How to : Specificity of Video Uploads for Labelbox

[ptancre]

Hello Community ,

This article provides an overview of Labelbox’s support and offers solutions to common video asset-related issues encountered by users.

Prerequisite : ffmpeg

Videos are encoded and decoded using various codecs to ensure compatibility and efficient playback across different browsers. The following list outlines some of the most common video codecs you may encounter when working with web-based video content: Web video codec guide - Web media technologies | MDN

Labelbox supports currently : H.264 & H.265

1. H.264 (AVC): Widely supported and known for its high compression efficiency, H.264 is a popular choice for web video delivery.

2. H.265 (HEVC): H.265 offers better compression efficiency than H.264, resulting in smaller file sizes while maintaining high-quality video.

I - Checking the video

Checking the video details via terminal/command prompt: codec, metadata, else…

ffmpeg -i <input.mp4>

II - Removing Frame-count inconsistency

Checking video for Frame-count consistency

ffmpeg -i <input.mp4> -vf vfrdet -an -f null -

If the result of this query is not 0.000

You would need to use this command to get it consistent :

ffmpeg -i <input.mp4> -vcodec libx264 -acodec aac <output.mp4>

Here is the result you are looking for :

Please note doing so may result in :

• dropping frames
• interpolating frames

III - Rotating video

In certain cases, videos may require rotation adjustments depending on their source. Similar to image manipulation, you can convert videos to display in your desired orientation. You may notice rotation under metadata while inspecting the video asset, which can be used to modify the video’s orientation.

Rotate a video clockwise 90 degrees

ffmpeg -i <input.mp4> -vf "transpose=1" <output.mp4>

If you want to rotate a video 90 degrees counter-clockwise :

ffmpeg -i <input.mp4> -vf "transpose=2" <output.mp4>

To clockwise rotate a video 180 degrees , simply apply the transpose operation twice :

ffmpeg -i <input.mp4> -vf "transpose=1,transpose=1" <output.mp4>

The video can also be rotated 90 degrees counter-clockwise , then flipped vertically :

ffmpeg -i <input.mp4> -vf "transpose=0" <output.mp4>

This rotates the video 90 degrees clockwise , then flips it vertically :

ffmpeg -i <input.mp4> -vf "transpose=3" <output.mp4>

IV - Changing FPS

You can also accelerate or slow down a video, here a sample to overwrite the input video to 30 fps
ffmpeg -i <input.mp4> -filter:v fps=fps=30 <output.mp4>

Sample asset :

We provide guidance on limit to make sure your experience is optimal, this is subject to changes :

• Video size - 250MB
• Frame - 20,000

Ref doc :

• Import video data
• Limits