Recherche avancée

Sur d’autres sites (7853)

• H.264 (MP4) video not play in IE9, but will play in Safari [closed]

  27 septembre 2011, par Austin S

  I have encoded a video using FFMPEG into three formats : WebM, MP4, and FLV. Chrome, Mozilla, and theoretically Opera (although I haven't tested it) should all use the WebM version. IE9, iOS devices, and Adriod should use the MP4 container. While all legacy browsers should default back to the flash version of the file. I'm using video-js to help serve the content. The content is set to preload and autoplay.

  I have found that everything is working as intended except for IE9, where all I get is the poster image and a white dot that typically spins indicating that the file is loading however it is not spinning in this scenario. The MP4 file opens in Safari, an iPad, an iPhone, and an Andriod - verifying that the file is infact legit.

  The following is the specs for the MP4 file when I stream it using VLC. I don't know if this is particularly useful, I'm just trying to provide as much detail as possible.

  VLC Codec Details

  • Stream 0

    Type : Video

    Codec : MPEG-4 Video (mp4v)

    Language : English

    Resolution : 480x270

    Frame rate : 2997

  • Stream 1

    Type : Audio

    Codec : MPEG AAC Audio (mp4a)

    Language : English

    Channels : Stereo

    Sample rate : 48000 Hz

  When accessing videojs.com from my coworkers computer, the video on their main page wouldn't play the video correctly in IE9, but we could hear the audio. When I went to another coworkers computer it played just fine. I'm wondering if IE9, or video-js, is tempermental depending on how updated your OS is.

  The fact that I'm working on XP with IE7 is making this all the more difficult to fix, so if you have any suggestions on what could point me in the right direction, I would greatly appreciate it !

  Thanks,

  Austin S

• FFMPEG : chroma key / greenscreen filter for images / video

  6 septembre 2016, par Daniel Ruf

  I need for a video to use chroma key filter / greenscreen filter and overlay it over another video and output it as new video.

  Are there any existing libraries, scripts, filters or solutions for this purpose ?

• Stream video from ffmpeg and capture with OpenCV

  10 décembre 2014, par chembrad

  I have a video stream coming in on rtp to ffmpeg and I want to pipe this to my OpenCV tools for live streaming processing. The rtp linkage is working because I am able to send the incoming data to a file and play it (or play if via ffplay). My OpenCV implementation is functional as well because I am able to capture video from a file and also a webcam.

  The problem is the streaming to OpenCV. I have heard that this may be done using a named pipe. First I could stream the ffmpeg output to the pipe and then have OpenCV open this pipe and begin processing.

  What I’ve tried :

  I make a named-pipe in my cygwin bash by :

      $ mkfifo stream_pipe

  Next I use my ffmpeg command to pull the stream from rtp and send it to the pipe :

      $ ffmpeg -f avi -i rtp://xxx.xxx.xxx.xxx:1234 -f avi -y out.avi > stream_pipe

  I am not sure if this is the right way to go about sending the stream to the named pipe but it seems to be accepting the command and work because of the output from ffmpeg gives me bitrates, fps, and such.

  Next I use the named pipe in my OpenCV capture function :

      $ ./cvcap.exe stream_pipe

  where the code for cvcap.cpp boils down to this :

      cv::VideoCapture *pIns = new cv::VideoCapture(argv[1]);

  The program seems to hang when reaching this one line, so, I am wondering if this is the right way of going about this. I have never used named pipes before and I am not sure if this is the correct usage. In addition, I don’t know if I need to handle the named pipe differently in OpenCV—change code around to accept this kind of input. Like I said, my code already accepts files and camera inputs, I am just hung up on a stream coming in. I have only heard that named pipes can be used for OpenCV—I haven’t seen any actual code or commands !

  Any help or insights are appreciated !

  UPDATE :

  I believe named pipes may not be working in the way I intended. As seen on this cygwin forum post :

  The problem is that Cygwin’s implementation of fifos is very buggy. I wouldn’t recommend using fifos for anything but the simplest of applications.

  I may need to find another way to do this. I have tried to pipe the ffmpeg output into a normal file and then have OpenCV read it at the same time. This works to some extent, but I imagine in can be dangerous to read and write from a file concurrently—who knows what would happen !