bytedeco/javacv

FFmpegFrameGrabber should throw an exception when attempting to access stream metadata before calling start()

Open

#2,382 创建于 2026年2月19日

在 GitHub 查看
 (4 评论) (0 反应) (0 负责人)Java (6,985 star) (1,583 fork)batch import
enhancementhelp wantedquestion

描述

As stated in the title, when using FFmpegFrameGrabber, if start() is not called beforehand, methods such as getImageWidth() will return 0. This behavior may cause errors to propagate downstream and lead to issues that are more difficult to trace. I believe an IllegalStateException should be thrown immediately to clearly indicate that this operation is invalid.

贡献者指南

技术栈
java
领域
backendapi
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
2
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
under 1 hour
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
fresh
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Basic understanding of FFmpegFrameGrabber lifecycle
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
90
研究方向
Look at the source code of FFmpegFrameGrabber (likely in a file like FFmpegFrameGrabber.java) to identify methods such as getImageWidth(), getImageHeight(), etc. that return metadata. Currently they return 0 when start() has not been called. The fix is to check if start() has been called (possibly using a flag) and throw an IllegalStateException with a descriptive message. Ensure consistent behavior across all such metadata access methods. No linked PRs or assignees exist, so this is available for implementation.
FFmpegFrameGrabber should throw an exception when attempting to access stream metadata before calling start() · bytedeco/javacv#2382 | Good First Issue