Audio tracks |
Audio or MIDI? [Light] [Beginner] [Professional] [Notation] [Composition Light] [Composition Pro] [Drums and Percussion] [Guitar] [Choir] [Keyboard] [Soloist] Up to now, we have only used MIDI to manipulate music and hear
the notes. Pizzicato plays the score by creating a series of MIDI
events. The sound card of your computer or your external
synthesizer uses those MIDI events and transforms them into a
real sound that you can hear through the speakers. This working
method is quite satisfactory in many cases. Most music
information can be indeed represented by a sequence of MIDI
events. However, there are cases where MIDI can not be used. For
instance, if you want to add your voice to a music arrangement,
or if you want to play a real instrument and record the exact way
it sounds, MIDI is of no use. In that case, the program must
record and store the sound itself (or at least its mathematical
representation). As we have seen in a previous lesson (see the "Music
notation" lesson), a sound is simply a vibration of air. It
has four main qualities: the pitch, the amplitude, the timber and
the duration. When an acoustic instrument plays, it vibrates at
certain frequencies and transmits that vibration to the air
around it. This vibration finally comes to your ear and you get
the sensation of sound, with its various qualities. To record sound, we need to measure the position of a particle
of air, around its central position, so that we can thereafter
reproduce the same vibration. For practical purpose, we can say
that the zero value will represent the position of a particle of
air when no sound travels through it. If the particle is pushed
forward, we can measure its displacement from its central
position and write it down. Such a measure is called a sample. As the vibrations of sound are quite fast, we must do so a lot
of times per second. In fact, as the human ear can only perceive
up to about 20 to 22 thousands vibrations per second, there is a
mathematical principle that tells us that we must measure the air
position at least two times that frequency, so that the sound is
recorded and stored accurately. This is the reason why, on a
music CD, the frequency has been fixed to 44100 samples per
second. This frequency is also called the sample rate and is
expressed in Hertz (abbreviation Hz) which means "vibrations
per second". If we record a sound with a much lower sample rate, a part of
its vibrations are lost when we reproduce it. Indeed, the
information is missing in the record and the sound quality
deteriorates. The most common example is a telephone line. In the
beginning, they used an 8000 sample rate. As the human voice is
not using the full spectrum of sound vibrations, the phone
quality was enough to transmit an understandable conversation.
But try to listen to a full symphony orchestra through a phone
and you will hear that the sound quality is quite poor, indeed. Another important parameter is the precision with which the
position of an air particle is measured. You could measure on a
scale that contains 10 positions or 10000 positions or more. If
there are too few positions on the scale, there will be an
approximation of the position. To give a comparison example, if
you measure the dimensions of a room with a meter that do not
have any centimeter graduations, you could then say the room is 3
meters or 4 meters, but you could not say exactly 3 meters and 23
centimeters. By transmitting the information that the room is 3
meters, it would not be exact and if an architect creating a big
building would use that precision level, there is no doubt that
the building would fall apart very soon. So the precision is
quite important. For the CD quality, a scale has been set that
goes from -32768 to +32767. The specificities of those numbers
come from the binary system used to encode them. Indeed, 2 to the
16th power equal 65536 so that there are so many possible values
to a sample (65536 = 32768 negative values + 32767 positive
values + 1 value for zero). So we say that the quality of a CD is
in 16 bits (a bit is a BInary digiT). As a summary, we can say that an audio recording is a series
of numbers that represent a sound and that may be used to
recreate that sound at any moment through the speakers of a
computer. In CD quality, one second of music is represented by
44100 times 2 numbers (because stereo is used, so there are two
channels), each one of them being in the range from -32768 to
+32767. When we put those numbers on a graph with time, we get a
picture like this: where the upper part is the left channel and the lower part is
the right channel. Those curves represent in fact the position of
an air particle when this sound is heard. Most software working
with audio will represent sound as above. What is an audio track? [Light] [Beginner] [Professional] [Notation] [Composition Light] [Composition Pro] [Drums and Percussion] [Guitar] [Choir] [Keyboard] [Soloist] An audio track is the representation of a sound for a specific
duration. For instance, you could have a track of 4 seconds in
duration. By playing this track, you will hear the sounds it
contains. Pizzicato lets you add one audio track (or several with
Pizzicato Professional or Composition Pro) to a
score. You can specify when the audio track begins, in relation
to the score and Pizzicato will play it together with your score. Each audio track is in fact represented by a wave file
(".wav" extension on Windows). There are lots of
existing audio file formats. Pizzicato works with WAVE files, as
they are very common and can be used on Windows as well as on the
Mac. You will find various software format converters on the
Internet, so that you can use wave files and then convert them
into or from mp3, aiff and many other audio
formats. You should well understand that the audio information is
stored in the wave file and not in the Pizzicato document. The
Pizzicato document contains a reference to the wave file, so that
it can play it at the same time than the score. If you want to
send a Pizzicato score containing audio tracks to a friend, do
not forget to send also the corresponding audio files. Existing
audio files may be inserted in the score, but you can also create
an empty audio file and record it yourself, with a microphone. Adding an audio track [Light] [Beginner] [Professional] [Notation] [Composition Light] [Composition Pro] [Drums and Percussion] [Guitar] [Choir] [Keyboard] [Soloist] Depending on the Pizzicato version you have, you access or add
an audio track differently. For most versions, do the following: For Pizzicato Professional or Composition,
do the following: The audio track selection dialog appears as
follows: This dialog lets you specify the associated audio wave file.
You may either select an existing audio file or create a new one.
We will first open an existing audio file. It is an 8 bits, mono, audio file, with a sample rate of
22050 samples per second and its duration is 6 seconds and
122 milliseconds. You may also create a new audio file and associate it with the
score. The Delete button is used mainly for the Pizzicato
versions with one audio track. Clicking on it just removes the
reference to the audio file from the Pizzicato score. Notice that
the audio file itself is not destroyed. Multiple audio tracks [Professional] [Composition Pro] With Pizzicato Professional or Composition Pro,
you may add several audio tracks to the same score. You may start
the audio tracks at different position in the score. When an
audio file has been added, it appears just below the score as a
colored band, at the position where it will start to play and
with the length showing its duration in relation to the score: The little icon on the left bottom of the score rectangle
shows that this score has associated audio tracks. Clicking on it
switches between viewing the audio tracks below the score or not
viewing them. To add another track, just do exactly the same as explained
above. In fact, you may add the same file more than once, at
various positions in the score. When adding more tracks, the
conductor view will display something like this: For each track, you may specify the starting point in the
score as well as the volume of the audio file. The starting point
may also be adjusted by directly dragging the yellow bands
horizontally. While doing so, there is a magnetic grid that
positions the starting point at multiples of half a beat, so as
to accurately place the audio file, but you may disable that
magnetism by holding down the CTRL key. When you click with the right mouse button (alt-click on Mac)
on an audio track, three menu items appear: Audio setup [Light] [Beginner] [Professional] [Notation] [Composition Light] [Composition Pro] [Drums and Percussion] [Guitar] [Choir] [Keyboard] [Soloist] The audio setup should work correctly by
default. You may access it in the Options menu, Audio
setup...: If you experience a jerky sound, increase the size of the
output buffer by steps of 100 until you hear a correct sound.
Conversely, to experience the shortest delay possible between the
coloring of the note and its sound, try to reduce the output
buffer size by steps of 50 or 100. When you close this dialog,
you may need to exit and restart Pizzicato for the changes to be
taken into account. The Default values button lets you reset the
parameters to their default values. If you experience a delay between the score (MIDI instruments)
and the audio track, you must add the same delay to MIDI, so as
to compensate. This is done by the MIDI play options...
item of the Options menu. There is a slider named MIDI
delay in milliseconds (correction for audio). Adjust its
value so that MIDI and audio are played exactly togther. The ASIO Setup... button will be explained in the
next section. Using an ASIO driver [Light] [Beginner] [Professional] [Notation] [Composition Light] [Composition Pro] [Drums and Percussion] [Guitar] [Choir] [Keyboard] [Soloist] Since version 3.5.2, Pizzicato can work with an ASIO driver to
handle audio. ASIO (Audio Stream Input/Output) is a standard
protocol to manage a sound card efficiently. It can reduce the
latency time, which is the delay between the moment that
Pizzicato writes sound data to the card and the moment when you
hear it. Many sound cards running on Windows have a latency time
that creates a delay that is disturbing when you play on the MIDI
keyboard and want to hear the Papelmedia sound library delivered
with Pizzicato. Some sound cards have their own ASIO drivers, but you can
always download and install a universal ASIO driver called
ASIO4ALL, which is free, on page: http://www.asio4all.com/ If you want to use the ASIO driver with Pizzicato (only on
Windows), click the "ASIO setup..." button in
the Audio setup dialog (Options menu). The following dialog appears: The menu entitled "Select ASIO driver to use"
let you choose the driver to use, as you can indeed find several
ASIO drivers installed on your computer. Try them all if
necessary and check the one that is running fine with Pizzicato
(in case of problems if Pizzicato won't start anymore, see the
remark at the end of this section). You have four other menus to select the left and right
channels, for ouput and input. The "ASIO control panel..." button calls a
dialog that depends on the ASIO driver. This control panel is
used to set up the driver according to the audio hardware you
have. The default value should work, but for more details, see
the documentation of the ASIO driver or sound card. If you want to go back to a normal audio setup, without ASIO,
click the Do not use the ASIO driver... button and it
will display the normal audio setup dialog. Confirm the ASIO setup by clicking on the OK button. Warning: Installing and setting up an ASIO
driver and making it work with Pizzicato is not always easy,
according to the hardware and software you have. In case of
problems, it may require technical skills to solve the situation.
We cannot here enter into such setup complexities. We have
described the basic procedure, that should work in most cases. If after trying to setup ASIO with Pizzicato, Pizzicato won't
start or crashes at startup, here is how to solve the situation.
Just remove the following file: My documents / Pizzicato 3.x / Prefs / Audio.dat Then start Pizzicato and the default audio setup will be
recreated (without ASIO).