An Audio Track Recorded from the Internal Output of Source Track doesn't Sound the Same


I tested recording an audio track’s output in 24 Bit (internally in Nuendo not through converters) onto another audio track without any plugins, eqs, comps etc. on the source track. The resulting audio does not sound the same on the destination track being recorded to. It sounds like the audio engine is in 32 Bit and the audio is being dithered back to 24 Bit during the recording. If I do the test with the project in 32 Bit float the resulting audio track being recorded is identical to the source track. If I take the 32 Bit wave from the 32 Bit float test into Wavelab and dither it to 24 Bit,the result sounds the same as the 24 Bit recording I had done internally in Nuendo. I discovered this flaw when a customer of mine using Pro Tools asked me to do some vocal tuning on 24 Bit vocal tracks. He pointed out that the resulting vocal track had lost some of its character and asked me whether I was using Pro Tools. I told him I was using Nuendo. Initially I thought it was AutoTune, but after testing the recording with no plugins the altered character of the recorded audio sounded the same as with AutoTune on the source track. I eventually had to rent Pro Tools and do the tuning with that as it didn’t alter the character of the audio. It would be great if this could be addressed in up and coming versions. :smiley:

No offense, but I don’t believe for a second that you or most people can hear the difference between an internal recording at 24 bit fixed versus 32 bit float.

If you actually hear a difference then something else is going on.

I guess you didn’t read what I was saying. I know what dither sounds like. Dither sounds different depending on what source its applied to. Sometimes you can hear the dither and sometimes you can’t. That’s why there is so many dither options available. It’s so you can choose the dither with the least side effects. My post is saying it sounds like there is a dither applied when recording 24Bit to 24Bit internally in Nuendo as the internal engine must be running 32Bit and being dithered back to 24 Bit. The source file I was using sound like it was dithered when I re-recorded it in Nuendo. I confirmed it was the sound of a dither by converting the source file to 32Bit (which sounded the same as the original 24 Bit file) and dithering the file in Wavelab back to 24Bit. The Wavelab dithered results sounded very similar to what I was experiencing in the internal recording in Nuendo. The source vocal file I was using had a large a mount of harmonic content (as it was tracked on a vintage Neumann U47 through a lot of analog gear). It was adversely affected by ANY dither applied to it.

Well then I would say that you’re stuck with essentially the same problem no matter what you do since Pro Tools also uses floating point processing internally. The only difference then would as you point out be the choice in dither.

But let’s say you’re stuck using this method, I have to ask how low the vocal signal level is. For the dither to be heard it’ll need to be close enough to the actual signal. I would imagine then that raising the outgoing level of the channel that you have processing on before it hits the track you record onto would possibly solve this problem.

Something else to consider would be to import 24-bit files but set your project to work with 32-bit float files. So any newly recorded files would be float, and then you can choose your own dither that you prefer. After all, any processing you do in 24-bit would eventually either cause quantization distortion or get dithered, no?

Lastly, I seem to recall several threads about this on Gearslutz, but I can’t remember what the final discoveries were. Basically a 32-bit float file has the same ‘resolution’ as a 24-bit fixed file, because the ‘other’ bits are not used for resolution but for scaling. So in a sense you’re not dithering in float, and there’s the case to be made for not doing it going to 24-bit fixed either (if I remember correctly). So I’d definitely say you should search on Gearslutz or elsewhere because this is exactly the type of stuff that DAW makers won’t discuss publicly for some bizarre reason.

PS: Actually, one more thing… Is it possible that the first instance where you ran into this ‘issue’ was simply a case of the plugin not acting the same in the two DAWs? I would think that it would be hypothetically possible. And if that was the case then what was audible could have been that problem rather than the eventual dithering going from float to fixed… If you do this for a living I would highly recommend looking into that as a possibility, even if it just serves to eliminate that as a problem. I would guess you should be able to for example import a file and set AT to a specific setting(s) in both apps, and then render out the same way using the same process for dithering. If a polarity inverse and sum results in only dither noise then it would seem AT isn’t an issue, but if you hear some weird voice artifacts then perhaps the plugin acts differently in different DAWs. And perhaps test with some automation as well…

just some food for thought…