File: evo.fm5, modified 7/24/99
PRELIMINARY INFORMATION
7-1
Video Out
Chapter 7
by Marc Duranton, Dave Wyland, Gert Slavenburg
7.1
NEW IN TM1100
The TM1100 Video Out has a number of enhancements
with respect to TM1000 Video Out, in particular:
improved
internal
clock
generator
(DDS)
with
reduced jitter
Full 129-level alpha blending (8-bit alpha value)
addition of chroma keying
genlock capability
programmable YUV output clipping values
7.2
DOCUMENT STRUCTURE
The chapter below first describes the TM1000 Video Out
functionality, with updated TM1100 clock generator, and
then has a separate section with the other TM1100 im-
provements. This chapter will soon be replaced by an in-
tegrated, TM1100 specific chapter.
7.3
SUMMARY OF FUNCTIONS
The TM1100 Video Out unit (VO) generates and trans-
mits continues digital video images. It connects to an off
chip video subsystem such as a digital video encoder
chip (DENC), a digital video recorder or the video input
of another TM1100 through a CCIR 656 compatible byte
parallel video interface. The VO can either supply or re-
ceive video pixel clock and/or synchronization signals to/
from the external interface. Pixel clock frequency and
video field/frame format can be precisely controlled
through programmable registers, to support PAL, NTSC,
16:9 and other video format including double pixel rate
non-interlaced video formats.
VO combines a background video image from SDRAM
with an optional foreground graphics overlay image from
SDRAM using per-pixel alpha blending, and sends the
composite result out as continuous video. Video image
data is taken from a planar memory format, with separate
Y,U and V planes in memory in YUV 4:2:2 or 4:2:0 for-
mat. The optional graphics overlay is taken from a pixel
packed YUV 4:2:2+
α data structure in memory.
VO can also be used to emit raw data or send uni-direc-
tional messages from one TM1100 to one or more other
TM1100’s. In the Data Streaming mode, the VO gener-
ates a continuous stream of arbitrary byte data using in-
ternal or external clocking. Dual buffers allow continuous
data streaming in this mode by allowing the DSPCPU to
set up a buffer while another is being emptied by the VO.
Messages can be sent to one or more TM1100 Video In
ports in the Message Passing mode. Start and end-of-
message signals are provided in this mode to synchro-
nize message passing to the other TM1100 message re-
ceivers.
The Video Out unit provides the following key functional-
ity:
Continuous digital video output of PAL or NTSC for-
mat data according to CCIR601.
YUV 4:2:2 co-sited pixel data output is transmitted
across a standard 8 bit parallel CCIR6561 interface.
Embedded SAV and EAV synchronization codes as
well as separate sync control signals compatible with
Philips DENC encoders are available.
A nominal PAL/NTSC data rate of 27 megabytes/sec-
ond = 13.5 megapixels/second, but any data rate up
to 60% of DSPCPU clock is supported.
Custom video formats with frames or elds of up to
4095 lines of up to 4095 pixels are supported, sub-
ject only to the data rate limitation.
The video image can be in planar YUV 4:2:2 co-
sited, planar YUV 4:2:2 interspersed, or planar YUV
4:2:0 memory format.
The optional graphics overlay image is in pixel-
packed YUV 4:2:2+
α format, and is alpha blended on
top of the video image. Each pixel has a 1-bit alpha,
which selects one of two global 8-bit alpha values.
With overlay enabled, the output pixel data rate is
limited to 45% of the SDRAM clock, or 60% of
DSPCPU clock, whichever is smaller.
The video image can optionally be horizontally
upscaled by a factor of 2 for display. The overlay is
always in display format.
In data streaming mode, VO acts as a high band-
width output data channel. The data rate is limited to
60% of DSPCPU clock.
In message passing mode, VO acts as transmitter
port for TM1100 to multi-TM1100 unidirectional mes-
sage passing. Byte data rate is limited to 60% of
DSPCPU clock.
VO output data can be internally looped back to the
Video In for diagnostic purposes. This is controlled
by the Video In DIAGMODE bit.
1.
Refer to CCIR recommendation 656: Interfaces for dig-
ital component video signals in 525 line and 625 line
television systems. Recommendation 656 is included in
the Philips Desktop Video Data Handbook.