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• C++/OpenCV - VideoCapture doesn't work but it worked before with exactly the same code

  5 mars 2015, par Damià Obrador

  I’m trying to write a shot boundary detection algorithm in C++ using OpenCV. After all, I have to say that I have no experience working with OpenCV.

  I have been improving the following code (and I am still in it) during the last two weeks and everything seems the works correctly, not in terms of perfect shot detection, but every line of code did what was expected from it.

  #include <cstdlib>
  
  #include <opencv2></opencv2>opencv.hpp>
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>video/background_segm.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <iostream>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include 
  
  #include <istream>
  
  #include <fstream>
  
  using namespace cv;
  
  
  
  
  
  
  
  int main(){
  
  
  
      VideoCapture capture("vdevendetta.mp4");
  
      if ( !capture.isOpened() )
  
       {
  
           std::cout &lt;&lt; "Cannot open the video file";
  
           return -1;
  
       }
  
      int numFrames=capture.get(CV_CAP_PROP_FRAME_COUNT);
  
      bool SB_counter=false;
  
      Mat currentFrame;
  
      Mat frame;
  
      Mat fore;
  
      Mat back;
  
      vector<mat> frames;
  
      FileStorage file;
  
      FileStorage file2;
  
      Mat prev_Y;
  
      Mat channels[3];
  
      for(int i=0;i>currentFrame;
  
              frame=currentFrame.clone();
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              prev_Y=channels[0];
  
              SB_counter=false;
  
          }
  
          else
  
          {
  
              capture>>currentFrame;
  
              frame=currentFrame.clone();
  
              Mat channels[3];
  
              cvtColor(frame,frame,CV_BGR2YUV);
  
              split( frame, channels );
  
              Mat curr_Y=channels[0];
  
              channels[0]=prev_Y;
  
              prev_Y=curr_Y;
  
              merge(channels,3,frame);
  
              cvtColor(frame,frame,CV_Luv2BGR);
  
              cvtColor(frame,frame,CV_BGR2GRAY);
  
              frames.push_back(frame);
  
          }
  
  
  
      }
  
  
  
      vector<double> MAFDs;
  
      vector<double> MAFD;
  
      vector<double> aux;
  
      double min;
  
      double min2;
  
  
  
      for(int j=1;j14)
  
          {
  
              std::cout&lt;&lt;"De"&lt;*
  
      std::ofstream fout("MAFD.txt");
  
      if(fout.is_open()==true)
  
      {
  
        //file opened successfully so we are here
  
        std::cout &lt;&lt; "File Opened successfully!!!. Writing data from array to file" &lt;&lt; std::endl;
  
  
  
          for(int i = 0; MAFD[i] != '\0'; i++)
  
          {
  
          fout &lt;&lt; MAFD[i]; //writing ith character of array in the file
  
          }
  
        std::cout &lt;&lt; "Array data successfully saved into the file test.txt" &lt;&lt; std::endl;
  
      }
  
      else //file could not be opened
  
      {
  
          std::cout &lt;&lt; "File could not be opened." &lt;&lt; std::endl;
  
      }*/
  
      return 0;
  
  }
  
  </double></double></double></mat></fstream></istream></iostream></cstdlib>

  Three days ago I had an strange problem. The line :

  VideoCapture capture("vdevendetta.mp4");

  stopped working. I spent many hours looking for the solution but nothing seems to repair it. After reading everything related with OpenCV, VideoCapture and ffmpeg that I found on internet I decided to reinstall everything taking care of each detail, but it still didn’t work. Finally I solved it changing the line with this other one :

  VideoCapture capture("/home/damia/Documentos/Universitat/ARA/PAEAV/workspace_cpp/SBD/src/vdevendetta.mp4");

  I did not know why this solved it because the video is in the same directory than the program, but I continued working because everything seemed correct.
  Today I had the same problem again on the new line.
  The terminal doesn’t show any error comment (exceptuating "Cannot open the video file", obviously) but the code doesn’t work again.

  I’m using Ubuntu 14.04 LTS, OpenCV 2.4.9 and Eclipse.

  I think if someone test the code it will run correctly, but I would like to know if there is something I have no taking into account.

  Thank you very match.

• ffmpeg : images to 29.97fps mpeg2, audio not sync [migrated]

  21 novembre 2011, par Andy Le

  I have spent a lot of time on this issue. Hope someone can help.

  I want to convert 3147 images + ac3 audio file into an mpeg2 video at 29.97fps (about 1m45s). My command :

  ~/ffmpeg/ffmpeg/ffmpeg -loop_input -t 105 -i v%4d.tga -i final.ac3 -vcodec mpeg2video -qscale 1 -s 400x400 -r 30000/1001 -acodec copy -y out.mpeg 2> out.txt

  However, the audio file ends before the frame sequence. Which means the video is slower then audio.

  I checked the output file with imageinfo and see :

  General
  
  Complete name                    : out.mpeg
  
  Format                           : MPEG-PS
  
  File size                        : 7.18 MiB
  
  Duration                         : 1mn 44s
  
  Overall bit rate                 : 574 Kbps
  
  
  
  Video
  
  ID                               : 224 (0xE0)
  
  Format                           : MPEG Video
  
  Format version                   : Version 2
  
  Format profile                   : Main@Main
  
  Format settings, BVOP            : No
  
  Format settings, Matrix          : Default
  
  Format_Settings_GOP              : M=1, N=12
  
  Duration                         : 1mn 44s
  
  Bit rate mode                    : Variable
  
  Bit rate                         : 103 Kbps
  
  Width                            : 400 pixels
  
  Height                           : 400 pixels
  
  Display aspect ratio             : 1.000
  
  Frame rate                       : 29.970 fps
  
  Resolution                       : 8 bits
  
  Colorimetry                      : 4:2:0
  
  Scan type                        : Progressive
  
  Bits/(Pixel*Frame)               : 0.021
  
  Stream size                      : 1.29 MiB (18%)
  
  
  
  Audio
  
  ID                               : 128 (0x80)
  
  Format                           : AC-3
  
  Format/Info                      : Audio Coding 3
  
  Duration                         : 1mn 44s
  
  Bit rate mode                    : Constant
  
  Bit rate                         : 448 Kbps
  
  Channel(s)                       : 6 channels
  
  Channel positions                : Front: L C R, Side: L R, LFE
  
  Sampling rate                    : 44.1 KHz
  
  Stream size                      : 5.61 MiB (78%)

  The log from ffmpeg shows many duplicate frames. But I don't know how to get rid of that.

  -loop_input is deprecated, use -loop 1
  
  [image2 @ 0x9c17a80] max_analyze_duration 5000000 reached at 5000000
  
  Input #0, image2, from 'v%4d.tga':
  
    Duration: 00:02:05.88, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: targa, bgr24, 400x400, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  -loop_input is deprecated, use -loop 1
  
  [ac3 @ 0x9ca5420] max_analyze_duration 5000000 reached at 5014400
  
  [ac3 @ 0x9ca5420] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, ac3, from 'Final.ac3':
  
    Duration: 00:20:10.68, start: 0.000000, bitrate: 447 kb/s
  
      Stream #1:0: Audio: ac3, 44100 Hz, 5.1(side), s16, 448 kb/s
  
  Incompatible pixel format 'bgr24' for codec 'mpeg2video', auto-selecting format 'yuv420p'
  
  [buffer @ 0x9c1e060] w:400 h:400 pixfmt:bgr24 tb:1/1000000 sar:0/1 sws_param:
  
  [buffersink @ 0x9dd56c0] auto-inserting filter 'auto-inserted scale 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x9c178e0] w:400 h:400 fmt:bgr24 -> w:400 h:400 fmt:yuv420p flags:0x4
  
  [mpeg @ 0x9d58060] VBV buffer size not set, muxing may fail
  
  Output #0, mpeg, to 'out.mpeg':
  
    Metadata:
  
      encoder         : Lavf53.21.0
  
      Stream #0:0: Video: mpeg2video, yuv420p, 400x400, q=2-31, 200 kb/s, 90k tbn, 29.97 tbc
  
      Stream #0:1: Audio: ac3, 44100 Hz, 5.1(side), 448 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (targa -> mpeg2video)
  
    Stream #1:0 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame=  267 fps=  0 q=1.0 size=     564kB time=00:00:08.87 bitrate= 520.6kbits/s dup=43 drop=0    
  
  frame=  544 fps=542 q=1.0 size=    1186kB time=00:00:18.11 bitrate= 536.2kbits/s dup=89 drop=0    
  
  frame=  821 fps=546 q=1.0 size=    1818kB time=00:00:27.36 bitrate= 544.3kbits/s dup=135 drop=0    
  
  frame= 1098 fps=548 q=1.0 size=    2444kB time=00:00:36.60 bitrate= 547.0kbits/s dup=181 drop=0    
  
  frame= 1376 fps=549 q=1.0 size=    3072kB time=00:00:45.87 bitrate= 548.5kbits/s dup=227 drop=0    
  
  frame= 1653 fps=550 q=1.0 size=    3700kB time=00:00:55.12 bitrate= 549.9kbits/s dup=273 drop=0    
  
  frame= 1930 fps=550 q=1.0 size=    4326kB time=00:01:04.36 bitrate= 550.6kbits/s dup=319 drop=0    
  
  frame= 2208 fps=551 q=1.0 size=    4960kB time=00:01:13.64 bitrate= 551.8kbits/s dup=365 drop=0    
  
  frame= 2462 fps=546 q=1.0 size=    5746kB time=00:01:22.11 bitrate= 573.2kbits/s dup=407 drop=0    
  
  frame= 2728 fps=544 q=1.0 size=    6354kB time=00:01:30.99 bitrate= 572.1kbits/s dup=451 drop=0    
  
  frame= 3007 fps=545 q=1.0 size=    6980kB time=00:01:40.28 bitrate= 570.2kbits/s dup=498 drop=0    
  
  frame= 3146 fps=546 q=1.0 Lsize=    7352kB time=00:01:44.93 bitrate= 573.9kbits/s dup=521 drop=0    
  
  
  
  video:1518kB audio:5745kB global headers:0kB muxing overhead 1.230493%

• How can i create a portrait video using Android's MediaRecorder

  23 mars 2015, par urudroid

  I have an Android application which is able to record and play a videos in portrait mode, those features are working fine on Android phones.

  The issue comes up because this video is needed to be played also on iOS devices (after being shared through a server).

  iOS is not correctly showing the video as it looks "cropped", but videos recorded on iOS are played without issues.

  So, the main difference between videos created on Android and iOS’ is the size and the rotation.

  Im using CWAC-Camera library for preview and recording and ffmpeg to scale the video down to 320x568px (as this is the standard size for both Android and iOS apps).

  Here is the metadata from an video created from Android :

  General
  
  Complete name                            : android_video.mp4
  
  Format                                   : MPEG-4
  
  Format profile                           : Base Media
  
  Codec ID                                 : isom
  
  File size                                : 447 KiB
  
  Duration                                 : 5s 596ms
  
  Overall bit rate                         : 654 Kbps
  
  Encoded date                             : UTC 1904-01-01 00:00:00
  
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  Writing application                      : Lavf56.4.101
  
  
  
  Video
  
  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L2.1
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 5s 406ms
  
  Bit rate                                 : 536 Kbps
  
  Width                                    : 568 pixels
  
  Height                                   : 320 pixels
  
  Display aspect ratio                     : 16:9
  
  Original display aspect ratio            : 16:9
  
  Rotation                                 : 270°
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 14.985 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.197
  
  Stream size                              : 354 KiB (79%)
  
  Writing library                          : x264 core 142
  
  Encoding settings                        : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=14 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=23.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
  
  Language                                 : English
  
  Encoded date                             : UTC 1904-01-01 00:00:00
  
  Tagged date                              : UTC 1904-01-01 00:00:00
  
  
  
  Audio
  
  ID                                       : 2
  
  Format                                   : AAC
  
  Format/Info                              : Advanced Audio Codec
  
  Format profile                           : LC
  
  Codec ID                                 : 40
  
  Duration                                 : 5s 596ms
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 132 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel(s)_Original                      : 1 channel
  
  Channel positions                        : Front: C
  
  Sampling rate                            : 44.1 KHz
  
  Compression mode                         : Lossy
  
  Stream size                              : 89.4 KiB (20%)
  
  Language                                 : English
  
  Encoded date                             : UTC 1904-01-01 00:00:00
  
  Tagged date                              : UTC 1904-01-01 00:00:00

  And here is the metadata from the video created on iOS :

  General
  
  Complete name                            : ios_video.mp4
  
  Format                                   : MPEG-4
  
  Format profile                           : Base Media / Version 2
  
  Codec ID                                 : mp42
  
  File size                                : 673 KiB
  
  Duration                                 : 7s 38ms
  
  Overall bit rate                         : 783 Kbps
  
  Encoded date                             : UTC 2015-03-17 19:16:36
  
  Tagged date                              : UTC 2015-03-17 19:16:37
  
  
  
  Video
  
  ID                                       : 2
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : Main@L3.0
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 2 frames
  
  Codec ID                                 : avc1
  
  Codec ID/Info                            : Advanced Video Coding
  
  Duration                                 : 7s 33ms
  
  Bit rate                                 : 711 Kbps
  
  Width                                    : 320 pixels
  
  Height                                   : 568 pixels
  
  Display aspect ratio                     : 0.563
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 30.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.130
  
  Stream size                              : 610 KiB (91%)
  
  Title                                    : Core Media Video
  
  Encoded date                             : UTC 2015-03-17 19:16:36
  
  Tagged date                              : UTC 2015-03-17 19:16:37
  
  Color primaries                          : BT.709
  
  Transfer characteristics                 : BT.709
  
  Matrix coefficients                      : BT.709
  
  Color range                              : Limited
  
  
  
  Audio
  
  ID                                       : 1
  
  Format                                   : AAC
  
  Format/Info                              : Advanced Audio Codec
  
  Format profile                           : LC
  
  Codec ID                                 : 40
  
  Duration                                 : 7s 38ms
  
  Source duration                          : 7s 105ms
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 64.0 Kbps
  
  Channel(s)                               : 2 channels
  
  Channel(s)_Original                      : 1 channel
  
  Channel positions                        : Front: C
  
  Sampling rate                            : 44.1 KHz
  
  Compression mode                         : Lossy
  
  Stream size                              : 56.8 KiB (8%)
  
  Source stream size                       : 57.2 KiB (9%)
  
  Title                                    : Core Media Audio
  
  Encoded date                             : UTC 2015-03-17 19:16:36
  
  Tagged date                              : UTC 2015-03-17 19:16:37

  The values width and height are inverted on Android, also the Rotation parameter is set to 270º (this is the rotation parameter for portrait videos).

  This is a sketch of how iOS’ videos look on iOS app :

  

  And this is how Android’s videos look on iOS app :

  

  So, in order to get the videos correctly displayed both on iOS and Android i need to be able to set the width to 320 and height to 568 on Android. I tried it from several places (outside and inside CWAC-Camera library) but i always get a Camera.Parameters error.

  It is possible to do this on Android ?

  EDIT :

  This is the result i get when i set the rotation to 0 with ffmpeg :