Clarification needed on some of the AVISynth functions

[rkr1958]

I've read and used in detail the manual at http://www.avisynth.org/index.php?page=AviSynthManual and the manual that's installed with the latest stable version (2.56a) of AVISynth. But, I'm looking more detaileds on the following.

1. GetParity() > I wasn't sure if true was TFF or BFF. After doing some search of this forum I found that true was TFF and I verified this on a clip that I knew to be BFF (I got false in this case). Is this correct?

2. Info() > I figured out was all it's outputs mean but "Video Pitch" is. What is it?

3. Assert > I've seen this used in several scripts. Is this function impilict to AVISynth? Is so, it appears to be used of error handling. How is properly used?

4. NOP > After searching several threats I found out this returns a null value from a function. Is this correct? What happens when you use it?

5. I figured out how to use ShowFrameNumber to print out on the video the number of the currrent frame/field (similar to info). If the frames are fields, is there any such similar function that'll print out if the field is Top or Bottom?

Thanks in advance.

[unskinnyboy]

1. GetParity() > I wasn't sure if true was TFF or BFF. After doing some search of this forum I found that true was TFF and I verified this on a clip that I knew to be BFF (I got false in this case). Is this correct?
Yes.
2. Info() > I figured out was all it's outputs mean but "Video Pitch" is. What is it?
This (http://forum.doom9.org/showthread.php?t=45638) thread should help. Just look at the parts where the pitch of a video is discussed.

3. Assert > I've seen this used in several scripts. Is this function impilict to AVISynth? Is so, it appears to be used of error handling. How is properly used?
Yes. It is a built-in funtion for error handling. From here (http://www.avisynth.org/ScriptFunctions),

For error reporting and catching bad input to user-defined function you can use (error-message if bool=false):
Assert (bool, string error-message)
4. NOP > After searching several threats I found out this returns a null value from a function. Is this correct? What happens when you use it?
It is to be used, for example in an IF-THEN-ELSE loop, if you don't need to use the ELSE condition. Look at the same link which I gave above for more info.

5. I figured out how to use ShowFrameNumber to print out on the video the number of the currrent frame/field (similar to info). If the frames are fields, is there any such similar function that'll print out if the field is Top or Bottom?
Try this (http://forum.doom9.org/showthread.php?p=188721#post188721).

[rkr1958]

unskinnyboy

Thanks for the quick reply, answers and links.

[stickboy]

1. GetParity() > I wasn't sure if true was TFF or BFF. After doing some search of this forum I found that true was TFF and I verified this on a clip that I knew to be BFF (I got false in this case). Is this correct?A good mnemonic is T = True = TFF.
3. Assert > I've seen this used in several scripts. Is this function impilict to AVISynth? Is so, it appears to be used of error handling. How is properly used?It's a built-in function. It causes a script to terminate immediately if an unexpected condition is encountered. Consult the AviSynth bundled documentation you get when you install AviSynth.
4. NOP > After searching several threats I found out this returns a null value from a function. Is this correct? What happens when you use it?Nothing! That's the point. NOP means "no operation". It's not something most people would use often.
5. I figured out how to use ShowFrameNumber to print out on the video the number of the currrent frame/field (similar to info). If the frames are fields, is there any such similar function that'll print out if the field is Top or Bottom?For field-separated video (i.e., the result of SeparateFields()), ShowFrameNumber already prints numbers on different sides of the frame depending on whether it's a top field or bottom field.