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Q: We are using two video decoders from Philips, the SAA7113 and SAA7144. These video decoders are connected to a TI DSP (DM642). When the video ranges, generated by the video decoder goes outside the normal CCIR 601 boundary ( 16-235 for Y, 16-240 for UV) and the hardware scaling of the TI is used; we see some saturation in the scaled video (in the TI). Is there a way, other than using the brightness, saturation and contrast control of the video decoder, to make sure that the SAA7113 and SAA7144 will not go outside the "standard" video ranges ( 16-235 for Y, 16-240 for UV).
A: The range of the YUV deviations is specified differently between CCIR 601 and 656. Of course, we allow the greatest deviation as the default, as this presents the best picture. We allow the user to change the range by setting the BCS registers. (1-254 vs. 16-235). On page 49 of the SAA7113 data sheet is the equation for setting up the BCS registers to accommodate CCIR 601 or 656. We would even recommend cutting this back 1 or 2 IRE (i.e. use 17-233) if the TI part does not properly clip the values as insurance. Both devices uses the same 9 bit A/D converter and can be adjusted the same.

Q: We are using two video decoders from Philips, the SAA7113 and SAA7144. These video decoders are connected to a TI DSP (DM642). When the video ranges, generated by the video decoder goes outside the normal CCIR 601 boundary ( 16-235 for Y, 16-240 for UV) and the hardware scaling of the TI is used; we see some saturation in the scaled video (in the TI). Is there a way, other than using the brightness, saturation and contrast control of the video decoder, to make sure that the SAA7113 and SAA7144 will not go outside the "standard" video ranges ( 16-235 for Y, 16-240 for UV).

A: The range of the YUV deviations is specified differently between CCIR 601 and 656. Of course, we allow the greatest deviation as the default, as this presents the best picture. We allow the user to change the range by setting the BCS registers. (1-254 vs. 16-235). On page 49 of the SAA7113 data sheet is the equation for setting up the BCS registers to accommodate CCIR 601 or 656. We would even recommend cutting this back 1 or 2 IRE (i.e. use 17-233) if the TI part does not properly clip the values as insurance. Both devices uses the same 9 bit A/D converter and can be adjusted the same.