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• iOS FFMPEG encode images to video

  10 avril 2013, par brad.roush

  I am trying to take a set of UIImages and create a video file out of them with FFMPEG. Seems there are lots of questions about this topic but non have been able to get this working correctly for me. This one was particularly helpful in giving me a starting point. This iFrameExtractor example was also very helpful but I want to do this in reverse, then add audio.

  This is the closest I have gotten and it creates a short silent video with flashing colors and no images :

  // Register all formats and codecs
  
  av_register_all();
  
  
  
  AVCodec *codec;
  
  AVCodecContext *c= NULL;
  
  
  
  int i, out_size, size, outbuf_size;
  
  FILE *file;
  
  AVFrame *picture;
  
  uint8_t *outbuf;
  
  
  
  NSLog(@"Video encoding");
  
  
  
  /* find the mpeg video encoder */
  
  codec = avcodec_find_encoder(CODEC_ID_MPEG2VIDEO);
  
  if (!codec) {
  
      fprintf(stderr, "codec not found\n");
  
      exit(1);
  
  }
  
  
  
  c= avcodec_alloc_context3(codec);
  
  picture= avcodec_alloc_frame();
  
  
  
  /* put sample parameters */
  
  c->bit_rate = 400000;
  
  /* resolution must be a multiple of two */
  
  c->width = 352;
  
  c->height = 288;
  
  /* frames per second */
  
  c->time_base= (AVRational){1,25};
  
  c->gop_size = 10; /* emit one intra frame every ten frames */
  
  c->max_b_frames=1;
  
  c->pix_fmt = PIX_FMT_YUV420P;
  
  
  
  /* open it */
  
  if (avcodec_open2(c, codec, nil) < 0) {
  
      fprintf(stderr, "could not open codec\n");
  
      exit(1);
  
  }
  
  
  
  // Put file in place
  
  
  
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  
  NSString *docs_dir = [paths objectAtIndex:0];
  
  NSString *filePath = [docs_dir stringByAppendingPathComponent:@"test.mpeg"];
  
  
  
  // Seed file
  
  NSString *sourcePath = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"mov"];
  
  NSError* error = nil;
  
  if (![[NSFileManager defaultManager] copyItemAtPath:sourcePath toPath:filePath error:&error]) {
  
      NSLog(@"Test Video creation failed:%@",[error userInfo]);
  
  } else NSLog(@"Test Video Created");
  
  
  
  const char *filename = [filePath UTF8String];
  
  file = fopen(filename, "wb");
  
  if (!file) {
  
      fprintf(stderr, "could not open %s\n", "filename");
  
      exit(1);
  
  }
  
  
  
  /* alloc image and output buffer */
  
  outbuf_size = 100000;
  
  outbuf = malloc(outbuf_size);
  
  size = c->width * c->height;
  
  
  
  //#pragma mark -
  
  AVFrame* outpic = avcodec_alloc_frame();
  
  int nbytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);
  
  
  
  //create buffer for the output image
  
  uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes);
  
  
  
  
  
  AVPacket packet;
  
  av_init_packet(&packet);
  
  
  
  
  
  //#pragma mark -
  
  for(i=1;i<50;i++) {
  
      fflush(stdout);
  
  
  
      int numBytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);
  
      uint8_t *buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
      UIImage *image = [UIImage imageWithContentsOfFile:[docs_dir stringByAppendingPathComponent:[NSString stringWithFormat:@"%d.png",i]]];
  
      CGImageRef newCgImage = [image CGImage];
  
  
  
      CGDataProviderRef dataProvider = CGImageGetDataProvider(newCgImage);
  
      CFDataRef bitmapData = CGDataProviderCopyData(dataProvider);
  
      buffer = (uint8_t *)CFDataGetBytePtr(bitmapData);
  
  
  
      avpicture_fill((AVPicture*)picture, buffer, PIX_FMT_RGB8, c->width, c->height);
  
      avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, c->width, c->height);
  
  
  
      struct SwsContext* fooContext = sws_getContext(c->width, c->height,
  
                                                     PIX_FMT_RGB8,
  
                                                     c->width, c->height,
  
                                                     PIX_FMT_YUV420P,
  
                                                     SWS_FAST_BILINEAR, NULL, NULL, NULL);
  
  
  
      //perform the conversion
  
  
  
      sws_scale(fooContext, outpic->data, outpic->linesize,
  
                0, c->height, outpic->data, outpic->linesize);
  
      // Tried This but it didn't work
  
      //sws_scale(fooContext, picture->data, picture->linesize, 0, c->height, outpic->data, outpic->linesize);
  
  
  
  
  
      out_size = avcodec_encode_video(c, outbuf, outbuf_size, outpic);
  
      // Tried this but it didn't work
  
      //int test = 0;
  
      //out_size = avcodec_encode_video2(c, &packet, outpic, &test);
  
  
  
  
  
  
  
      printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
      fwrite(outbuf, 1, out_size, file);
  
  
  
      free(buffer);
  
      buffer = NULL;
  
  
  
  }
  
  
  
  /* get the delayed frames */
  
  /*
  
  for(; out_size; i++) {
  
      fflush(stdout);
  
  
  
      out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
  
      printf("write frame %3d (size=%5d)\n", i, out_size);
  
      fwrite(outbuf, 1, outbuf_size, file);
  
  }
  
  */
  
  
  
  /* add sequence end code to have a real mpeg file */
  
  outbuf[0] = 0x00;
  
  outbuf[1] = 0x00;
  
  outbuf[2] = 0x01;
  
  outbuf[3] = 0xb7;
  
  fwrite(outbuf, 1, 4, file);
  
  fclose(file);
  
  free(outbuf);
  
  
  
  avcodec_close(c);
  
  av_free(c);
  
  av_free(picture);
  
  printf("\n");

  Any ideas will be helpful here. If anyone knows of any other good objective-c examples, this would also be great.

• command line audio ducking

  25 mai 2015, par DomsaN

  I got a music file and need to add a spoken quote to this file. THerefore the music volume should be lowered in order to hear the spoken quote. After the quote ends the music’s volume should be as it was before.

  Problem : I need to do this with command line. Can I do this with FFmpeg ? If not any ideas ?

  Greetings

• Images and audio to slideshow movie

  16 juin 2015, par Terji Petersen

  I’m trying to get FFmpeg to generate a slide show mp4 movie using an mp3 audio track and several jpg images. Having trouble getting the length of the movie to match the length of the mp3 file and the images evenly spaced.
  Following is the closest I’ve gotten :

  ffmpeg -framerate 1/5 -i img%02d.jpg -i input.mp3 -c:v libx264 -r 30 
  
  -shortest -t 19 output.mp4

  The output here is a 15 second movie, 5 seconds per image but the mp3 file is 19 seconds long.

  Any ideas ?