Nevion ARC-SD-DMUX User Manual
Page 11
ARC-SD-DMUX
Rev. B
nevion.com | 11
However, the fill factor descriptor may contain a code to indicate that the fill factor of the
picture is unknown. In that case, the code for the input aspect ratio is used.
SMPTE352M is a data packet that can be used to identify the aspect ratio of the picture.
Wide Screen Signaling present in the input video (WSS) can also be used to identify the
aspect ratio of the picture but is not implemented yet (contact Nevion sales if this is a
requirement).
3.5.1.1 Mode 1: Full automatic mode
The aspect ratio control block will start by looking for AFD presence in the input signal to
select the aspect conversion. If it is not present it will look for VI and then SMPTE S352M
information. If no aspect ratio information is present in the video, the default scaling setting
will be used.
When a valid format descriptor is present, either from AFD or VI, all the conversions in the
AFD code drawing are possible for the given output environment.
In the case where only input environment information is available, a subset of the
conversions is used. The desired filling method must be set. This may be one of the
following:-
Full frame. The image will be zoomed and cropped. No curtains.
14:9 pillar box / letterbox. The image will be zoomed and cropped. Narrow curtains.
4:3 letterbox / 16:9 pillar box. The image will be zoomed. Full curtains.
If the input environment is the same as the output environment, no conversion will be
performed.
3.5.1.2 Mode 2: AFD or default
This mode will only use the AFD information if present. The default scaling will be used if
there is no AFD packet, no video index or the active format descriptor is set to ‘Unknown’.
3.5.1.3 Mode 3: Fill mode or default
This mode will only use the input aspect information from the AFD information if present.
The S352M packet will be used if it is present and neither AFD packets nor VI are present.
The default scaling will be used if there is no AFD packet, no video index and no S352M
packet.