Playback Controls

Conclusion. The development of low-complexity time-domain methods for time-scale or pitch-scale modifications has already made it possible to incorporate such systems in consumer products such as telephone answering systems, effect boxes and semi-professional CD players. They could easily be implemented in record or playback devices such as DAT or CD players, offering the user additional control over... 

The basic operation of a sampling synthesizer is to playback digitized recordings of entire musical instrument notes under musical control. Playback of a note can be triggered by depressing a key on a musical keyboard, or from some other controller, or from a computer. The simplest samplers are only capable of reproducing one note at a time, while more sophisticated samplers can produce polyphonic (multi-note), multi-timbral (multi-instrument) performances. 

The scalability is an important aspect when designing multimedia distributed systems and the proposed framework is developed according to the rules that define the scalability. The differences between the client components for the web access and the compwnents that allow the access from the desktop/Pocket PC are insignificant. They are developed as extensions of the client-side generic components that implement basic functionalities such as interface between the apvplication and the peripherals (access control to sound and video blasters, or TV tuner), audio/video data manipulation (data transmission/retrieval to/ from the media server), audio rendering, video playback, and handwriting/drawing features. 

In 1975, the PAR Model 374 Polarographic Analyzer was introduced, at a price of 9500. This instrument employed a 16-bit microprocessor to control acquisition and analysis of data. During data collection, scale expansion and autoranging were automatic, and invalid data points could be rejected by comparison with pre-set criteria. In the PLAYBACK mode, the entire curve was reread and plotted on the recorder, with all peaks on scale. If desired, baseline and background corrections were measured, and concentrations calculated from pre-set standards. This was the first pulse voltammetric instrument designed around a microprocessor. Like the Southern Analytical pulse instrument based on vacuum tube technology, it came a bit too soon, before the technology (or the customer) was quite ready. 

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). 

The Transport Controls are used to playback and navigate around media files. 

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. 

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. 

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. 

Transport controls— These control playback of the media file. 

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. 

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. 

ACID will immediately begin playback and will generate the MTC at the same time, using the output device or port specified in the Preferences dialog box. ACID s transport controls (Play and Stop) will be used to control the external devices. 

More advanced streaming properties may require a server to properly stream. The server controls how the stream is being sent and may be able to compensate for network traffic problems, allow variable bit-rate playback, and let the listener randomly access different parts of the file (instead of listening in a linear fashion). Streaming media servers are sold by a number of streaming format companies and must be installed on the sending computer. This means that you may need to find an ISP that specializes in streaming media to distribute your media or work with your local ISP to get the proper server software installed. 

X Draw contents of events— This controls whether the waveforms are drawn inside events on the timeline. Deselecting this can speed up the performance of ACID when scrolling or zooming on the timeline, but it will not improve playback or rendering. 

X Enable multimedia keyboard support—Multimedia keyboards are simply keyboards that have special additional hot keys used to control the playback of media files. When this option is selected, these hot keys can also be used to control playback in ACID. 

This tab controls which MIDI devices will be available on the track header for MIDI tracks for playback. More information on using this tab in conjunction with MIDI tracks is detailed in Chapter 10. 

Many Keyboard Navigation and Selection shortcuts also work in the Chopper window, in addition to some playback (transport) controls and zoom shortcuts. 

P2P VoD system is of receiver-driven and each peer controls playback rate by himself. Unlike live peer, VoD user has more flexibility to choose different playback patterns, such as skipping, fast forwards and fast backwards. 

The main screen of the program provides access to the three main working areas of the system the Bankset view, where one selects programs and sampled wave templates the Program view (Figure 8.10), where the editable controls of a sound are located and the Options view, where one can set up a number of global playback utensils such as the master volume, a reverb, a chorus and the MIDI source (Figure 8.11). 

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). 

Additionally, some more controls for the playback can be implemented, in addition to the already available volume control. Pause/Play and even fast for-ward/reverse are possible functions. Concerning the C code that is executed on the Armada board, it would also be an advantage being able to load other formats than PCM WAV. 

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