Newest 'ffmpeg' Questions - Stack Overflow

Articles published on the website

• Looking for method to combine images to make a video through phonegap platform for android and ios

  28 November 2012, by Pat

  I'm looking to write an application that could combine images and then to form a video. I'm working with Phonegap framework to be available for use on Android and IOS.

  My question is what sort of process is involved to achieve this?

  At this stage I've tried to read about ffmpeg, most of the questions existing on stackoverflow talk of having to get the source, compiling to make a series of libraries for use. With those libraries it needs to be tied in with the Android/IOS libraries? (I notice there is an 'android.jar' with the project file in eclipse. Would it exist in there?) Afterwards my confusion lies with how is this implemented into Phonegap. Develop a plugin?

  Just to add, libav according to wiki, has hardware accelerated H.264 decoding whilst using x.264 for encoding for Android. How does that work? Is this something accessed from libav libraries and then have to compiled in within the android.jar?

  I may have confused terms in trying to describe what I do not know.

  Any help would be appreciated.

• How YouTube identifies if a movie is shaky [closed]

  28 November 2012, by MollyRazor

  After uploading a movie to Youtube, it analyzes the movie and if it's shaky, then it gives the option to correct it. The correction works with ffmpeg, but is there any open source method to analyze whether a movie is shaky?

  I can't understand StackOverflow moderators. This place is full of self righteous bastards.

  Mr. Moderator says in a comment: ffmpeg is open source. O REALLY? Then what parameters to use so ffmpeg outputs => yes, this is a shaky movie or no, this isnt. Ah, you can't answer that, so you close this question.

  Have you even read the question thoroughly? Then do so again please. I think by the age of 50 you can correctly interpret what was written and what the question was.

  Thank you.

• Write video in a memory stream using libav

  28 November 2012, by Dídac Pérez

  I am successfully capturing video packets from the network using libav. Currently, I have an AVFormatContext object in which I can write the header, the packets, etc... The point is that I want to dump everything on this context into a file when required. What should I do ?

  Thanks in advance, Dídac Pérez

• Displaying YUV420 data using Opengles shader is too slow

  28 November 2012, by user1278982

  I have a child thread called A to decode video using ffmpeg on iPhone 3GS, another thread called B to display yuv data, in thread B, I used glSubTexImage2D to upload Y U V textures, and then convert yuv data to RGB in shader, but the frame rate in the decode thread is only 15fps.Why?

  Update: The frame size is 720 * 576. I also found something interesting that if I didn't start the thread displaying the YUV data, the frame rate calculated in the decode thread is 22 fps,otherwise 15 fps.So I think that my displaying method must be inefficient.the code as below.

  I have a callback in the decode thread:

  typedef struct _DVDVideoPicture
  {
     char *plane[4];
     int iLineSize[4];
  }DVDVideoPicture;
  
  void YUVCallBack(void *pYUVData, void *pContext)
  {
     VideoView *view = (VideoView *)pContext;
     [view.glView copyYUVData:(DVDVideoPicture *)pData];
     [view calculateFrameRate];
  }
  

  The copyYUVData method extract the y u v planes separately. The following is displaying thread method.

• How to open a video/audio capture device with ffmpeg programatically?

  28 November 2012, by user71512

  I am following the guide http://dranger.com/ffmpeg/tutorial01.html about ffmpeg and sdl and i would like to instead of opening a video file, use a video capture device as the source. How does one pragmatically do it? I assume one will modify the Context, but i just a specific example. I know how to do it with the command line.

  AVFormatContext *pFormatCtx;
  
  // Open video file
  if(av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)!=0)
    return -1; // Couldn't open file
  

  Looking at the doxygen, i don't see an analagous function for devices.