bytedeco/javacv

OutputStream seeking, video length (duration) determination problems

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#839 opened on Nov 23, 2017

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Description

When using

mFrameRecorder.setFormat("matroska");

and File

    public FFmpegFrameRecorder(File file, int imageWidth, int imageHeight) {
        this((File)file, imageWidth, imageHeight, 0);
    }

recording works ok.

When using OutputStream 

    public FFmpegFrameRecorder(OutputStream outputStream, int imageWidth, int imageHeight) {
        this(outputStream.toString(), imageWidth, imageHeight);
        this.outputStream = outputStream;
    }


 DocumentFile newFile = mDocumentFileDir.createFile("video/mkv", "test.mkv");
        try {
            pfd = mContext.getContentResolver().openFileDescriptor(newFile.getUri(), "rw");
            mOutputStream = new FileOutputStream(pfd.getFileDescriptor());
            mFrameRecorder = new FFmpegFrameRecorder(mOutputStream, videoWidth, videoHeight);

            //I close `mOutputStream/pfd` after stopping ffmpeg recording

recording also works ok, I can watch recorded video using android MX Player, but it cannot determine the length of the video and because MX Player doesn't know the length, I can't seek though the video

33134840-705864c0-cfa9-11e7-9b12-75f2f6b49103

Is this a known issue?

Contributor guide

Research direction
Check how FFmpeg handles metadata writing when output is an output stream vs a file. In FFmpegFrameRecorder, ensure the avformat write header and av write trailer are called properly. Look into the output stream implementation and whether the header is flushed before recording stops.
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.
Mostly clear
Prerequisites
JavaFFmpeg basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45