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• FFMpeg Mobile video encoding stutter

  15 février 2014, par Sammaye

  I have been playing around with ffmpeg and video encoding and even though my mp4's work great on desktop, they are smooth etc they are terrible on mobile devices. They stutter and load very slowly and I am trying to figure out the problem.

  As an example I made a page using the media element plugin : http://mediaelementjs.com/ and on it I first placed the video that comes with mediaelementjs and it worked well, it scaled to desktop and mobile and loaded quickly and played without any stutter.

  However I loaded my video and it was slow and full of stutter, but only on mobile. So I thought it might be S3 (where it is hosted) but saved the file locally and same thing.

  I am hoping someone who knows h.264 and/or ffmpeg can point me in the direction of why ; here is the current command I am running on ffmpeg :

  ffmpeg -i $input_file_name -vcodec libx264 -r 100 -bt 300k -ac 2 -ar 48000 -ab 192k -strict -2 -y $output_temp_file 2>&1

  So what have I missed ?

• Soft subtitles on iPhone

  12 novembre 2012, par forthrin

  I know this question (or similar ones) has been asked all over the Web, but I still can't find a straight answer :

  1. Is it possible to mux soft subtitles into an mp4 video file (quickly, without re-encoding the video stream) that iPhone will actually display on the screen ? I have tried ffmpeg, MP4Box, Subler, Submerge and mp4v2 and none of them were successful in producing mp4 file that would display subtitles on iPhone (though some of them had subtitles when playing the video in VLC or iTunes).

  2. If iPhone does not support soft subtitles in mp4 files, then is there any command line utility (like the ones mentioned in question 1) that will render hard subtitles onto the video stream ? (I guess then this process will take hours since the video will have to be re-encoded)

  3. Finally, if there is no command line utility that can do hard subtitles, what options are there for GUI-based utilities ? Is Handbrake the best option ?

  If possible, please supply a command line example.

• Revision 609e91f9b7 : vp8 denoiser : fix to zero_mv mode selection. In the current logic, if the sse f

  28 mai 2014, par Marco Paniconi

  Changed Paths :
   Modify /vp8/encoder/denoising.c

  
  
  vp8 denoiser : fix to zero_mv mode selection.

  In the current logic, if the sse for zero motion is smaller
  than the sse for new_mv (i.e., best_sse), we may still end up
  using the non-zero mv for denoising (if the magnitude of new_mv is above
  threshold).
  This can happen for very noisy content, and can lead to artifacts.

  This change ensures that we always use zero_mv (over new_mv) for
  denoisng if sse_zero_mv <= best_sse.

  Change-Id : I8ef9294d837b077013b77a46c9a71d17c648b48a