How to get Frame Type( I、P、B）by JavaCV

[steeveen]

Frame frame=ffmpegGrameGrabber.grabFrame(false,true,true,false,false)；
But all frame.opaque.pict_type()==AV_PICTURE_TYPE_NONE

[saudet]

It's not currently copied, but it shouldn't be too hard to fetch that information around this line:
https://github.com/bytedeco/javacv/blob/master/src/main/java/org/bytedeco/javacv/FFmpegFrameGrabber.java#L1402
Contributions are welcome!

[steeveen]

I’m not very familiar with its code.... It seems that I should add an attribute like pictType in Frame Class? and then assign picture.pict_type() to it?

[saudet]

Sounds reasonable, yes.

[steeveen]

OK， I will have a try

[steeveen]

I am adding pictType to Frame class. And adding pkt_dts, pts to it at the same time. which I think it might be useful.
But I met some problem when testing it. Idea tell me some class in the source code doesn't exist. Such as FLYCAPTURE_OK,FlyCaptureInfoEx
I think this maybe caused by maven? Some change on pom? or by pulling mistaken branch?(I made the change on master)
Can you give me some help?
Or I can just PR the commit to this repo?After all these changes are very simple

[saudet]

That file shouldn't get compiled, you can ignore it.

I don't think we should expose dts and pts. AFAIK that's only useful for packets, not frames, right?

In any case, a reference to the original AVFrame is in Frame.opaque, so you could access it that way in your code without modifying JavaCV, if that's OK with you?

[steeveen]

Yes. Frame.opaque is a good way to access the unused attributes.
But my motivation for adding them is that I find frame.opaque.pts always return Long.MIN_VALUE. As opaque.pkt_dts returning Long.MIN_VALUE. frame.opaque.pict_type returning 0.
Haven't you encountered this problem?

[saudet]

Ah, yes, you're right, those fields are not getting set in that AVFrame. I've added a call to av_frame_copy_props() in commit 33bea56, that should do it. Please give it a try with the snapshots: http://bytedeco.org/builds/

[steeveen]

Hi,saudet.
I have commited the change. https://github.com/bytedeco/javacv/pull/1730
You can have a look at the PR.