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• Read Audio and Video, edit Video frame, then write back Audio and Video - Using python

  19 avril 2021, par CowKeyMan

  I'm looking to do exactly as the title says, ie :

  


  

  1. Read a file containing both audio and video

  


  2. Edit the video frames individually

  


  3. Write back the video with the new frames but the same exact audio as before

  


  


  OpenCV is not a good option for reading and writing since it doesn't handle audio, altough I can use opencv in step 2.

  


  The language I am using is Python, as this needs to be integrated with a bigger system.

  


  My question is this : What software stack / librarries are appropriate for this kind of task and if anyone can point me to some resources it would be highly appreciated

  


  So far I have found the following options, but would like some feedback on them based on experience :

  


  

  1. ffmpeg

  


  2. MoviePy

  


  3. libav

  


  


• MediaPlayer miscalculates audio duration. getCurrentPosition() goes back when audio reaches the end

  26 mars 2017, par Kacy

  I’m streaming .ogg files from my server. The MediaPlayer plays the song to completion, but when it reaches the end of the song, getCurrentPosition() returns a time less than the actual duration of the song. For 1 song it’s only off by a second, but for another song it’s off by 13 seconds.

  I have a SeekBar that’s updated every second by calling getCurrentPosition(), and once the bar reaches the end, it actually jumps back a few seconds. And I can no longer use seekTo() into the segment of the song that’s past the miscalculated duration because I receive the error : Attempt to seek to past end of file.

  Chrome’s html video element simply displays the songs with the incorrect durations.

  Other tools like ffmpeg or this app on Windows 10 called PowerMediaPlayer both calculate the songs’ durations perfectly.

  I believe this problem is related to this answer, but the solution assumes ffmpeg also miscalculates the duration, which is not the case here. Using the -vn flag when converting audio files to ogg didn’t change anything.

  What are my options ? Is there a way to get the MediaPlayer to calculate the correct duration ?

  Update :

  Converting to mp3 has no issues (although I used audioBitrate('96k')instead of audioQuality(2), but I require a solution to get ogg files working. Below is how I’m using ffmpeg to perform the conversion. Another thing worth noting is that when I used 'vorbis' instead of 'libvorbis' for the codec the durations were off by less than a second, if at all. However, I must use 'libvorbis' because 'vorbis' is experimental and results in significanlty inconsistent bitrates across different files given the same audio quality parameter. (And it ignores audioBitrate() entirely.)

  ffmpeg( filepath )
  
      .toFormat( 'ogg' )
  
      .audioCodec( 'libvorbis' )
  
      .audioQuality( 2 )
  
      .output( destination )
  
      .run();

• Live video broadcasting in android using front and back facing cameras [on hold]

  1er décembre 2016, par Jun Kim

  This is my first time I am posting a question on Stack Overflow.

  I am currently developing an android application. My goal is to make an app that captures and records video and broadcasts it to other mobile devices as well as web browsers like facebook live.
  (Nowadays, famous apps like Youtube, Facebook, Twitch, Periscope has this function)

  Now, I am just researching what technologies and ways to develop this app.

  I have been researching and reading a lot of blogs and documentations for the past five weeks about FFMpeg, different types of streaming technologies, types of web servers etc. I decided to use MPEG-DASH for my app and nginx server (Nginx-rtmp-module).

  While searching further, I got stuck and confused about how I can possibly capture & record video using internal camera of Android mobile devices.

  I was thinking that I could use MediaRecorder to capture & record (I could hardly find an example using MediaRecorder to record video) and use FFMpeg
  to somehow encode with the certain video and audio codecs to make a container format and send it to nginx server to broadcast other devices.
  But then.... i am not sure if this is the right way to do it...

  My questions is... I would like to know the whole process (in detail if it possible) how I can possible record and broadcast to other devices.

  The whole process of recording video using internal camera that is in user’s mobile device and send the frame to the server to broadcast to other devices seems difficult to imagine for me... Can anyone elaborate ?

  Or any suggestion about how can I reach my goal ?
  Every help would be appreciated.