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• configure : Enable GCC vectorization on ≥4.9 on x86

  30 janvier 2016, par Timothy Gu

  configure : Enable GCC vectorization on ≥4.9 on x86
  4.9 was released precisely nine years after the first GCC version with
  
  autovectorizer (4.0) and six years after the first GCC version with
  
  `-ftree-vectorize` default to enabled on `-O3` (4.3). We’ve given GCC
  
  enough time to fix those bugs.
  FATE passes here on a x86-64 machine with both GCC 4.9.2 and 5.3.1.
  Some optimization hotspots benefit greatly from this change, especially
  
  those without handwritten assembly. For instance, the main function in
  
  vf_phase is now 1.6x faster (1.2x overall) on my machine.
  

  • [DH] configure

• Use ffmpeg to edit metadata titles for multiple files

  19 mars 2017, par Nicholas Wireman

  I’d like to be able to add/edit video metadata titles to multiple files at once or with a single command, but I don’t know how to tell ffmpeg to do this.

  I read a similar post on the Ubuntu Forums, but I have never used string manipulation in Linux before, so the commands I’m seeing in the post are way out of my comprehension at the moment, and much of the discussion goes over my head.

  I’ve got all of my video files in a filename format that includes the show name, the episode number, and episode title. For example :

  show_name - episode_number - episode_title.extension

  Bleach - 001 - A Shinigami Is Born !.avi

  Is there a simple way to read the title and episode number from the filename and put it into a metadata tag without having to go through each and every file manually ?

  EDIT 1 : So I found out that I can iterate through files in a directory, and echo the filename, and I was told by a friend to try bash to parse the strings and return values from that to use in the ffmpeg command line. The problem is, I have absolutely no idea how to do this. The string manipulation in bash is very confusing on first look, and I can’t seem to get it to output what I want into my variables. My test bash :

   for file in "Bleach - 206 - The Past Chapter Begins! The Truth from 110 Years Ago.mkv"; do   extension=${file##*.} showName=${file%% *} episode=${file:9:3}; echo Extension: $extension Show: $showName Episode: $episode;    done

  That outputs

  Extension : mkv Show : Bleach Episode : 206

  Which are all the variables I’m going to need, I just don’t know how to move those to be run in ffmpeg now.

  EDIT 2 : I believe I was able, through much trial and error, to find a bash command that would do exactly what I wanted.

  for file in *; do   newname=${file:0:-4}_2 ext=${file##*.} filename=${file} showname=${file%% *} episode=${file:9:3} nameext=${file##*- } title=${nameext%.*};     ffmpeg -i "$filename" -metadata title="$title" -metadata track=$episode -metadata album=$showname -c copy "$newname.$ext";    mv -f "$newname.$ext" "$filename";    done

  This lets me parse the information from the filename, copy it to some variables, and then run ffmpeg using those variables. It outputs to a second file, then moves that file to the original location, overwriting the original. One could remove that section out if you’re not sure about how it’s going to parse your files, but I’m glad I was able to get a solution that works for me.

• Using ffmpeg to split video files by size

  8 juillet 2016, par user2548469

  I’m trying to write a batch file using ffmpeg to automate the redundant daily task of taking footage from work that’s recorded in 4gb blocks (which is standard in most DSLR cameras & GoPro’s), and split the clips into 2gb files for streaming purposes. The idea is to have the script check external drive FOOTAGE’s folder @import and split files after 2gb (since the max size is 4gb, this will alleviate the need for more than one split).

  I’m also trying to amend the filenames of the split files, so FILE1 is 4gb, it splits into FILE1_1 and FILE1_2 which are 2gb each, respectively. Everything I’ve tried has just copied the original file into two new, identical files - no split or anything.

  After doing some Googling and reading some of the answers here, I found this post, but it’s based on duration, not size (recording video footage at varying levels of quality makes this pointless) : Split into equal parts and convert many mp4 videos using ffmpeg

  Can someone help me with this ? I haven’t come across any usable solutions utilizing what I understand to be the method, using -fs limit_size, and I really want to understand how this works.

  UPDATE : Also found this, but it hasn’t been updated in four years and I don’t see anything in there regarding splitting that will prove helpful :

  https://github.com/kcm1700/VideoSplitter/blob/master/