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• FFmpeg what exactly is the filtergraph pipeline like during transcoding ?

  8 septembre 2017, par Jeff Gong

  I have been studying the source code for FFmpeg to attempt to understand its threading model and how it processes inputs. For example, when I run a command like :

  ffmpeg -i video.mp4 -s hd720 -c:v libx264 --preset medium -c:a aac -profile:v main -r 60 -f null /dev/null

  The input itself is irrelevant, but I am trying to understand how the transcoding pipeline works. In the source code, I see that the main steps occur in the functions transcode and transcode_step.

  It seems like for a single input, a single frame is read in, decoded, encoded, and written out. The process is obviously very complex but what I am really not understanding is what FFmpeg is doing when it attempts to build out a filtergraph. For example, in transcode_step of ffmpeg.c, there is the following code that happens right after an output stream has been selected :

  if (ost->filter && !ost->filter->graph->graph) {
  
      if (ifilter_has_all_input_formats(ost->filter->graph)) {
  
          ret = configure_filtergraph(ost->filter->graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Error reinitializing filters!\n");
  
              return ret;
  
          }
  
      }
  
  }

  Does this only apply if I specify a specific series of filtering options to FFmpeg, like the one in this link ? For the sample command I input above, is this code still executed ?

  One last other question I had was for the case where I run an FFmpeg instance with a single input but multiple outputs (perhaps different variants for transcoding). In this scenario, does a single phase of transcode_step take in an input frame and send that frame through decoding and encoding for only a single one of the outputs ? Or does it take a frame at a time and process this frame for each of the outputs we have specified ?

• libavfilter : vf_drawbox filter support draw box with detection bounding boxes in...

  14 mai 2021, par Ting Fu

  libavfilter : vf_drawbox filter support draw box with detection bounding boxes in side_data
  This feature can be used with dnn detection by setting vf_drawbox's
  
  option box_source=side_data_detection_bboxes, for example :
  
  ./ffmpeg -i face.jpeg -vf dnn_detect=dnn_backend=openvino:model=face-detection-adas-0001.xml :\
  
  input=data:output=detection_out:labels=face-detection-adas-0001.label,\
  
  drawbox=box_source=side_data_detection_bboxes -y face_detect.jpeg
  Signed-off-by : Ting Fu <ting.fu@intel.com>
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/vf_drawbox.c

• ffmpeg stuck in generating thumbnail of video [closed]

  10 décembre 2019, par user6121419

  I’m trying to create a thumbnail of a .mov video with ffmpeg, but it gets stuck.
  I tried the same command on 2 different machines and with different types of arguments, but nothing changed the result. The video itself can be viewed without a problem, so it shouldn’t be corrupted.
  The video was taken on an iphone at 4k 60fps.

  What I’ve tried :

  ffmpeg -i IMG_1001.MOV -ss 00:00:02 -vframes 1 thumbnail.jpg

  It gets stuck at the third last line frame= 0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x and from then on, I stopped the process with ctrl+c

  Output :

  ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
 built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
 configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
 libavutil      55. 78.100 / 55. 78.100
 libavcodec     57.107.100 / 57.107.100
 libavformat    57. 83.100 / 57. 83.100
 libavdevice    57. 10.100 / 57. 10.100
 libavfilter     6.107.100 /  6.107.100
 libavresample   3.  7.  0 /  3.  7.  0
 libswscale      4.  8.100 /  4.  8.100
 libswresample   2.  9.100 /  2.  9.100
 libpostproc    54.  7.100 / 54.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'IMG_1001.MOV':
 Metadata:
   major_brand     : qt
   minor_version   : 0
   compatible_brands: qt
   creation_time   : 2019-11-xx
   com.apple.quicktime.make: Apple
   com.apple.quicktime.model: iPhone 8
   com.apple.quicktime.software: 13.2.2
   com.apple.quicktime.creationdate: 2019-11-xx
 Duration: 00:00:05.18, start: 0.000000, bitrate: 54961 kb/s
   Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709), 3840x2160, 54851 kb/s, 60 fps, 60 tbr, 600 tbn, 600 tbc (default)
   Metadata:
     creation_time   : 2019-11-xx
     handler_name    : Core Media Data Handler
     encoder         : HEVC
   Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 94 kb/s (default)
   Metadata:
     creation_time   : 2019-11-xx
     handler_name    : Core Media Data Handler
   Stream #0:2(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
   Metadata:
     creation_time   : 2019-11-xx
     handler_name    : Core Media Data Handler
   Stream #0:3(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
   Metadata:
     creation_time   : 2019-11-xx
     handler_name    : Core Media Data Handler
Stream mapping:
 Stream #0:0 -> #0:0 (hevc (native) -> mjpeg (native))
Press [q] to stop, [?] for help
[swscaler @ 0x55d83a288940] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'thumbnail.jpg':
 Metadata:
   major_brand     : qt
   minor_version   : 0
   compatible_brands: qt
   com.apple.quicktime.creationdate: 2019-11-xx
   com.apple.quicktime.make: Apple
   com.apple.quicktime.model: iPhone 8
   com.apple.quicktime.software: 13.2.2
   encoder         : Lavf57.83.100
   Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 3840x2160, q=2-31, 200 kb/s, 60 fps, 60 tbn, 60 tbc (default)
   Metadata:
     creation_time   : 2019-11-xx
     handler_name    : Core Media Data Handler
     encoder         : Lavc57.107.100 mjpeg
   Side data:
     cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)

  Any idea on what it could be ? Am I missing something or could it be that the encoding can’t be read properly by ffmpeg ? Besides that I haven’t found any alternative to generate thumbnails from videos on linux