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• Anomalie #2943 : filtre logique défaillant

  4 février 2013, par Fil Up

  il faudrait certainement se replonger dans la discussion qui avait abouti à "zéro n’est pas vide" : https://www.google.com/search?q=%22z%C3%A9ro+n’est+pas+vide%22+%22spip%22

• check media resolution, if resolution is big ffmpeg it, if output is smaller than original delete the original else delete the output

  13 avril 2015, par The Wolf

  I have my storage VPS filled with videos, and hoping I can free up some space, their resolution is pretty big so I decided to re encode them with ffmpeg to a smaller resolution, I am doing every thing manually, first I check using mediainfo test5.mkv the resolution

  ...
  
  Width                                    : 1 280 pixels
  
  ...

  if the width is greater than 720 pixels I issue the following command :

  ffmpeg -i 'test5.mkv' -vf scale=720:-2 -acodec copy -vcodec libx264 -scodec copy -threads 12 -crf 28 -x264-params keyint=240:min-keyint=20 -preset:v slow '[Encoded] test5.mkv'

  then after that I delete the original video if the output has smaller size than the original

  I am hoping there is a script that can automate this, like I will run on a directory then, it will look for all .mkv to subdirectories recursively to perform this checks and actions. How to do this ?

  Also, I am worried that it could fail if I reach automation, since there are special characters in the video’s name of some like single quotes, double quotes, or `, so I will it can be escaped properly.

  Thanks !

  After some google I ended up with the following snippet, I am worried if this is enough, but I’m afraid to run it since I am not sure if it would damage my unix

  #!/bin/sh
  
  
  
  for file in *.{mkv}; do
  
  target="[720p]-${file%.*}.mkv"
  
  [[ -f "$target" ]] && { echo "skipping $file - $target exists" ; continue; }
  
  
  
  
  
  eval $(ffprobe -v error -of flat=s=_ -select_streams v:0 -show_entries stream=height,width "$file")
  
  size=${streams_stream_0_width}x${streams_stream_0_height}
  
  if [ "$streams_stream_0_width" -ge 720 ]; then
  
  echo ffmpeg -i "$file" -vf scale=720:-2 -acodec copy -vcodec libx264 -scodec copy -threads 12 -crf 28 -x264-params keyint=240:min-keyint=20 -preset:v slow "$target"
  
  
  
  fi
  
  done

  can somebody please tell me if my snippet should work ?

  UPDATE

  as it turns out if [ "$streams_stream_0_width" -ge 720 ]; then fails because the width is not integer ? line 10: [: : integer expression expected I am not sure why it is not integer, how can I make it integer ?

• Decoding RIMM streaming file format

  10 septembre 2011, par Thomas

  I want to decode the video (visual) frames within a Blackberry RIMM file. So far I have a parser, and some corresponding container documentation from RIM. 

  The video codec is H264 and is explicitly set on the device using one of the video.encodings properties. However, FFMPEG is not able to decode the frames and this is driving me nuts.

  Edit 1 : The issues seems to be lack of SPS and PPS in the frames, and artificially inserting them have proven unsuccessful so far (all grey image). Blackberry 9700 sends

  0x00 0x00 0x ?? 0x ?? 0xType

  where Type is according to table 7-1 in the H264 spec (I and P frames). We believe the 0x ?? 0x ?? represent the size of the frame, however the size does not always correspond to the size found by the parser (the parser seems to be working correctly).

  I have a windows decoder codec from blackberry, called mc_demux_mp2_ds.ax, and can play some MPEG-4 files captured the same way, but it is a binary for windows. And the H264 files will not play either way. I am aware of previous attempts. The capture url for javax.microedition.media.Manager is

  encoding=video-3gpp_width=176_height=144_video_codec=H264_audio_codec=AAC

  and I am writing to an output stream. Some example files here.

  Edit 2 :Turns out that about 3-4 of the 12-15 available video capture modes are flat out failing and refusing to output data, even in the simplest of test applications. So any working solution should implement MPEG-4, H264 and H263 in both AMR and AAC, in so getting fallback alternatives when one sound codec and/or resolution fails. Reboots, hangs and what not litters the Blackberry video implementation and vary from firmware to firmware ; total suckage.