2/24/2008 9T6WP
BCM7405
Preliminary Hardware Data Module
Functional Description
06/29/07
Bro a d c o m C o rp o r a ti o n
Page 1-42
Video and Graphics Display
Document
7405-1HDM00-R
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Reverse 2:2 pull-down for improved quality from film based sources.
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Optional CPU control over 2:2 cadence detection and correction.
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Automatic handling of mixed interlaced, 3:2 and 2:2 pull-down
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50-Hz interlaced PAL to 60 Hz progressive PAL support
Film Grain Technology
Film Grain Technology (FGT) is a set of algorithms that allows preservation of the film grain characteristics through the
passage from film to digital media, ensuring the quality of the image presented to the viewer.
FGT is responsible for the grain noise generation with regard to the Supplemental Enhancement Information (SEI)
messages, the film grain database, and the computed blocks averages.
The FGT implementation involves the following steps:
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Select film grain parameters:
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Average computation for a block (8x8 or 1x8) pixels, from all of the color components (YUV) of the decoded frame.
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Comparison of the above average value with the SEI message to select the film grain parameters for the current
decoded pixels block.
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Creation of a film grain block of pixels:
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Retrieving a block film grain samples from film grain database according to the film grain parameters.
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Scaling those samples to the proper intensity.
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Deblocking vertical edges between adjacent film grain blocks:
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A deblocking filter is applied between adjacent film grain blocks to ensure seamless formation of film grain patterns.
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Blending the film grain with the incoming decoded frame.
Compositor
The compositor is responsible for the final construction of the outgoing video. There are two possible video surfaces, two
possible graphics surfaces. Once the order of the surfaces is determined, they are blended together from the bottom up to
form the final result.
To facilitate blending, the surfaces are all translated into an AYUV4:4:4:4 format type. This simplifies the blending
mathematics.
Each compositor input can be manipulated through a matrix to allow manipulation of the individual color components. This
can be used for color space conversion as well as contrast, tint, and brightness adjustments.
Capture Block
The capture block simply stores YUV4:2:2 data back to memory. This is used if analog video is being received so that the
data can be resynchronized. The capture block has been expanded to support video cropping to save bandwidth.