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• Detecting Successful Conversion with ffmpeg

  22 février 2017, par J M

  I have code that scans a file system for videos files encoded with H.264 and re-encodes them with H.265. It runs pretty much on its own constantly, generating various log files for me to review periodically.

  One thing that I want to further improve is the successful conversion detection. Right now, a file returns as being successfully converted after it meets these criteria/checks :

  1. The output file exists
  2. ffprobe can detect that the output file is in hevc format
  3. The duration of the output file matches that of the input file (within 3 seconds)
  4. The length of the output file is greater than 30 MB (it’s rare that I have a video so short where after conversion it is less than this, usually this happens when an error occurs or conversion terminates early).

  Obviously, this is rather computationally intense as there are many file checks to confirm all of this information. I do this because if the file is detected as successful conversion, the old file is overwritten and the new converted file takes it’s place. I don’t want to overwrite a file because I overlooked a scenario where I think conversion is successful but was in fact not. The files are under a crashplan constant backup, so I don’t lose them, but I also do not go through and review every file.

  So, my basic question is if you see any area of improvement for this detection. My goal is to determine, to my best extent, if after conversion the video remains "playable". So deciding programmatically how/what that means is what I’m attempting to do.

  I can post code if you want it (powershell), but the question seems independent of actual program language choice.

• build : Fine-grained link-time dependency settings

  22 janvier 2017, par Diego Biurrun

  build : Fine-grained link-time dependency settings
  Previously, all link-time dependencies were added for all libraries,
  
  resulting in bogus link-time dependencies since not all dependencies
  
  are shared across libraries. Also, in some cases like libavutil, not
  
  all dependencies were taken into account, resulting in some cases of
  
  underlinking.
  To address all this mess a machinery is added for tracking which
  
  dependency belongs to which library component and then leveraged
  
  to determine correct dependencies for all individual libraries.
  

  • [DBH] Makefile
  • [DBH] avbuild/common.mak
  • [DBH] avbuild/library.mak
  • [DBH] configure
  • [DBH] tests/checkasm/Makefile

• timelapse images into a movie, 500 at a time

  2 mars 2017, par molly78

  I am trying to make a script to turn a bunch of timelapse images into a movie, using ffmpeg.

  The latest problem is how to loop thru the images in, say, batches of 500.

  There could be 100 images from the day, or there could be 5000 images.

  The reason for breaking this apart is due to running out of memory.

  Afterwards I would need to cat them using MP4Box to join all together...

  I am entirely new to bash, but not entirely programming.

  What I think needs to happen is this

  1) read in the folders contents as the images may not be consecutively named

  2) send ffmpeg a list of 500 at a time to process (https://trac.ffmpeg.org/wiki/Concatenate)

  2b) while you’re looping thru this, set a counter to determine how many loops you’ve done

  3) use the number of loops to create the MP4Box cat command line to join them all at the end.

  the basic script that works if there’s only say 500 images is :

  #!/bin/bash
  
  
  
  dy=$(date '+%Y-%m-%d')
  
  
  
  ffmpeg -framerate 24 -s hd1080 -pattern_type glob -i "/mnt/cams/Camera1/$dy/*.jpg" -vcodec libx264 -pix_fmt yuv420p Cam1-"$dy".mp4

  MP4Box’s cat command looks like :

  MP4Box -cat Cam1-$dy7.mp4 -cat Cam1-$dy6.mp4 -cat Cam1-$dy5.mp4 -cat Cam1-$dy4.mp4 -cat Cam1-$dy3.mp4 -cat Cam1-$dy2.mp4 -cat Cam1-$dy1.mp4 "Cam1 - $dy1 to $dy7.mp4"

  Needless to say help is immensely appreciated for my project