I can imagine an audio optimisation tool in C2, to let the common C2 users do it themselves the testing of the different combinations of: sample rate/number of bits/number of channels/encoding bitrate values.
I have some experiance about the digital file formats, cause I'm originally a sound engineer...:)
This tool is unavoidable cause of the very different properties of each SFX or music.
Rumble SFX with a very low tone: the initial wav file have a 44,1Khz sample rate, 16 bit, PCM - not compressed.
- The 44,1Khz means that the maximal frequency of the sound could be 22,05Khz what is not hearable for most people above 20 years. If You change the sample rate to 22,05KHz, the change in sound quality may not be hearable, but You have a sound file, what is half in size.
- If You make the bit depth to 8 from 16, cause of the low tone, that makes relatively large waveforms, You may also cant notice any difference, but again have half file size.
- For a very low tone, You ears can not detect direction information, so You can switch to mono from stereo mode. It's also a half in size.
I did not done any tests with ogg/aac encoding, but the original wave file size could be reduced to 1/8 in the exapmle above. It can not be an averange, but about 40-60% reduce in sound file sizes may not be unreal, so its even a very good point of size optimisation.
I would like to recommend a tool in C2 that have prelisten mode with A/B testing: play, and in playtime switch to original and optimized.
By this, any C2 users could be able to deside what is the optimal sound quality/size ratio for their game. It may be apply only on exporting, so we can keep the original files in project, and do not need to reimport when want to set a better quality.
I have ideas about a basic FFT graph to help users to decide to cut sample rate, but this is not a must-have...
I can offer to make a tutorial about this feature with sample sounds, basic optimisation tips and I can perform the encoding tests too.