[jpsdr]

@pinterf
In the process of avs+ upgrade/improvements, i suggest the following to fill the missing gaps.
It would work the way the new bitdepth functions works : "Do nothing" or return a default value if we are on standard avisynth.

It should be nice to add these missing metadata :
Range mode, result would be : NONE, FULL_RANGE, LIMITED_Y, LIMITED_C.
Two limited modes, because a grey plane can be either a true greyscale plane, or an extract of an RGB plane, or an extract of a YUV plane, in that case it can be a chroma plane.
For YUV mode, LIMITED_Y or LIMITED_C would be the same thing, but i propose the used of LIMITED_Y by default.
Color mode, result would be : NONE, REC601, etc...
MPEG mode, result would be : NONE, MPEG-1, MPEG-2.
Frame mode, result would be : NONE, PROGRESSIVE,INTERLACED.

Several way to handle them.
A function wich return the status, with NONE returned on not avs+.
A function which manualy set it, "doing nothing" on not avs+.
And the last, the "automatic" way.
The default value, when a clip is created, would be the default value used in functions specifying them.
For exemple, a ConvertYV16 has a default color matrix value, this is this default value which will be used when a clip is created.
Same for all the others tags.
When a function with one or more of these parameters exist is used, the behavior would be the following :
- If the meta data is not NONE, and the parameter is not specified, the value used is the one of the meta data.
- If the meta data is NONE, the meta data get the value of the default value of the parameter if it's not specified.
- If the parameter is specified, the metadata get the value of the parameter.
Some metadata are kept even if the format don't need it.
For exemple, an YUV clip converted to RGB, would it be directly converted, or would it be converted and result put in a different clip, the resulting RGB clip will keep the Color mode. Because this same color mode will be used if converted back to YUV without the color matrix specified in the called function.
Some metadata will be automaticaly changed according what is done, unless a parameter in the function specify it.
For exemple, an YUV clip converted to RGB will have the range parameter changed from LIMITED_x to FULL_RANGE. On the other way, an RGB clip converted to YUV will have the parameter changed from FULL_RANGE to LIMITED_Y (unless parameter specification, of course).
RGB will allways be FULL_RANGE, because it's RGB we're working with, not R'G'B'.
Extracted plane would have the parameter set accordingly.
En extracted plane from RGB or from YUV set to FULL_RANGE will be FULL_RANGE. Y or U/V plane extracted to LIMITED_x will be set accordingly.

Well, i think you see the picture.
What do you think ?
I personnaly think these metadata realy should be present, and adding them is within the actual avs+ improvement way.