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• Inconsistent behavior when placing adjacent video overlays

  24 juillet 2023, par abingham

  This script uses ffmpeg to overlay a red [1] and blue [2] stream atop a yellow [0] stream. The intent is that the red stream will be exactly adjacent to the blue stream ; at frame 1731 the output video should transition immediately from pure red to pure blue :

  


  # These values result in a blank frame where the videos join at around 58s
LENGTH=1800
SPLIT_AT=1731

# These values work just fine.
# LENGTH=1800
# SPLIT_AT=2

ffmpeg \
-f lavfi -r 30 -i "color=c=yellow:s=1920x1080" \
-f lavfi -r 30 -i "color=c=990000:s=1920x1080" \
-f lavfi -r 30 -i "color=c=000099:s=1920x1080" \
-filter_complex \
"[1]concat=n=1[red_concat];"\
"[red_concat]tpad=start=0[red_pad];"\
"[0][red_pad]overlay=enable=between(n\,0\,$SPLIT_AT):eof_action=repeat[red_overlay];"\
"[2]concat=n=1[blue_concat];"\
"[blue_concat]tpad=start=$SPLIT_AT[blue_pad];"\
"[red_overlay][blue_pad]overlay=enable=between(n\,$SPLIT_AT\,$LENGTH):eof_action=repeat[blue_overlay];"\
"[blue_overlay]trim=end_frame=$LENGTH[full];" \
 -map "[full]" video.mp4 -y


  


  However, what I see is that there is a single black frame between the pure red and pure blue. This black seems to be coming from the frames that tpad adds.

  


  What I don't understand is why I'm seeing that black frame. As far as I can tell, my uses of tpad and overlay/enable-between should produce a seamless transition from red to blue. And indeed, if I change the SPLIT_AT value to almost anything else I get exactly that ; the value 1731 is "special" in some way.

  


  Can anyone explain what's going on ? Maybe more importantly, can anyone reproduce this problem ?

  


  My first thought was that I've got some form of fencepost error in how I'm using tpad or enable-between. However, that doesn't explain why the script works for most values but not 1731. This difference in results feels like there's a rounding error somewhere, but since I'm dealing purely in terms of integer frame numbers, I don't see how I could be introducing them.

  


  A few notes :

  


  


  • This is a drastically reduced example from a larger video compositing system. Things like the use of concat may appear unnecessary, but they're representative of what the larger system is doing.

    


  


  • I'm using ffmpeg-6.0 installed via homebrew on an M1 macbook

    


  


  


• How to convert png images to a HEVC(h265) video with alpha

  20 décembre 2022, par ImWH

  I want to convert a sequence of png images to a HEVC video with alpha, I would like to use ffmpeg to do this work and find the following command(images name are p01.png, p02.png...) :

  


  ffmpeg -framerate 10 -i p%02d.png -c:v hevc_videotoolbox -require_sw 1 -allow_sw 1 -alpha_quality 0.5 -vtag hvc1 hevc.mov


  


  the print is here :

  


  ffmpeg version 5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
  built with Apple clang version 14.0.0 (clang-1400.0.29.202)
  configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/5.1.2_1 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-neon
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, image2, from 'p%02d.png':
  Duration: 00:00:09.60, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: png, rgba(pc), 375x812 [SAR 3779:3779 DAR 375:812], 10 fps, 10 tbr, 10 tbn
Stream mapping:
  Stream #0:0 -> #0:0 (png (native) -> hevc (hevc_videotoolbox))
Press [q] to stop, [?] for help
[1]    16348 trace trap  ffmpeg -framerate 10 -i p%02d.png -c:v hevc_videotoolbox -require_sw 1  1  0.


  


  It seems like there is no error and the video has been generated but the size of video is always 0kb, I try to change the parameter for command but nothing changed, so is there something working with the command ? or Is there is a simple way to create the HEVC video using png image ? Thanks

  


  My Environment :
Apple silicon(MacBook with M1 Pro clip) Mac OS 13.0
ffmpeg : 5.1.2

  


• Processing 3.0 get Error=2 No such file or directory

  29 octobre 2016, par Tuang Pingfavilunda

  I cannot figure it out what happen to my Processing file. I am trying to use VideoExport library and my Macbook Pro cannot play it, but the Mac-mini is able to do so.

  Before the error happened it is another error=13 permission denied thing, so I messed in the terminal for a while with chmod 777 and finding the file with ls. I don’t know if that may be the reason that caused this happen. FYI, I also installed ffmpeg already.

  And this is the full error :

      java.io.IOException: Cannot run program "/Users/Tuang/Desktop/DMA_WORKS/Work1_Facial Muscles/Cam_Rec/sketch_161027a/sketch_161027a.pde": error=2, No such file or directory
  
      at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
  
      at com.hamoid.VideoExport.startFfmpeg(Unknown Source)
  
      at com.hamoid.VideoExport.initialize(Unknown Source)
  
      at com.hamoid.VideoExport.saveFrame(Unknown Source)
  
      at Basic.draw(Basic.java:32)
  
      at processing.core.PApplet.handleDraw(PApplet.java:2412)
  
      at processing.awt.PSurfaceAWT$12.callDraw(PSurfaceAWT.java:1540)
  
      at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:316)
  
  Caused by: java.io.IOException: error=2, No such file or directory
  
      at java.lang.UNIXProcess.forkAndExec(Native Method)
  
      at java.lang.UNIXProcess.<init>(UNIXProcess.java:247)
  
      at java.lang.ProcessImpl.start(ProcessImpl.java:134)
  
      at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
  
      ... 7 more
  
  VideoExport error: Ffmpeg failed. Study /Users/Tuang/Desktop/DMA_WORKS/Work1_Facial_Muscles/Camera_Recorder/Basic/basic.mp4.txt for more details.
  
  Could not run the sketch (Target VM failed to initialize).
  
  For more information, read revisions.txt and Help → Troubleshooting.
  
  </init>

  ---

  1) The java.io.IOException : trying to call "/Work1_Facial Muscles/Cam_Rec/sketch_161027a/sketch_161027a.pde" which doesn’t exist for real. It is gone for a long time but seems like the program stuck here.

  2) "basic" is a file name from the Example of the Library. I just use it to test. Surprisingly, Every files that have been saved and changed the name still get the java.io.IOException’s error of the missing sketch_161027a.pde file.

  ---

  What I have done :
  1 I have already done the Homebrew thing to install ffmpeg.
  2 I deleted everything of Processing and reinstall it again.

  Any suggestion ?