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• ffmpeg filter to make video rectangular/square

  1er août 2021, par MiGu3X

  So, I've been trying for a while To convert this videos I have to a more "squared" way, so it doesn't look circular as they are being recorded.

  


  An example image of the video is the following :


  


  I've been trying using lenscorrection filter with ffmpeg attempting to convert that image into something like I could do in photoshop to something like this :


  


  But it seemed impossible. I've got information that the camera has a lens of 1.77 mm with focal length F2.4

  


  I don't know a lot about cameras that's why I couldn't understand which parameters top input into the lenscorrection filter or lensfun filter on ffmpeg and if someone could help me it'd be great.
I've read other posts on stackoverflow and blogposts but couldn't find the optimal parameters.

  


• FFmpeg output image distorted occasionally

  7 août 2021, par srelliott

  I'm using FFmpeg to export a poster image, but occasionally it exports an image that has different dimensions than the video. I basically end up with a nearly square poster image (distorted), but a video that plays at the correct dimensions. The particular issue I'm noticing it on is with a source video that's a .mov file with yuv422p. I'm converting all videos to .mp4 (yuv420p) in a different command.

  


  My image output command is :

  


  ffmpeg -ss 3 -i sourceVideo.mov -f image2 -vframes 1 -pix_fmt yuv420p -vf scale=720:-2 outputImage.jpg


  


  The log for this particular source video shows this :

  


  Stream #0:0(eng): Video: dvvideo (dvh3 / 0x33687664), yuv422p(progressive), 1280x1080 [SAR 3:2 DAR 16:9], 115084 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 29.97 tbc (default)

  


  When the image is generated, the resulting distorted image is 720x608. It seems the image is being exported based on the Sample Aspect Ratio (SAR) instead of the Display Aspect Ratio (DAR). I expect it to export at something more like 720x405. If manually resized to 720x405, it looks fine.

  


  The image output log shows :

  


  Stream #0:0(eng): Video: mjpeg, yuvj420p(pc), 720x608 [SAR 608:405 DAR 16:9], q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc (default)

  


  ADDITIONAL INFO

  


  When the .mp4 video is exported (separately through a different command), the video is displaying in the html5 player at something more like 1280x720 (which matches the DAR) and looks just fine.

  


  Stream #0:0(eng): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p(bottom coded first (swapped)), 1280x1080 [SAR 3:2 DAR 16:9], q=-1--1, 0.03 fps, 30k tbn, 29.97 tbc (default)

  


  **If the distorted image is opened in Photoshop, it throws an alert about pixel aspect ratio correction, then adjusts it to display the image correctly.

  


• How can I combine HDR video with a still PNG in FFMPEG without messing up colors ?

  2 juin 2022, par Robert

  I'm trying to add a still image to the end of a video as a title-card. Normally this is simple, but the video is HDR (shot on an iPhone) and for reasons I don't understand that's causing the colors in the PNG to go nuts.

  


  Here's the original png :


  


  Here's a screenshot from the end of the output video :


  


  Clearly something is amiss. I made the PNG image in Photoshop from a photo, and I've tried it with and without embedding the color profile without any noticeable difference.

  


  Here's the command for ffmpeg :

  


  ffmpeg -y\
 -t 5 -i '../inputs/video.MOV'\
 -loop 1 -t 5 -i '../../common/end-youtube.png'\
 -filter_complex '
[1:v] fade=type=in:duration=1:alpha=1, setpts=PTS-STARTPTS+5/TB[end];
[0:v][end] overlay [outV]
'\
 -map [outV] '../test.mp4'


  


  I've tried this with non-HDR videos and the colors look perfectly normal, so clearly the HDRness is somehow involved. I've also tried adding this line to set the colorspace etc of the output. It helps with the PNG (although it's not perfect) but then the video is washed out.

  


   -colorspace bt709 -color_trc bt709 -color_primaries bt709 -color_range mpeg \


  


  I don't really care if the output video is HDR or not, as long as the video and png parts both look visually close to the inputs. This is something I'll need to do to many videos, so if possible a solution that doesn't involve tweaking colors for each one would be ideal.