| 摘要 |
COMPOSITE VIDEO SIGNAL WITH AUDIO A method for inserting an audio signal into a composite video signal having A front porch, a back porch, a horizontal sync pulse with a leading edge, and a luminance portion to provide an audio-on-video signal, includes removing one or more video parts at least partially from the luminance portion, sampling one or more audio parts, biasing a zero magnitude of the audio parts to the midpoint of the maximum luminance magnitude, and placing the sampled parts at least partially within the luminance portion of the composite video signal to form the audio-on-video signal. The method for inserting also includes inserting audio parts into blanking parts that follow leading and trailing equalizing pulses; and the method for inserting further includes inserting audio parts into blanking portions of test signals that follow the trailing equalizing pulses. A method for separating an audio signal from the audio-on-video signal includes sampling an audio plus magnitude of the audio parts at least partially within the luminance portion, subtracting a bias magnitude to provide an audio sample magnitude, holding the audio sample magnitude, replacing the held audio sample magnitude with a successive audio sample magnitude to provide a stepped audio output, low pass filtering to smooth the stepped audio output and to prevent Nyquist problems, and high pass filtering to prevent noise when an audio sample magnitude is held during a vertical sync pulse.
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