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• Record audio inside docker container from Ubuntu host

  13 mai 2020, par abhinavkulkarni

  I have a basic Dockerfile as follows :

  



  FROM ubuntu:16.04

RUN apt-get update \
        && apt-get install -y pulseaudio alsa-utils alsa-base ffmpeg 


  



  On my host, I am able to record an audio file as follows :

  



  ffmpeg -f pulse -i default -f wav out.wav


  



  I would like to do the same inside the docker container.

  



  How do I go about this ?

  



  Thanks !

  


• avformat/matroskaenc : Fix memleak upon encountering bogus chapter

  27 avril 2020, par Andreas Rheinhardt

  avformat/matroskaenc : Fix memleak upon encountering bogus chapter
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• Using ffmpeg inside C/C++ code to record a window or rectangular portion of it

  5 janvier 2016, par jster

  I’m trying to use ffmpeg within my code to record a window or a rectangular portion of that window into a video file (e.g. whole Windows Media Player window or say just the outline of the YouTube player embedded in a web page).

  The code I have records the whole screen into a video file successfully. I wanna make it record just a window (not the whole screen). I think I’m passing the right hWnd into an avformat_open_input() call (see code fragment below), but the video file comes out looking blank and black.

  When I switch to recording the whole screen again, the same code works fine. The screen is captured and the video file looks good.(the hWnd passed in is NULL).

  Testing

  I’m using Windows Media Player to play out a stored video file (screen cap here) and recording a rectangular portion of the Windows Media Player window to create the output video file. I notice that when I record a browser window, it records fine.. I’m puzzled why it doesn’t work for WMP ?!

  I’ve tried Hardcoding window handles

  I’ve used Winlister & Spy++ to look for all associated window handles associated with Windows Media Player and tried hardcoding the window handle passed into avformat_open_input(). I’ve tried all the window handles one-by-one to no avail. The video file comes out blank no matter which WMP-associated window handle I use.

  Code fragment below :-
  `

              AVDictionary* options = NULL;
  
              char s[128]; 
  
              AVInputFormat* ifmt = av_find_input_format("gdigrab2");
  
              if(ifmt == NULL){
  
                  break;
  
              }
  
  
  
              snprintf(s, sizeof(s), "%lu", (unsigned long)ul_FrameRate);
  
              av_dict_set(&options, "framerate", s, 0);
  
  
  
              snprintf(s, sizeof(s), "%lu", (unsigned long)ul_OffsetX);
  
              av_dict_set(&options, "offset_x", s, 0);
  
  
  
              snprintf(s, sizeof(s), "%lu", (unsigned long)ul_OffsetY);
  
              av_dict_set(&options, "offset_y", s, 0);
  
  
  
              if(ulWidth != 0 && ulHeight != 0){
  
                  snprintf(s, sizeof(s), "%lux%lu", (unsigned long)ulWidth, (unsigned long)ulHeight);
  
                  av_dict_set(&options, "video_size", s, 0);
  
              }
  
  
  
              snprintf(s, sizeof(s), "hwnd=0x%.08X", hWnd);
  
  
  
              if(avformat_open_input(&pVideoSource, s, ifmt, &options) < 0){
  
                  dprintf("failed to open video capture source\n");
  
                  break;
  
              }

  `

  What might I be doing wrong ? Any help would be appreciated. Thanks.

  PS : I must add that when the code boots up, it starts recording the whole screen.. ie. the window handle passed to the ffmpeg screen recording code is 0x00000000.

  To record a window, the code allows the user to use a rectangular selection tool to retrieve a rectangular selection from which it extracts a RECT and uses WindowFromPoint() to retrieve the Window handle, then uses ::GetAncestor(hWnd, GA_ROOTOWNER) to retrieve the owner window handle..which gets passed into avformat_open_input().

     POINT pt{r.left, r.top}; // r is a CRect.
   HWND hWnd = WindowFromPoint(pt);
   HWND hWndRoot = ::GetAncestor(hWnd, GA_ROOTOWNER);
   if (hWndRoot != NULL)
       hWnd = hWndRoot;
   // ...snip...
   // ...snip...
   // ...snip...
   snprintf(s, sizeof(s), "hwnd=0x%.08X", hWnd);
   if(avformat_open_input(&pVideoSource, s, ifmt, &options) < 0){
       dprintf("failed to open video capture source\n");
       break;
   }