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