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• ffmpeg for loop into bash script

  18 mars 2015, par gaz

  I use a for loop on the mac command line to convert a bunch of avi’s to mp4’s
  I would like to put this into a bash script so I can just run the script on any given directory.

  e.g shelf script name [directory

  and let it do its thing.

  Do I just open a text editor and add

  #!/bin/bash

  then my for loop and ffmpeg arguments
  then end it all with
  fi ?

  Then make it executable ? Is is that simple.

  @Robert Rowntree

  Many thanks for the link. This looks like it could be very useful to me. I am not familiar with the concatenate so I would have never found that information.

  It appears that I can give ffmpeg a bunch of files at the command line or to read from a text file and ffmpeg will output them all into a single format, In my case MP4’s. Well at least this is what I think it does.

  The "The inputs have to be of the same frame size, and a handful of other attributes have to match" worries me a bit, do i need to check the frame rate of every movie to ensure they all match ?

  My ultimate goal would be to run a script on say, 30 mixed video files, avi, wmv, mkv, mpg etc and output the lot to mp4, but I think this is way too complicated for me.

  I normally just repack mkv’s to mp4 and the quality and size are good and I’m pleased with the results and speed. However, I tried just repacking a the aforementioned avi’s and the quality was poor and pixelated. I searched around and finally found this example ;

  ffmpeg -i input.avi -c:v libx264 -crf 19 -preset slow -c:a aac -strict experimental -b:a 192k -ac 2 out.mp4 (can this be improved ? Sped up ?)

  Which produces great quality mp4 files from the avi’s I have got but does take a long time. Hence why I originally asked for help creating a script. Which I intended running on the folder of avi’s.

  Be great to be able just to run a script on every non mp4 files and have great results every time :) But with different codecs and frame rates etc etc I suppose this will never be possible.

  Any further help or input will be greatly received.

  Thanks again.

• ffmpeg conversion command to output to h.264 for iPad

  23 juin 2016, par janet-PCF

  I’m looking for a good (general) conversion command that will convert any input file to h.264 sized for the iPad.

  Currently I have this command that works, that was adapted from robert.swain

  With presets :

  $ ffmpeg -i INPUT -acodec aac -ab 160000 -s 1024x768 -vcodec libx264 \
  
           -vpre slow -vpre ipod640 -b 1200kb -threads 0 -f mp4 OUTPUT.mp4

  Long form, no presets :

  $ ffmpeg -i INPUT -acodec aac -ab 160000 -s 1024x768 -vcodec libx264 \
  
           -coder 1 -flags +loop -cmp +chroma \
  
           -partitions +parti8x8+parti4x4+partp8x8+partb8x8 -me_method umh \
  
           -subq 8 -me_range 16 -g 250 -keyint_min 25 -sc_threshold 40 \
  
           -i_qfactor 0.71 -b_strategy 2 -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 \
  
           -bf 3 -refs 5 -directpred 3 -trellis 1 \
  
           -flags2 +bpyramid+mixed_refs+wpred+dct8x8+fastpskip -wpredp 2 \
  
           -rc_lookahead 50 -coder 0 -bf 0 -refs 1 -flags2 -wpred-dct8x8 \
  
           -level 30 -maxrate 10000000 -bufsize 10000000 -wpredp 0 -b 1200k \
  
           -threads 0 -f mp4 OUTPUT.mp4

  Note : I’m skipping the aspect ratio because we handle that in the program, and we only resize it if the input resolution is greater than the output resolution.

  If there’s any suggestions for improvement, we are looking to balance speed, quality and conversion time.

• How to encode jpeg images to H264 very fast (transform images to video)

  17 juillet 2013, par Paul

  I have 30 JPEG images (.jpg) at a resolution of 480 x 640.
  Each image takes aboout 20KB (all of them takes about 600KB).

  I am using FFmpeg command to encode these images into a video in H264 format.

  I need this to be done very fast - about 1 second.

  Using the classic command :

  ffmpeg -y  -f  image2   -r 1/5   -i image_%d.jpg   -c:v libx264   -r 30   video.mp4

  takes about 90 seconds.

  After adding -preset ultrafast :

  ffmpeg -y  -f  image2   -r 1/5   -i image_%d.jpg   -c:v libx264   -preset ultrafast    -r 30   video.mp4

  the encoding takes about 15 seconds which is much better, but still not enough

  I've tried others parameters also, like :

  -profile:v baseline
  
  
  
  -qscale:v
  
  
  
  -b:v 1000k
  
  
  
  -crf 24

  but the encoding time does not fall below 10 seconds.

  I'm not familiar with FFmpeg commands nor with the parameters I need to use, and this is the reason I post here this question.

  The video quality needs to be ok, doesn't need to be perfect.

  As a note : I am running these commands in an Android application where I have the ffmpeg executable, using an ProcessBuilder.

  Reply1 (to Robert Rowntree) :

  ArrayList<string> l2 = new ArrayList<string>();
  
  
  
          //l2.add("ffmpeg");
  
          l2.add("/data/data/" + packageName + "/ffmpeg");
  
          l2.add("-y");
  
          l2.add("-loop");
  
          l2.add("1");
  
  
  
          l2.add("-i");
  
          l2.add("frame_%d.jpg");
  
  
  
  //            l2.add("-t");
  
  //            l2.add(strngs[3]);
  
  
  
          l2.add("-r");
  
          l2.add("1/2");
  
          l2.add("-preset");
  
          l2.add("superfast");
  
          l2.add("-tune");
  
          l2.add("zerolatency");
  
  
  
  //            l2.add("-pass");
  
  //            l2.add(Integer.valueOf(pass).toString());
  
  
  
          l2.add("-vcodec");
  
          l2.add("libx264");
  
          l2.add("-b:v");
  
          l2.add("200k");
  
          l2.add("-bt");
  
          l2.add("50k");
  
          l2.add("-threads");
  
          l2.add("0");
  
          l2.add("-b_strategy");
  
          l2.add("1");
  
  
  
  //            if(pass ==1){
  
  //                l2.add("-an");
  
  //            } else {
  
  //                l2.add("-acodec");
  
  //                l2.add("copy");
  
  //            }
  
  
  
          l2.add("-f");
  
          l2.add("mp4");
  
          l2.add("-strict");
  
          l2.add("-2");
  
  //            l2.add("-passlogfile");
  
  //            l2.add(strngs[4]);
  
  
  
  //            if(pass ==1){
  
  //                l2.add("/dev/null");
  
  //            } else {
  
  //                l2.add(strngs[5]);
  
  //            }
  
  
  
          l2.add("video.mp4");
  
          //return l2;
  
  </string></string>