The following procedure uses the Media Control Interface to play part of a waveform file.
TO PLAY.WAVEFORM
IGNORE MCI [open c:\\windows\\media\\ding.wav type waveaudio alias ding]
MCI [set ding time format samples]
MCI [play ding from 0 to 5000]
WAIT 120
MCI [close ding]
END
Let's take a closer look at each instruction in the example above.
The procedure first opens "c:\windows\media\ding.wav" by issuing an open
command.
We use the alias
parameter so that we can refer to this media entity as ding
instead of always using the full path to ding.wav.
Unlike most other commands, the open
command outputs a value on success.
Since Logo programs must do something with every value that is output, we simply IGNORE it.
The set
command is used to specify the time format as "samples".
A sample is the smallest unit of sound within a given waveform file.
The play
command is used to start playing from one time to another.
The waveform plays asynchronously, which means that FMSLogo doesn't wait for the audio clip to finish playing before running the next instruction.
If you wanted to wait until the track was done before moving on to the next instruction, you could add wait
to the end of the MCI instruction, as in
MCI [play ding from 0 to 5000 wait]
It is not necessary to specify an end time for the play
command.
If you wanted to play the entire waveform, you could do so with:
MCI [play ding from 0]
The WAIT instruction just waits for two seconds. This has nothing to do with MCI, it just gives you some time to listen to your waveform.
The close
command is used to tell the Media Control Interface that you are done with the waveform file.