bytedeco/javacv

GetTimestamp always return 0 when I set video codec name to h264_cuvid

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#1,035 opened on Jul 18, 2018

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Description

I'm using JavaCV 1.4.2

I want to decode video with HWAcceleration. However, I notice that getTimestamp always return 0 when I set video codec name to h264_cuvid.

    public static void main(String[] args) {
        try {
            FFmpegFrameGrabber grabber = new FFmpegFrameGrabber("input.mp4");
            grabber.setVideoCodecName("h264_cuvid");
            grabber.start();

            while (grabber.grabImage() != null) {
                System.out.println(grabber.getTimestamp());
            }
            
            grabber.stop();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

This program print only zero. But frame decoding works fine. When I set video codec something, for example h264 or h264_qsv , you can see increasing timestamp.

https://github.com/bytedeco/javacv/blob/af8214569daf4df683f131a53e96650d377ce6dd/src/main/java/org/bytedeco/javacv/FFmpegFrameGrabber.java#L1159-L1161

On debugging, I found pts value is always -9223372036854775808. I don't know FFmpeg's api, but it looks like bug on FFmpeg. Is this possible to fix in JavaCV?. Thank you.

Contributor guide

Research direction
Investigate FFmpeg's h264 cuvid decoder to understand why it returns AV NOPTS VALUE (INT64 MIN) for pts. Check if JavaCV can work around this by using other packet properties or by falling back to software decoding for timestamp extraction.
Tech stack
java
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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.
30