EM2820 = PC Cam + Video Decoder + Scaler
EM2840 = PC Cam + Video Decoder + Scaler + I2S + VBI support
  
EM2820/2840 USB Video Capture Device (UVCD) is a highly integrated VLSI that provides a cost-effective
solution for video capture applications on USB 2.0. Typical applications of this device are:
 
NTSC/PAL Video Capture
 
 
As illustrated in the functional block diagram, an USB video subsystem consists of the UVCD, a video source, and optionally an audio source. The video source can be a CMOS sensor or an NTSC/PAL video decoder. The audio source can be an AC97 codec or an I2S stereo decoder. The USB host configures (programs) the video/audio source via the 2-wire serial bus or the AC97-link. Source video stream is transferred to the UVCD via the 8-bit video bus. Source audio stream is transferred to the UVCD via the AC97-link or the I2S bus.

As shown in the functional block diagram, the UVCD consists of 7 main blocks.
 
Video Interface
 
Video Pipeline
 
Audio Interface
 
Stream Buffer
 
Serial Interface Engine
 
USB 2.0 PHY
 
2-Wire Serial Interface
 
 
 
 
No external memory required
   
Flexible Video Input Port
8-bit video input port
Interlace and non-interlace video
CCIR-601 4:2:2 YUV
CCIR-656 YUV with embedded sync and field ID
   
Programmable Video Timing Generator
Generate clock, H-sync and V-sync for CMOS sensor
 
Bayer RGB Color Processor
Black clamping
Gamma correction
Bayer pattern filtering
Gain and offset adjustment in RGB space
Support for auto exposure and white balance
  Defect pixel compensation
 
YUV Color Processor
Gain and offset adjustment in YUV space
Sharpness enhancement
 
Compressing Engine
Proprietary, high-quality compression
Programmable compression rate
 
Video Scaler
Random-ratio down scaling in X and Y directions
High fidelity color reproduction by the scaler
 
VBI Capture (EM2840 ONLY)
Raw VBI capture
Sliced VBI capture
 
USB Stream Buffer
  Deep buffer to support uncompressed 720x480 video at 30 fp
   
Audio Interface
  Support AC97 CODEC
  Support I2S device (EM2840 ONLY)
  Software direct access to AC97 CODEC registers
  Support audio sample rates of 48K, 44.1K, 32K, 22.05K, and 8K.
   
USB Port
  Integrated USB 2.0 PHY with High-Speed and Full-Speed Transceivers
  Second generation USB 2.0 PHY with reduced power
  USB 2.0 and 1.1 compliant
  Support Iso-chronous audio pipe up to 0.2 MB/sec
  Support Iso-chronous video pipe up to 24 MB/sec
  Support Bulk video pipe
   
EEPROM Interface
  Support 512-byte or 256-byte 2-wire serial EEPROM
  Use EEPROM to store chip configurations and USB descriptors
  Customized Vendor ID and Product ID
  Customized Vendor String, Product String, and Serial Number String
  Software may use EEPROM to store board configurations
  Software may use EEPROM to store defect pixel coordinates
   
Miscellaneous
  2-wire serial bus to program front-end video/audio devices
  Power-down control to front-end video/audio devices
  8 General-Purposed I/O ports
  Snap shot button input
  LED control output
  0.25 micron, 2.5V Core, 3.3V I/O CMOS process
  64-pin LQFP package