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• FFMpeg for iPhone

  10 août 2012, par iHorse

  I am trying to create an app that will allow me to stream video FROM the iPhone TO a server. my current theory as to how to do this is to create a series of FFMpeg files and send them to the server. as far as i can tell i have compiled the FFMpeg library correctly for the iPhone.
  i followed these instructions here. a series of executable files appeared in the folder so i'm assuming it worked.

  my question is now what ? how do i get these into an app ? how do i make calls to these executable files ? and most importantly will this even work the way i want it to ?

• Best tool to convert mp3 to aac (FFmpeg Vs NeroAacEnc) [closed]

  3 août 2012, par Soham Dasgupta

  My question is straight forward. I want to convert mp3 to aac. I have knowledge of two such tools which does the job - NeroAacEnc and FFMpeg. Now which one produces the best output and least size is for maestros to answer, so I summon them here to help me accomplish the same. Please also help me with some commands with which I can use.

  Just out of curiosity, is the (ALAC)Apple Lossless Audio Codec which is included with FFMpeg better than Nero Aac Encoder. If so, then how can I use it to convert mp3 to aac.

• Getting artifacts when trying to read video stream from YouTube

  23 février 2012, par givi

  I'm trying to read the video frames from the RTSP stream that I get from YouTube. Here is the link for my test video :

  rtsp ://v8.cache5.c.youtube.com/CiILENy73wIaGQkJlrXMiAG8BxMYDSANFEgGUgZ2aWRlb3MM/0/0/0/video.3gp

  If I'm reading frames from the local file - everything is fine, but when read them from a stream I get nothing but lots of artifacts. I've googled around and found out that there might be a problem with UDP packets and switching to TCP may help but I really can't find where it is possible to change this.

  Here is the function for reading a frame :

  bool nextFrame(AVFormatContext *pFormatCtx, AVCodecContext *pCodecCtx, int videoStream, AVFrame *pFrame) {  AVPacket packet;
  
      int frameFinished = 0;
  
  
  
      while( !frameFinished && av_read_frame(pFormatCtx, &packet) >= 0 ) {
  
          // Is this a packet from the video stream?
  
          if( packet.stream_index == videoStream ) {
  
              // Decode video frame
  
              avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
          }
  
  
  
          // Free the packet that was allocated by av_read_frame
  
          av_free_packet(&packet);    
  
         }    
  
         return frameFinished!=0;  
  
  }

  I'm also getting lots of error messages in my log :

  [h263 @ 0x7804c00] warning: first frame is no keyframe
  
  [h263 @ 0x7804c00] illegal ac vlc code at 6x1
  
  [h263 @ 0x7804c00] Error at MB: 18
  
  [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 10 4
  
  [h263 @ 0x7804c00] Error at MB: 58
  
  [h263 @ 0x7804c00] concealing 99 DC, 99 AC, 99 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 6 6
  
  [h263 @ 0x7804c00] Error at MB: 78
  
  [h263 @ 0x7804c00] concealing 76 DC, 76 AC, 76 MV errors
  
  [h263 @ 0x7804c00] I cbpy damaged at 5 5
  
  [h263 @ 0x7804c00] Error at MB: 65
  
  [h263 @ 0x7804c00] concealing 88 DC, 88 AC, 88 MV errors
  
  [h263 @ 0x7804c00] illegal ac vlc code at 7x5
  
  [h263 @ 0x7804c00] Error at MB: 67
  
  [h263 @ 0x7804c00] concealing 86 DC, 86 AC, 86 MV errors

  ...and so on

  edit : this is 99.9% a UDP-TCP problem. I've found this link :

  rtsp ://195.200.199.8/mpeg4/media.amp

  This is some test camera available online. It streams with artifacts. However if it has get parameter 'tcp' and if I use this

  rtsp ://195.200.199.8/mpeg4/media.amp ?tcp

  everything works without artifacts.

  So to correct my question : is there any way to force YouTube or ffmpeg to use TCP ?