Loops playback

Use looping playback to isolate smaller sections of the project. 

Press the L key on your keyboard to turn on Loop Playback. 

Every time you click the Start and Stop button in the Record dialog box, a new track and a new file are created. Takes can also automatically be recorded to a single track as you use looping playback to continuously record takes without interruption. 

Every effect has its own array of controls that are used to modify the parameters of the plug-in. These are discussed in detail later in the chapter. There are some general procedures that will allow you to effectively audition and modify effects. Effects can be modified as the project is playing back, which means that you can change the effects variables in real-time while you listen to the results. With the Audio Plug-In window open to the plug-in that you want to work on, click on the timeline (or press Alt-1-0 [zero]) to set the focus to the timeline and press Play. It is often useful to use a looped playback of a shorter section of a project to hear the results of an effect. While playback continues, go back to the Audio Plug-In window and modify the effect. 

The Stutter plug-in seems to react slowly to changes, and the preview on the timeline might take a second or two to update if you are continuously looping playback while you work. 

Unlike audio recordings, MIDI data cannot be recorded into separate takes by turning on Loop playback mode while recording. This is because regions cannot be saved with the MIDI file but only with the project. 

Results of video playback experiments add an interesting twist to the story. For both S. uetzi and S. stridulans, courtship sequences were digitized and modified into three separate video loops in which the male foreleg ornamentation was modified in the following way (1) brushes of hair were added (S. uetzi) or enlarged (S. stridulans) on the male s foreleg tibiae - brushes video, (2) no changes were... 

Right-click the Marker bar to insert a region. Regions are identified by two green markers. The Loop Region (visible in the lower image) is dark blue and is used to repeatedly loop project playback. 

Events are easily split by positioning the timeline cursor on an event where you want a split to occur and then pressing the S key on your keyboard. Since you will probably want only one take at any particular time, you can split all of the takes at the same time and at the same position by selecting all of the events. Looping the playback one section at a time and then soloing one take at a time will allow you to audit the best version. 

Playback will loop, and you can continue to record takes until you are satisfied. Click the Stop button to stop. 

While recording an audio source is a fundamentally different operation firom recording MIDI data, the procedure for doing so is very similar. Audio is recorded as sounds, and MIDI is recorded as data that can be used to recreate the performance (for example, what note was played, how hard the key was pressed, and how long the note lasted). MIDI can be recorded into individual tracks or multiple takes can be recorded into a single file by looping the playback. MIDI setup and configuration are dealt with in much more detail in Chapter 10. 

Transport controls— These control the playback of the media file. The Loop button repeats the loop region over and over. 

The Stretch tab for loop-type tracks and files sets how ACID adjusts the loop when it is inserted into a project. It controls the tempo and where the beats fall. For loop fdes, ACID stretches and compresses smaller subdivisions in the file to force the beat to match the project. This means that the playback of a loop file may vary over time. Here is what you will find on this tab ... 

Transport controls—These control playback and looping just as other ACID transport controls do. 

Technically, Loop tracks do not have a tempo adjustment, but the Number of beats item on the Stretch tab in the Track Properties window can control the speed of playback in a rough way. Loop media files are recorded at a set tempo, however, and, as with other ACIDized media files, this information is saved with the file. The Save button in the Track Properties window does not save Number of beats or tempo information for loop files. 

As previously mentioned, the Number of heats item can adjust the tempo of a loop in an indirect and rough way. The default number of beats is saved to the media file of a loop when the loop is rendered out of ACID. It is simply the number of measures times four. In a project with a tempo of 150 bpm, a loop that is created fi m a loop region of four measures will have a Number of beats entry of 16. If you change this to 8, ACID will play the file as if it had only eight beats and it will play back at twice the rate. If you used this media file in a project that had a tempo of 75 bpm (half of the original tempo) and you changed the Number of beats to 8 (playback at twice the speed), it would play back at the rate it was created. 

Variation of the chemical composition of the BZ reaction has remarkable effects on the tip motion of a spiral wave [19-22]. Here the effects induced by lowering the acidity (and thus the excitability) of the medium are discussed. Figure 9A depicts the path of the spiral tip for five different proton concentrations. The traces were obtained by copying the spiral tip from the video screen on a transparency during a slow motion playback of the recorded video movies. The trajectories may be considered as prolate hypocycloids [39] observing by definition Agladze s rule [20], e.g., a counterclockwise overall motion superimposed by a clockwise motion within the loops or vice versa. In the following the trajectories will be discussed in terms of epicycles. 

Fig. 9. Traces of the motion of the spiral tip in BZ media differing only in the initial sulfuric acid concentration. The traces were copied onto a transparency from the video screen during a slow motion playback of the video film recorded simultaneously with the digital spectrophotometric images. Estimated time period per loop 0.15 M, 175 s 0.19 M, 73 s 0.23 M, 54 s 0.26 M, 30 s 0.37 M, 19 s. The photograph shows a spiral on which the trace of three loops of the tip motion is superimposed (white dots). Image area 7x7 mm. From [21].

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