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• Anomalie #2388 : formulaires CVT multi-etapes et formulaires_editer_objet_charger

  1er novembre 2011, par Severo Lipari

  ah pardon, if (is_numeric($id_chat) && intval($id_chat)==$id_chat) $valeurs = formulaires_editer_objet_charger(’chat’,$id_chat,$id_rubrique,$lier_trad,$retour,$config_fonc,$row,$hidden) ; else $valeurs = array() ; $valeurs[’nom’] = ’’ ; $valeurs[’race’] = ’’ ; $valeurs[’date’] = ’’ ; (...)

• Changing YUV values of AVFrames

  31 janvier 2012, par Kage

  I'm trying to apply an effect to a video by altering the YUV values using FFMpeg programmatically in C.

  Let's say I want to increase the luminescence of each pixel of each frame by 10.

  At the moment I can open a video, get the video stream, find a frame, decode the frame, alter the YUV values of the AvFrame->data, encode the frame, and save the frame to be played back.

  When I play back the video, the first frame looks as expected, but the next is even brighter and the one after that is even brighter, and each frame seems to be having more and more added to the Y values instead of just 10.

  I tried changing the code so instead of altering the pixels for each frame, it just alters the first AVFrame's data. However when I play the video back, it is not only the first frame that has been altered, but like the first 30 or so frames.

  Why are the other frames effected when I only change the AVFrame->data of the first frame ?

• FFmpeg Libraries : How Do I Convert a Video to 4 Level Grayscale Video at 160x100 Pixels and as Raw Data

  15 avril 2014, par pimathbrainiac

  This seems like an odd question, so I am going to start from the beginning :

  I am a calculator programmer, specifically a Ti-89 programmer, and I'm trying to make a video player for it. I have the code for the calculator side done already, but I need to be able to convert video to a specific format that works as follows :

  Each frame is 4 level grayscale, where there are 2 bytes for every 8 horizontal pixels, a "back," or dark byte, and a "front," or light byte. Basically, every frame is 2 monochrome binary images, with the first byte of the first one is followed by the first byte of the second one, so data is stored as follows :

  FB(front buffer)[1],BB(back buffer)[1],FB[2],BB[2], etc...

  Here's how the display works : (defining 0 as white and 3 as black, with 1 and 2 being in-between shades)
  Each front buffer bit is worth 1, so if the front buffer were displayed with nothing in the back buffer, the "1" (or true) bits would show up as light gray pixels. These are then added to the back buffer bits, which are worth 2 (so if the back buffer were displayed with nothing in the front buffer, the "1" (or true) bits would show up as dark gray pixels) to get :

  "0" bit on either buffer = white pixel (0+0=0)

  "1" bit on front buffer but not back buffer = light gray pixel (1+0=1)

  "1" bit on back buffer but not front buffer = dark gray pixel (0+2=2)

  "1" bit on both buffers = black pixel (1+2=3)

  I have this down calculator-side, but I need to know : 1) How to convert the video to a specific framerate using the libs 2) How to convert these frames to 4-level grayscale at 160x100 pixels and 3) How to save these frames as raw data in the format I described. Thank you in advance for your answer(s).