Sequences
A sequence tells which samples to play for the
subject in which order and possibly with pauses between samples.
Free sequence
A free sequence means that a fixed
sample sequence is not used or enforced. The subject selects
which samples to play and in which order.
A free sequence is selected by setting the
sequenceType-parameter in the test parameter file to
'free':
# use free sequence
sequenceType=free
The sequence-parameter is not needed (and will be
ignored if used) in a free sequence test.
Fixed sequence
A fixed sequence means that the sequence of samples
presented to the subject is fixed and enforced so that the subject
can't affect the playing of samples. It is possible to use pauses
between samples.
A fixed sequence is selected by setting the
sequenceType-parameter in the test parameter file to
'fixed' and setting the sequence-parameter
to the sequence definition:
# use fixed sequence
sequenceType=fixed
sequence=<sequence>
The <sequence> is the
sample sequence definition, see
below for the format.
Defining sample sequence
A sequence is defined with a string that defines the order of samples
and pauses between samples. A sequence consists of sequence
items each of which define the pause length in the beginning
of the sample and the sample name. The length of pause is given in
seconds or in sample frames and may be omitted. The name of sample is
required. The pause length and sample name are separated by a comma.
<sequenceitem> = [<pause>,]<sample>
<pause> = <seconds>s | <frames>
The <seconds> (float) is the number of seconds. The
letter 's' is used to indicate that the number is in seconds instead
of sample frames. The <frames> (int) is the number of
sample frames. Some examples:
0.1s,A
22050,B
A
the first plays sample A after a pause of 0.1 seconds. Second plays
sample B after a pause of 22050 sample frames. If sample rate is
44100, 22050 is equivalent to 0.5s. The third plays sample A without
a pause between A and the previous sample.
The whole sequence is a list of sequence items
separated with a semicolon.
<sequence> = [<sequence>;]<sequenceitem>
Here is an example:
A;0.1s,B;0.5s,A,0.1s,B
The example plays samples A and B with a pause of 0.1 secods between
the samples and a pause of 0.5 seconds between the sample pairs.
Here's an example of using this sequence in the test config file:
# use fixed sequence
sequenceType=fixed
sequence=A;0.1s,B;0.5s,A,0.1s,B
Automatic sample play when item starts
In free sequence tests you can start playing a
sample automatically when the item starts. To do this, define the
autoPlaySample parameter with a sample parameter
name. For example:
# Start automatically playing sample A when item starts.
autoPlaySample=A
This will start playing the sample given with the item parameter A.
This has the same effect as playing the 'A' button on the subject UI's
sample-play controller (if there is one).
If this parameter is not defined, a sample is not automatically started.
Notes
Some notes about using sequences:
- There should not be any extra spaces in the sequence.
- The test system currently ignores the pause of the first
sequence item in a sequence.
- The sample names used don't refer to the sample IDs in sample
lists. They refer to the parameter names of test items. For
example, a test item for a A/B test contains the parameter names
A and B whose values are the sample IDs of the samples that
correspond to the names A and B.
- If fixed sequence is used, there should not be a sample playing
controller is the subject's UI. If it is there, it will be
ignored. If free sequence is used, there must be a sample
playing controller in the subject's UI.
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Last modified: Wed Jan 13 14:42:26 EET 1999