sigma studio? 

  Br Andreas

• 0
  
  Andreas W. October 31, 2022 18:35

  Good evening, 

  ehm I took some research about the ADAU1451 for setting up the samle rate in sigma studio. I always forgot to set the core system clock:

  https://wiki.analog.com/resources/tools-software/sigmastudio/usingsigmastudio/samplingrateconsiderations#adau144x 

  

   

  So from my beginners view there is no easy way set 44.1khz to the project. I assume that this is also the reason for no output. So the drop down is only for "calculate and download the new coefficients for time-dependent algorithms"

  What esle need to be done to get it ready for 44.1khz. 

  Or does the DSP simply not support this sample rate? 

  Br Andreas

   

• 0
  
  HiFiBerry team October 31, 2022 19:32

  The DSP supports all kinds of sample rates using the programmable PLL. You would have to program new PLL coefficients. However, I can't give you a simple step-by-step guide. You need to consult the chipset documentation and the SigmaStudio documentation. 

• 0
  
  Andreas W. November 03, 2022 19:29

  Hi Daniel, 

  alright, yeah that is something I cannot spent too much effort on it. So I will send the board back. I didnt know before that your documentation does not show how to change the sample rate. I think you should put that information to the datasheet of the DSP products and add it to repository, that from factory state it only handle 48khz at default with tested and delivered profiles. Its static. For me, the DACs specification may indicate that the DSP is handling all supported sample rates as well with only another profile. I saw also generic profiles with 96khz and 192khz, so clear that assumtion to get 48khz is obvious. But thats simply not the case because I think programming new cooeficients can be really tricky. Please dont get me wrong, its really nice to see a product like this which can be modified by everybody to perform customizly. Of course 48khz is a good compromise. With that pre-deilivered profile it is a really good DIY solution, some bugs might be more or less aceptable. But without a good documented guideline that is hard to implement. Anyhow, thank you very much for the dialog.

  Cheers
  Andreas

  Edited by Andreas W. November 03, 2022 21:49