GUIDE TO INSTALLATION AND OPERATION
IRD-3811 |
45
4.5 Using the Up/Down/Cross Option
The Up/Down/Cross Option allows the user to re-scale the input signal to any supported output resolution. Possible
conversions are:
Down scaling from 1080i to 720p (same frame rate)
Up scaling from 720p to 1080i (same frame rate)
Down scaling to 525 or 625 depending on frame rate
Up scaling from 525 or 625 to 720 or 1080i keeping same frame rate
In addition to resolution conversion, the option allows aspect ratio conversion to occur. The user can either manually
select the desired conversion method or use the AFD from the source to automatically resize the picture. In manual
mode, the following scaling options are available:
•
NONE:
No aspect ratio conversion done. Any 16:9 pictures will appear as anamorphic 16:9 if
down converted to SD.
•
AUTO:
The scaling method is selected automatically. In this mode, the AFD flag is used along
with the aspect ratio of the output to select the best method. If no AFD is present, the
default AFD flag is used.
•
STRETCH:
Use this mode to stretch the picture vertically. This mode is useful when the input
picture has the wrong aspect ratio.
•
CENTER CUT:
When converting from 16:9 to 4:3, use this to crop both sides of the picture and fill the
entire screen while keeping the aspect ratio.
•
LETTER BOX:
Adds black curtains to the 16:9 picture for 4:3 monitors
•
PILLAR BOX:
Adds black bars to the 16:9 picture to properly display 4:3 images on 16:9 monitors.
Some modes may not apply depending on the input signal and desired output format.
If the selected mode is not possible the result will be the same as if NONE was selected.
The AUTO mode will use the input AFD to automatically choose the best rescaling method. The decisions follow the
CEA-CEB16 recommendation for receivers/decoders.
4.6 About AFD processing
According to ATSC A/53 part 4, AFD and BAR data can be carried in MPEG signals. The AFD information and BAR
data are extracted from the MPEG signal if present.
The user can configure the IRD to trigger on the AFD flags to automatically rescale the picture so that it is optimally
displayed. Alternatively, the user can set the scaling mode to OFF and simply carry the AFD flags to the outputs for
further processing. A card like the XVP-38xx from Miranda could then use the flag to rescale the picture properly.
In any case, the embedded AFD flag at the output follows any transformation that might have occurred. Therefore
should the picture be rescaled, the embedded AFD reflects the actual status of the picture at the output. For example,
an MPEG signal in full 16:9 (AFD code 8) down converted to SD 4:3 in letterbox will have the AFD flag 10 inserted to
signal letterbox.
Alternatively to AFD, the user can select VLI or WSS (PAL only).
