Audio distorted only in Resolve

Hi,

I'm having issues with .wav 44100hz 16bit stereo files. More than one file.

The timeline and export sound is distorted, as if badly clipped. But this only happens inside Resolve. Anywhere else, whether is playing the files from the Finder (I'm on a Mac), or Quicktime or other NLEs, the files sound totally ok. No clipping, no distortion.

Any clues?? I'm using Resolve 15

Thank you very much

I just converted some 48 kHz 24-bit files to 44.1 kHz 16-bit to see if I could duplicate the problem on my Mac with Resolve 15, but they sound fine.

A few possibilities:

1. Are you normalizing your clips? If so, are you normalizing to 0dbfs (which is the default level in Resolve)? Try normalizing to -6 dbfs instead.

2. What about the clip volume? If that's set too high you can get distortion.

3. What do you have chosen for Audio I/O in your Resolve preferences? I wonder if that setting might be causing the problem?

Experienced this recently on certain source audio running at 16bit/44.1kHz, where the source is distorted within (and only within) Resolve, with artefacts present during playback.

1:1 digital copies aren't possible when transferring the above source material to my stem recorders, with Resolve as the playout system.

ProTools Ultimate 2018.7, soundBlade HD 2.3.2, Reaper 5.95, iZotope RX7 Advanced, Bias Peak Pro XT, and Quicktime Player 10.4 do not exhibit the same behaviour and source playback is possible without artefacts, and 1:1 digital copies are possible with these audio workstations as playout systems, and the identical source audio.

The issue is only present within Resolve 15.x

Workaround:
Open Patch Input/Output window and unpatch the "Control Room Monitor Out", which by default is routed to the Audio Outputs.

Control Room Monitor Out.png (49.08 KiB) Viewed 5239 times

Instead, patch the "Control Room Monitor Direct" outputs to the Audio Outputs.

Control Room Direct Out.png (50 KiB) Viewed 5239 times

The above workaround allows 1:1 digital copies to be produced with the stem recorders, with Resolve as the playout system, with the same source audio.

Patching the Oscillator and running sinusoidal tone through the "Control Room Monitor Out" matches the same signal routed through the "Control Room Monitor Direct", so Resolve's internal gain structure is correct and within spec - so the above workaround should have no effect, yet it does in my tests.

I suspect the issue may have something to do with lossy (e.g. MP3) sources being converted to broadcast wave files prior to submission, as upconverting the source to 16bit/48kHz prior to import in to Resolve has no affect on the playback behaviour within Resolve. Often, the original files aren't accessible (only generational copies are available), so confirming my suspicion may prove difficult.

Usually, this isn't a major issue, as the commonality between sources is that the material is often temp music or temp SFX.

Still in process of finding the true source of this issue.

Thank you very much for both your replies.

Brad, all the setting were at default, so no normalisation, clip and track volume zeroed, and tried different I/O but it would happen even when coming out of the built in headphone jack.

Reynard, that worked! I don't know how you managed to find out that workaround but it worked for me. Thank you very much.

This workaround needs to be set every time you open the project, right? It does not save as a project setting.

I'll try to look at the source of the files that triggered the issue. One of them is the master of a song, so I assume it was kept uncompressed throughout the process, and that this export is as high quality as possible.
The other file is the audio from a theatre performance, and it's a mix, so that'll be more difficult to assess

Thanks for the help
Jose

This workaround needs to be set every time you open the project, right? It does not save as a project setting.

Patching should save with the Project, and recall correctly upon Project reload.

I'll try to look at the source of the files that triggered the issue
...
so that'll be more difficult to assess

Open a Spectrum Analyser, lossy encoders (MP3 and AAC) usually discard everything above 16kHz with a very steep low pass filter (encoding at 128kbps).

Spectrum.png (227.25 KiB) Viewed 5194 times

15.2 update fixes this issue on my systems, the suggested workaround is no longer required.

Thank you very much for the shout Reynaud. I hadn't seen the update yet
All the best
Jose