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SIDPLAYER NEWS #4  April 1986

This is the fourth news file for Sidplayer, the music system published in "All
About The Commodore 64, Volume Two" by COMPUTE! Books.  This news file offers
many hints, tips, and suggestions on how to more easily create better sounding
songs.  The information presented here will be of interest to both novices and
experienced users.

Please keep in mind that the Sidplayer Editor is to be used only by those who
have purchased Volume Two.  The Editor is not a Public Domain program.  This
document is not intended to be a guide on how to use the Editor for people who
have not purchased the book.

The main part of this document consists of suggestions organized by command
name.  After these suggestions you will find some shorter sections that
describe the symptoms of Master Composer Syndrome, encourage you to hook your
computer up to a stereo, and offer some advanced techniques to ponder.

TEM
1. The Editor lacks a feature to play just a given measure.  Although a fast
forward feature is available, it can still take a while to skip past part of a
song.  A faster way to skip over a part is to insert the command TEM 900 at
the beginning of the part to be skipped, and then insert a TEM command for the
correct tempo at the place you want to hear.  When you play the song, the part
to be skipped will be played even faster than is permitted by the fast forward
feature, and you won't run a risk of getting a CLOBBER error (unless you use
the fast forward feature as well).  There are two restrictions to the use of
this technique.  If the part to be skipped contains thirty second notes, tempo
450 will have to be used instead.  If the part uses utility durations, this
technique cannot be used.
2. The tempo chart on page 285 is so handy, it may be worthwhile to photocopy
the page for quick reference for when you enter a song.

UTL
1. If you need to get a portamento glide that is longer than a whole note, you
can always use the utility duration.  This will permit a glide of any duration
up to four seconds.

VOL
1. It is strongly recommended that you not use volumes above level 12, except
when you are using the triangle waveform which is naturally quieter.  If you
use volume levels above 12, especially with the pulse wave, the song may
overpower the speaker on some televisions, causing the sound to be distorted,
and thereby detracting from the quality of your song.  Not everybody has their
C64 hooked up to a nice stereo that can handle the volume.
2. You need to use the VOL command on only one voice.  The master volume sets
the volume for all three voices.  If a VOL command is used on more than one
voice at the same time, the VOL on the highest numbered voice is the one that
will take effect.  Usually the VOL and BMP commands are used only on voice one.
3. Be aware that a popping noise occurs when the master volume is changed by
large amounts.  Some people feel that the popping detracts from the song, and
try to minimize the popping in their songs.  To reduce the popping, try using
smaller volume level changes and different positions for the volume changes.
The sustain levels can also be adjusted to control the overall volume.

BMP
1. As with the VOL command, use BMP in only one voice.  If two voices use a
BMP command at the same time, the volume will be bumped by two levels instead
of one.
2. BMP can be used to fade out a song when the last measure or two are
repeated.  Some songs also use BMP to fade out the last note, but this creates
a noticeable "stepping" effect in the volume as it changes.  A better way to
fade out a note is to use a long release (a large RLS value).

HED and TAL
1. Remember that repeat loops cannot be nested.  Be especially careful of this
when you have a repeat loop that contains a phrase call, and the phrase also
contains a repeat loop.
2. If at all possible, try to avoid using HED 0 for endless repetition.  A
song that does not end does not work very well with an autoplayer.

DEF
1. Some songs contain several phrase definitions right at the beginning of
each voice, which often set up waveforms and envelopes that are not used until
later in the song.  This may be convenient but it is not always a good
practice.  When Sidplayer has to process several commands before the first
note, the chance of getting a CLOBBER error is increased.  This error occurs
when too many commands are placed between notes, and they cannot all be
processed in one jiffy (one sixtieth of a second).  The intended way for a
phrase to be used is to define the phrase as it is played the first time, and
then to call it when it needs to be played again later.  See pages 300 to 304
for a complete explanation of phrases.

F-M and FLT
1. Sometimes it can be handy when editing a song to play only one voice at a
time.  Unfortunately, this cannot be done if the voice contains a call to a
phrase defined in a voice that is not being played.  A way to get around this
limitation is to play the voice that contains the phrase definition but to
include the commands F-M N and FLT Y at the beginning of the voice.  Selecting
a filter mode of N (no mode) and passing the voice through the filter makes
the voice inaudible.  This allows you to play the voice so that the phrase
gets defined, without hearing the voice itself.

F-X
1. In addition to generating tones for music, the SID chip also picks up a lot
of the "noise" from the circuitry inside the computer.  This undesirable
background noise can be significantly reduced on some computers by turning on
the external filter input.  To take advantage of this, just include an F-X Y
command at the beginning of each song you create.  The songs will be free of a
lot of the background hiss when played.  Other than making the song sound much
cleaner, enabling the external filter input will not have any effect on the
song.

ATK
1. It is not always desirable to use a value of 0 for the ATK command.  When
all three voices have an attack rate of 0, and all three voices start playing
new notes at the same time, sometimes the SID chip will not gate (start
playing) the notes together, and one note will noticeably start to sound
before the others.  The phenomenon is sporadic, but does not occur with slower
attack rates, so you can use ATK 1 to get around the problem.

DCY
1. To minimize the "biting" effect of the volume falling from the attack peak
to a much lower sustain level, a slower decay rate can be used.

SUS
1. Unfortunately, the SID chip does not provide a volume control for each
voice (the VOL command affects all three voices), but to some extent, the
sustain level of a voice can be used to control the volume of a voice.
2. If one voice is playing a melody and other voices are supporting it by
playing harmony, it is a good idea to have the SUS level for the harmony
voices set at least one level lower than the sustain level for the melody
voice.  If they are equal, the harmony voices can overpower the melody voice.
Setting their SUS levels lower makes the melody voice stand out, and generally
the song will sound a bit nicer.

RLS
1. As with the ATK command, it is a good practice to avoid using the value 0
with the RLS command.  A release rate of 0 sometimes makes voices cut off
unevenly.  It is more noticeable when the song is played on a stereo instead
of a television or monitor speaker.  Values from 1 to 15 are recommended for a
more pleasant effect.

PNT
1. The release point, set by the PNT command, determines the number of jiffies
from the end of a note that the note should start to release.  Always remember
that the release point must be less than the duration of the note being
played, or the note will not be played properly.  For example, in tempo 100 a
sixteenth note is 9 jiffies long.  If the release point is set to 12, the note
will start to release as soon as it starts playing.  It will never have a
chance to complete its attack, and so will not be heard, or will be hardly
audible.  For this reason the release point is usually set around 4 or 5.  If
you have the release point set larger and have to play some shorter notes, it
may be necessary to temporarily set the release point smaller for those notes.
You can refer to the tempo chart on page 285 to determine the exact jiffy
count for any note in any tempo.
2. If notes of longer durations are being played, a reason to use a larger
release point is to create a more staccato effect.
3. Setting the release point to 0 means that notes played will never be
released.  This is the same thing as tying the notes together.  Therefore, if
you need to enter a lot of notes that are all tied together, for a legato
effect, set the release point to 0 instead of entering a tie for each note.
4. If a voice contains alternating notes and rests of the same duration, such
as a quarter note, quarter rest, quarter note, quarter rest sequence in a bass
line, a shortcut can be used.  The technique is combine the notes and rests
into notes of equivalent total duration and then set the release point to make
the release begin where the rest would normally begin.  For example, let's say
that the above quarter notes and quarter rests were played in tempo 100, so
each note and rest was 36 jiffies long, and the release point was set at 4.
Instead of entering quarter note and quarter rest pairs, you could enter half
notes and set the release point at 40, where the 40 is 36 jiffies for the
quarter rest and 4 jiffies for the normal release point of the quarter note.

WAV
1. For some reason, pitches played using the pulse wave in octaves 0, 1, and
some of 2 sound out of tune.  It may be best to avoid using the pulse waveform
when playing notes in the lowest octaves.
2. The pulse waveform can be combined with the triangle waveform to create a
new and useful waveform type.  Just enter the number 5 (4 for pulse plus 1 for
triangle) to select the WAV TP command.  The resultant waveform is especially
useful for harpsichord effects.
3. The waveform combination SP is much quieter and therefore is not as useful.
All other combinations seem to be inaudible.
4. Don't put a WAV command right before a rest.  The release of a preceding
note may continue into a rest, and a waveform change before the rest may clip
the end of the note and be noticeable.  Instead, just put the WAV command
right before the next note to be played.

P-W
1. Do not use the pulse wave with a pulse width less than 100.  Notes played
with a width much less than 150 are inaudible on some SID chips.
2. When using the TP waveform combination, be sure to have the pulse width set
below 2048.  The volume of the TP waveform decreases as the pulse width goes
above 2000.  Also set the width below 2048 when using waveform SP.

P-S
1. Pulse width sweeping works by adding the pulse sweep value to the pulse
width once each jiffy.  The only problem with this is that with larger sweep
rates, the pulse width can exceed 4095, in which case it wraps around and
starts back at 0.  This causes a very noticeable popping noise which can
really detract from a song.  To avoid the wraparound you can use a slower
sweep rate or set the pulse width lower (or higher if you are sweeping
backwards).  If you want to keep the same pulse width and sweep rate, first
determine on which notes the wraparound occurs.  These will be the notes with
the longest durations.  Then take each note which causes popping, divide it
into two halves tied together, and insert a P-S command between them with the
same sweep rate but the opposite direction.  For example, if popping occurs on
a half note when the sweep rate is 30, instead enter a quarter note tied to
another quarter note of the same pitch, with a P-S -30 command between them.
You will also need to enter a P-S 30 command after them to reset the direction
of the sweep for the next note.

SNC and RNG
1. Refer to pages 324 to 325 and 333 to 337 of Volume Two for the correct way
to set up synchronization and ring modulation effects.

VDP and VRT
1. For a more natural vibrato effect, you can change the vibrato depth while a
note is playing.  Just break the note into smaller notes of the same total
duration, all tied together, and put VDP commands of increasing values between
them.  Again, remember to reset the depth back to the original value.
2. Be aware that the vibrato processing is done only for the duration of a
note, and is not done when a rest is being played.  When a note with a slow
release rate is followed by a rest, the voice may continue to fade away during
the first part of the rest.  If vibrato is used on the note, it is sometimes
noticeable that the vibrato all of a sudden stops as the note is fading away.
To prevent this from happening, you can delete the rest, add its duration to
the preceding note, and set the release point higher for that note as
discussed in the above section on the PNT command.

TPS
1. The SID chip cannot play pitches beyond octave 7, even when the TPS command
is used.  If you try to play a note above B7, the note will be played with the
same pitch but in octave 7.  Thus an E transposed to octave 8 will be played
as an E in octave 7.  To determine if a voice is being transposed out of
range, watch the voice on KPLAY and see if the key goes off the right edge of
the piano keyboard display and disappears.
2. It is possible for the SID chip to play pitches in octave -1 by using the
TPS command with negative values, but this is rarely useful.

AUX
1. When using the AUX command to change the color of the piano keys in KPLAY,
do not use values outside the range of 0 to 15.  Values larger than 15 do not
give you any new colors, and songs using larger values may forfeit
compatibility with future editions of players.

Sidplayer News Part 4 continues in SIDNP2.DOC