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NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 11: QVCP
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
11-359
complete before the start of the next horizontal blanking interval). In the current
design, the VBI packet can be inserted only between the EAV and the SAV time
codes.
2.3.2
Pixel Formatter Unit (PFU)
The PFU retrieves the raw data stream, for a particular image source, from the
system memory and formats it according to the specied pixel format.
Table 1summarizes the various native pixel formats supported by the PFU.
Remark: Semiplanar YUV 4:2:0 is supported by the software API. However the
support is achieved by duplicating the UV samples. Therefore it is not a true 4:2:0
support. True 4:2:0 support can be achived by using the MBS module to convert the
4:2:0 pixels into 4:2:2 or 4:4:4 pixels before entering QVCP.
Remark: The PFU does not do the pixel conversion it just formats properly the raw
data into the QVCP pipeline, therefore it requires to know the input pixel format.
2.3.3
Chroma Key and Undither (CKEY/UDTH) Unit
Chroma keying allows overlaying of video and/or graphic layers, depending on
whether the considered pixel lies within a specied color range. This feature allows
video transparency or “green screening” — a technique used for compositing a
foreground imagery with a background. Undithering allows recovery of 9 bits of
precision from the dithered 8 bits stored in memory (where QVCP fetches the pixels
for video processing).
CKEY
Chroma key matching is usually performed on a range of values rather than on a
single value as in
color keying; a Key Mask is provided to allow chroma keying on
specic bits within the data word considered. In QVCP, the
color key is generated in
each layer in the source color space. Every layer can use up to four color keys.
Table 1: Summary of Native Pixel Formats
Format
Description
1 bpp indexed
CLUT entry = 24-b color + 8-b alpha
2 bpp indexed
CLUT entry = 24-b color + 8-b alpha
4 bpp indexed
CLUT entry = 24-b color + 8-b alpha
8 bpp indexed
CLUT entry = 24-b color + 8-b alpha
RGBa 444
16-b unit, containing 1 pixel with alpha
RGBa 4534
16-b unit, containing 1 pixel with alpha
RGB565
16-b unit, containing 1 pixel, no alpha
RGBa 8888
32-b unit, containing 1 pixel with alpha
Packed YUVa 4:4:4
32-b unit, containing 1 pixel with alpha
Packed YUV 4:2:2 (UYVY)
16-b unit, 2 successive units contain 2 horizontally-adjacent
pixels, no alpha
Packed YUV 4:2:2 (YUY2,
2vuy)
16-b unit, 2 successive units contain 2 horizontally-adjacent
pixels, no alpha
Semiplanar YUV 4:2:2
Separate memory planes for Y and UV (both 8 and 10 bpp)