Understanding DoP audio

November 17, 2022
 by Paul McGowan

12 comments on “Understanding DoP audio”

  1. I think I already understand how DOP works from your previous videos, but the train analogy was perfect. What I always wonder, is there an advantage to have my Audirvana software set to convert everything to DSD over PCM no matter what the original source is?

    1. I wouldn't think so. Best to have exactly the source format always be the default. Worst one can do is upsample everything to this or that like the built in audio engine in your computer does. But with Audirvana you should not have that problem to deal with.

      1. Good afternoon Paul!
        For my Leak ST-130WL integrated amp, I had to install on my computer, drivers that Leak calls Ion.
        I use Foobar2000 on my computer to play DSd files.
        But I had to find the speaker icon in Foobar2000 that's labled Ion.
        After that, I had to set Foobar2000 to deliver the DSD files in to dpo.
        Which is, DSD over PCM.
        I don't hear any diffrences, it all sounds like pure native DSD to me.
        But only when I play a PCM wave file, I hear that PCM sound.
        Oh by the way, I tried passing a DSD file from my Yamaha WXC-50 music streamer to my Leak ST-130WL via optical digital audio cable.
        This is when things got quiat.
        No sound came out.
        Can you explain to me as to why this happens?
        Thanks in advance!

  2. Another question for Paul: when I get a DSD download, it has PC files with *.dsf extensions. These play just fine in an application that recognizes DSD, and they stream from my NAS to my streamer/DAC without issue…
    Why was dsf chosen over dsd?

  3. Hi John,

    I'm not sure Paul addressed the intent of your question. The '.dsf' file thing is a conceptual level of abstraction above what Paul explained about the 'DSD over PCM' (DoP) idea. Although both concepts are using the same idea of 'containerization' in order to allow a computer to productively manage the data in a way that suits your needs.

    As you are probably aware, there are many types of file extension like '.dsf'. By design, the file management syetems in computer operating systems are usually oblivious to a file's contents. They only understand that a file is a 'container' of binary data that is assigned some arbitrary name (according to the naming conventions of that particular file management system) and kept on some storage medium (for example, a magnetic disc drive). By convention, a file extension just tells the operating system to which application the file name should be passed, loading the application into memory and initiating its execution if required.

    From time to time, groups of people representing interested players in an industry get together and agree on what extensions will be used to represent the different 'patterns' of binary data that different files may contain. In the case of DSD data, for whatever reason, two extensions were chosen and are now in use to represent the format of how DSD data is stored in a file. One is the 'DSD Stream File Format' (DSDSFF) or simply DSF and the other is the 'DSD Interchange File Format' (DSDIFF) or simply DFF. Each stores DSD data but in slightly different formats. DSF is more commonly used. My guess is that it's design more easily accommodates metadata than does DFF.

    At any rate, it's only after the file name is passed to the appropriate 'streamer' or 'player' application that DoP may come into play. As Paul mentioned in the video, unless you have a special piece of software ('driver') installed on your computer that knows how to handle it, DoP is used to chop up and package the DSD bit stream so that a computer's 'standard' communication protocols can pass the data onto your DAC.

    I hope I haven't totally misinterpretted your question. 🙂

    1. Good description. Since I downloaded DSD Music from NativeDSD for me it was not clear how the DSD is transfered and processed by the PC programs.
      NativeDSD has some pages for this topic and there are some papers with specs from Philips and probably SONY. Further Pyramix has also some pages on their website. For me it seems that when a PC and a file are involved it is always a some kind of container as Paul explained. If I hopefully understand it right Pyramix must transfer DSD to a high grade PCM for mixing and manipulation. Then converting back to DSD. Since my DAC cannot use DSD direct it must be read from the DSD music file (with containers) and my player program convert it to PCM and transfers via USB connection to the DAC. For any input clearing my cloudy knowledge of these specialized digital processes and formats, thanks in advance.

      1. You're close but I would like to unravel your last sentence: "Since my DAC cannot use DSD direct it must be read from the DSD music file (with containers) and my player program convert it to PCM and transfers via USB connection to the DAC. "

        I am assuming your DAC can play DSD. It just cannot directly accept it?

        In that case, you're very close in your understanding. The one thing to be clear, the player program does not actually convert DSD to PC. The player program merely breaks apart the DSD stream into packets and containerizes them for transportation. To the computer and your DAC these containerized data bits (still DSD) look like PCM.

        They are then unloaded from their journey, unpacked, and reassembled as DSD. At no time were they ever converted to PCM.

  4. Paul, early bird, thank you. Will need to contact the Audirvana forum and probably Audiolab for my M-DAC, the original one. I like this one because it has an external mains plug power supply. Since the M-DAC is a retired product I am not sure to get any information from them.

  5. Had a phone talk with Audiolab UK regarding the M-DAC. It is not capable of accepting DoP signals. Need that the music player software converts it to PCM for my M-DAC. Audirvana does this pretty well. Also JRiver. Roon is too expensive for my usage and has features which I don't need such as streaming. Usually I play stored music from an external SSD storage connected USB.

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