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• Android ffmpeg - 3gp to mp4(or avi) videos - not playing

  18 juillet 2013, par santhosh

  I am doing an android application which is used to merge two videos and after merge completed play the result video. For this I am using ffmpeg.

  When I record two mpeg or mp4 videos, the result merged video playing fine. Now I record the videos as 3gp and convert it into mp4(or avi) and merged it. Then the result video is not playing.

  Can anybody help me What may be the problem ?

  I am using the following code :

  String args[] = {"ffmpeg","-i",""+filename[i]+"",
  
                              "-qscale","1",
  
                              ""+Environment.getExternalStorageDirectory().getPath()+"/Movies/i"+(i + 1)+".mp4(or avi)"};

  To merge the videos :

  String args[] = {"ffmpeg","-i","concat:"+concatPath.toString()+"",
  
                                "-vcodec", "copy" ,
  
                                "-acodec" ,"copy",
  
                                "-vbsf", "aac_adtstoasc",
  
                                ""+Environment.getExternalStorageDirectory().getPath()+"/Movies/3.mp4"};

• FFMPEG : Get the Scene Change Detection value for all frame

  19 novembre 2016, par celacanto

  I’m trying to measure how much a movies is "fast" (more action in the screen and quick scene chances). I don’t want just a single value for the movie, but values along the movie to see how the action varies during it. After normalize the frame rate of the movies (10 fps), my idea is to compare each frame with the previous. I’m not only interest if the scene has changed, but also, if there was no cut, how much movement there is. Not only people/object movement but also, camera movement. In summary the paced (I think that the term) of the scenes.

  My idea was to use the scene function from ffmpeg as a metric. But looking at the document and examples online I’m thinking I can only use the value of the Scene Change Detection as a threshold to return frames informations, but I can’t get ffmpeg to return the value. Is that right ? There is any way I can make it return the value ?

• Should libavcodec handle non-packed/non-byte-aligned mp3 packets ?

  27 août 2015, par Rhythmic Fistman

  I’m transcoding shoutcast streams using libavcodec and I noticed that during the day I get a few 10s’ of packets that it cannot decode without some help :

  1. Leading zero bytes before a packet sync word, e.g. 0x0000fffa

  2. non-byte aligned syncword, e.g 0x82a0fffa

  In the first case I have to toss out the zero bytes and in the second I have to shift the data up by an odd number of nibbles.

  I don’t have a watertight knowledge of the mp3 spec (is there one ?), but my impression was that the packet format was a bit oriented, not byte, so both types of packets look right to me.

  So who is in the wrong here ?

  Is it libavcodec for not parsing valid packets ?

  Or the stream encoder for producing non-standard packets ?