How to Fade-In/Fade-Out a Sampled/Repeating/Mixed Sound

OK,  Here is the answer:

There are three implementors of 'storeSampleCound:bigEndian:on:' :

        AbstractSound>>storeSampleCount: samplesToStore bigEndian: bigEndianFlag on: aBinaryStream

        LoopedSampledSound>>storeSampleCount: samplesToStore bigEndian: bigEndianFlag on: aBinaryStream

        SampledSound>>storeSampleCount: samplesToStore bigEndian: bigEndianFlag on: aBinaryStream

The AbstractSound implementation does what you want, while the other two (which are identical) do not account for the envelopes.  These were all present as of December 2001,  attributed to John Maloney and were modified by Stephane Ducasse in 2003 to clean up the way that the current endianness is checked.

I don't know why there are two essentially different implementations.  My initial inclination is that the 'LoopedSampledSound' and 'SampledSound' implementaions are unnecessary and should be removed, but I really don't know what John was thinking about, and the comments don't really say.  Does anybody know the history on this?  I don't know if it would break any extant code if only the 'AbstractSound' implementation were kept.

Regarding 'RepeatingSound', that will take some more digging.  I can say that if you add the envelope to the SampledSound that is created from the wave file, then create a RepeatingSound using the SampledSound that has an amplitude envelope, you will hear the envelope for each repetition.

This might be a weakness in how envelopes are used for playback.  Presumably, an envelope applied to the 'RepeatingSound' should control the overall volume of the composite sound, but that doesn't seem to be what is happening.

As Chris mentioned, the debugger is your friend.  Add "self halt." before a message send you want to debug, click on 'Debug' when the 'Halt' notification window pops up and then use the 'Over' and 'Into' buttons to single step through the code.

        -Dean

Hi Rob,

If you try this:

       snd := (SampledSound fromWaveFileNamed: 'aWAVFile.wav').
      snd addEnvelope: (VolumeEnvelope exponentialDecay: 0.96).
       snd play.

You will hear the effect of the envelope, as desired.

This:

       snd storeWAVOnFileNamed: ' out.wav'.

should have done what you want, but obviously it does not.  I have spent a little time tracking this, but I haven't found the problem yet.

I will send another reply when I figure this out (maybe today, or later this weekend).


       -Dean

Dean,

Thanks for all your help trying to figure this out.  However, I am still not able to create any effect on even a SampledSound with a VolumeEnvelope like you suggested.  To help hear what is going on I have created a new method, newExponentialDecay in the  Envelope class where I have changed:

    mSecsPerStep := 10.

    to:   mSecsPerStep := 50.

just to drag out the decay a little longer.  When I do that,

snd := FMSound new.
snd addEnvelope: (VolumeEnvelope newExponentialDecay: 0.96).
snd setPitch: 200 dur: 5.0 loudness: 0.25.
snd play.

fades out as expected, but then when I turn that tone into a WAV and read it back in:

snd := FMSound new.
snd setPitch: 200 dur: 5.0 loudness: 0.25.
snd storeWAVOnFileNamed: 'tone.wav'.
snd := (SampledSound fromWaveFileNamed: 'tone.wav').
snd addEnvelope: (VolumeEnvelope newExponentialDecay: 0.96).
snd play.

The tone just plays at a constant volume!  Things that make you go...hmm...

Thanks again,

Rob

Hi Rob,

This begs the question:  "What version of Squeak are you running, and on what platform?"

I just tried your example on Squeak 3.7-5989 on my G4 iBook (OS X 10.4.6, Squeak 3.8.12beta4U VM), and your example works fine.  It writes out the tone to a file without any decay, then the SampledSound plays with the decay after reading the tone back in and adding the envelope.

Your earlier problem really is a problem.  We'll have to see what the others say for future versions, but for now you could just make a new method on SampledSound, something like:

        SampledSound>>myStoreSampleCount: samplesToStore bigEndian: bigEndianFlag on: aBinaryStream
                super storeSampleCount: samplesToStore bigEndian: bigEndianFlag on: aBinaryStream.

which would just execute the AbstractSound implementation.

So, I'll need some help trying to reproduce your current problem.

        -Dean

Hello Dean,

As I said before, something was funky with my image.  In a clean 3.8 image (although I have changed the SoundPlayer SamplingRate to 44100), I created a new storeWAVOnFileNamed method for a SampledSound as you suggested, and that worked!  However, when I tried it with the pre-existing WAV sample I originally wanted to use, it didn't work--which led me to the following:

"This works when creating a mono sound"

snd := FMSound new.
snd setPitch: 200 dur: 5.0 loudness: 0.25.

snd storeWAVOnFileNamed: 'monotone.wav'.
snd := (SampledSound fromWaveFileNamed: 'monotone.wav ').

snd addEnvelope: (VolumeEnvelope newExponentialDecay: 0.96).
snd play.

"It does not work for stereo..."

snd := FMSound new.
snd setPitch: 200 dur: 5.0 loudness: 0.25.

"Turn the sound into a stereo sound and save it as a WAV"
mix := MixedSound new.
mix add: snd.
mix storeWAVOnFileNamed: 'stereotone.wav'.

"Read a STEREO sound from a WAV as a SampledSound and try to modify it"
snd := (SampledSound fromWaveFileNamed: ' stereotone.wav').

snd addEnvelope: (VolumeEnvelope newExponentialDecay: 0.96).
snd play.