Enables effect processing for the specified channel. This command continues to add effects to a channel (up to 16) until FSOUND_FX_Disable is called.<BR>
<TD>A single fx enum value to enable certain effects. <BR>
</TD></TABLE>
<H3>Return Value</H3>
On success, an FX id is returned.<BR>
On failure, -1 is returned.<BR>
<H3>Remarks</H3>
FSOUND_ALL is supported. Passing this will enable fx on ALL channels available.<BR>
This command can only be issued while the channel is paused.<BR>
If an effect is not enabled, then it will not be affected by its corresponding FSOUND_FX_Set functions.<BR>
This function must be played after a paused PlaySoundEx (ie FSOUND_PlaySoundEx(FSOUND_FREE, sound, NULL, TRUE)), and before<BR>
the FSOUND_SetPaused(FALSE) so that the hardware can get the resource before it starts playing.<BR>
A total of 16 FX per channel is allowed, any more will result in an error. FX are reset to 0 after a sound is stopped or played. (but as above, before the unpausing of a play-paused sound).<BR>
Warning : This function is expensive to call as it has to set up fx buffers etc. It is best to call it once, reserve the channel then reuse the channel index when calling playsound without calling it again.<BR>
Note : Under DirectX 8, channels with FX enabled sounds cannot have their frequency changed. DirectX 9 and above do not have this limitation.<BR>
