Dummies Guide to Pi2AES! Throw away your PC or laptop.

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by purr1n, Jan 29, 2020.

  1. arboria

    arboria Rando

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    You mean the audio data is buffered by the pi2aes from the CPU so it is not affected by latency from the playback software/mixer? Guess rt-kernel is only useful for live low latency recording.. just to make sure
     
    Last edited: Nov 6, 2022
  2. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    The pi2aes does not buffer the data. It simply provides the bit and word clocks the pi then uses to clock out the data to the pi2aes.
     
  3. arboria

    arboria Rando

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    Ok. My question then is: can a real-time kernel on the PI improve the accuracy/reliability of the audio data clocked out to the pi2aes?
    What happens when the playback software or alsa mixer has latency delivering the audio data, does it fill the pi2aes clocks with zeroes?
     
  4. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Accuracy is determined by the PI2AES clocks. Latency is a whole different issue as are dropouts. If the PI has not data to send then it sends zero's. The PI2AES clocks just keep on clocking, it does not "fill" anything. Again, the PI2AES just sends clocks to the PI and receives whatever is on the data line.
     
  5. arboria

    arboria Rando

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    I didn't say the pi2aes fills with zeroes, but the software on the Raspberry PI.
    When I said accuracy/reliability of audio data I'm not talking about pi2aes clock accuracy now, but audio data.
    Since I'm discussing the convenience of rt-kernel from the start I am concerned about latency and dropouts with respect to fidelity of the signal to the pi2aes.

    I'm amazed whether there's not a software buffer that holds enough audio data in raspberry os audio stack for the output so as not to fill in zeroes in case of normal os latency..
     
    Last edited: Nov 8, 2022
  6. Dandou

    Dandou Acquaintance

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    I don't know the Linux distribution that you are using.
    But in GentooPlayer, MIN, RT and ST kernels work all very well with the RBi3 and RBi4 without any latency or dropouts issues.
     
    Last edited: Nov 8, 2022
  7. arboria

    arboria Rando

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    I don't doubt it.. but how can we know there aren't any zeroes added regularly because of latency that we don't hear, i.e: a few samples per second or so. If there is a software buffer as in windows this can be discarded (we'd need a latency bigger than say a second buffer). I guess linux has one as well so we can discard a rt-kernel since it's not necessary...
     
  8. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    Can I ask that you take this issue to another thread? This has zero to do with the PI2AES.
     
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  9. arboria

    arboria Rando

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    Yes I can, but I disagree it has zero to do with PI2AES. This is an audiophile-oriented board, specialized in accurate and clean digital signal. It needs the Raspberry Pi to function. I heard different audio OS perform differently sound quality-wise. So I think my question about the convenience or effect of a real-time kernel is relevant, and even you said dropouts or latency os-wise could have an effect.
     
  10. rlow

    rlow A happy woofer

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    Here’s the place you’re looking for: https://audiophilestyle.com/forums/
     
  11. Dandou

    Dandou Acquaintance

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    Hello,
    Does anyone know if the I2S output of the PI2AES is compatible with the I2S input of Gustard DACs (the x26 Pro, and the R26 R2R)?
     
    Last edited: Nov 17, 2022
  12. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    PI2AES rev. P3.3 and earlier supports the Gustard pinout. P4 supports the PS Audio pinout. Mercury V1 supports PS Audio while V2 will have adjustable pinout supporting both, as well as most others.
     
  13. Dandou

    Dandou Acquaintance

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    Thank you.

    I ordered my PI2AES on February 2022.
    Is it revision P3.3 or P4?
     
  14. Michael Kelly

    Michael Kelly MOT: Pi 2 Design

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    should be P4, but it is marked on the board itself next to the LEDs.
     

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