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• How to convert iphone's caf to ogg on ubuntu

  24 novembre 2012, par Amure Pinho - Syncmobile

  i really need your support to solve that problem :

  We developed an iOS application that sends a sound file to our server and then, we share this audio.

  The problem is we didnt find any solution to convert the audio inside the iOS.

  We tought : Ok, thats a problem, but we can still convert the audio in the server right ?

  We are trying to make this using afconvert, ffmpeg but with no sucess.

  Do you have any basic guide or hint so we can write this in our server application and convert all the .CAF files to another format like OGG or MP3 ?

  Thanks a lot !

• A very simple lightweight video editor

  11 novembre 2011, par algorithmicCoder

  I want to make an editor that does the following :

  1) takes an mp3 audio file

  2) Takes a picture —a jpg file

  3) Outputs a simple video format e.g. .mov which consists of the jpg file with the mp3 file in the background

  4) Does NOTHING else

  I want to use this as a project to learn just the basics of all this stuff however I do not want to code basic things by hand. Where do I start and what key steps do I take to accomplish this ?

  I am decent with PHP and Java and do not mind learning Python for this. I actually would ideally want to write this in Python to gain experience.

  Thanks !

• How to start an FFmpeg process, create a pipe and write data from the parent process ?

  3 mai 2021, par xlxs

  My code is based on https://stackoverflow.com/a/32279430/5941827.

  


  I run FFmpeg with the following params :

  


  std::stringstream sstm;
sstm << "ffmpeg -loglevel error -y -f rawvideo -vcodec rawvideo -s " << std::to_string(width) << "x" << std::to_string(height) //
        << " -pix_fmt rgb24 -framerate " << std::to_string(fps) << " -i - -c:v libx264 -preset " << getPreset(encodeSpeed) << //
        " -crf " << std::to_string(crf) << " -shortest " << path;


  


  (the variables are initialized in a class constructor correctly)

  


  Then I open the pipe with pPipe = popen(sstm.str().c_str(), "w").The problem is after I fwrite to it and calling fclose, based on the contents I write sometimes less or more bytes reach FFmpeg, and I get

  


  [rawvideo @ 000000000010c3df] Invalid buffer size, packet size 196606 < expected frame_size 196608
Error while decoding stream #0:0: Invalid argument


  


  The saved output video usually has one frame more or less than the expected.
I have checked the array I'm sending trough the pipe with fwrite and it's size is correct.
It appears that based on the data I send some bytes don't get there, or more bytes than I send go through the pipe.

  


  I have also tried two different FFmpeg versions, but with the same error message.