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ITU-R 656 Modes
In VBI mode, the program must specify the number of total (active plus vertical blanking) lines per frame in the
EPPI_FRAME
register. The program must specify the number of total (active plus horizontal blanking plus 8) sam-
ples per line in the
EPPI_LINE
In this mode, any input data sequence that is considered as part of the preamble is not sent to memory such as in 8-
bit ITU mode. If 0xFF or 0x00 appears in the input data stream, these values are considered part of the preamble.
The part of the preamble can appear individually, and not be tagged along with the preamble sequence FF, 00, 00.
This functionality applies to active video mode too.
ITU-R 656 Output in General-Purpose Transmit Modes
In GP transmit mode, the EPPI frames an ITU-R 656 output stream with the proper preambles and blanking inter-
vals by setting the EPPI_CTL.BLANKGEN bit. The EPPI fetches active data from memory through the DMA
channel, saving DMA bandwidth. The EPPI generates and embeds the proper preamble, status word (EAV and SAV
sequences), and blanking data along with the active video from memory. Program the EPPI_FS1_PASPL,
EPPI_FS2_WLVB, EPPI_FS2_PALPF, and
EPPI can also drive out the frame syncs using the EPPI_CTL.FSCFG bit setting.
The 16-Bit Transmit with Internal Blanking Generation figure shows the bit stream format in 16-bit transmit
modes with blanking generation (EPPI_CTL.BLANKGEN enabled). Each 16-bit data sample consists of 8-bit lu-
ma (Y) and 8-bit chroma (Cr or Cb) components. During transmission, the chroma data and blanking bytes of val-
ue 0x80 are placed on the upper half (MSBs) of the data lines. The luma data and blacking bytes of value 0x10 are
placed on the lower half (LSBs) of the data lines.
Figure 18-11: 16-Bit Transmit with Internal Blanking Generation
The Generated Blanking Preamble Sequence figure shows the data transmitted by the EPPI in this mode. After the
EPPI is enabled, and if the EPPI FIFO is not empty, the transmission starts by sending out an EAV sequence for a
vertical blanking line. For interlaced video, F starts at 1. For progressive video, F is always 0.
Internal blanking generation functionality is valid only when the data length is 8, 10, or 16 bits and when
NOTE:
the EPPI is in GP transmit modes. The EPPI_CTL.BLANKGEN bit generates preambles even in GP 2FS
mode.
The internal blanking generation functionality of the ITU-R 656 output mode can also be bypassed by clearing the
EPPI_CTL.BLANKGEN bit. (For example, if sending ancillary data in the blanking interval). The
EPPI_CTL.BLANKGEN bit generates preambles even in GP 2FS mode.
18–18
register.
EPPI_FS1_WLHB
END OF ACTIVE VIDEO
EAV
HORIZONTAL
SAV
CODE
BLANKING
CODE
(H = 1)
(H = 0)
F
0
0
A
1
1
1
1
1
1
F
0
F
0
0
B
0
0
0
0
0
0
F
0
F
0
0
A
8
8
8
8
8
8
F
0
F
0
0
B
0
0
0
0
0
0
F
0
ADSP-SC58x/ADSP-2158x SHARC+ Processor Hardware Reference
registers to perform the desired functions. The
START OF ACTIVE VIDEO
START OF
NEXT LINE
DIGITAL
0
A
Y
Y Y Y
Y Y F
VIDEO
0
B
F
STREAM
DIGITAL
0
A
C
C C
C
C
C F
VIDEO
0
B
B
R
B
B
B
R
F
STREAM
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