To prepare the encoder to capture uncompressed audio and video, the Fabrikam technicians first make sure audio and video are present at the inputs of the capture card. Then they can adjust audio and video so the levels match those coming from the Digital Betacam. If the video capture card does not provide audio output, they can use a second sound card or built-in sound system to monitor sound. If you are capturing digitally with the SDI, AES/EBU, or IEEE 1394 ports, you cannot adjust video and audio parameters.
To properly adjust the input audio level on the computer, you need a volume control and an audio meter. You can use an audio program that provides an audio meter, such as Sound Forge or Cool Edit. Follow these steps:
Open the audio program’s recorder dialog box, and then make sure monitoring is active.
Open the volume controls by double-clicking the speaker icon in the taskbar. If the speaker icon is not displayed in your taskbar, click Start , click Control Panel , then double-click Sound, Speech and Audio Devices . Make sure the correct recording device is selected.
In the Properties dialog box for the Volume Control , select Adjust volume for Recording . The recording controls adjust the signal entering the video card. The playback or master volume controls adjust the audio output.
As you play back the bars and tone, adjust the
control to match the
Open the Master or Playback Volume controls, and adjust the Line In control to adjust the monitor volume.
On the mixer, press the Solo button on the encoding computer channel and adjust the monitor level to hear the sound through the computer.
After the input and output levels are adjusted, close the volume controls and audio program. Once set, the volume controls should not need to be readjusted as long as the audio entering the computer has been adjusted properly.
Video levels are adjusted in the video capture program—in this case Windows Media 9 Capture. The technicians select the video capture card as the source and enable the preview function, so they can view live video as it is coming into the card. Configuration options are in the video source configuration dialog box. You will typically find the following four video setting controls, which
Brightness. Controls the intensity of the picture (same as the Video control).
Contrast. Controls the range between the brightest and darkest
Saturation. Controls the
Hue. Controls the hue of all colors (same as the Chroma phase control).
The Fabrikam technicians follow this procedure to set up the video levels.
While viewing playback of color bars, adjust Contrast and Brightness until whites are as white as possible, blacks are black as possible, and all the gray bars are differentiated.
Turn up Saturation until color intensity seems correct. Avoid turning it up too high.
Adjust Hue for the correct colors.
Video configuration is not as objective as that of audio without meters or scopes to work with. Software waveform
After the input levels have been set, the technicians configure the capture program with the following settings:
Select Full Frames (uncompressed) as the video compression type, and select None (PCM) for audio compression.
Enter YUV12 as the color format. This is the color format Windows Media Encoder uses when encoding the final file.
Enter a video size, such as 320 x 240 , and a frame rate, such as 30 .