Optimizing Sound


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When you are using sound you will notice that on the MacOS you have more options and possibilities than on the Windows platform, still a proof that the MacOS is leading in the multimedia area. But this gap will be closed by the end of the year, thanks to QTW 2.5 and other developments. So watch this area closely. If you are creating a cross-platform title you have learned that you have to use sounds stored in WAV format. But if you have sounds that are long (ex 1 minute) this can take a lot of space. Loading time can become very long for those screens and your title will be using too much memory. What can we do about this?


sound [1]: Change Sound Quality

You can first try to reduce the size of your sound by lowering the quality.

Frequency: Use the right frequency for the type of sound

1. Voice - 11KHz is good
2. Music - 22KHz or 44KHz.


Stereo/Monophonic:

If it's not stereo don't record it in stereo, because stereo sound takes up twice the space.


8-Bit/16-Bit:

If sound is stored as 16-bit you will have very high quality sounds, but it will take up twice the space of 8-bit sounds.

sound [2]: Use compression


If your title needs to run on MacOS only you can reduce the size of your sound by using compression. IMA compression is used on 16-bit sound files and reduces the size of your sound by about 4 times. You can also use IMA compression when your sound is stored as a QuickTime movie (see tip 4). In the case you use compression your sound has to be stored in the AIFF format. MACE compression is used on 8 bit sound files. You can choose between 2 different types: 3:1 and 6:1 In the case of 3:1 your file will be about 3 times smaller. 6:1 it is 6 times smaller. MACE compression works only on the MacOS.

It is possible to save WAV files as IMA APDCM , which is comparable with AIFF IMA that we can use on the MacOS.

But.....

1. it is different then we have on the MacOS, so not compatible: You have to store twice your sound files. (for AMT users it means they have to change manually the file names in the media.k file for the windows version, and recreate your title with Runtime Maker.)

2. only possible with ambient sounds, not with simple sound beeps (but this isn't a big problem because you don't need high quality beeps....)

3. I only did the test on a Windows 95 machine I hope somebody can do the same tests on Windows 3.1.

sound [3]: Use ambient sound if possible


With the new version of AMT, we can use ambient sounds. You have to create them the same way as interlude sounds but they work differently: they keep playing even while you are going to another screen. The advantages of ambient sounds:

When not to use ambient sounds:

sound [4]: Audio-only QuickTime movies


If you can't use ambient sounds, consider using audio-only QuickTime movies for longer sounds. Audio-only QuickTime movies can use IMA compression which is becoming a very popular format for storing high quality sounds.

Remark: You will read more about this in the Movies section, but QuickTime movies are slow to open. So if you have 4 different sounds on your screen don't replace them with 4 different QuickTime movies. Create only one QuickTime movie and use the GoToTime commands to begin playing the right section.


sound [5]: Midi


Since QuickTime 2.0, you can create movies that contain MIDI (Musical Instrument Digital Interface) tracks. MIDI takes less space than digitized sound. QuickTime 2.5 will even support more MIDI possibilities.

Other resources

http://www.eeb.ele.tue.nl/midi/index.html This web-site contains a lot of information about MIDI.
http://www.macworld.com On this web-site you can find a software library where you can download a series of sound tools.

Tools

MoviePlayer 2.1 With MoviePlayer you can convert your sound files to movies and vice versa. (free)
SoundEdit Pro 2.0 From MacroMedia; it is a well known sound program. ($249)
SoundEffects 0.9.2 A sharp-looking, flexible program that's similar to MacroMedia's SoundEdit Pro. You can amplify, echo, filter, fade out, play backwards, or turn your voice into a hollow-sounding robotic monotone. (Shareware $15).
SoundApp 2.0 FAT SoundApp is the premiere sound playback and conversion utility for the Macintosh. (Freeware)