What is the data format accepted by 5431 apart from .bmp and video files?

[Bipin]

I have to convert .trp(MPEG-2) format data which has a well defined format and give it to 5431 card for generation of Test signals.

[LocalDSP]

The NI-5431 is a modified version of the NI-5411 Arbitrary Waveform Generator and takes the same type of input data. If you want to replay your MPEG-2 file you have to first convert it to a "decoded" PAL or NTSC I16 data file (Signed Integer 16-bit that is data range [-32768,+32767] ). The default scaling is, as indicated for example in the Video Wizard, Gain = 250 and offset -4000, when the input signal is represented in IRE. So IRE=100 (white) is mapped to +100*250-4000 = 21000 and IRE=-43 (PAL Sync-tip) is mapped to -43*250-4000 = -14750.

[Bipin]

Hi,

Thanks for the information. So the PAL/NTSC composite video signal can be decoded by considering the gain and offset given. How about the colour burst signals. Can you provide more details about representing the decoded data file for one entire frame starting from vertical blanking, horizontal blanking, synch pulses, video, color. You dont have to give the converted values only the procedure about how different parts of the analog video is decoded to I16.

[LocalDSP]

The information I gave you was only about how to scale your decoded signal before passing it to the 5431. Before anything else you need to convert (decode) your MPEG to a PAL (or NTSC) signal. This is not trivial but I was assuming you knew how to do that since you said that it was a "well defined signal".

But thinking more about it, even if you succeed in converting to a PAL/NTSC signal, you'll have to resample your waveform to fit the rate required by the 5431. To do so you'll have to make sure the number of samples per line is exactly 1280 (for PAL) or 1272 (for NTSC). Then the previously mentioned scaling will have to be done. Finally your overall repetition will have to fit the number of frames required by the PAL/NTSC norms to keep phase
continuity for your chroma signal.

So all together there is a significant amount of work ahead and I am not sure it will end working the way you want. Can you explain more about your exact application and maybe we can think of a better way of solving your problem.

To answer your question on the PAL/NTSC format, you can find more information on the signal and the definitions as well as a detailled explaination on how the 5431 works in your NI-5431 Software Manual (especially the Appendices). Go to Start>>Programs>>Nat. Inst Composite Video Generator>>Documentation

[Bipin]

Hi,


Thanks for your prompt reply. My immediate application involves inserting Teletext signal during the vertical blanking interval of a composite video basband signal(PAL 625). Later I intend to insert teletext on to MPEG-2 format Television data. Currently I am looking at a PCI teletext insertion card by a third party vendor(http://www.cebra.dk) and 5431 video signal generator card to achieve my first task. I hope the above mentioned details are sufficient. Regarding conversion of MPEG-2 to PAL I feel there are many third party softwares available can we use any of that, do I have to take care about anything in particular in doing so or can I use any MPEG-2 to PAL 625 decoder or encoder.

Best regards,

Bipin

[LocalDSP]

Since I am not sure whether you already have a 5431 or are just considering getting one let me ask: Are you aware that the 5431 is only able to repeat a PAL signal in a loop and that the typical size of the buffer corresponds to "few" frames, typically 8 for PAL. This means that the repetition time is only 320 ms. Is this sufficient for your application?

The NI-54** series does have some looping and linking options that would allow you to repeat a (static) picture while replacing few lines (like the vertical blanking interval) with your teletext signal. Doing this you could probably extend your repetition time to several seconds, but you'll still 1) display a static picture 2) have a limited repetition time and 3) would not
be able to update your teletext signal on-the-fly (without having to briefly stop your generation while downloading new waveforms, thus loosing video-sync for maybe a couple of seconds). Finally programming the looping/linking feature will be at a relatively low-level programming (read painful). But in case you decide to go that way, let me know, I do have some examples of looping/linking video I can send you.

[Bipin]

Hi,

I was planning to buy a 5431 card. And as my application involves on the fly insertion of teletext signal, I now feel that 5431 card was a wrong choice. Now all that I want to know is

1) whether there is any other alternative product from NI which can do the online teletext insertion ?

2) If there is any alternative product, then can it also take MPEG-2 and do the same teletext insertion on MPEg-2 ?

2) Are you aware of any other product which can do the above task?

Thanks in advance.

Best Regards,

Bipin

[LocalDSP]

The answer to question 1 is unfortunately: "no" NI does not offer at this time a dedicated product for (on-the-fly) teletext insertion. To get a broader forum reading your other questions, I'd suggest you to re-post them in a new thread.