Why does playback in Studio sound different to my audio editor?

(Joseph Harvey) #1

When I audition files I’ve put into Studio events, they sound different to how they do in the DAW I made them in. I thought I was imagining it at first, but then I double-checked, and there’s definitely differences. What might be causing these differences?

(Joseph Harvey) #2

When playing back an audio file which has been placed in an event, the audio signal may go through several processes before reaching the speakers which can result in volume differences, bass loss or reduced stereo image. Understanding the signal path from audio file to sound card can help explain and remove some of these differences if they are not desired.

The Signal Path

When creating a new event by dragging an audio file into the Event Browser, a signal path with the following processes will be set up:

Resampling: the audio file is first resampled to the project’s sample rate of 48kHz.

Channel Mapping: Channels from the audio file are automatically mapped to channels in the signal chain.

3D panning (removable): each channel in the signal chain is panned to surround (or stereo if the project format has been set to stereo) according to the sound object’s 3D position.

Up-mixing: if the 3D Panner has been removed and the audio file is not multi-channel, the signal will be up-mixed to the project’s output format set in the project’s preferences.

Down-mixing: if the audio device’s output format does not match the project’s format, Studio will down-mix the master mix to the device’s format.

Other processes added by the user may also affect the final sound, the less obvious one being explicit up- or down-mixing using the bus panners on event tracks and mixer buses.

Processes affecting volume

Down-mixing will reduce the overall volume. It involves summing multiple channels to single channels and attenuation is therefore applied to limit the maximum levels on the target channels and avoid saturation.

3D panning won’t reduce the overall volume unless the sound is positioned away from the listener so that distance attenuation is applied. The process of 3D panning is often an up-mix to a surround format and the overall signal energy will be preserved by using constant power panning.

Editors will sometimes use other up-mixing and channel mapping algorithms which do not preserve energy and this difference can also be responsible for volume discrepancies.

Processes affecting stereo image

When the 3D panner pans stereo signals, it will spread each left and right channel across left and right sides of the listener and maintain the stereo channel orientation regardless of the direction of the 3D stereo source. This prevents the left and right channels flipping whenever the listener moves past the source. The cost of this method is some channel bleed which results in a narrower stereo image. The same effect will occur when a surround bus panner receiving a stereo signal is set to ‘Distributed’ mode.

It is still possible apply 3D panning to stereo sources while maintaining full stereo width. This can be achieved removing the 3D panner and adding surround bus panner (‘L / R’ mode) and fader automation on the event’s built-in direction and distance parameters.

Processes affecting bass response

The final down-mix from the project format to the audio device’s format can result in bass loss depending on the down-mix algorithm applied. It may also vary between platforms. FMOD supports Dolby PL2, SRS Circle Surround and its own down-mix algorithm, each exhibiting different frequency and phase responses.