cx25840 Conexant Systems, Inc., cx25840 Datasheet - Page 131

• Manufacturer Part Number: cx25840
• Description: Video Decoder And Broadcast Audio
• Manufacturer: Conexant Systems, Inc.

CX25840/1/2/3 Data Sheet
Figure 3-45. Effects of Compression on the Signal
102284B
8/3/05
Compressor
Compressor
Compressor
Output
Input
Gain
For example, in
compressor’s threshold. Note the overshoot when the signal level increases; it takes
some time for the gain to decrease, and the attenuation when the input signal returns
to the first level, and the gain increases. The release time is generally longer than the
attack time.
The gain control block has a number of parameters. Initially, a threshold and
compression ratio must be set. Additionally, an attack and release time are required to
specify how fast the gain value is allowed to adjust in either direction.
There are two modes of operation: independent and stereo. A mode selection bit in the
Path1 AVC Control1 (0x8D1) and Path2 AVC Control2 (0x8E1) selects between
stereo and independent modes. In independent mode, left and right audio signals are
operated on separately—the value of the left signal has no effect on the AVC of the
right signal and vice versa.
1
Figure
Attack
Time
3-45, only the middle portion of the input is above the
Conexant
Release Time
Detailed Functional Description
Time
Time
Time
102284_048
3-105