Hi all.
I've been working with analog audio for quite some time now. I've been in the broadcast industry working on studios, transmitters, etc. I've built a few mixers and amps over the years as home brew, fill-gap solutions.
Lately I've been getting back into digital for some other projects. More and more I'm wanting to get into digital audio. There are a lot of resources out there...not the least of which is all you on these forums. Some many different viewpoints and ideas to accomplish the same goals. I really appreciate the knowledge.
As luck would have it I had a friend approach me recently wanting to replace on old analog audio snake. While looking with him for a replacement I ran across digital snakes. I knew they were out there but I really had not given them much thought.
It got me thinking: How does a 24-channel digital snake work under the covers. There's got to be more to it than just ((ADC + a bunch of wire + a DAC) x 24) and you have a 24 channel digital snake.
So...for the education of it all...I had my first project: design and construct a digital snake (maybe 8 channel). I think my prototype will be targeted to provide CD-quality audio (44.1 MHz - 16-bit) or maybe a little higher if the codecs dictate.
I've been researching this for several weeks now and have been having a blast. The issue I've been having is understanding how to effectively move the audio from source to destination. ADC and DAC...I get it.
I even looked at some codec chips that offer TDM multiplexing (CS42436 from Cirrus Logic) can transport 6 channels. Cool stuff. Cirrus Logic sent me 4 samples. Good bunch of people over there.
Then I found CobraNet. It kind of blew my mind and got me thinking on several tangents as to what could be done. I downloaded all the PDFs that Cirrus Logic had on CobraNet. I went to the CobraNet community web site and scoured it. I've searched this forum back and forth on all the CobraNet threads I could find.
I've ordered a few CobraNet chips:
2 x CS181002 - Audio DSPs 2-Ch 48-96kHz CobraNet Processor
1 x CS181012 - Audio DSPs 8-Ch 48-96kHz CobraNet Processor
2 x CS181022 - Audio DSPs 16-Ch 48-96kHz CobraNet Processor
...and I've reviewed the documents and reference design schematics but I have a few questions. So I decided to register with the forums and make my first post. Maybe someone here can point me in the right direction.
Question 1: Looking at the ICs and Reference designs...it appears that the CobraNet devices are not actually doing to conversion of Analog to digital and back. It appears to me that I need to provide them audio in a digital format already. However, I can't seem to find what format of audio I need to provide to the various digital inputs so CobraNet can wrap-n-send it down the line. Is there a specific format that CobraNet is looking for me to provide it?
EDIT: I found by re-reading the input info again (closer this time) that "...typically the synchronous serial is wired to ADCs and/or DACs..." So...that answers that.
Question 2: Say I wanted to be able to send audio from the stage to two separate mixers: house and monitor. Obviously...CobraNet should be able to send one copy of the stream to 2 destinations via multi-unicast or pure multicast (if the network is dedicated to CobraNet alone). Do I understand this correctly.
Question 3 (somewhat non-CobraNet related): in your opinion what is the best open standard for audio-over-ethernet that hobbyists can play with? I take it that most of the reference designs for these open standards are probably based around FPGA or something related? I have some FPGA hardware so I understand what it going on with it. If there is a viable option out there...maybe I'll steer clear of CobraNet and give away my DSPs to whoever is the most helpful. 😛
Seriously...thanks much for any thoughts, links, or insights you might be able to provide! Maybe audio-over-ethernet isn't the way I should be looking? I'm open to playing and experimenting.
-Data
I've been working with analog audio for quite some time now. I've been in the broadcast industry working on studios, transmitters, etc. I've built a few mixers and amps over the years as home brew, fill-gap solutions.
Lately I've been getting back into digital for some other projects. More and more I'm wanting to get into digital audio. There are a lot of resources out there...not the least of which is all you on these forums. Some many different viewpoints and ideas to accomplish the same goals. I really appreciate the knowledge.
As luck would have it I had a friend approach me recently wanting to replace on old analog audio snake. While looking with him for a replacement I ran across digital snakes. I knew they were out there but I really had not given them much thought.
It got me thinking: How does a 24-channel digital snake work under the covers. There's got to be more to it than just ((ADC + a bunch of wire + a DAC) x 24) and you have a 24 channel digital snake.
So...for the education of it all...I had my first project: design and construct a digital snake (maybe 8 channel). I think my prototype will be targeted to provide CD-quality audio (44.1 MHz - 16-bit) or maybe a little higher if the codecs dictate.
I've been researching this for several weeks now and have been having a blast. The issue I've been having is understanding how to effectively move the audio from source to destination. ADC and DAC...I get it.
I even looked at some codec chips that offer TDM multiplexing (CS42436 from Cirrus Logic) can transport 6 channels. Cool stuff. Cirrus Logic sent me 4 samples. Good bunch of people over there.
Then I found CobraNet. It kind of blew my mind and got me thinking on several tangents as to what could be done. I downloaded all the PDFs that Cirrus Logic had on CobraNet. I went to the CobraNet community web site and scoured it. I've searched this forum back and forth on all the CobraNet threads I could find.
I've ordered a few CobraNet chips:
2 x CS181002 - Audio DSPs 2-Ch 48-96kHz CobraNet Processor
1 x CS181012 - Audio DSPs 8-Ch 48-96kHz CobraNet Processor
2 x CS181022 - Audio DSPs 16-Ch 48-96kHz CobraNet Processor
...and I've reviewed the documents and reference design schematics but I have a few questions. So I decided to register with the forums and make my first post. Maybe someone here can point me in the right direction.
Question 1: Looking at the ICs and Reference designs...it appears that the CobraNet devices are not actually doing to conversion of Analog to digital and back. It appears to me that I need to provide them audio in a digital format already. However, I can't seem to find what format of audio I need to provide to the various digital inputs so CobraNet can wrap-n-send it down the line. Is there a specific format that CobraNet is looking for me to provide it?
EDIT: I found by re-reading the input info again (closer this time) that "...typically the synchronous serial is wired to ADCs and/or DACs..." So...that answers that.
Question 2: Say I wanted to be able to send audio from the stage to two separate mixers: house and monitor. Obviously...CobraNet should be able to send one copy of the stream to 2 destinations via multi-unicast or pure multicast (if the network is dedicated to CobraNet alone). Do I understand this correctly.
Question 3 (somewhat non-CobraNet related): in your opinion what is the best open standard for audio-over-ethernet that hobbyists can play with? I take it that most of the reference designs for these open standards are probably based around FPGA or something related? I have some FPGA hardware so I understand what it going on with it. If there is a viable option out there...maybe I'll steer clear of CobraNet and give away my DSPs to whoever is the most helpful. 😛
Seriously...thanks much for any thoughts, links, or insights you might be able to provide! Maybe audio-over-ethernet isn't the way I should be looking? I'm open to playing and experimenting.
-Data
Last edited:
Relocated to Digital Line Level as the answers you seek are more likely here than in the construction thread.
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