bytedeco/javacv

About FFmpeg interrupt_callback

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#2355 opened on Sep 18, 2025

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Description

您好，我正在使用javacv，它非常好用。

关于javacv示例中实现的interrupt_callback我有一些疑问，为什么需要再调用avformat_alloc_context，getFormatContext已经返回了context，是不是可以直接使用，我尝试了这样做，测试中未发现问题。

希望你今天过的很愉快

Hello, I'm using JavaCV and it's been very successful.

I have some questions about the interrupt_callback implementation in the JavaCV examples. Why is it necessary to call avformat_alloc_context? Since getFormatContext already returns the context, can I use it directly? I've tried this and haven't found any issues in my testing.

I hope you have a great day.

Contributor guide

Tech stack
java
Domain
documentation
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.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaJavaCV basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
The user is questioning why `avformat alloc context` is called in the `FFmpegStreamingTimeout.java` example when `getFormatContext` already returns a context. To answer, review the implementation of `getFormatContext` in the same file to see if it allocates the context or not. Also consult FFmpeg documentation for `avformat alloc context` and the interrupt callback mechanism. Check if calling `avformat alloc context` again is redundant or necessary for proper callback setup. Reference the linked sample file and any related FFmpeg API docs.