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• ffmpeg : Unable to find a suitable output format, libfaac

  29 juin 2013, par StackOverflowNewbie

  I just downloaded "FFmpeg git-070b0e1 32-bit Static (Latest)" from http://ffmpeg.zeranoe.com/builds/. I extracted the files on my Vista machine and then updated my PATH to point to presets and bin folders.

  The first command I ran was this :

  ffmpeg -i C:/a.avi  -vcodec libtheora  -qscale 6  -acodec libvorbis  -ab 128k  -vf scale="480:-1"   C:/a.ogv

  I got this error :

  Please use -q:a or -q:v, -qscale is ambiguous
  
  [NULL @ 0200F800] Unable to find a suitable output format for 'C:/a.ogv''
  
  C:/a.ogv': Invalid argument

  The second command I ran was this :

  ffmpeg -i C:/a.avi  -vcodec libx264  -preset slow  -profile main  -crf 20  -acodec libfaac  -ab 128k  -vf scale="480:-1"   C:/a.mp4

  I got this error : Unknown encoder 'libfaac'

  Questions :

  1. I'm trying to convert an input video (I don't know what the MIME type is) and output it as ogv and mp4 so I can play it on a website. Of course, I'm looking for highest possible quality at the lowest possible file size. I've pieced my commands from what I can find on the net. Am I on the right track ? What can I do to improve ?

     1. Any ideas how to address the errors I'm getting ?

• How to extract frame from video and save it into memory ?

  11 septembre 2012, par Alrick

  I tried extract frame and save it as output.jpg On server side :

  f = "ffmpeg -vframes 1 -y -ss "+time+" -i ./media/somemov.mp4 ./media/output.jpg"
  
  subprocess.call(f, shell=True)

  And on client side used :

  getImage(noOfFrame);  //send the request for call the ffmpeg function from views.py
  
  
  
  document.getElementById("main").style.backgroundImage="url(http://localhost:8000/media/output.jpg#"+ new Date().getTime();+")";

  But its too slow. DIV displays always the old image becose creates image takes a long time.
  for example i want image no 3 and DIV has no 2, i want image no 4, and div has no 3.

  Is there any way how to extract frame from video (by ffmpeg) and send it into Python without creation the output.jpg file ?

  I want get the image data and send it from server (django) to webpage and set it as background-image of any DIV.

  Is the "pure data sending" solution better then mine ?

  Thanks for help.

• Encoding raw nv12 frames with ffmpeg

  3 août 2012, par nirjhor

  I am trying to encode raw frames in nv12 format. Frame rate is 15. I am using avcodec to encode. My capture device has a callback function which is activated when a raw viewfinder frame is available. I am copying the raw viewfinder frame and making a AVFrame from the data. Then I supply the frame to avcodec_encode_video as described in the api sample but somehow I am not getting expected result. I am using posix thread. I keep the raw frames on a buffer. Then my encoder thread collects data from the buffer and encodes it. The speed of encoding is too slow (h264 and mpeg1 -tested). Is it a problem with my threading or something else ? I am at loss. The output is mysterious. The whole encoding process is a single function and single threaded but I find a bunch of frame encoded at a time. How exactly does the encoder function ?Here is the code snippet for encoding :

  while(cameraRunning)
  
  {
  
      pthread_mutex_lock(&lock_encoder);
  
      if(vr->buffer->getTotalData()>0)
  
      {
  
          i++;
  
          fprintf(stderr,"Encoding %d\n",i);
  
          AVFrame *picture;
  
          int y = 0,x;
  
          picture = avcodec_alloc_frame();
  
          av_image_alloc(picture->data, picture->linesize,c->width, c->height,c->pix_fmt, 1);
  
          uint8_t* buf_source = new uint8_t[vr->width*vr->height*3/2];
  
          uint8_t* data = vr->buffer->Read(vr->width*vr->height*3/2);
  
          memcpy(buf_source,data,vr->width*vr->height*3/2);
  
          //free(&vr->buffer->Buffer[vr->buffer->getRead()-1][0]);
  
          /*for (y = 0; y < vr->height*vr->width; y++)
  
          {
  
              picture->data[0][(y/vr->width) * picture->linesize[0] + (y%vr->width)] = buf_source[(y/vr->width)+(y%vr->width)]x + y + i * 7;
  
              if(yheight*vr->width/4)
  
              {
  
                  picture->data[1][(y/vr->width) * picture->linesize[1] + (y%vr->width)] = buf_source[vr->width*vr->height + 2 * ((y/vr->width)+(y%vr->width))]128 + y + i * 2;
  
                  picture->data[2][(y/vr->width) * picture->linesize[2] + (y%vr->width)] = buf_source[vr->width*vr->height +  2 * ((y/vr->width)+(y%vr->width)) + 1]64 + x + i * 5;
  
              }
  
          }

  */

          for(y=0;yheight;y++) {
  
                      for(x=0;xwidth;x++) {
  
                          picture->data[0][y * picture->linesize[0] + x] = x + y + i * 7;
  
                      }
  
                  }
  
  
  
                  /* Cb and Cr */
  
                  for(y=0;yheight/2;y++) {
  
                      for(x=0;xwidth/2;x++) {
  
                          picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
                          picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
                      }
  
                  }
  
          free(buf_source);
  
          fprintf(stderr,"Data ready\n");
  
  
  
          outbuf_size = 100000 + c->width*c->height*3/2;
  
          outbuf = (uint8_t*)malloc(outbuf_size);
  
          fprintf(stderr,"Preparation done!!!\n");
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
          had_output |= out_size;
  
          printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
          fwrite(outbuf, 1, out_size, f);
  
          av_free(picture->data[0]);
  
          av_free(picture);
  
  
  
      }
  
      pthread_mutex_unlock(&lock_encoder);
  
  }