STV3550B STMicroelectronics, STV3550B Datasheet - Page 27

• Manufacturer Part Number: STV3550B
• Manufacturer: STMicroelectronics

Specifications of STV3550B

• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Compliant

STV3550
Video function description
The rescaling function is performed by two 32-phase polyphase filters (Horizontal and
Vertical), of which all coefficients are stored in a programmable table. In this case, if needed,
the transfer function of the filter can be optimized by referring to a specific up-conversion
process. This scaling factor is programmable from 0.25 to 4 for horizontal scaling and 0.5 to
4 for vertical scaling with an accuracy of 1/8192. This allows for continuous linear zoom
variations.
Non-linear zoom
The rescaling block performs the horizontal and vertical non-linear zoom as shown in
Figure
9. The picture can be divided into 5 different segments in all directions.
Letter-box format detection
Letter-box format detection is included in order to automatically detect the horizontal black
bars used with letter-box input video (Cinemascope,...) signals. This detection system is
based on a proprietary algorithm that measures a certain level of data on a field basis.
This function can also detect video effects such as logos or subtitles inserted in the black
parts of the video. The programmer can use this data to create an automatic format
conversion for all the various cinema formats.
Format conversion
The horizontal and vertical polyphase filters can be also used for the format conversions
required for adapting the input video to the display format. Various examples are shown in
the following figures. All formats are software-controlled and the letter-box format detector
can also be used to automatically select the best-suited display format to prevent the
horizontal black bars from being displayed.
Figure 10. Display formats for 4:3 input, 4:3 aspect ratio and 16:9 TV screen
Zoom 1
Zoom 2
H compression 33%
No Zoom
H compression 16.5%
V expansion 16.5%
Zoom 5
Zoom 3
Non-linear H (Panoramic1)
V expansion 33%
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