FFmpegFrameGrabber.grabFrame，AVPacket.stream_index，Lock

[dute7liang]

Hi everyone,I'm having an unsolvable problem when trying to take a screenshot of a video

The version number I use : 1.5.6

my code

private static void cutOutFirstOfVideo(String path,File targetFile) throws FrameGrabber.Exception {
        StopWatch stopWatch = new StopWatch("javacv-screenshot");
        stopWatch.start();
        FFmpegFrameGrabber ff = FFmpegFrameGrabber.createDefault(path);
        OpenCVFrameConverter.ToIplImage converter = null;
        IplImage src = null;
        Frame f = null;
        try{
            ff.start();
            int lenght = ff.getLengthInFrames();
            int i = 0;
            while (i < lenght) {
                f = ff.grabFrame();
                if ((i > 1) && (f.image != null)) {
                    f.close();
                    break;
                }
                i++;
                f.close();
            }
            String rotate =ff.getVideoMetadata("rotate");
            f =ff.grabImage();
            if(null != rotate && rotate.length() > 1) {
                converter = new OpenCVFrameConverter.ToIplImage();
                src  = converter.convert(f);
                f = converter.convert(rotate(src, Integer.parseInt(rotate)));
            }
            doExecuteFrame(f,targetFile);
        } finally {
            if(src != null){
                src.close();
            }
            if(f != null){
                f.close();
            }
            if(converter != null){
                converter.close();
            }
            stopWatch.stop();
            log.info("截图处理: javacv 截图结束 耗时={}毫秒",stopWatch.getTotalTimeMillis());
        }
    }

private static void doExecuteFrame(Frame f,File targetFile) {
        if (null ==f || null ==f.image) {
            return;
        }
        try (Java2DFrameConverter converter =new Java2DFrameConverter();
             FileOutputStream fileOutputStream = new FileOutputStream(targetFile)){
            BufferedImage buffImg =converter.getBufferedImage(f);
            ImageIO.write(buffImg,FileSuffixConstant.JPEG,fileOutputStream);
            buffImg.flush();
        }catch (IOException e) {
            log.error("视频保存失败",e);
            throw new RuntimeException(e.getMessage(),e);
        }
    }

jstack

"pool-16-thread-3" #527 prio=5 os_prio=0 tid=0x00007fbe48058000 nid=0x232 runnable [0x00007fba7026c000]
   java.lang.Thread.State: RUNNABLE
	at org.bytedeco.ffmpeg.avcodec.AVPacket.stream_index(Native Method)
	at org.bytedeco.javacv.FFmpegFrameGrabber.grabFrame(FFmpegFrameGrabber.java:1357)
	- locked <0x00000004cb29e470> (a org.bytedeco.javacv.FFmpegFrameGrabber)
	at org.bytedeco.javacv.FFmpegFrameGrabber.grabImage(FFmpegFrameGrabber.java:1283)
	at com.fcbox.vas.dispatch.util.JavacvUtil.cutOutFirstOfVideo(JavacvUtil.java:82)
	at com.fcbox.vas.dispatch.util.JavacvUtil.cutOutFirstOfVideo(JavacvUtil.java:43)
	at com.fcbox.vas.dispatch.util.VideoUtil.cutPicture(VideoUtil.java:67)
	at com.fcbox.vas.dispatch.task.handle.ScreenshotHandle.transFileAndCutPicture(ScreenshotHandle.java:182)
	at com.fcbox.vas.dispatch.task.handle.ScreenshotHandle.run(ScreenshotHandle.java:139)
	at com.fcbox.vas.dispatch.task.handle.ScreenshotHandle.lambda$handle$20(ScreenshotHandle.java:103)
	at com.fcbox.vas.dispatch.task.handle.ScreenshotHandle$$Lambda$1071/1600206385.run(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745) 

It's been stuck here for more than 5 hours,no sign of release. Seems to be stuck somewhere in FFmpegFrameGrabber.grabFrame、AVPacket.stream_index.

It should be noted that this method I will use in multi-threading

This happens occasionally, and it can't be fixed. This has caused me a lot of trouble. What can I do to fix it?

[saudet]

There's nothing related to FFmpeg in AVPacket.stream_index() than can block, it's just literally return stream_index. What is causing this issue is thus JNI and something in the JVM. You'll need to figure out what that is, but it's unrelated to JavaCV, JavaCPP, or FFmpeg.

[dute7liang]

Thank you very much, I found the problem, because the network is unstable, the URL has been blocked, maybe I need to add a timeout mechanism

[tank520]

Thank you very much, I found the problem, because the network is unstable, the URL has been blocked, maybe I need to add a timeout mechanism

how do you resolve it，i found the same problem，grabber.grabFrame() gets stuck for a long time。