Project Playback

The Hmecode at the upper left of the program specifies the current position of the timeline cursor (Hme at Cursor) in a selected format and the measure and beat. The timeline cursor is a vertical line that runs from the top of the timeline to the bottom and moves when the project is played back. It may be thought of as being analogous to the playback head on a tape recorder. 

The Transport Controls (see Figure 1.6) operate like standard media file playback or VCR controls. These buttons are used to move the timeline cursor around on the timeline and to control playback and recording in a project. A few transport controls are also available in the Explorer and Chopper windows (defined later). 

Notice that the Video Preview and the Mixer windows are in their own regions by themselves. This allows these windows to remain visible at all times for important previewing and monitoring of project playback. Windows in the docking area can be rearranged by dragging them by the handle on the left side of the window. 

The Save and Save As commands are used only to save proprietary ACID project files (. acd). When you are ready to create a song for general playback on any media player, to hum to a CD, or to publish on the Internet, use the Render As command. 

Previewing a project and playing it back is accomplished by using the Transport controls (see Figure 2.26) just below the timeline. What you hear when you play a project back is the sum total of all of the events as mixed together by ACID. The position of the playback is indicated both by the timeline cursor and by the position numbers at the top of the Thack Header. Since this is such a common operation, there are a number of important shortcuts that make this process easier. 

Use looping playback to isolate smaller sections of the project. 

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. 

Click the Start button. The project begins playback and the recording starts. 

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 Accuracy list simply adjusts the quality of the plug-in. Higher quality means that your computer needs to work harder. Faster machines (-1- 700 MHz CPU) should use the High setting unless you have a particularly complex project with a lot of effects. This really affects only timeline playback of the project in real time. You should definitely use High whenever you render, because the computer will take as much time as it needs to create the final output. 

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 ... 

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. 

ACID MIDI tracks need to use the Master bus (DirectX SoftSynth) to render projects. Other MIDI devices listed on the Bus Selector (see Figure 10.2) act as external devices and are used only for playback. All MIDI tracks in a project automatically use the same device changing the device on one MIDI track changes all MIDI tracks. As one example, if you are using a Yamaha SXG software synthesizer, your project will sound as if the MIDI track was being mixed into the project. In reality, the audio tracks in the project are mixing in ACID, but the MIDI track is being processed by an external device (software, in this case) that is mixed with the output from ACID outside of ACID on the sound card. Therefore, when you render the project, the MIDI track is silent. There is a way around this problem, however. 

The most important aspect of using the Master device for MIDI is when you render projects, as discussed above. Since the Master device is internal to ACID and the other devices are external, tracks that use these devices for MIDI playback will not be able to take advantage of any FX or pitch shifting. Notice that the Master device track (bottom) in Figure 10.3 has an FX button,... 

DownLoadable Sound sets (DLS) on your computer. As the name suggests, DLS fdes have a. dls extension and can be downloaded from a number of sites on the Internet. Some examples of some DLS sets are the Roland GS or Yamaha XG sets. DLS sets use the DirectX SoftSynth for playback and thus can be mixed into ACID projects and rendered out using the Master device. Both DLS-1 and DLS-2 formats are supported in ACID, but your sound card may not support both. The difference between the two is not important in ACID. The default GS sound set (16 bit) is found here C WINDOWS SYSTEM32 DRIVERS GM.DLS. The Load button allows you to add DLS fdes to the Voice set list. 

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. 

ACID can act as a MIDI device in a studio setup, both outputting MIDI Time Code (MTC) to other devices and accepting MIDI triggers from other devices and applications. The purpose of this is to synchronize ACID with your MIDI setup by allowing other devices to start ACID playback or to start and synchronize other devices from within ACID when you start playback of a project. The MIDI device or software application needs to be able to send and/or receive MTC, so simple dummy keyboards will not work. More complex synthesizers with sequencers, however, often have this capability. In professional MIDI studios, there is often a small box that is dedicated to generating timecode and synchronization and sometimes called a controller or a sync unit. 

Every time you stop playback in ACID, you will need to re-arm SONAR to listen for MIDI Clock. SONAR will automatically sync playback beginning at any point in your ACID project. See Figure 10.16 for a summary of the various settings and what you should see when everything is... 

The first item allows you to select which devices (hardware and/or software synthesizers) are used for MIDI playback and tune code generation. Selected items will show up on the device list in the track header for MIDI tracks. Although you can select from a number of devices for playback, only the default Master hus (DirectX SoftSynth) will allow you to render projects with MIDI files. 

In this Advanced Embedded Systems Lab (AESL) project, the onboard audio codec is used to play PCM audio data from a WAV file via the E2LP-board. The goal of the project is to read in data with the SD card module, store the file in DDR2 or VHDL synthesized block RAM and proceed the data via the audio chip. Additionally functions to control the playback can be programmed and customized. 

Current version of the project uses block RAM to store audio data which is sent via the Armada extension board. This data is then continuously sent to the audio chip for playback. Additionally, a volume control module is implemented, and the audio chip can be switched into bypass mode (Line-In is directly connected to the headphones). 

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