To Upsample or not to Upsample. That is the question.

    • February 14, 2023 at 2:08 pm #4900
      Gregory Pastic

        If I’ve been given a mix at 24/44.1, 24/48, or higher, or a floating point mix at 32/48, should I set up the mastering session at the same bit rate and resolution as the mix?  Using Studio One 6, are there any advantages or disadvantages to importing the mix to 64 bit 96 or higher?
        I know this topic will be covered in the Fourth Edition of Bob’s mastering book, but I was hoping to get some guidance now.  I’ll still buy the book though!
        Thanks!  Gregory

      • February 14, 2023 at 6:07 pm #4902
        Bob Katz

          Gregory, welcome to the forum!

          I definitely cover this topic in the third edition of my book, which I sent you just the other day :-). And soon, my talk I just gave to the San Francisco AES section will be available on YouTube.

          While you’re waiting till the video become available, I’ll tell you that in my studio, I routinely upsample any single sample rate mixes to double sample rate at 32 bit float before beginning mastering. Keeping in mind that your DAW will calculate at its internal wordlength/precision regardless of what is input, I’m comfortable saying that if you upsample to 96k at 32 bit float, it should be fine.  If your DAW can accept 64 bit float and your SRC can output at 64 bit float I see no harm, maybe some wasted space, but it shouldn’t be harmful, though I doubt the difference will be audible. Certainly not intuitively obvious to the most casual observer. 🙂

          Reaper reportedly processes at 64 bit float, so for example, if you import a 32 bit float file Reaper will output 64 bit float for any multiply.

          Hope this helps,



        • February 14, 2023 at 9:33 pm #4911
          Bob Olhsson

            I up-sample everything also because the final down-sampled results have sounded better every time I’ve compared it.

          • February 14, 2023 at 11:03 pm #4914
            James Johnston

              For capture 24 bit integer is probably more than most physical devices will handle.

              For computation,however, 32 bit float is very close to allowing some intrusion of calculation into the lsb’s of the final 24 bit integer product, so while it’s most often fine, sometimes using double precision float is not a bad idea. If you’re using recursive filters, maybe stick to double precision, anyhow.

            • February 15, 2023 at 12:13 am #4915
              Gregory Pastic

                Thanks for the clarification. It confirms that I’m doing the right thing. I’ve already been setting up all my mastering sessions at 64/96 (for mixes given to me at 24/48) or 64/88.2 (for mixes given to me at 24 / 44.1).  I use Lynx Hilo A/D D/A.
                I sculpt the sound with plugins and outboard analogue equipment.  The upsampling in Studio One 6 is excellent.  Here’s an interesting resource I found for comparing software sampling rate converters.

              • February 15, 2023 at 11:11 am #4923
                Bob Olhsson

                  Some people have been playing with actually dithering double precision float calculations out to 32 float. This is way over my head.

                  • April 7, 2023 at 11:36 am #5714

                    If the dithering is done right, dithering 64-bit double-precision to 32-bit single-precision floats doesn’t hurt.  And if you’re archiving the audio to a file with 32-bit floats, it probably should be done, because the only cost is some processing.  And MIPS are cheap in a non-realtime process.

                    It’s just that the quantization level is 150 dB below the loudest audio in the recording (so, even if you have 10 dB of headroom, with 32-bit floats, then the quantization level is -160 dBFS) and I sorta doubt that even bad quantization can be heard.

                    From a DSP programming perspective, it’s more of a pain-in-arse to dither and noise shape floating point, but it can be done.  It’s just code and MIPS.  May as well do it, if  it’s not real time and no one is worrying about the MIPS.

                • April 7, 2023 at 12:56 pm #5715
                  Bob Olhsson

                    My concern is the buildup of distortion as additional processing occurs.

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