You must write the 6 programs described below. All of these are command-line tools that follow the Unix style of passing switches and arguments on the command line. As such, your programs should never prompt the user for anything. You may assume that all switches appear before the first argument. The requirements below are minimal requirements; you may provide extra functionality or handle extra cases as you choose. For example, you might include a --debug switch that causes extra debugging information to be written to standard error. As a general rule, your programs should be user friendly". That means they should print useful error messages whenever possible. Additionally, your programs should print any messages or diagnostic information to standard error, with standard output reserved for sound output. I do not require that your programs be absolutely \quiet", but take care that the default behaviour prints at most a few messages.
All programs should handle the following 2 formats for sound files: .cs229 format, and .wav format, described in Appendix B. Similarly, all programs should accept the -h switch, which causes the program to display a "help" screen and then terminate. The help screen should describe the program, its usage, and all legal switches (including any extra ones you implemented).
1.0 sndinfo
This program reads all sound files passed as arguments, and for each one, displays the following.
The file name
The file type (.cs229 or .wav)
The sample rate
The bit depth
The number of channels
The number of samples
The length of the sound (in seconds)
If no files are passed as arguments, then the program should read from standard input. The only required switch for this program is -h.
1.1 sndcat
This program reads all sound files passed as arguments, and writes a single sound file that is the concatenation of the inputs. If no files are passed as arguments, then the program should read from standard input. You must support the following switches.
-h: show the help screen.
-o file: specify the output file name; if omitted, write to standard output.
-w: output in .wav format instead of .cs229 format
1.2 sndchan
This program reads all sound les passed as arguments, and produces a single sound le where each channel corresponds to one of the input le channels (channel order should be preserved). For instance, if the first sound le has 2 channels and the second sound le has 3 channels, then this produces a sound le with 5 channels. If no les are passed as arguments, then the program should read from standard input. You must support the following switches.
-c n : output channel n only; otherwise all channels
-h : show the help screen.
-o file : specify the output le name; if omitted, write to standard output.
-w : output in .wav format instead of .cs229 format.
1.3 sndmix
This program reads all sound les passed as arguments, and "mixes" them into a single sound le. The program is invoked as
sndmix [switches] mult1 file1 ...multn filen
where the sample data of filei is multiplied by multi (a real value between -10 and 10); the scaled data is summed to produce the output le. You must support the following switches.
-h : show the help screen.
-o file : specify the output le name; if omitted, write to standard output.
-w : output in .wav format instead of .cs229 format.
1.4 sndgen
This program is a mess of switches. It produces a sound of a specified frequency and waveform, using a simple ADSR envelope (see Appendix D). You must support the following switches.
-h : show the help screen.
-o file: specify the output le name; if omitted, write to standard output.
-w: output in .wav format instead of .cs229 format
--bits n : use a bit depth of n
--sr n : use a sample rate of n
-f r : use a frequency of r Hz
-t r : total duration of r seconds
-v p : Peak volume. 0 p 1
-a r : attack time of r seconds
-d r : decay time of r seconds
-s p : sustain volume. 0 p 1
-r r : release time of r seconds
--sine : generate a sine wave
--triangle : generate a triangle wave
--sawtooth : generate a sawtooth wave
--pulse : generate a pulse wave
--pf p : Fraction of the time the pulse wave is "up"
Note that the volume parameters are given as the percentage of the maximum volume.
1.5 sndplay
This program reads a music file in .abc229 format and produces a sound file of that music.
You must support the following switches.
-h : show the help screen.
-o file : specify the output file name; if omitted, write to standard output.
-w: output in .wav format instead of .cs229 format
--bits n: use a bit depth of n
--sr n : use a sample rate of n
--mute n : do not play instrument n