Mobile Audio Compression

[johnknaack]

I've taken a look at: http://udn.epicgames.com/Three/MobileAudioSystem.html
And: http://udn.epicgames.com/Three/AudioSystem.html

I have a few questions about the audio pipeline for UDK. As far as I can tell:

• Import audio file (Only allows 16bit wav files. The 'Content Browser' gives and error if you select anything other)
• Audio files stored in .UPK package files with other assets (Meshes, Textures, etc)
• Audio compression level can be set via a normalized compression level
• Audio files are cooked to platform settings (ogg? for PC, mp3/uncompressed? for iOS, etc) at build time using normalized compression level (IE:an XMA quality of 40 was equivalent to an ogg vorbis quality of 0.15)
  
  • This is where I can't find any documentation on how to change the desired compression. If I wanted to compare audio compression formats on an actual build, how do I go about choosing a compression format?

To me, it looks like the UDK Audio System handles all the platform specific audio format settings when the build is cooked. Is this true?

What audio compressions does UDK Mobile use? The 'MobileAudioSystem' page recommends using mp3. Where can I find a list of the other options?

If I'm building an audio heavy game and need compression over CPU can I change the compression for iOS to use Ogg Vorbis?

[ScottS_80]

Wow, posted almost a month ago and still no responses. I'm definitely curious as to how the mobile platform handles audio compression as well.

Right now I'm currently doing the sound design for a couple of projects using UDK. However, we're getting some pretty bad memory issues on the iOS considering we're using uncompressed 44.1 PCM wav files.

When perusing the Content Browser, I found that if you right click a SoundNodeWave, and go to Properties, the first option in the menu that pops up is "Compression" with a default value of 40. However, I haven't been able to see how modifying this value can save us memory in any way.

We're actually trying to find a way to bypass UDK's audio engine and use in-house audio engine instead. We've been using that one for many of our iOS projects, and it uses ADPCM wavs so memory issues aren't as abundant.

I also find it odd that on the main UDK webpage, it says that the editor supports OGG files, yet, as you said, an error pops up when you try to import one.

[Wraiyth]

iOS only allows you to play one compressed stream at a time, so everything else will be imported and loaded uncompressed.
Its something that you just have to live with, I guess. Its one of the quirks of designing for a mobile platform. Allocate a budget for audio, use the build in soundcue stuff for your variation (modulation etc) and keep your samples short.