Sensoray 615 - Manual (Page 5)

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Once a video input is connected through the crosspoint switch to a decoder input, it takes up to 3
frames for the decoder to synchronize (lock) to the video. This is an important consideration when
selecting a channel-polling algorithm. After a new input channel is connected to a decoder through the
crosspoint switch, there has to be at least a 3-frame delay before the image could be captured from
this decoder. However, the other decoders may be synchronized and available for capture.
The following algorithm is recommended when cycling through all 16 video inputs (it is assumed that
initially decoder 0 is connected to input 1, decoder 1 – to input 2, decoder 2 – to input 3, decoder 3 to
input 4):
1. Capture from decoder 0 (input 1), switch decoder 0 to input 5;
2. Capture from decoder 1 (input 2), switch decoder 1 to input 6;
3. Capture from decoder 2 (input 3), switch decoder 2 to input 7;
4. Capture from decoder 3 (input 4), switch decoder 3 to input 8;
5. Capture from decoder 0 (input 5), switch decoder 0 to input 9;
6. Capture from decoder 1 (input 6), switch decoder 1 to input 10;
7. Capture from decoder 2 (input 7), switch decoder 2 to input 11;
8. Capture from decoder 3 (input 8), switch decoder 3 to input 12;
9. Capture from decoder 0 (input 9), switch decoder 0 to input 13;
10. Capture from decoder 1 (input 10), switch decoder 1 to input 14;
11. Capture from decoder 2 (input 11), switch decoder 2 to input 15;
12. Capture from decoder 3 (input 12), switch decoder 3 to input 16;
13. Capture from decoder 0 (input 13), switch decoder 0 to input 1;
14. Capture from decoder 1 (input 14), switch decoder 1 to input 2;
15. Capture from decoder 2 (input 15), switch decoder 2 to input 3;
16. Capture from decoder 3 (input 16), switch decoder 3 to input 4;
Other algorithms may be implemented, provided the above-mentioned condition (3 frame delay after
input switching) is satisfied. Please refer to the Software Reference for the implementation details.
Various features (operation modes) are selected in software by means of a call to S615_SetMode
function or by setting corresponding fields in the COMMAND structure. Those controlled by
S615_SetMode function cannot be changed on a frame-to-frame basis. Those controlled by COMMAND
structure can be changed on a frame-to-frame basis.
JPEG capture
JPEG capture can be enabled/disabled on a frame-to-frame basis. If enabled, the memory image of a
compressed frame is returned in the BUFFER structure. Saving to a file is done on the application level.
The following options are available for JPEG capture:
§ JPEG size: controls the size of compressed image. For NTSC video signal the following options are
available: 704x480, 640x480, 352x240, 320x240. For PAL(SECAM) the following options are
available: 704x576, 352x288. Note: the 640 and 320 horizontal sizes for NTSC are clipped versions
of 704 and 352 images, respectively.
§ compression factor: controls compression level. The higher compression factor values yield higher
compression (smaller file size).
All JPEG capture options cannot be changed on a frame-to-frame basis.