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• In my django app, celery task converts uploaded video w/ ffmpeg, but converted video won't save to s3 ?

  29 janvier 2013, par GetItDone

  I use Heroku to host my website, and Amazon s3 to store my static and media files. I have a celery task that converts the video file to flv, but the flv doesn't store anywhere. There isn't any error, just there is no file uploaded to my s3 bucket. How can I force the file to save to my s3 bucket after the conversion ? I'm still pretty new web development in general, and I have been stuck trying to get my video conversion working properly for weeks. To be honest, I'm not even sure that I'm doing the right thing with my task. Here is the code in my celery task :

  @task(name='celeryfiles.tasks.convert_flv')
  
  def convert_flv(video_id):
  
      video = VideoUpload.objects.get(pk=video_id)
  
      filename = video.video_upload
  
      sourcefile = "%s%s" % (settings.MEDIA_URL, filename)
  
      vidfilename = "%s.flv" % video.id
  
      targetfile = "%svideos/flv/%s" % (settings.MEDIA_URL, vidfilename)
  
      ffmpeg = "ffmpeg -i %s -ar 22050 -f flv -s 320x240 %s" % (sourcefile, targetfile)
  
      #The next lines are code that I couldn't get to work in place of the line above, and are left commented out.
  
      #I am open to suggestions or alternatives for this also.
  
      #ffmpeg = "ffmpeg -i %s -acodec libmp3lame -ar 22050 -f flv -s 320x240 %s" % (sourcefile, targetfile)
  
      #ffmpeg = "ffmpeg -i %s -acodec mp3 -ar 22050 -f flv -s 320x240 %s" % (sourcefile, targetfile)
  
      try:
  
          ffmpegresult = commands.getoutput(ffmpeg)
  
          print "---------------FFMPEG---------------"
  
          print "FFMPEGRESULT: %s" % ffmpegresult
  
      except Exception as e:
  
          ffmpegresult = None
  
          print("Failed to convert video file %s to %s" % (sourcefile, targetfile))
  
          print(traceback.format_exc())
  
      video.flvfilename = vidfilename
  
      video.save()

  My view :

  def upload_video(request):
  
      if request.method == 'POST':
  
          form = VideoUploadForm(request.POST, request.FILES)
  
          if form.is_valid():
  
              video_upload=form.save()
  
              video_id=video_upload.id
  
              video_conversion = convert_flv.delay(video_id)
  
              return HttpResponseRedirect('/current_classes/')
  
      else:
  
      ...

  Any advice, insight, or ideas in general would be greatly appreciated. Obviously I am missing something, but I can't figure out what. I have been stuck with different aspects of getting my video conversion to work with ffmpeg using a celery task for weeks. Thanks in advance.

• Encode video with changing bit rates using FFmpeg [migrated]

  4 décembre 2012, par Pavan K

  I would like to encode a 30 min video using ffmpeg. I am able to achieve this using

  ffmpeg -i in.mp4 -vcodec libvpx -vb 1024k -keyint_min 150 -g 150 -an out.webm

  But I would like to encode different segments of the video at different rate and not use a constant rate of 1024k. Is this possible ?

  I know what time they have to switch encoding. For example say 5 min of video I want an encoding rate of 1024k and next 5 min I am okay with 250k bitrate. I do not want to use VBR or I don't want to cut the video and encode them at different rates and then join them.

  Is this possible. I read the man page for ffmpeg and saw there were options for

  startime and time 

  But I am not sure how exactly I can do this assuming this to be possible.

• Merge videos with different Frame Rates using MP4Parser

  30 juillet 2017, par BorisB

  I am currently successful at using MP4Parser library (https://github.com/sannies/mp4parser) to merge two videos created by my phones camera with same frame rates and resolutions. However when I try to merge one I encode via Android MediaCodec with the same resolution and same codec to the one recorded via the phones camera it produces an unplayable file with no errors.

  The only difference between the two files that I can see is the Camera file has frame rates of this :

  Frame rate mode : Variable
  Frame rate : 29.970 (29970/1000) FPS
  Minimum frame rate : 29.831 FPS
  Maximum frame rate : 30.030 FPS

  and the one I generate via Media Codec has this :

  Frame rate mode : Constant
  Frame rate : 30.000 FPS

  MP4 parser documentation says :
  ’It is important to emphasize that you cannot append any two tracks with : Different resolutions or Different frame-rates’

  So yeah I guess I’m out of luck with that solution.

  Now the only two others solutions I have come across are FFMPEG (which I don’t want to bother with because of licensing issues) and using Mediacodec to first decoded and then encode the video files together.

  Is using Mediacodec basically the most sound approach here ? Will there be problems when I need to add audio into the mix later on ? Most importantly does anyone have a good examples of doing this type of merge ?

  I know http://bigflake.com/mediacodec/ is the best source for these types of examples but I can’t really see anything there that does exactly this. Any help would be greatly appreciated.