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Analog stereo has two channels. One for every speaker. Now, when can sample and convert the two streams of data from analog to digital.

But the problem, is what we will have is two streams of digital data. But digital audio is one stream of data.

So is there a way (or a protocol, or specification) to convert the two streams of data to one?

I am talking about raw sound, not encoding and complression algorithsm (like mp3)

Is there a thing called digital stereo? And how are the two channels mixed into one?

This is what i am trying to do btw. Create digital stereo (one stream), from analog stereo (two streams)

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  • \$\begingroup\$ CD it is working like this \$\endgroup\$ – GR Tech Nov 10 '14 at 16:07
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What you are looking for is the protocol called "I2S", which is a streamed stereo (or more) digital protocol.

It uses a method called TDM - Time Division Multiplexing - to interleave the left and right audio signals. Eg:

enter image description here

First it sends, as a serial data stream, the left channel data for one sample, then an IO pin changes state (from low to high) and the right channel data for the same sample is sent. The IO pin drops back low again, and the cycle starts again.

By using multiple IO lines for sample channel selection you can effectively have as many channels interleaved as you like, but 2 is the "norm" for most systems.

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  • \$\begingroup\$ thanks! this is the first time i hear this protocol! so in order to do it, would i have to do this procedure myself with my microcontorller/SoC, after i have smapled and converted the two signals to digital, or are there ready chips out there that receive two analog stereo streams and produce one digital stream via this protocol? and the other wasy around, are there chips that using I2S, decode one digital channel to two analog channels? Again, thanks a ton! \$\endgroup\$ – user1584421 Nov 10 '14 at 14:46
  • \$\begingroup\$ You can find millions of chips that do what you want in varying degrees of complexity. Audio ADC chips, and chips known as CODEC chips all generally speak I2S. \$\endgroup\$ – Majenko Nov 10 '14 at 14:54

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