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• Writing a series of images into a video file using libavcodec (ffmpeg)

  19 novembre 2013, par user2978372

  Requirements :

  I have a bunch of images (to be more specific they are 1024x768, 24bpp RGB PNG files) that I want to encode into a video files.

  And I need to use 'libavcodec' library, not 'ffmpeg' tool. (well I know they are basically same in the origin, I am emphasizing because someone may answer to use 'ffmpeg' tool, but that's not a solution what I am looking for)

  I am using h264 encoder.

  Target :
  A high quality video with equal resolution (1024 x 768), YUV420P
  each image has a duration of 1 second.
  24 fps

  Problems :
  i've tried with many different (but same resolution and bits) png images, and all have failed to output a good video.

  For some series of images, only the frames of first second was shown in a good shape, but the remaining frames was distorted and color changed (lighter).

  For some series of images, it seemed the images were zoomed-in and distorted again.

  and etc.

  Question :
  I am a total AV newbie and I need someone to verify my steps for encoding. I am total AV newbie.

  1) av_register_all()

  2) avcodec_register_all()

  3) avcodec_find_encoder()

  4) avcodec_alloc_context3()

  5) sets codec configuraton to context.

  6) avcodec_open2()

  7) opens a output file using fopen_s()

  8)

  for(int second=1; second<=10; ++seconds)
  
  {
  
  
  
    Read a image from local using Gdiplus
  
  
  
    Create a gdiplus bitmap and draw the image onto this bitmap
  
  
  
    Get the raw byte data using LockBits
  
  
  
    Transfer this RGB raw byte into YUV420 frame using 'swscontext', 'sws_scale'
  
  
  
    for(int f=0; f<24; ++f)
  
    {
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;
  
      pkt.size = 0;
  
  
  
      pFrame->pts = f;
  
      ret = avcodec_encode_video2(pContext, &pkt, pFrame, &got_output);
  
  
  
      if(got_output)
  
      {
  
          fwrite(pkt.data, 1, pkt.size, outputFile);
  
          av_free_packet(&pkt);
  
      }
  
    }
  
  }
  
  
  
  /* get the delayed frames */
  
  for (got_output = 1; got_output; i++) {
  
      fflush(stdout);
  
  
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  close everything required

  I am sure that I misunderstood some steps using ffmpeg api. The above pseudo codes are based on the 'encoding' example of ffmpeg. which part am I doing wrong ? please can someone help me ?

  p.s sorry about broken english. english is not my natvie language. I tried my best =P

• How to get a 7.1 PCMle encode in an MOV container to stay a single track while also rendering as 8 mono tracks in an NLE like an MXF container

  26 février 2024, par varys_da_spidah

  I've been trying to convert Blu-Ray footage to the most efficient, yet least time consuming format for editing footage from them. For a while, I would make an MXF container and encode the h264 to DNxHD and the lossless compressed audio to pcm_s24le. I really liked how convenient it was to have my audio linked to my video, how it could be played as a single track in a media player, but then be inserted into my NLE as 6-8 separate mono tracks.

  


  However, I found the DNxHD encodes to be unnecessary as they took up too much storage space and my NLE could perfectly handle the original h264 files in an MOV or MP4 container. But I noticed that switching from MXF to an MOV container meant that things that were jettisoned from the former were in the latter. Some of this was actually welcome, like the chapter markers, but I noticed that 7.1 audio (but not 5.1 for some reason) would now render in my NLE as a single 7.1 track.

  


  I looked in MediaInfo and think I figured out that the issue is that the MOV container formats the channel layout while the MXF one doesn't. I'll paste the info to show what I mean

  


  MOV FILE

  


  


  

  • ID : 2

  


  • Format : PCM

  


  • Format settings : Little / Signed

  


  • Codec ID : in24

  


  • Duration : 1 min 41 s

  


  • Bit rate mode : Constant

  


  • Bit rate : 9 216 kb/s

  


  • Channel(s) : 8 channels

  


  • Channel layout : L R C LFE Ls Rs Lb Rb

  


  • Sampling rate : 48.0 kHz

  


  • Bit depth : 24 bits

  


  • Stream size : 111 MiB (34%)

  


  • Title : English

  


  • Language : English

  


  • Default : Yes

  


  • Alternate group : 1

  


  • Menus : 3

  


  


  


  MXF FILE

  


  


  

  • ID : 3

  


  • Format : PCM

  


  • Format settings : Little

  


  • Format settings, wrapping mode : Frame (AES)

  


  • Codec ID : 0D01030102060300

  


  • Duration : 1 min 13 s

  


  • Bit rate mode : Constant

  


  • Bit rate : 9 216 kb/s

  


  • Channel(s) : 8 channels

  


  • Sampling rate : 48.0 kHz

  


  • Frame rate : 23.976 FPS (2002 SPF)

  


  • Bit depth : 24 bits

  


  • Stream size : 81.1 MiB (5%)

  


  • Delay_SDTI : 0

  


  • Locked : Yes

  


  


  


  Any ideas ?

  


  I tried this code :

  


  ffmpeg -i "INPUT.mkv" -c:v copy -r 23.976 -c:a pcm_s24le -filter_complex "[0:a:0]pan=mono|c0=c0[a0]; [0:a:1]pan=mono|c0=c0[a1]; [0:a:2]pan=mono|c0=c0[a2]; [0:a:3]pan=mono|c0=c0[a3]; [0:a:4]pan=mono|c0=c0[a4]; [0:a:5]pan=mono|c0=c0[a5]; [0:a:6]pan=mono|c0=c0[a6]; [0:a:7]pan=mono|c0=c0[a7]; [a0][a1][a2][a3][a4][a5][a6][a7]amerge=inputs=8" "OUTPUT.mov”

  


  And got this error message :

  


  Stream specifier ':a:4' in filtergraph description [0:a:0]pan=mono|c0=c0[a0]; [0:a:1]pan=mono|c0=c0[a1]; [0:a:2]pan=mono|c0=c0[a2]; [0:a:3]pan=mono|c0=c0[a3]; [0:a:4]pan=mono|c0=c0[a4]; [0:a:5]pan=mono|c0=c0[a5]; [0:a:6]pan=mono|c0=c0[a6]; [0:a:7]pan=mono|c0=c0[a7]; [a0][a1][a2][a3][a4][a5][a6][a7]amerge=inputs=8 matches no streams.

  


• How to seal subtitle on the video permanently ? ffmpeg

  10 octobre 2017, par Robert Choy

  I am able to add subtitle to my mp4 ; however, when i upload it on youtube, the subtitle is gone, disappeared.

  So i am asking if there is any method to make the subtitle on the video (forever, permanently, seal it, burn it, force everyone watch the video with subtitle, can’t even turn it off manually)

  ffmpeg -i video.mp4 -i subtitle.srt -c copy -c:s mov_text -disposition:s:0 forced \
  
  permanently-subtitle-video-please.mp4

  i dont like the design of youtube subtitle, so i would love to upload my video + subtitle as one thing.

  sorry i a not an English native speaker, hope you understand what i am trying to ask. thanks