AMD SC1201, SC1200 manual Ping-pongs between the two buffers during runtime, Capture VBI Mode

Video Processor Module 32579B

Ping-pongs between the two buffers during runtime

Video Data Odd Base	Video Frame Buffer #1
	1 Odd Field
F4BAR2+Memory Offset 20h
Video Data Even Base	Even Field
4BAR2+Memory Offset 24h	Line 2 Odd
	Line 2 Even
	Line n-1 Odd Field
	Line n-1 Even Field
	Line n Odd Field
	Line n Even Field

Video Data Even Base	Video Frame Buffer #2
	Line 1 Odd Field
F4BAR2+Memory Offset 20h
Video Data Even Base	Line 1 Even Field
F4BAR2+Memory Offset 24h	Line 2 Odd Field
	Line 2 Even Field
VID_START_OFFSET
GX_BASE+Memory Offset 8320h
Ping-pongs between the	Line n-1 Odd Field
two buffers during runtime	Line n-1 Even Field
	Line n Odd Field
Odd and Even fields are	Line n Even Field
“Weaved” together

30 frames per second

Capture video fill sequence

GX1 Module’s Display Controller empty sequence

GX1 Module’s Video Frame Buffer

Buf #1 Buf #2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

				5
1	2	3	4	5	6	7	8	9	10 11 12 13 14 15 16 17 18 19 20 21	22	23

85 frames per second

Figure 7-6. Capture Video Mode Weave Example Using Two Video Frame Buffers

7.2.1.4Capture VBI Mode

There are three types of VBI data defined by the CCIR-656 protocol: Task A data, Task B data, and Ancillary data. The VIP block supports the capture for each data type. Gener- ally Task A data is the data type captured. Just as in Cap- ture Video mode, there are three registers that tell the bus master where to put the raw VBI data in the GX1 module’s frame buffer. Once the raw VBI data has been captured, the data can be manipulated or decoded. The VIP block has two options of what to do with the altered VBI data. These options are independent functions so both options can be done simultaneously.

1)The data can be used by an application. An example of this would be an Internet address that is encoded on one or more of the VBI lines, or have an application decode the Closed Captioning information put in the graphics frame buffer.

2)The altered VBI data can be sent to the TVOUT block of the Video Processor via the video frame buffer or graphics frame buffer. See VIP block diagram (Figure 7-4 on page 315). The Closed Captioning data could be altered and then sent out this way. One reason to capture the Closed Captioning data would be to do a language conversion. If the VIP block is in Capture Video mode then this option is not possible because the video frame buffer can be used for sending video or VBI, but not simultaneously.

The registers, F4BAR2+Memory Offset 40h, 44h, and 48h, tell the bus master the destination addresses for the VBI data in the GX1 module’s frame buffer. Five bits (F4BAR2+Memory Offset 00h[21:17]) are used to tell the bus master the data types to store. Capture VBI mode needs to be enabled at F4BAR2+Memory Offset 04h[9,1:0]. The Field Interrupt bit (F4BAR2+Memory Offset 04h[16]) should be used by the software driver to know when the captured VBI data has been completed for a field.

AMD Geode™ SC1200/SC1201 Processor Data Book 319