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• Can ffmpeg convert a string of hex (wav) to a string of hex (mp3) [closed]

  28 mai 2021, par CLipp

  I have written a program (python) to write specialized headers for wav files as hex. I would also like to save the file as an mp3 for backup purposes. I have used ffmpeg to convert audio files before.

  


  Is it possible to use ffmpeg to save the string of hex (which includes both the specialized header and the data chunk) wav and mp3 without writing the wav file to disk then reading it back for conversion ?

  


• Extract Motion Vectors From x264 source code

  27 mai 2021, par Essam Aly

  If you are familiar with the x264 source code, where in the code I can extract the MV (motion vectors) of each frame ? Can you point please to a line of code I can intercept and save the MVs to disk ?
Thank you.

  


• Adding watermark bitmap over video in android : 4.3's MediaMuxer or ffmpeg

  7 avril 2017, par Alin

  Here is my scenario :

  • Download an avi movie from the web
  • Open a bitmap resource
  • Overlay this bitmap at the bottom of the movie on all frames in the background
  • Save the video on extarnal storage
  • The video length is 15 seconds usually

  Is this possible to achieve using MediaMuxer ? Any info on the matter is gladly received

  I’ve been looking to http://bigflake.com/mediacodec/#DecodeEditEncodeTest (Thanks @fadden) and it says there :

  "Decoding the frame and copying it into a ByteBuffer with
  glReadPixels() takes about 8ms on the Nexus 5, easily fast enough to
  keep pace with 30fps input, but the additional steps required to save
  it to disk as a PNG are expensive (about half a second)"

  So having almost 1 sec/frame is not acceptable. From what I am thinking one way would be to save each frame as PNG, open it, add the bitmap overlay on it and then save it. However this would take an enormous time to accomplish.

  I wonder if there is a way to do things like this :

  1. Open video file from external storage
  2. Start decoding it
  3. Each decoded frame will be altered with the bitmap overlay in memory
  4. The frame is sent to an encoder.

  On iOS I saw that there a way to take the original audio + original video + an image and add them in a container and then just encode the whole thing...

  Should I switch to ffmpeg ? How stable and compatible is ffmpeg ? Am I risking compatibility issues with android 4.0+ devices ? Is there a way to use ffmpeg to acomplish this ? I am new to this domain and still doing research.

  ---

  Years later edit :
  Years have passed since the question and ffmpeg isn’t really easy to add to a commercial software in terms of license. How did this evolved ? Newer versions of android are more capable on this with the default sdk ?