DotricDJ Waveform Capture and Analysis

Description

DotricDJ is a Windows application written in the C++ programming language. It uses the computer sound card to record audio signals from sources such as a microphone, CD player, record player or radio tuner. These recorded audio signals are stored on the computer hard disc as wave files.

The recorded audio signals may be played back using the DotricDJ program, the Windows Media Player program supplied with most computers, or any program that can read wave files.

DotricDJ displays an analogue waveform interpretation of the recorded audio signals. A zoom facility is provided for analysis of the waveforms for educational purposes. Parts of the displayed waveform may be saved in separate files for audio editing purposes.

DotricDJ is able to capture very long audio sequences and may be used to record entire LP records for subsequent transfer to CDs. The editing facilities may be used to save individual tracks from the LP to separate wave files.

Hardware Considerations

DotricDJ creates and plays wave files in one format only. This format is stereo, 16 bits per channel and 44100 samples per second. This is the highest fidelity possible for the sound cards supplied with most computers.

Details on how to connect microphones and other external devices to a computer are beyond the scope of this document. However, sound cards typically provide a number of sockets at the back of the computer. These include "Line In", "Line Out" and "Mic" sockets. External CD players, record players, radio tuners etc. may typically be connected via the "Line In" sockets. Microphones may typically be connected via the "Mic" sockets. If an audio signal is being sourced from within the computer, perhaps from a web site, it may be necessary to connect the "Line Out" socket to the "Line In" socket to record that signal.

In all cases the manufacturer's specifications for the computer sound card and any external audio device should be checked to ensure compatibility.

WARNING: When recording, DotricDJ consumes hard disc space at the rate of approximately 10 MB per minute. So, while DotricDJ is capable of recording one hour or more of audio material, it should be noted that one hour approximately represents a 600MB wave file.

Software Requirements

DotricDJ requires Microsoft Foundation Classes (MFC) and DirectX. MFC is a set of routines that aid software development and give applications a familiar look and feel. Microsoft Office, in fact, uses MFC, so if Microsoft Office is running on your PC then you have MFC. DirectX is a multimedia interface. Multimedia functionality has expanded rapidly in recent times, so Direct X has seen frequent upgrades. Any version greater that version 5 should work with this application which means Windows 98 or greater or maybe a visit to www.microsoft.com.

Recording

To start the recording procedure select Options and Record from the menu bar or press the button with the red dot on the tool bar.

The Save As dialog will be displayed. Because the files it generates are potentially very large, DotricDJ operates in a different manner to most Windows programs. Most Windows programs ask for a file name after some data has been collected. DotricDJ asks for a file name before the data collection process begins.

Enter the name of the file into which sound is to be recorded. It will be a wave file. Press the Save button. A message box will be displayed indicating the maximum possible record time. If more than ample disc space is available then this time will be 6 hours 45 minutes 47 seconds - the limit for DotricDJ. If disc space is constrained, then the maximum possible record time is based on the available disc space minus 5MB. Press the OK button on the message box.

The Recording dialog will be displayed. Before starting a recording session, the volume controls for the sound card should be displayed on the desktop. To do this double click on the little speaker icon that is displayed near the bottom right hand corner of most computer screens. Some sound cards may have other relevant controls accessible via other icons in the same area. Sound card volume controls are also available via the Start button under Accessories and Entertainment.

Prepare the audio material and press the Record button. If the recording process is working correctly, the number of blue squares in the two progress bars will increase and decrease with the audio signal. The progress bars operate in a similar manner to the VU meters found on most cassette recorders. The progress bars, in fact, display the value of the digitized sound samples as they are saved to the wave file. The sound card volume controls should be adjusted to maximize blue square activity. To avoid recording distorted signals, all of the blue squares should not be displayed for extended periods of time.

To end the recording session and save the recorded audio material press the OK button on the Recording dialog. To end the recording session and abandon the recorded audio material press the Cancel button.

If the OK button is pressed, the saved file will be re-opened in play mode and its waveform will be displayed.

Opening A File For Playing

To open a file select File and Open from the menu bar or press the button with the open folder on the tool bar.

The Open dialog will be displayed. Select a file and press the Open button. The waveform for the file will be displayed.

To Play A Displayed Waveform

To play the whole waveform, from the beginning, select Options and Play from the menu bar or press the button with the black triangle on the tool bar.

To play the waveform from an area of interest, position the mouse pointer over the area of interest and press either the left or right mouse button. If the left mouse button is pressed, a blue line will appear at the area of interest. If the right mouse button is pressed a red line will appear at the area of interest.

Select Options and either Blue Play or Red Play from the menu bar as appropriate. Alternatively press either the button with the blue triangle or the button with the red triangle on the tool bar.

To stop playing the waveform, select Options and Stop from the menu bar or press the button with the black square on the tool bar.

NOTE: In play mode, DotricDJ only has access to the sound card while it has focus on the computer screen.

The Zoom Facility

To zoom in on half the waveform, with the centre of the waveform as the zoom centre, select View and Zoom In 2:1 from the menu bar or press the button with the magnifying glass and plus sign on the tool bar.

To zoom in on a selected area, position the mouse pointer to the left of the area of interest and press the left mouse button. Then position the mouse pointer to the right of the area of interest and press the right mouse button. Select View and Zoom In Between from the menu bar or press the button with the magnifying glass and the blue and red lines on the tool bar.

To return to the whole waveform display, select View and Normal Size from the menu bar or press the button with the white rectangle on the tool bar.

Saving An Area Of Interest

To save part of the waveform, position the mouse pointer to the left of the area of interest and press the left mouse button. Then position the mouse pointer to the right of the area of interest and press the right mouse button.

Select File and Save Between from the menu bar or press the button with the floppy disc and the blue and red lines on the tool bar.

The Save As dialog will be displayed. Type in the name of the new wave file and press the Save button.

Closing A File

To close a displayed waveform, select File and Close from the menu bar or press the button with the cross on the tool bar.

Installation Instructions

Two methods of installation are provided here. Method 1 is the easiest to use. The whole process of creating a directory, installing the executable file and setting up a desk top icon is done automatically. Method 2 is totally manual.

Method 1
Click here, press the Open button in the first dialog box and follow the instructions in the subsequent windows. NOTE: If you use this method and you wish to remove the DotricDJ program from your computer in the future, you must use Add or Remove Programs in the Windows Control Panel.

Method 2
Click here and save the file to a folder on your computer. Click here and save this file to the same folder. Using Windows Explorer or My Computer, go to the folder where you saved the files and double click on the DotricDJ.exe Icon.