Newest 'ffmpeg' Questions - Stack Overflow

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• Simulate concatenated file using hard link ?

  16 décembre 2011, par Sugrue

  I have multiple parts of a single file which I want a 3rd party c++/c# plugin to read as a single file. Basically, when the plugin file reader gets to the end of one file-part, I want it to continue to the next one.

  (For anyone interested, the plugin is Aforge.Net FFMpeg, and I am trying to import VOB files)

  It looks like quite a task to reprogram the plugin. An alternative solution is to copy the file parts to a concatenated file, but this is slow because I am dealing with many GBs of data.

  Is it possible to use a file system hard link to point to multiple files? Or is there some other way to 'fake' a concatenated file? Using command line FFMpeg I can use 'type' to live stream a concatenate file in, but I can't figure out how to achieve this in c# with this plugin.

  I am on Windows 7.

• need to Setup ffmpeg in eclipse for windows

  16 décembre 2011, par user1101687

  i am getting this error!

  Building target: cyg.exe
  Invoking: Cygwin C Linker
  gcc -L"C:\cygwin\usr\libjjmpeg.so" -o "cyg.exe"  ./tut.o   -lavcodec
  /usr/lib/gcc/i686-pc-cygwin/4.5.3/../../../../i686-pc-cygwin/bin/ld: cannot find -lavcodec
  collect2: ld returned 1 exit status
  makefile:29: recipe for target `cyg.exe' failed
  make: *** [cyg.exe] Error 1
  

• ffmpeg return black and white image

  16 décembre 2011, par njai

  Video capture device is kworld dvd maker 2 (em2861) It returns the image in "black and white" with green line at the bottom of screen; but when I tested it with webcam, it worked properly.

  Here is 30s video. http://www.youtube.com/watch?v=7q2wFGVwGGI

  How can I convert it to color?

  [root@localhost ~]# ffmpeg -f video4linux2 -i /dev/video0 -vcodec mpeg4 -y output.mp4
  ffmpeg version git-2011-11-05-5fd1a69, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  5 2011 21:10:52 with gcc 4.4.4 20100726 (Red Hat 4.4.4-13)
  configuration: --enable-libx264 --enable-gpl --enable-libvpx
  libavutil    51. 23. 0 / 51. 23. 0
  libavcodec   53. 27. 0 / 53. 27. 0
  libavformat  53. 18. 0 / 53. 18. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0
  [video4linux2,v4l2 @ 0x2a64780] Estimating duration from bitrate, this may be inaccurate
  Input #0, video4linux2,v4l2, from '/dev/video0':
  Duration: N/A, start: 1320637788.113946, bitrate: 165888 kb/s
  Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 720x576, 165888 kb/s, 25 tbr, 1000k tbn, 25 tbc
  Incompatible pixel format 'yuyv422' for codec 'mpeg4', auto-selecting format 'yuv420p'
  [buffer @ 0x2a63920] w:720 h:576 pixfmt:yuyv422 tb:1/1000000 sar:0/1 sws_param:
  [buffersink @ 0x2a63cc0] auto-inserting filter 'auto-inserted scale 0' between the filter    'src' and the filter 'out'
  [scale @ 0x2a64560] w:720 h:576 fmt:yuyv422 -> w:720 h:576 fmt:yuv420p flags:0x4
  Output #0, mp4, to 'output.mp4':
  Metadata:
  encoder         : Lavf53.18.0
  Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 720x576, q=2-31, 200 kb/s, 25    tbn, 25 tbc
  Stream mapping:
  Stream #0.0 -> #0.0 (rawvideo -> mpeg4)
  Press [q] to stop, [?] for help
  frame=  969 fps= 25 q=31.0 Lsize=    1547kB time=00:00:38.76 bitrate= 327.0kbits/s    
  video:1538kB audio:0kB global headers:0kB muxing overhead 0.561411%
  

• FFMPEG for iPhone recorded video encoding

  16 décembre 2011, par Sarah

  Hi found lots and lots of links for video encoding through ffmpeg 1,2,3,4 etc but they all start with using terminal commands but when i try to implement any on terminal like:

  git clone git://github.com/lajos/iFrameExtractor.gitit says that-bash: git: command not found.

  Also as per my knowledge it is not possible to use terminal command on iPhone. Can anybody point out how to encode a video recorded through ffmpeg in mp4 format and also to reduce the size of the video?Thanks in advance.

  EDIT: I am already implementing this method to resize my video and it successfully takes place and I am able to send the video on server but then on server side it's giving problem in retrieving the data and to use it.

  - (void)imagePickerController:(UIImagePickerController *)picker 
  didFinishPickingMediaWithInfo:(NSDictionary *)info
  {
      [self convertVideoToLowQuailtyWithInputURL:videoURL1 outputURL:[NSURL fileURLWithPath:videoStoragePath] handler:^(AVAssetExportSession *exportSession)
       {
           if (exportSession.status == AVAssetExportSessionStatusCompleted)
           {
               NSLog(@"%@",exportSession.error);
               printf("completed\n");
           }
           else
           {
               NSLog(@"%@",exportSession.error);
               printf("error\n");
           }
       }];
  }
  
  - (void)convertVideoToLowQuailtyWithInputURL:(NSURL*)inputURL 
                                     outputURL:(NSURL*)outputURL 
                                       handler:(void (^)(AVAssetExportSession*))handler
  {
      [[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
      AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
      AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality];
      exportSession.outputURL = outputURL;
      exportSession.outputFileType = AVFileTypeQuickTimeMovie;
      [exportSession exportAsynchronouslyWithCompletionHandler:^(void) 
       {
           handler(exportSession);
           [exportSession release];
       }];
  }
  

• How do I dump the buffer when encoding H264 with FFMPEG ?

  16 décembre 2011, par Sean

  I'm using a c++ library to write images captured from a webcam to an libx264 encoded mp4 file. The encoding is working properly but when it starts it writes 40 frames to the buffer. When I close the file these frames aren't flushed so about 6 seconds of video are left unwritten (cam is about 6fps).

  So i'm calling:

  out_size = libffmpeg::avcodec_encode_video( codecContext, data->VideoOutputBuffer,data->VideoOutputBufferSize, data->VideoFrame );
  
  // if zero size, it means the image was buffered
  if ( out_size > 0 )
  {
  //... write to file
  }
  

  I can't see a way of accessing the images that are left in the buffer. Any ideas?