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• converting images to mp4 using ffmpeg on iphone

  29 novembre 2011, par user633901

  Up till now, i can create mpeg1 but with no luck for mp4.Maybe we can talk and share information.Someone told me that i have to set some flags for using mp4.But i am stuck at using it...

  following is the working code :

  av_register_all();
  
  printf("Video encoding\n"); 
  
  
  
  /// find the mpeg video encoder 
  
  //codec=avcodec_find_encoder(CODEC_ID_MPEG1VIDEO); 
  
  codec = avcodec_find_encoder(CODEC_ID_MPEG4); 
  
  
  
  if (!codec) { 
  
      fprintf(stderr, "codec not found\n"); 
  
      exit(1); 
  
  } 
  
  
  
  c = avcodec_alloc_context(); 
  
  picture = avcodec_alloc_frame(); 
  
  
  
  // put sample parameters 
  
  c->bit_rate = 400000;
  
  /// resolution must be a multiple of two 
  
  c->width = 240; 
  
  c->height = 320; 
  
  //c->codec_id = fmt->video_codec;
  
  //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; // PIX_FMT_YUV420P
  
  
  
  if (avcodec_open(c, codec) < 0) { 
  
      fprintf(stderr, "could not open codec\n"); 
  
      exit(1); 
  
  }
  
  
  
  f = fopen([[NSHomeDirectory() stringByAppendingPathComponent:@"test.mp4"] UTF8String], "wb"); 
  
  
  
  if (!f) { 
  
      fprintf(stderr, "could not open %s\n",[@"test.mp4" UTF8String]); 
  
      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); //this is half size of numbytes. 
  
  
  
  //create buffer for the output image 
  
  uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes); 
  
  
  
  #pragma mark -  
  
  for(k=0;k<1;k++) { 
  
      for(i=0;i<25;i++) { 
  
          fflush(stdout); 
  
  
  
          int numBytes = avpicture_get_size(PIX_FMT_RGBA, c->width, c->height); 
  
          uint8_t *buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t)); 
  
  
  
          UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"%d.png", i+1]]; 
  
          CGImageRef newCgImage = [image CGImage]; 
  
  
  
          CGDataProviderRef dataProvider = CGImageGetDataProvider(newCgImage); 
  
          CFDataRef bitmapData = CGDataProviderCopyData(dataProvider); 
  
          buffer = (uint8_t *)CFDataGetBytePtr(bitmapData);   
  
          /////////////////////////// 
  
          //outbuffer=(uint8_t *)CFDataGetBytePtr(bitmapData); 
  
          ////////////////////////// 
  
          avpicture_fill((AVPicture*)picture, buffer, PIX_FMT_RGBA, c->width, c->height); 
  
          avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, c->width, c->height);//does not have image data. 
  
  
  
          struct SwsContext* fooContext = sws_getContext(c->width, c->height, 
  
                                                        PIX_FMT_RGBA, 
  
                                                        c->width, c->height, 
  
                                                        PIX_FMT_YUV420P, 
  
                                                        SWS_FAST_BILINEAR, NULL, NULL, NULL); 
  
  
  
          //perform the conversion 
  
          sws_scale(fooContext, picture->data, picture->linesize, 0, c->height, outpic->data, outpic->linesize); 
  
          // Here is where I try to convert to YUV 
  
  
  
          // encode the image 
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, outpic); 
  
          printf("encoding frame %3d (size=%5d)\n", i, out_size); 
  
          fwrite(outbuf, 1, out_size, f); 
  
  
  
          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, f);       
  
      } 
  
  }
  
  
  
  // 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, f); 
  
  fclose(f); 
  
  free(picture_buf);
  
  free(outbuf); 
  
  
  
  avcodec_close(c); 
  
  av_free(c); 
  
  av_free(picture); 
  
  //av_free(outpic); 
  
  printf("\n"); 

  my msn:hieeli@hotmail.com

• avconv : make timer_start a local var in transcode().

  17 août 2011, par Anton Khirnov

  avconv : make timer_start a local var in transcode().

• How to eliminate ffplay delay on a local network

  29 mai 2021, par Vigrond

  I am streaming audio from one computer to another on my local LAN.

  


  Server command :

  


  ffmpeg -re -f alsa -ac 2 -i default -fflags nobuffer -flags low_delay -sdp_file ~/sdp_stream -f rtp rtp://192.168.1.5:1234


  


  Client command :

  


  ffplay -fflags nobuffer -flags low_delay -nodisp -fast -framedrop -infbuf -protocol_whitelist rtp,file,udp sdp_stream


  


  This works with near-zero delay for a while, but after a bit the delay increases over time.

  


  My perception of delay is due to playing a YouTube video or Spotify on the server, and experiencing a delay on the client (both monitors in front of me).

  


  I am certain that it should be possible to set this up correctly with a near-zero delay on my local hardwired network, but I can't seem to find the correct setting in the FFmpeg documentation.