Volume control when sending output to the internal DAC

gibson12345
Posts: 53
Joined: Wed Jul 17, 2019 11:45 pm

Volume control when sending output to the internal DAC

Postby gibson12345 » Wed Jul 24, 2019 4:57 am

Hello,

I noticed with the examples for playing mp3 files there are ways to control volume when sending the i2s stream to an external codex chip but theres not reference or way to change volume if you're outputting to the internal DAC. I have tried to dive into the API docs a bit but there seems to be a lot missing and I can't determine how to get direct access to the stream of bits to perform manual division for volume change. If someone could please advise

Cheers,
Gibson

ESP_Sprite
Posts: 2832
Joined: Thu Nov 26, 2015 4:08 am

Re: Volume control when sending output to the internal DAC

Postby ESP_Sprite » Thu Jul 25, 2019 3:32 am

Can't help you directly, but you may want to ask yourself if you really want software volume control on an 8-bit DAC... the quality of 8-bit audio already isn't great, and you'd be shaving off more bits as you lower the volume.

gibson12345
Posts: 53
Joined: Wed Jul 17, 2019 11:45 pm

Re: Volume control when sending output to the internal DAC

Postby gibson12345 » Sun Jul 28, 2019 11:30 pm

Hey Sprite,

Thanks for the response. The decision to the use the internal 8-bit DAC was not my own as our electronics team handled that decision. I understand that things link quantisation errors will be an issue using the internal DAC but that's what I'm trying to test out to prove to my colleagues that an external chip would be extremely beneficial for our project. Could you advise or maybe contact someone internally that has worked on the ADF directly?

Cheers,
Gibson

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