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• Video Conversion ? with ffmpeg

  10 août 2017, par Lee Brindley

  I’m building a react native app for both Android and IOS, the back-end API is written with NodeJS.

  Users may upload video from their phones, once uploaded the user and their friends will be able to view the video - so the videos need to be stored in a format which is playable on both Android & IOS.

  My question relates to the conversion of video, uploaded by the user. I have developed a similar app a couple of years ago, I used the repo node-fluent-ffmpeg which provides a nice API to interact with ffmpeg.

  In the previous project (which was a web app), I converted the uploaded videos into two files, one .mp4 and one .webm - if a user uploaded a mp4, then I would skip the mp4 step, likewise if they uploaded a .webm.

  This was kind of slow. Now i’ve come across the same requirement years later, after some research I think I was wrong to convert the videos in the last project.

  I’ve read that I can simply use ffmpeg to change the container format of the videos, which is a much faster process than converting them from scratch.

  The video conversion code I used last time went something along the lines of :

  var convertVideo = function (source, format, output, success, failure, progress) {
  
  
  
      var converter = ffmpeg(source);
  
  
  
      var audioCodec = "libvorbis";
  
  
  
      if (format.indexOf("mp4") != -1) {
  
          audioCodec = "aac";
  
      }
  
  
  
      converter.format(format)
  
          .withVideoBitrate(1024)
  
          .withAudioCodec(audioCodec)
  
          .on('end', success)
  
          .on('progress', progress)
  
          .on('error', failure);
  
  
  
      converter.save(output);
  
  };

  Usage :

  Convert to mp4 :

  convertVideo("PATH_TO_VIDEO", "mp4", "foo.mp4", () => {console.log("success");});

  Convert to webm :

  convertVideo("PATH_TO_VIDEO", "webm", "foo.webm", () => {console.log("success");});

  Can anyone point out a code smell here regarding performance of this operation ? Is this code doing a lot more than it should to achieve cross platform compatibility between IOS and Android ?

  Might be worth mentioning that support for older OS versions is not such a big deal in this project.

• FFMPEG batch file to re-encode movies that don't contain string "h265" in file name ?

  11 juillet 2017, par gregm

  I have a batch file that uses FFMPEG to re-encode movies to h265 to reduce file size. I have a few videos that I previously re-encoded over the past couple of years. I want to skip those and at the moment I just manually move them from subfolders before running my script, but this is getting tedious. I’d like to add a command to my batch file that skips those files automatically. All files that have been re-encoded in the past have h265 appended before the file extension. My batch file looks like this, but it isn’t skipping the files with h265 in them :

  for %%a in ("*.*") do findstr /v /c:"h265" "%%a" >nul && \
  
  ffmpeg -i "%%a" -c:v libx265 -preset ultrafast \
  
  -x265-params [parameters] -c:a copy "%%~na.h265.mp4"
  
  
  
  pause

  What do I need to change to get this to work ?

• subprocess "TypeError : a bytes-like object is required, not 'str'" (Python 2 -> 3 issue maybe ?)

  8 juillet 2017, par chatbottest

  I’m using this code from a previously asked question a few years ago, however I believe this is outdated. Trying to run the code, I receive the error above. I’m still a novice in python, so I could not get much clarification from similar questions. Anyone know why this is happening ?

  import subprocess
  
  
  
  def getLength(filename):
  
    result = subprocess.Popen(["ffprobe", filename],
  
      stdout = subprocess.PIPE, stderr = subprocess.STDOUT)
  
    return [x for x in result.stdout.readlines() if "Duration" in x]
  
  
  
  print(getLength('bell.mp4'))

  Traceback

  Traceback (most recent call last):
  
    File "B:\Program Files\ffmpeg\bin\test3.py", line 7, in <module>
  
      print(getLength('bell.mp4'))
  
    File "B:\Program Files\ffmpeg\bin\test3.py", line 6, in getLength
  
      return [x for x in result.stdout.readlines() if "Duration" in x]
  
    File "B:\Program Files\ffmpeg\bin\test3.py", line 6, in <listcomp>
  
      return [x for x in result.stdout.readlines() if "Duration" in x]
  
  TypeError: a bytes-like object is required, not 'str'
  
  </listcomp></module>