Texas Instruments TMS320DM648 manual Y/C Video Display Mode, 1 Y/C Display Timing Reference Codes

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Y/C Video Display Mode

4.3Y/C Video Display Mode

The Y/C display mode is similar to the BT.656 display mode but outputs 8-bit data on separate luma and chroma data streams. One data stream contains Y samples and the other stream contains multiplexed Cb and Cr samples co-sited with every other luminance sample. The Y samples are read from the Y FIFO and the Cb and Cr samples are read from the Cb and Cr FIFOs and combined on the chroma output.

The Y/C display mode can generate HDTV standard output such as BT.1120, SMPTE260, or SMPTE296 with embedded EAV and SAV codes. It can also output separate control signals.

Because 16 bits are used for data output, the Y/C output mode requires both halves of the video port data bus. If the DCHDIS bit in VPCTL is set, then Y/C mode cannot be selected.

4.3.1 Y/C Display Timing Reference Codes

The EAV and SAV embedded timing codes are identical to those output in BT.656 mode and timing is controlled in the same manner. In Y/C mode, however, the codes must be output on both the Y and C data streams (VDOUT[9-2] and VDOUT[19-12]). An example of BT.1120 line timing is shown in Figure 4-13.

Figure 4-13. Y/C Horizontal Blanking Timing (BT.1120 60I)

FPCOUNT

VCLKOUT

1920 1921 1922 1923 1924 1925 1926 1927

4 272

One Line

2194 2195 2196 2197 2198 2199 0 1 2 3 4 5

4 1920

						Next Line
1916	1917	1918	1919	1920	1921	1922	1923	1924	1925	1926	1927

Blanking Active Video

VDOUT[9−2] FF.C 00.0 00.0 XY.0 10.0 10.0 10.0 10.0 10.0 10.0 FF.C 00.0 00.0 XY.0 Y 0 Y 1 Y 2 Y 3 Y 4 Y 5

EAV Blanking Data SAV

VDOUT[19−12] FF.C 00.0 00.0 XY.0 80.0 80.0 80.0 80.0 80.0 80.0 FF.C 00.0 00.0 XY.0 Cb0 Cr0 Cb1 Cr1 Cb2 Cr2

EAV Blanking Data SAV

Y 1916	Y 1917	Y 1918	Y 1919	FF.C	00.0	00.0	XY.0	10.0	10.0	10.0	10.0
					EAV
Cb 958	Cr 958	Cb 959	Cr 959	FF.C	00.0	00.0	XY.0	80.0	80.0	80.0	80.0

EAV

4.3.2 Y/C Blanking Codes

The time between the EAV and SAV code on each line represents the horizontal blanking interval. During this time, the video port outputs the digital video blanking values. These values are 10h for luma (Y) samples and 80h for chroma (Cb/Cr) samples. These values are also output during the active line period of vertical blanking (between SAV and EAV when V = 1), unless replaced by VBI data. In addition, if the DVEN bit in VDCTL is 0, the blanking values are output during the portion of active video lines that are not a part of the displayed image.

4.3.3 Y/C Image Display

Many of the standards supported by the Y/C display mode provide for both interlaced and progressive scan formats. For interlaced display, the display controls are programmed identically to BT.656 mode. For progressive scan formats, the frame size is programmed to the size of a single field and only field 1 is used.

The Y/C display mode uses the same FIFO organization as the BT.656 display mode and generates EDMA events in the same manner.

102 Video Display Port SPRUEM1 –May 2007

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