Inserting different ITS lines to a video signal

[Quintin]

I am working with a 5431 Video Generator and I need to create a test signal by inserting one of two possible ITS at a different line in each frame.  I downloaded the example code from the link listed below and I am confused about the indexing of the sequence created.  Is anyone familiar with this example and could lend me some assistance? 

Also, a few other questions I have:  (1) Are the ITS files downloaded to the 5431 or are the frames with the inserted ITS line downloaded to the 5431 (the latter case would consume more onboard memory).  (2) Does the next ITS line inserted modify the last frame or the original video file downloaded to the 5431?  i.e. I insert an ITS at line 100, then the next frame I want to insert an ITS at line 120, will the corresponding frame show the ITS inserted at both line 100 and 120 or just the more recent insertion at 120?

thanks,

Quintin

http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DAA956A4E034080020E74861

[Minh T.]

Good afternoon Quintin,

We talked via e-mail about this but I'm posting my response to you also on the forum for everyone else to view as well:

Got word back from an Engineer in R&D this morning.  If you have NI-video

installed, which should come with the 5431, then you can navigate to:
 C:\Program Files\National Instruments\NI-video\Generator\BMPs

This will give you an idea of the standard sizes of BMPs you can use (i.e.

640x480).  In terms of creating these bitmaps, any standard image software

should allow you to save to this format, i.e. MS-Paint,
Adobe Photoshop, Adobe Illustrator etc.

Here are some of the basics video generation for the 5431 and LabVIEW, which

has largely been relayed from the R&D Engineer:

Basically, one bitmap is made to make a video waveform in the I16 data type. 

There are two frames in the waveform, odd and even.     There are 525 lines

per frame, so there are 1050 lines in the video file.  The video is

interlaced, which means there are two fields per frame, so there are 4 fields

in the file.  A field will generate every other line.  So, the odd field will

generate the odd lines, and the even field will generate the even lines.  So,

it goes Odd Frame:Odd Field, Odd Frame:Even Field, Even Frame:Odd Field, Even

Frame:Even Field. 

Ni Video makes NTSC waveforms as follows.  1272 samples per line, 525 lines

per frame, and two frames.  So, there are 1272 X 525 X 2 = 11,335,600 samples

in a video waveform.

An ITS line is just a special signal that is generated on a line in the video

signal so that measurements can be made to monitor the status or test video

signals.  Since there are 525 lines in a video frame, and there are only 480

lines in the image, that leaves 45 lines that are not seen on your TV.  The

ITS lines are usually in the non-viewable lines.  Say 1 through 22.

The example you're looking at is basically set up to create a large sequence. 

  Lets say we want to replace line 20 of the video signal every frame.  We

have to break up the video file (at this point it is just array manipulation) 

We break it up into three chunks.  Lines 1 - 19, 21 - 544, and 546-1050. 

(Actually, this can be simplified to two waveforms by concatenating the first

and last.  There is no reason to have a break between line 1050 and line 1.)  

 Lets name these A, B, and C

The ITS lines have to be created specifically for line 20.  Then say we have 4

different ITS lines, each one 1272 samples.  Lets name these D, E, F, and G.

So, now we create a waveform sequence as follows.  A, D, B, E, C, A, F, B, G,

C, and this will continually loop generating two frames, with the ITS lines

cycling every two frames.

A great resource for more information on video generation with the 5431 is the

NI Signal Generators Help.  It should be located at Start > Programs >

National Instruments > NI-FGEN > Documentation
Navigate from there to Programming > NI 5431 Composite Video Generator Help

Minh Tran

Applications Engineering

National Instruments