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Converting analogue source to digital stream on the fly
15-01-2015, 13:42
Post: #1
Converting analogue source to digital stream on the fly
Can anyone offer information or advice as to how one might go about creating a high quality digital stream from an analogue source? I have an old Thorens turntable connected to an Arcam amplifier and I would like to be able to convert the output to digital so that it could be recorded and/or streamed, ideally, say, by MinimStreamer running on a RaspberryPi. The idea solution would be an A/D card for the Pi, similar to the Hifiberry DAC, but no such product exists and the people behind the Hifiberry card say there isn't sufficient demand to merit producing such a thing, which would be challenging anyway. I thought I had a relatively low cost solution in the Roland UA-55 Quad-Capture Audio Interface, but it turns out it uses a proprietary software that is only Windows or Mac compatible. Can anyone recommend something of similar specs that would be Linux compatible?
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15-01-2015, 13:53
Post: #2
RE: Converting analogue source to digital stream on the fly
(15-01-2015 13:42)nickc Wrote:  Can anyone offer information or advice as to how one might go about creating a high quality digital stream from an analogue source? I have an old Thorens turntable connected to an Arcam amplifier and I would like to be able to convert the output to digital so that it could be recorded and/or streamed, ideally, say, by MinimStreamer running on a RaspberryPi. The idea solution would be an A/D card for the Pi, similar to the Hifiberry DAC, but no such product exists and the people behind the Hifiberry card say there isn't sufficient demand to merit producing such a thing, which would be challenging anyway. I thought I had a relatively low cost solution in the Roland UA-55 Quad-Capture Audio Interface, but it turns out it uses a proprietary software that is only Windows or Mac compatible. Can anyone recommend something of similar specs that would be Linux compatible?

The Wolfson (now Cirrus Logic) audio card for the Raspberry Pi does this. I have used it for playback but not for recording. The hardware is good but I haven't been impressed by the usability of the software. For example, you need to use a Wolfson/Cirrus custom version of Raspbian because Wolfson/Cirrus hasn't yet integrated the drivers into the main Raspbian build.
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15-01-2015, 15:33
Post: #3
RE: Converting analogue source to digital stream on the fly
Aha! This is good news - I hadn't realised the Wolfson card could convert the other way too. Thanks for pointing that out. Unfortunately they don't seem to have yet produced the promised version for the RaspberryPi B+ .... hopefully that will come soon! Maybe with improved software too, with a bit of luck!
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15-01-2015, 15:37
Post: #4
RE: Converting analogue source to digital stream on the fly
(15-01-2015 15:33)nickc Wrote:  Aha! This is good news - I hadn't realised the Wolfson card could convert the other way too. Thanks for pointing that out. Unfortunately they don't seem to have yet produced the promised version for the RaspberryPi B+ .... hopefully that will come soon! Maybe with improved software too, with a bit of luck!

They have produced the B+ version, together with a Wolfson/Cirrus specific 3.12 kernel. Element14/Farnell have been selling for a while.
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15-01-2015, 16:00
Post: #5
RE: Converting analogue source to digital stream on the fly
(15-01-2015 15:37)DaveWr Wrote:  They have produced the B+ version, together with a Wolfson/Cirrus specific 3.12 kernel. Element14/Farnell have been selling for a while.

The B+ version is called the Cirrus Logic card and the B version is called the Wolfson card.
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15-01-2015, 16:12
Post: #6
RE: Converting analogue source to digital stream on the fly
Thanks, yes, I've found it now. I'd been looking at some older posts before.
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15-01-2015, 18:46 (This post was last modified: 15-01-2015 18:47 by nickc.)
Post: #7
RE: Converting analogue source to digital stream on the fly
Having had a look at the Cirrus Logic card's user manual, I can see what you mean, Simon, re the software: " The hardware is good but I haven't been impressed by the usability of the software. For example, you need to use a Wolfson/Cirrus custom version of Raspbian because Wolfson/Cirrus hasn't yet integrated the drivers into the main Raspbian build. "
I can see how it should be possible to use it to record from an analogue source, but what about live streaming? Would MinimServer/MinimStreamer install ok on the modified OS? And, assuming they would, is there a way they and the output of the card could be configured to, as it were, talk to each other, ie MinimStreamer relaying the output from the card to the home network? For example, might it be possible to set a folder on the sd card of the Pi (or on an attached usb stick) for the soundcard to record to, and have MinimServer playing the file in that folder as it's recorded? (As I'm sure you realise, I'm out of my depth here!)
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15-01-2015, 20:52
Post: #8
RE: Converting analogue source to digital stream on the fly
(15-01-2015 18:46)nickc Wrote:  Having had a look at the Cirrus Logic card's user manual, I can see what you mean, Simon, re the software: " The hardware is good but I haven't been impressed by the usability of the software. For example, you need to use a Wolfson/Cirrus custom version of Raspbian because Wolfson/Cirrus hasn't yet integrated the drivers into the main Raspbian build. "
I can see how it should be possible to use it to record from an analogue source, but what about live streaming? Would MinimServer/MinimStreamer install ok on the modified OS? And, assuming they would, is there a way they and the output of the card could be configured to, as it were, talk to each other, ie MinimStreamer relaying the output from the card to the home network? For example, might it be possible to set a folder on the sd card of the Pi (or on an attached usb stick) for the soundcard to record to, and have MinimServer playing the file in that folder as it's recorded? (As I'm sure you realise, I'm out of my depth here!)

MinimServer and MinimStreamer can be installed on the modified OS and they support playback through the Wolfson card if a suitable UPnP software renderer is running on the Raspberry Pi.

There isn't any way to feed the ADC output into MinimServer or MinimStreamer. I have never attempted to do anything like this. MinimServer can stream disk files and MinimStreamer can stream HTTP network streams. A live capture stream from an ADC is neither of these.
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16-01-2015, 11:00
Post: #9
RE: Converting analogue source to digital stream on the fly
(15-01-2015 20:52)simoncn Wrote:  MinimServer and MinimStreamer can be installed on the modified OS and they support playback through the Wolfson card if a suitable UPnP software renderer is running on the Raspberry Pi.

There isn't any way to feed the ADC output into MinimServer or MinimStreamer. I have never attempted to do anything like this. MinimServer can stream disk files and MinimStreamer can stream HTTP network streams. A live capture stream from an ADC is neither of these.

Thanks for clarifying that.
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16-01-2015, 16:42 (This post was last modified: 16-01-2015 16:44 by simoncn.)
Post: #10
RE: Converting analogue source to digital stream on the fly
(15-01-2015 18:46)nickc Wrote:  Having had a look at the Cirrus Logic card's user manual, I can see what you mean, Simon, re the software: " The hardware is good but I haven't been impressed by the usability of the software. For example, you need to use a Wolfson/Cirrus custom version of Raspbian because Wolfson/Cirrus hasn't yet integrated the drivers into the main Raspbian build. "

I've been experimenting with RuneAudio and the Wolfson card. It provides a simple web interface for sending audio output to the Wolfson card (including selecting a custom Linux kernel) and enabling a built-in UPnP renderer. You can also install MinimServer and control it from another computer via MinimWatch. It's very slick and impressive.

As far as I know, it doesn't support audio recording (getting back on topic for this thread).

Warning: don't try to use Kinsky with the built-in UPnP renderer. There's some nasty incompatibility that causes Kinsky to hang. BubbleUPnP is working well.
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