Name

qplay — convert QBASIC play strings to PCM

Syntax

qplay [-i part] [-q part] [-r rate] [file...] | aplay -f dat -c 1

Description

qplay will convert QBASIC-style strings for its "PLAY" command to linear 16-bit raw PCM. Normally, you will be wanting to pipe it into a raw PCM player like aplay(1) to actually output it to a sound device. Be sure to lower the volume beforehand to avoid nasty surprises that come with square waves. By default, bsvplay will mix 1:1 square:sine waves to give a medium tone hardness.

Options

-q part: Part to mix square waves in (default: 1.0)
-i part: Part to mix sine waves in (default: 1.0). If -q2 -i1 is specified for example, the final PCM output will consist of 2/3*squarepcm + 1/3*sinpcm.
-r rate: PCM sample rate (default: 48000 Hz)

File format / PLAY statements

The file format qplay expects is of course not BASIC, but raw PLAY command strings. Lines that start with a leading hash mark ('#') are ignored.

Commands are case insensitive and whitespace is mostly ignored. The original QBasic manpage is slightly incorrect; below is what qplay supports.

Octave commands

on: Sets the current octave. There are seven octaves, n = 0-6.
>: Increases octave by 1. The upper octave limit in QBasic was 6; qplay has a limit of 9.
<: Decreases octave by 1. Octave cannot drop below 0.

Tone commands

A - G: Plays a note in the range A-G. The number sign (#) or the plus sign (+) after a note specifies sharp; a minus sign (-) specifies flat. N n Plays note n. The range for n is 0-84 (in the seven possible octaves, there are 84 notes); n = 0 means a rest.

Suffixes

# or +: Follows a specified note and turns it into a sharp.
-: Follows a specified note and turns it into a flat.

Duration commands

L n: Sets the length of each note. L4 is a quarter note, L1 is a whole note, etc. The range for n is 1-64. The length may also follow the note when a change of length only is desired for a particualr note. For example, A16 can be equivalent to L16A.
MN: Sets "music normal" so that each note will play 7/8 of the time determined by the length (L).
ML: Sets "music legato" so that each note will play the full period set by lengt (L).
MS: Sets "music staccato" so that each note will play 3/4 of the time determined by the length (L).

Tempo commands

P n: Specifies a pause, ranging from 1-64. This option corresponds to the length of each note, set with L n. T n Sets the "tempo", or the number of L4 quarter notes in one minute. The range for n is 32-255. The default for n is 120.
.: A period after a note causes the note to play 3/2 times the length determined by L (length) times T (tempo). The period has the same meaning as in a musical score. Multiple periods can appear after a note. Each period adds a length equal to one-half the length of the previous period. For example, the command A. plays 1 + 1/2, or 3/2 times the length, and A.. plays 1 + 1/2 + 1/4, or 7/4 times the length. Periods can appear after a pause (P). In this case, the pause length is scaled in the same way notes are scaled.

Variables

X(var): Play the string in the variable var.

Variable definitions in qplay syntax are for example:

	$var = "CDEF";

and they must stand on a single line.

Examples

	echo "L16O2CDEFGAB>CDEFGAB>L4C" | qplay - | aplay -fdat -c1

will play a tone ladder.