Video decoder
A video decoder is an electronic circuit, often contained within a single integrated circuit chip, that converts base-band analog video signals to digital video. Video decoders commonly allow programmable control over video characteristics such as hue, contrast, and saturation. A video decoder performs the inverse function of a video encoder, which converts raw digital video to analog video. Video decoders are commonly used in video capture devices and frame grabbers.
Signals
The input signal to a video decoder is analog video that conforms to a standard format. For example, a standard definition decoder accepts that conforms to SD formats such as NTSC or PAL. High definition decoders accept analog HD formats such as AHD, HD-TVI, or HD-CVI.The output digital video may be formatted in various ways, such as 8-bit or 16-bit 4:2:2, 12-bit 4:1:1, BT.656 or BT.1120. Usually, in addition to the digital video output bus, a video decoder will also generate a clock signal and other signals such as:
- Sync — indicates the beginning of a video frame
- Blanking — indicates video blanking interval
- Field — indicates whether the current video field is even or odd
- Lock — indicates the decoder has detected and is locked to a valid analog input video signal
Functional blocks
- Analog processors
- Y/C separation
- Chrominance processor
- Luminance processor
- Clock/timing processor
- A/D converters for Y/C
- Output formatter
- Host communication interface
Process