Need help with understanding file format pipeline


I was reading documents and forums but still don`t understand how this complete audio file chain works. I am talking all the way from source audio files in Fmod to Ue4 output.

My situation is like this, i am a sound designer with no programming skills doing sound for a game in Ue4, all of my audio files are pcm wav 48/16. And game is not for mobile, only for Desktop. So far my banks were built at PCM 48 Khz. There was no problems but i would like to understand better the whole process so later when we gett closer to finish, problems don`t start to happen.

Performance reference for FMOD says that Vorbis is prefered format for all sounds, FADPCM is secondary and PCM is not recomended. But seeing that is also sais XMA and AT9 are not available this document might be old and outdated.

However Ue4 states in their docs that engine supports 16 bit wave files at any sample rate, but 44100 or 22050 are recommended. They also say “specifications : PCM, ADPCM, DVI ADPCM”

There are few things that i would like to understand

1 - What happens to source files once the bank is built using Vorbis and than sent to UE4, which per documents does not accept Vorbis?
I tested this and UE4 worked without a problem. Banks were smaller, memory usage was about 100 mb less and that was it. Since disk size is not a big thing i would like to keep my
encoding to pcm.

2 - Why does it say that PCM is not recomended? Explain please the downsides
3 - What are your experiences with build banks @48Khz and @44.1Khz in PCM for UE4?

Thank you

Whatever UE4 supports is irrelevant since we have our own codecs / output.

Vorbis is considered best for Desktop because it provides the best compression, FADPCM second and PCM third (in order to decreasing compression).

Even though disk space may not be an issue, you still need to consider in-memory size too, loading Vorbis into memory is quite space efficient compared with PCM which can be over 10x more memory.

XMA / AT9 are platform specific so they are only mentioned in their platform specific docs and are not available for windows.

1 Like

“Whatever UE4 supports is irrelevant since we have our own codecs / output.”

So from this i understand that FMOD plugin takes over completely the audio output of UE4 and communicates directly to Windows audio driver or Sound card driver? Is that close to truth? : ) And this goes also for the built game and “in editor” play?


That is correct.

Ok, thanks