Different framesCount between in the original video file and the key in the JSON

[yayayru]

Describe the bug
I am a label studio beginner in the labeling setup of Video Object Tracking. I noticed different frames counts between the original video file and key framesCount in JSON why? They must be the same. Maybe BUG? Or do I need to set up something?

To Reproduce
Steps to reproduce the behavior:

1. Go to http://localhost:8080/projects
2. Create project and name it
3. import video mp4
4. Chose Video -> Video Object Tracking
5. After adding label click </> and see the error(does not match) "framesCount": 106 see the screenshot

Expected behavior
framesCount must be the same in Label studio and in Supervise.ly . By the way, you can check any video file with cv2 in python

Screenshots

Environment (please complete the following information):

• OS: Ubuntu desktop 20.04
• Label Studio Version 1.6.0

Additional context
In Screenshots see different framesCount of one video file in Label studio and in Supervise.ly , I'm sure the correct framesCount is in Supervise.ly

[makseq]

@yayayru Did you set framerate attribute in the Video tag of the labeling config correctly?

[yayayru]

@yayayru Did you set framerate attribute in the Video tag of the labeling config correctly?

@makseq Thanks I found the attribute:

<Video name="video" value="$video" framerate="25.0"/>

But I want to set the original framerate of each video file how? Because I have folders of video files with different framerates

[makseq]

Unfortunately only constant is support at this moment.

<Video name="video" value="$video" framerate="$fps"/>

I would expect this one works, however it seems like a bug there and it doesn't :-(

[yayayru]

Unfortunately only constant is support at this moment.

<Video name="video" value="$video" framerate="$fps"/>

I would expect this one works, however it seems like a bug there and it doesn't :-(

Yes, I didn't get the code "$fps" . Thanks for the info, I hope you fix the bug in the future.

[MetaHG]

Unfortunately only constant is support at this moment.

<Video name="video" value="$video" framerate="$fps"/>

I would expect this one works, however it seems like a bug there and it doesn't :-(

Hi @makseq,

I am also affected by this issue.
My dataset contains multiple videos with several different framerates. At the moment, transcoding the videos to an identical framerate is not an option.

Two questions related to this issue:

• Is there any ETA for this bug fix?
• Is there a separate ticket somewhere to track this specific issue? (I couldn't find it if there is one)

[makseq]

@MetaHG No, there is no separate ticket. I will try to force fixing it with our team (DEV-4028).

[MetaHG]

Hi @makseq,

I have an additional question regarding the parameter fps in the labeling interface.

It is not uncommon in media files to have variable frame rate to maximize file compression. Does the video player and more generally label-studio allows to proceed accurately with such files?

• If yes, does that mean that fps needs to be sepcified as the average fps?
• If no, what would exactly be the issue with such files? Is it only a video player synchronization issue? The annotation format adopted by label-studio looks suitable even for media files with a variable framerate as label-studio keyframes (not video encoding keyframes) are all saved with their corresponding frame number.

[hlomzik]

Hi, @MetaHG!
Unfortunately browser doesn't have access to video frames, so that's very important to set frameRate for every video. Video is played well anyway, the only thing is affected is timeline, we detect current frame as (time passed / given frame rate), so it can be only linear.
So for dynamic frame rates current frame could be not exactly the correct one.