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• mplayer can't read udp video stream

  23 avril 2014, par Bruno Marques

  Im trying to compare latency between different video codecs using ffmpeg and mplayer’s benchmark.

  I am using this command line to generate and send the stream :

  ffmpeg -s 1280x720 -r 100 -f x11grab -i :0.0 -vcodec mpeg2video -b:v 8000 -f mpegts udp://localhost:4242

  And I’m successfully using ffplay to receive and read it in real time :

  ffplay -an -sn -i -fflags nobuffer udp://localhost:4242?listen

  Now instead of playing the stream with ffplay, i’d like to use the mplayer benchmark to get some information on the latency :

  mplayer -msglevel all=6 -benchmark udp://localhost:4242

  But I get this output instead :

  Playing udp://localhost:4242.
  
  get_path('sub/') -> '/home/XXXXX/.mplayer/sub/'
  
  STREAM_UDP, URL: udp://localhost:4242
  
  Filename for url is now udp://localhost:4242
  
  Listening for traffic on localhost:4242 ...
  
  Timeout! No data from host localhost
  
  udp_streaming_start failed
  
  No stream found to handle url udp://localhost:4242

  I tried with rtp protocol instead, didn’t work either...

  Does anyone have an idea what i’m doing wrong ?

• Something wrong with recording video and merging audio and video by using FFmpeg

  16 mars 2014, par VaFancy

  At the beginning, I have to admit that I am a newbie in FFmpeg and also raspbian. Unfortunately, I need to solve this problem as soon as possible.

  I tried to record videos on my Raspberry PI by using PIcamera and USB webcam separately. When I used command :

  ffmpeg -t 10 -f video4linux2 -r 25 -i /dev/video0 out.h264

  However, something was very wrong because there was nothing saved in that video file. I copy the log.

  [video4linux2,v4l2 @ 0x267ad80] The driver changed the time per frame from 1/25 to 1/30
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 37562.908020, bitrate: 147456 kb/s
  
      Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 640x480, 147456 kb/s, 30 fps, 30 tbr, 1000k tbn, 1000k tbc
  
  File 'out.h264' already exists. Overwrite ? [y/N] y
  
  No pixel format specified, yuv422p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x267ca60] using cpu capabilities: ARMv6
  
  [libx264 @ 0x267ca60] profile High 4:2:2, level 3.0, 4:2:2 8-bit
  
  Output #0, h264, to 'out.h264':
  
    Metadata:
  
      encoder         : Lavf55.34.101
  
      Stream #0:0: Video: h264 (libx264), yuv422p, 640x480, q=-1--1, 90k tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo -> libx264)
  
  Press [q] to stop, [?] for help
  
  DTS 140730117085, next:18648459 st:0 invalid dropping00.00 bitrate=N/A    
  
  PTS 140730117085, next:18648459 invalid dropping st:0
  
  DTS 140740452429, next:6538221 st:0 invalid dropping:00.00 bitrate=N/A    
  
  PTS 140740452429, next:6538221 invalid dropping st:0
  
  frame=   44 fps=1.1 q=28.0 size=      18kB time=00:00:00.04 bitrate=3712.6kbits/
  
  frame=   45 fps=0.8 q=28.0 size=      22kB time=00:00:00.08 bitrate=2262.8kbits/
  
  frame=   46 fps=0.7 q=28.0 size=      27kB time=00:00:00.12 bitrate=1813.4kbits/
  
  frame=   47 fps=0.6 q=28.0 size=      30kB time=00:00:00.16 bitrate=1559.2kbits/
  
  frame=   48 fps=0.5 q=28.0 size=      34kB time=00:00:00.20 bitrate=1397.7kbits/
  
  frame=   49 fps=0.5 q=28.0 size=      39kB time=00:00:00.24 bitrate=1324.3kbits/
  
  frame=   50 fps=0.4 q=28.0 size=      42kB time=00:00:00.28 bitrate=1241.7kbits/ 

  As you can see, the size of each frame was only few kb and fps was so low. Thus each frame was taken by using a long time(4s in this case). Then I test my USB webcam by using command :

  ffplay -f video4linux2 /dev/video0

  The video stream which displayed on the screen was so unnatural. It looked like there was such a long delay between each frame. So the video was hardly moved. The log I have copied :

  pi@raspberrypi ~ $ ffplay -f video4linux2 /dev/video0
  
  avplay version 0.8.6-6:0.8.6-1+rpi1, Copyright (c) 2003-2013 the Libav developers
  
    built on Mar 31 2013 13:58:10 with gcc 4.6.3
  
  [video4linux2 @ 0x1ad83c0] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, video4linux2, from '/dev/video0':
  
    Duration: N/A, start: 36107.154598, bitrate: 147456 kb/s
  
      Stream #0.0: Video: rawvideo, yuyv422, 640x480, 147456 kb/s, 30 tbr, 1000k tbn, 30 tbc
  
  [avsink @ 0x1ad9960] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x1ad9d20] w:640 h:480 fmt:yuyv422 -> w:640 h:480 fmt:yuv420p flags:0x4
  
  36163.33 A-V:  0.000 s:0.0 aq=    0KB vq= 3000KB sq=    0B f=8/8 

  The final problem is that no sound was added in video file when I tried to add some in. I used the command :

  avconv -i /home/pi/Desktop/test.mp4 -i /home/pi/Desktop/test.mp3 -map 0:0 -vcodec copy -map 1:0 -acodec copy output.h264

  I have checked separately that the video and audio were both able to play. However the merged file only had video but no audio. The log is shown below, it seems that the process was succeed.

  pi@raspberrypi ~ $ avconv -i /home/pi/Desktop/test.mp4 -i /home/pi/Desktop/test.mp3 -map 0:0 -vcodec copy -map 1:0 -acodec copy output.h264
  
  avconv version 0.8.6-6:0.8.6-1+rpi1, Copyright (c) 2000-2013 the Libav developers
  
    built on Mar 31 2013 13:58:10 with gcc 4.6.3
  
  [h264 @ 0x1aa6680] max_analyze_duration reached
  
  [h264 @ 0x1aa6680] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, h264, from '/home/pi/Desktop/test.mp4':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0.0: Video: h264 (High), yuv420p, 640x480, 25 fps, 25 tbr, 1200k tbn, 2400k tbc
  
  [mp3 @ 0x1aaa120] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, mp3, from '/home/pi/Desktop/test.mp3':
  
    Metadata:
  
      title           : We Are Legend (Original Mix)
  
      artist          : Dimitri Vegas & Like Mike & Steve Aoki
  
      album           : SPINNIN RECORDS
  
      encoded_by      : iTunes 11.1.5
  
      TBP             : 128
  
      genre           : Progressive House
  
      date            : 2013
  
    Duration: 00:00:11.14, start: 0.000000, bitrate: 191 kb/s
  
      Stream #1.0: Audio: mp3, 48000 Hz, stereo, s16, 192 kb/s
  
  File 'output.h264' already exists. Overwrite ? [y/N] y
  
  Output #0, h264, to 'output.h264':
  
    Metadata:
  
      encoder         : Lavf53.21.1
  
      Stream #0.0: Video: libx264, yuv420p, 640x480, q=2-31, 90k tbn, 1200k tbc
  
      Stream #0.1: Audio: libmp3lame, 48000 Hz, stereo, 192 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #1:0 -> #0:1 (copy)
  
  Press ctrl-c to stop encoding
  
  frame=  144 fps=  0 q=-1.0 Lsize=    1684kB time=5.06 bitrate=2724.7kbits/s    
  
  video:1566kB audio:119kB global headers:0kB muxing overhead 0.000000%

  Could somebody helps me, please. And sorry for my bad english.

  BTW : When I finally captured 200 frames, it turns out all of them were green.

• Qt 5.2 / OpenCV 2.4.8 - Can’t open video files via VideoCapture

  21 février 2014, par Zamahra

  I have a big problem that i can’t solve by myself. OpenCV itself works fine, but i’m not able to load videos. Here’s my code :

  PRO- File

  QT       += core gui
  
  
  
  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
  
  
  
  TARGET = videoredux
  
  TEMPLATE = app
  
  
  
  INCLUDEPATH += C:/OpenCV/opencv_bin/install/include
  
  LIBS += -LC:\\OpenCV\\opencv_bin\\bin \
  
      libopencv_core248d \
  
      libopencv_highgui248d \
  
      libopencv_imgproc248d \
  
      libopencv_features2d248d \
  
      libopencv_calib3d248d \
  
      libopencv_video248d \
  
  
  
  
  
  SOURCES += main.cpp\
  
          mainwindow.cpp
  
  
  
  HEADERS  += mainwindow.h
  
  
  
  FORMS    += mainwindow.ui

  and the MainWindow Class :

  #include "mainwindow.h"
  
  #include "ui_mainwindow.h"
  
  #include <qfiledialog>
  
  #include <iostream>
  
  #include 
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include <opencv></opencv>cv.h>
  
  
  
  
  
  MainWindow::MainWindow(QWidget *parent) :
  
  QMainWindow(parent),
  
  ui(new Ui::MainWindow)
  
  {
  
      ui->setupUi(this);
  
      ui->videoStatusLabel->setText("Kein Video geladen.");
  
  
  
      // SIGNALS &amp; SLOTS
  
  
  
      QObject::connect(ui->chooseVideoButton,SIGNAL(clicked()),
  
                   this,SLOT(chooseVideo()));
  
      QObject::connect(ui->startButton,SIGNAL(clicked()),
  
                   this,SLOT(startProcess()));
  
  
  
  }
  
  
  
  void MainWindow::chooseVideo(){
  
  
  
      QString fileName = QFileDialog::getOpenFileName(this,
  
           tr("Open Video"), "/home", tr("Video Files (*.avi *.mp4 *.mpeg *.mpg)"));
  
      qDebug() &lt;&lt; "Path:" &lt;&lt; fileName;
  
      ui->videoStatusLabel->setText(fileName);
  
  }
  
  
  
  void MainWindow::startProcess(){
  
      QString videoPath = ui->videoStatusLabel->text();
  
      QFileInfo video(videoPath);
  
      if(video.exists()){
  
          const std::string path = videoPath.toUtf8().constData();
  
          cv::VideoCapture capture(path);
  
          cv::Mat frame;
  
  
  
          if(!capture.isOpened()){
  
              qDebug() &lt;&lt; "Error, video not loaded";
  
          }
  
  
  
          cv::namedWindow("window",1);
  
          while(true)
  
          {
  
              bool success = capture.read(frame);
  
              if(success == false){
  
                  break;
  
              }
  
              cv::imshow("window",frame);
  
              cv::waitKey(20);
  
          }
  
          cv::waitKey(0);
  
      }
  
      else{
  
          qDebug() &lt;&lt; "Error, File doesn&#39;t exist";
  
      }
  
  }
  
  </iostream></qfiledialog>

  The paths are correct, I tried many different video formats but he never loads the videos. I’m running Qt on a Windows 8 machine and i have “K-Lite Codec Pack 10.2.0 Basic” and ffmpeg installed. The videos are playing properly with my video players. I also tried to copy the .dll to the working directory, searched for opencv dll's in the system32 directory and rebuild OpenCV with mingw on this computer. I know that many people have the same problems, but none of their suggestions solved it. Does anyone know how to solve this problem ?

  Thank you very much !

  Nadine

  ----UPDATE---- I still can't open video files, so I programmed the application on a Windows7 64-Bit system. It worked fine, but when I try to open the application on a Windows8 computer it still can't open the file. It doesn't matter which codecs are installed, because it generally runs on every Windows7 computer and fails on every Windows8 computer.. The same for older OpenCV-Versions. Is there a general problem with OpenCV and Windows8 ?