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• ffmepg why error :Failed to write core dump

  9 juillet 2021, par dmouse

  I wang to implement a feature that allows me to save RTSP stram as a file,
use javacv implement a demo,but there's an error.
i debug the demo , execute 'recorder.record(frame) ;' error, "ulimit -c unlimited" is useless,the program still reports an error.
review of the source code did note find the problem principle.pleace give me a hand.

  


  import org.bytedeco.javacpp.avcodec;
import org.bytedeco.javacv.FFmpegFrameGrabber;
import org.bytedeco.javacv.FFmpegFrameRecorder;
import org.bytedeco.javacv.Frame;

import java.io.File;
import java.io.IOException;

/**
 * @ClassName video
 * @Description TODO
 * @Author mouse
 * @Date 2021/7/9 11:13
 * @Version 1.0
 **/
public class Video {
    public static void main(String[] args) {
        String streamUrl = "rtsp://admin:12345678.@192.168.20.180:554/h265/ch1/main/av_stream";
        String filePath = "./video/hello.mp3";
        File outFile = new File(filePath);
        FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(streamUrl);
        if (!outFile.getParentFile().exists()) {
            outFile.getParentFile().mkdirs();
        }
        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(filePath,1080,1440, 1);
        recorder.setVideoCodec(avcodec.AV_CODEC_ID_H265);
        recorder.setFormat("flv");
        recorder.setVideoBitrate(4000);
        try {
            grabber.start();
            recorder.start();
            Frame frame = grabber.grabFrame();
            while (frame!=null){
                recorder.record(frame);
                frame = grabber.grabFrame();
            }
            recorder.record(frame);
            recorder.stop();
            grabber.stop();

        } catch (FFmpegFrameGrabber.Exception e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (recorder != null) {
                    recorder.stop();
                }
                if (grabber != null) {
                    grabber.stop();
                }
            } catch (FFmpegFrameRecorder.Exception | FFmpegFrameGrabber.Exception e) {
                e.printStackTrace();
            }
        }
    }
}



  


  log error

  


  #
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x0000000131fef233, pid=50498, tid=0x0000000000001003
#
# JRE version: Java(TM) SE Runtime Environment (8.0_281-b09) (build 1.8.0_281-b09)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.281-b09 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C  [libavformat.57.dylib+0xbf233]  av_write_frame+0x993
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#


  


  pom :

  


          <dependency>&#xA;            <groupid>org.bytedeco</groupid>&#xA;            <artifactid>javacv</artifactid>&#xA;            <version>1.4.3</version>&#xA;        </dependency>&#xA;        <dependency>&#xA;            <groupid>org.bytedeco.javacpp-presets</groupid>&#xA;            <artifactid>ffmpeg-platform</artifactid>&#xA;            <version>4.0.2-1.4.3</version>&#xA;        </dependency>&#xA;

  


  My os : macOS Bgi Sur 11.4 ;
  
JDK : 1.8.0_281
  
execute 'recorder.record(frame) ;' error,
"ulimit -c unlimited" is useless,the program still reports an error .

  


• ffmpeg : nvidia gpu performance sub-optimal

  3 août 2021, par david furst

  the problem seems fairly basic : i'd like to create thumbnails from incoming video in the shortest time possible, and i'm trying to do this by offloading processing to an nvidia gpu.

  


  while i run ffmpeg, i'm monitoring the gpu usage with the nvidia-smi utility. gpu usage never goes above 15% and the amount of time to encode the thumbnails with gpu is only 10% less than the time required without the gpu. these performance levels are very disappointing.

  


  my question : am i going about this the wrong way (and if so, how should i go about it), or is this gpu performance 'normal'/'reasonable' ?

  


  SYSTEM INFORMATION

  


  the machine is a desktop pc running windows 10, 8gb ram, intel i7-7700. the gpu is an nvidia quadro pro 4000 with cuda 11.4 installed. ffmpeg is version N-101372-gb5cb8c8767-g2fc309e699+4 (2021) running under mingw, with --enable-cuda --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-libnpp --enable-nvdec and --enable-nvenc.

  


  a typical ffmpeg command line i've used is :

  


   1 ffmpeg -hide_banner \
 2     -init_hw_device cuda=cuda:0 -filter_hw_device cuda \
 3     -hwaccel_output_format cuda \
 4     -i "$infile" \
 5     -vf "hwupload_cuda,scale_npp=w=200:h=150:format=yuv420p:interp_algo=lanczos,fps=1/1,hwdownload,format=yuv420p" \
 6     -y "$outdir/%08d.png"


  


  i've varied the above by supplementing some cuda-related parameters according to posts i've read here on stackoverflow and on the nvidia transcoding guide, but haven't been able to improve performance. adding any of -hwaccel cuda, -hwaccel cuvid, -hwaccel nvenc at the beginning of line 3 results in the error :
Impossible to convert between the formats supported by the filter 'graph 0 input from stream 0:0' and the filter 'auto_scaler_0'

  


  any pointers appreciated.

  


• Why Video and Audio Don't Match ?

  19 août 2021, par Ohpy

  there is an ffmpeg code.

  


  fmpeg -i "1.mp4" -vf "zoompan=z='if(lte(mod(time,4.99),2.03),4,0)':d=1:x=iw/2-(iw/zoom/2):y=ih/2-(ih/zoom/2):fps=23.98" -af "firequalizer=gain_entry='entry(0,-23);entry(250,-1100.5);entry(1000,0);entry(4000,1);entry(16000,16)'" -metadata title="" -metadata artist="" -metadata album_artist="" -metadata album="" -metadata date="" -metadata track="" -metadata genre="" -metadata publisher="" -metadata encoded_by="" -metadata copyright="" -metadata composer="" -metadata performer="" -metadata TIT1="" -metadata TIT3="" -metadata disc="" -metadata TKEY="" -metadata TBPM="" -metadata language="eng" -metadata encoder="" -threads 0 -preset superfast 1OUT.mp4


  


  This code zooms in and out of the image in the video. It also changes the sound frequency.

  


  When the process of the video is finished, the image in the video and the sound do not match.

  


  For example, the sound that should be at the 10th second of the video is at the 15th second. How can I prevent this ?

  


  Can you help me ?