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• Looping over images in a batch script [on hold]

  31 juillet 2018, par Santosh Kr

  I’m trying to convert .jpg images in a directory to .yuv images with the ffmpeg command :

  ffmpeg -i 1.jpg -s 6720x3360 -pix_fmt nv12 1.yuv

  I’m trying to loop over them using a batch script as follows :

  set "sourcedir=C:\Users\santvenk\Desktop\Repo\Testing"
  
  PUSHD "%sourcedir%"
  
  for %%f in (*.jpg) DO ffmpeg -i "%%f" -s 6720x3360 -pix_fmt nv12 "%sourcedir%\%%~nf.yuv"

  But this is how it’s printing in the command prompt :

  ffmpeg -i "2.JPG" -s 6720x3360 -pix_fmt nv12 "C:\Users\santvenk\Desktop\Repo\Testing\2.JPG.yuv"

  How do I fix this ?

  EDIT : I had made few syntactical errors and now I have corrected it. The correct syntax for anyone looking for a solution to a similar problem is :

  FOR %%f in (*.jpg) DO ffmpeg -i %%f -s 6720x3360 -pix_fmt nv12 %%~nf.yuv

• Add lensfun filter

  13 juillet 2018, par Stephen Seo

  Add lensfun filter
  Lensfun is a library that applies lens correction to an image using a
  
  database of cameras/lenses (you provide the camera and lens models, and
  
  it uses the corresponding database entry's parameters to apply lens
  
  correction). It is licensed under LGPL3.
  The lensfun filter utilizes the lensfun library to apply lens
  
  correction to videos as well as images.
  This filter was created out of necessity since I wanted to apply lens
  
  correction to a video and the lenscorrection filter did not work for me.
  While this filter requires little info from the user to apply lens
  
  correction, the flaw is that lensfun is intended to be used on indvidual
  
  images. When used on a video, the parameters such as focal length is
  
  constant, so lens correction may fail on videos where the camera's focal
  
  length changes (zooming in or out via zoom lens). To use this filter
  
  correctly on videos where such parameters change, timeline editing may
  
  be used since this filter supports it.
  Note that valgrind shows a small memory leak which is not from this
  
  filter but from the lensfun library (memory is allocated when loading
  
  the lensfun database but it somehow isn't deallocated even during
  
  cleanup ; it is briefly created in the init function of the filter, and
  
  destroyed before the init function returns). This may have been fixed by
  
  the latest commit in the lensfun repository ; the current latest release
  
  of lensfun is almost 3 years ago.
  Bi-Linear interpolation is used by default as lanczos interpolation
  
  shows more artifacts in the corrected image in my tests.
  The lanczos interpolation is derived from lenstool's implementation of
  
  lanczos interpolation. Lenstool is an app within the lensfun repository
  
  which is licensed under GPL3.
  v2 of this patch fixes license notice in libavfilter/vf_lensfun.c
  v3 of this patch fixes code style and dependency to gplv3 (thanks to
  
  Paul B Mahol for pointing out the mentioned issues).
  v4 of this patch fixes more code style issues that were missed in
  
  v3.
  v5 of this patch adds line breaks to some of the documentation in
  
  doc/filters.texi (thanks to Gyan Doshi for pointing out the issue).
  v6 of this patch fixes more problems (thanks to Moritz Barsnick for
  
  pointing them out).
  v7 of this patch fixes use of sqrt() (changed to sqrtf() ; thanks to
  
  Moritz Barsnick for pointing this out). Also should be rebased off of
  
  latest master branch commits at this point.
  Signed-off-by : Stephen Seo <seo.disparate@gmail.com>
  

  • [DH] configure
  • [DH] doc/filters.texi
  • [DH] libavfilter/Makefile
  • [DH] libavfilter/allfilters.c
  • [DH] libavfilter/vf_lensfun.c

• ffmpeg - Timecode & Fractional Frame Rate (Duplicating Frames)

  29 mars 2018, par Nimble

  I record two different frame rates using ffmpeg, 60 and 100. Or at least I thought I was recording 60 and 100, now it seems it’s actually 59.94 and 99.98.

  Here is the command I was using :

  ffmpeg -y -thread_queue_size 9999 -guess_layout_max 0 -f dshow -video_size 1920x1080 -rtbufsize 2147.48M -framerate 60 ^
  
  -pixel_format yuyv422 -i video="Game Capture HD60 S (Video) (#01)":audio="ADAT (5+6) (RME Fireface UC)" -map 0:0,0:1 ^
  
  -map 0:1 -c:v h264_nvenc -preset: llhp -pix_fmt yuv420p -b:v 40M -minrate 40M -maxrate 40M -bufsize 40M -b:a 384k -ac 2 ^
  
  -r 60 -af "pan=mono|c0=c0, adelay=84" -vsync 1 -max_muxing_queue_size 9999 -f segment -segment_time 600 ^
  
  -segment_wrap 9 -reset_timestamps 1 C:\Users\djcim\Videos\PC\Camera\CPC%02d.ts ^
  
  -thread_queue_size 9999 -f dshow -video_size 3440x1440 -rtbufsize 2147.48M -framerate 100 -pixel_format nv12 ^
  
  -itsoffset 00:00:00.215 -i video="Video (00 Pro Capture HDMI 4K+)" -thread_queue_size 9999 -guess_layout_max 0 -f dshow ^
  
  -rtbufsize 2147.48M -i audio="SPDIF/ADAT (1+2) (RME Fireface UC)" -map 1:0,2:0 -map 6:0 -c:v h264_nvenc -preset: llhp ^
  
  -pix_fmt nv12 -b:v 250M -minrate 250M -maxrate 250M -bufsize 250M -b:a 384k -ac 2 -r 100 -af "adelay=141|141" -vsync 1 ^
  
  -max_muxing_queue_size 9999 -f segment -segment_time 600 -segment_wrap 9 -reset_timestamps 1 ^
  
  C:\Users\djcim\Videos\PC\PC\PC%02d.ts

  I thought all was well with my frame rates, sure ffmpeg was duplicating frames every once in a while, but I thought it was just a random occurrence caused by ffmpeg dropping a frame during processing and therefore needed to duplicate one to make it up. I didn’t think duplicating a few frames would be noticeable in the footage... until I was reviewing some from the first output, which is actually a camera, and noticed very slight stutters consistently 3 times a minute. This began to bug me, it was very noticeable and I wanted smooth footage. A bit confused I decided to try the first output by itself and watch ffmpeg to see when frames were being duplicated and found that it was duplicating frames every 17 second (16.66 to be more precise).

  After doing the math (1/16.66=.06) I realized that the frame rate of that first capture card was actually 59.94. Doing the same thing for the other output I found that my "100fps" footage is actually 99.98. But what does that really entail ?

  Should I change the fps to 59.94 and 99.98 ? Wont that cause synchronization issues as 99.98 (100*.0002=99.98) isn’t the same standard as 59.94 (60*.001=59.94) ? Or does that mean I just need to set the second output to 99.9 (100*.001=99.9) to match the standard of the first output and drop frames ? If that is the case does this mean in my editing program, Adobe Premiere, I would need to export the final video as 59.94fps not 60fps to avoid duplication of frames ? Or is there some method within timecode that remedies this issue ?

  I guess I just really don’t understand drop frame and non-drop frame timecode / timecode in general. Up until yesterday when something said 60fps I thought it meant literally 60fps but I guess 99% of the time it actually means 59.94. I’d really like to just avoid the duplication of frames as it ruins what would be a smooth experience but don’t know if I can while trying to keep everything synchronized.

  Any help or insight would be appreciated, sorry if my question is a bit confusing I am undoubtedly confused.