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• Save base64 bit encoded tring to the file in php

  10 mai 2016, par ppeiris

  I have a php application which takes base64 encoded wav file from the client (browser) via ajax and save to the database. No I have to re encode the wav file using ffmpeg before I save the file in to the database (I can do this using system calls). But the questions is I need the input file (name.wav) for ffmpeg to do the work and as of right now I have only base64 encoded string in my php variable. I need to save this file to the disk using these base64 encoded string. How can I do this in php.

  my server is running on RedHat and apache.

  Thanks for your help in advance

  Prabath

• Correcting color cast with ffmpeg

  16 mai 2018, par Henry H

  I have two videos that have a pretty significant blue cast to them. I took some stills at the same time and I’m happy enough with the colors on those and I’d like to re-encode the videos, adjusting the colors to something similar to the stills.

  • A frame from the original video can be seen here : http://www.dotrose.com/temp/img_20180513_153484_original.png
  • An attempt at correcting the color, which would be acceptable : http://www.dotrose.com/temp/img_20180513_153484_corrected.png
  • A still image taken at the same time (but with some help from a flash) : http://www.dotrose.com/temp/img_20180513_153476.jpg

  I understand I could either create a large collection of jpg images from the video and color correct them before reassembling them into a new video or I could use ffmpeg’s color level’s filter to do it directly. What I don’t know is how to get the numbers to pass to the filter. I’m assuming I want to do something like this :

  ffmpeg -i video.mov -vf "colorlevels=rimin=##/255:gimin=##/255:bimin=#/255:rimax=###/255:gimax=###/255:bimax=###/255, eq=gamma=#.##" -y out.mov

  How do I get the values to use for each of the r, g, and b min and max settings and gamma to use in place of the ###s ? Assuming this is the right approach, of course.

  Update : Perhaps this question would be better asked in a forum for gimp or photoshop. But I know how to adjust the color in those. What I need to know is how I translate those changes to what ffmpeg is expecting.

• Adding unique RGB color watermark per video frame with FFmpeg

  8 juin 2016, par Dustin Kerstein

  I’d like to add a unique watermark onto each unique video frame in an h264 mp4 video. More specifically, I want the watermark to be a X by X pixel square solid 8-bit RGB color, and each color watermark should be unique across all frames in the video (up to the theoretical 24 bit max of 16.7 million colors/frames).

  Is this possible to do programatically using FFmpeg filters (or another tool) without requiring a photo for each possible color watermark ?

  If not, assuming I already have the full set of 1029 solid color photos downloaded from http://www.solidbackgrounds.com, can anyone think of an easy way to watermark a video with <= 1029 frames using FFmpeg ?