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• Using ffmpeg to convert mp3 to mp4 - how to draw filename on generated video ?

  22 mai 2020, par akouris

  Using trial and error I am using the following script on an OSX, to bulk convert a whole folder full of mp3 files, to mp4, by looping a specific video file :

  



  for i in *.mp3; do /usr/local/bin/ffmpeg -stream_loop -1 -i /path_to_filename.mp4 -c copy -v 0 -f nut - | /usr/local/bin/ffmpeg -thread_queue_size 10K -i - -i "$i" -c copy -map 0:v -map 1:a -shortest "$(basename "$i" )".mp4 ; done; for f in *.mp3.mp4; do mv -v "$f" "${f/.mp3.mp4/.mp4}"; done


  



  How can I also print/add/burn the mp3 filename, without the extension (.mp3), as an additional video layer at the bottom of the generated video screen, and with the added difficulty of word wrapping the text if is too long ?

  


• How to set the value of an arbitrary pixel in ffmpeg ?

  14 mai 2017, par Neb

  I want to modify the rgb value of each pixel inside ffmpeg.

  I need to implement the following function :

  A[x + expr_1][y] = expr_2

  where x and y are the current sampled pixel, A is the input frame whose pixel need to be modified and expr_1, expr_2 are two independent expressions.

  I tried using the geq filter but it seems there no way to set the value of a pixel other than from that currently sampled. For istance, the function p(x,y) only returns the value of the pixel at the specified location, but doesn’t allow to set a value for that pixel. In other word, ffmpeg seems allowing only something like :

  A[x][y] = expr

  Is there a way to tell ffmpeg to set the value of a specific pixel ?

  Thanks for your time.

• Screenshot of the Nexus One from adb ?

  23 avril 2015, par Marcus

  My goal is to be able to type a one word command and get a screenshot from a rooted Nexus One attached by USB.

  So far, I can get the framebuffer which I believe is a 32bit xRGB888 raw image by pulling it like this :

  adb pull /dev/graphics/fb0 fb0

  From there though, I’m having a hard time getting it converted to a png. I’m trying with ffmpeg like this :

  ffmpeg -vframes 1 -vcodec rawvideo -f rawvideo -pix_fmt rgb8888 -s 480x800 -i fb0 -f image2 -vcodec png image.png

  That creates a lovely purple image that has parts that vaguely resemble the screen, but it’s by no means a clean screenshot.