TC5747 Datasheet, PDF (31/44 Pages) List of Unclassifed Manufacturers – Single Chip CMOS Imager with Integrated Image Signal Processor and JPEG Codec

TC5747 Preliminary Data Sheet
Single Chip CMOS Imager
4.2.7.3 Avoiding Marker Emulation
When the Send-Markers mode is enabled, care has to be taken to avoid marker-emulation inside the data
itself.
When YCrCb 4:2:2 output mode is selected, there is no contention between marker header contents and
the transmitted data, because the Y data values are limited to the range of 16-235, and the Cr and Cb
data values are limited to the 16-240 range. 0x00 and 0xFF values never occur inside the image data
values.
When Bayer output is selected, the data has to be modified, so that 0xFF and 0x00 values are removed
from the data content, and replaced by their nearest allowed values (0xFE and 0x01 respectively).
When RGB565 output is selected, the data has to be modified, as in the case of the Bayer output. 0xFF
and 0x00 values are removed from the data content, and replaced by their nearest allowed values.
The first byte of RGB565 is replaced by 0xF7 or 0x08.
The second byte of RGB565 is replaced by 0xFE or 0x01.
When RGB666 output is selected, the data has to be modified, as in the case of the Bayer output. 0xFF
and 0x00 values are removed from the data content, and replaced by their nearest allowed values.
TBD
When RGB444 output is selected, the data has to be modified, as in the case of the Bayer output. 0xFF
and 0x00 values are removed from the data content, and replaced by their nearest allowed values.
The first byte of RGB444 is replaced by 0xEF or 0x10.
The second byte of RGB444 is replaced by 0xF0 or 0x01.
JPEG code cannot be modified. However, there is no need for any modification if Ancillary format is
used for JPEG transmission.
4.2.8 Ancillary Data Format
The ITU-1364 defines the ancillary data format that may be transmitted during blank lines of video, as
defined in the ITU 656 standard.
Immediately following a blank line “ Timing signal” , an ancillary data packet may be added. If an ancillary
data header is detected instead of the blank video data, as defined by the standard (a sequence of 0x80
0x10), ancillary data can be extracted.
An ancillary data header is defined as a sequence of 6 bytes:
0x00 0xFF 0xFF ID1 ID2 Data-SIZE/4
The header is followed by data (4 to 252 bytes).
A Check-sum byte follows the data as the last byte of the packet.
The ancillary header and checksum are optionally produced by the JPEG unit. The PVI does not differentiate
between header and JPEG code.
TransChip ©
25