Newest 'ffmpeg' Questions - Stack Overflow

Les articles publiés sur le site

• Motion Vectors and DC coefficients from MPEG4 stream

  9 octobre 2013, par Lampis

  I need to extract information about motion vectors and DC coefficients from an MPEG4 video. I've searched relevant sites and topics and I found that a good solution is to work with the code of ffmpeg codec. Especially the ff_print_debug_info function in libavcodec/mpegvideo.c calculates relevant information.

  However, I'm new on the C/C++ field and if there is any example code that describes or explains how to extract MVs and DC coefficients that would be very helpful.

  In the more recent version I use (FFmpeg 0.10.2 from http://ffmpeg.org/download.html) there is another file mpeg4videodec.c. Is there any chance to retrieve the needed information by this code?

• nobody can't exec ffmpeg command

  9 octobre 2013, par joaner

  I'm try to get the tag info from media file use ffmpeg. It work fine on system user xiaoai.

  // it should output the info, but nothing
  exec("/usr/bin/ffmpeg -i /home/xiaoai/music/Roar.mp3", $say, $code);
  var_dump($code); // code is 1, I know it's a error: Catchall for general errors.
  

  So I think about permission, my script run as nobody. I give the mp3 file 777 permission, /usr/bin/ffmpeg 777, and user change to nobody. but still not work.

  I must use this ffmpeg, this is only way for aac as i know, mp3, m4a, ogg. Please tell me how to do or other way.

• Reading RTMP streams using FFMPEG returns AVERROR_EOF randomly

  9 octobre 2013, par user2628781

  I am using FFMpeg to receive RTMP streams. This logic is placed in a custom video player I am building.

  I managed to successfully connect to the RTMP stream and display the video correctly. However, after a period in time, the stream terminates prematurely with an AVERROR_EOF when I perform av_read_frame().

  This indicates to me that the file has ended so my demux, video and audio threads terminates thinking that the video has ended. However, the video playback hasn't yet reached its end (in the case of a file streamed through rtmp) or from a live stream (which runs forever). The EOFs are received very randomly so it may run for say 7 min before this occurs or after 3 mins.

  Is this a characteristic behaviour of RTMP or am I doing something incorrectly? I am also having a similar problem with Http Live Streams using FFMpeg.

  A small snippet of the code is provided below:

   AVPacket packet;
  //start timeout timer and timeout
  __interrupt_timer.start();
  
  int ret = av_read_frame(format_context, &packet); //0: ok, <0: error/end
  
  
  //invalidate the timer
  __interrupt_timer.invalidate();
  
  if (ret != 0) {
      if (ret == AVERROR_EOF) { //end of file. FIXME: why no eof if replaying by seek(0)?            
          if (!eof) {
              eof = true;
              started_ = false;
              pkt->data = QByteArray(); //flush
              pkt->markEnd();
              qDebug("End of file. %s %d", __FUNCTION__, __LINE__);
              emit finished();
              return true;
          }
          pkt->data = QByteArray(); //flush
          //return true;
          return false; //frames after eof are eof frames
      } else if (ret == AVERROR_INVALIDDATA) {
          qWarning("AVERROR_INVALIDDATA");
      } else if (ret == AVERROR(EAGAIN)) {
          return true;
      }
      qWarning("[AVDemuxer] error: %s", av_err2str(ret));
      return false;
  }
  

• Trying to compile the FFMPEG libraries for iPhoneOS platform with armv6 and arv7 architecture

  9 octobre 2013, par Er Amit Sachdeva

  I'm trying to compile the FFMPEG Libraries for IOS platform with arm7 architecture. I downloaded the FFMPEG libraries from http://www.ffmpeg.org.

  I'm successfully able to build the static libraries for the i386 architecture for the iPhoneSimulator. But I need the libraries for iPhoneOS. Using the configure command I'm getting an error. Below are my command details.

  For i386(which is error free):

  ./configure  --enable-cross-compile --disable-debug --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-doc --disable-network  --disable-everything  --enable-protocol=file --enable-demuxer=mov  --enable-muxer=mpegts --enable-bsf=h264_mp4toannexb   --arch=i386 --target-os=darwin --cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc --as='./gas-preprocessor/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc' --sysroot=/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneOS6.1.sdk --cpu=i386 --extra-cflags='-arch i386' --extra-ldflags='-arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.1.sdk' --prefix="/Users/amit/Desktop/LivuLib-master/LivuLIb/ffmpeg/bin/newLib"
  

  For armv7:

  ./configure  --enable-cross-compile --disable-debug --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-doc --disable-network  --disable-everything  --enable-protocol=file --enable-demuxer=mov  --enable-muxer=mpegts --enable-bsf=h264_mp4toannexb   --arch=armv7 --target-os=darwin --cc=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc --as='./gas-preprocessor/gas-preprocessor.pl /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc' --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk --cpu=cortex-a9 --extra-cflags='-arch armv7' --extra-ldflags='-arch armv7 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk' --prefix="/Users/amit/Desktop/LivuLib-master/LivuLIb/ffmpeg/bin/newLib"
  

  For above command for Arm7 I'm getting this error:

  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc is unable to create an executable file.
  C compiler test failed.
  
  If you think configure made a mistake, make sure you are using the latest
  version from SVN.
  

  So please suggest me a possible solution. Why is it not working? Or do I need to update anything. Thanks.

• FFmpeg libx264 iOS

  8 octobre 2013, par user441918

  I have to stream a RTSP video from IP camera in iOS. I found that I can use FFmpeg to stream the RTSP and it seems working. When I reviewed the legal terms of FFmpeg, it says "Make sure your program is not using any GPL libraries (notably libx264)". Does it mean, I cannot use libx264 library in iOS application or do I have to compile the FFmpeg library with "disable-gpl" option?

  If FFmpeg with libx264 cannot be used in iOS, is there any other alternative library available?