bytedeco/javacv

How to grab fast/low quality frames

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#1,887 opened on Sep 9, 2022

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Description

I'm building a local video player and I'm currently trying to create the feature similar to youtube where it shows little preview frames when hovering on the seekbar/slider at the bottom of the screen. However its currently very heavy on the cpu and lags noticeably with higher resolution videos. Is there a way to grab lower quality frames or decrease the resolution or bitrate to make the feature more efficient? (I already tried setVideoOption("preset", "ultrafast"), but it didn't have any noticeable impact.)

Contributor guide

Research direction
Use FFmpeg's scaling filter to reduce frame resolution before decoding: add ' vf scale=iw/4:ih/4' to the FFmpeg command. Consider using 'skip frame nokey' to only decode keyframes, or 'vsync 0' with 'select' filter to sample frames at intervals. Also explore the 'thumbnail' filter for scene detection. Check javacv's FFmpegFrameGrabber.setFrameNumber() and setVideoOption() for frame skipping.
Tech stack
java
Domain
desktop
Issue type
Research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaFFmpeg
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60