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• ffmpeg status & quality / cuda (CPU/GPU)

  18 avril 2015, par cocco

  ffmpeg am i doing it right ?

  So much time has passed since i use ffmpeg to convert clips on my home web server, now that mp4 (h264 & aac) is the current overall standard (works on every console, smartphone, smartTV, pc) i decided to convert my old clips from various digital cameras to to this new container/codecs.

  1. less space & the same quality.
  2. compatibility
  3. support for tags (subler for mac)

  after some research i opted for ffmpeg because of various reasons

  1. commandline (i made my simple web interface with default settings wich i execute with php’s exec)
  2. the quality/size amount

  I read that many expensive video conversion softwares are not able to handle low bitrate videos properly. I also tested some of them and personally i could not find the proper export settings or i was not impressed by the results... some had fixed default export setings, most had a lower video quality at the same filesize. ffmpeg allows me to set the -crf (18-24 usually) and -preset (veryslow, fast..) witch allows me to reduce the filesize drastically mantaining the same
  visible quality.

  Said that i’m using the preset at veryslow.(there is also placebo but the final video file is only 1% smaller in size).

  And here is the command i use

  ffmpeg
  
  -y //overwrite the file if it exists
  
  
  
  -i INPUTFILE // replace with the input file
  
  
  
  -metadata title=THETITLE // set a nice title, visible on modern devices
  
  -metadata date=THEDATE // set a nice title, visible on modern devices
  
  
  
  -c:v libx264 // use the h264 codec
  
   -crf 21 // try different numbers between 18-26
  
   -preset veryslow // placebo,slow,fast,ultrafast==big file 
  
   -tune film // tune it a little
  
   -pix_fmt yuv420p // preferred on most modern devices
  
   -profile:v main // preferred on most modern devices
  
   -level 3.1 // preferred on most modern devices 
  
   -refs 4 // preferred on most modern devices
  
  
  
  -c:a libfdk_aac // use aac
  
   -metadata:s:a language=eng // set a language, visible on modern devices 
  
   -b:a 128k // audio bitrate 128k is like mp3 192k
  
   -ar 48000 // 44100 ... whatever
  
   -ac 2 // audiochannels
  
   -movflags +faststart //move the metadata in the front of the video so it loads faster
  
  
  
  OUTPUTFILE

  some camcorder clips with m2ts already have the avc/h264 compatible codec so i just copy the stream.
  some have the ac3/dolby sorround audio. I convert the audio but keep the ac3 as second audio track mapping the ffmpeg streams.this allows me to watch the mp4 on browsers and mobile devices but i’m able to keep the surround sound to playback on some tv’s, advanced media players or devices like apple tv.

  not that i’m not happy with the speed (using quad core’s) but i recently read again about cuda opencl and there is also the simple fact that i’m not using other converters than ffmpeg since alot of time.

  Is ffmpeg (with the setting i use) a good converter to keep the same video quality than the source reducing the space occupied by and average of 30-40% ?

  Is GPU conversion really that bad (cuda .. testing a gtx970) ?
  it would be nice to add some more speed to the conversions by using both the gpu and the cpu..but for my understanding they cannot work together ??? and using only gpu is a drastical quality loss...cpu si more precise, gpu is faster in calculation are too imprecise from what i read.. so expensive softwares use cuda only for preview purpose... right ?

  Is ffmpeg or another software compatible with CPU+GPU encoding ?
  i really don’t remember where, but i read that the ffmpeg is not a good videoconverter.

  i’m really happy with the size/quality, i gained an average of 30% in space with no visible quality loss. With some extra parameters i can adjust some really old analog videos that are deinterlaced in a really bad way.

  maybe i could gain more size/quality with another software ???

  note : i like ffmpeg.it’s free and it has commandline so i can create my own interface with php html & js and use it on various machines without the need to install it in every device i use. i uplad the idevice clips directly to the ffmpeg server.

  btw. : explain the downvotes...

  EDIT :

  @talonmies ...cuda tag removed :

  http://www.nvidia.com/object/cuda_home_new.html

  CUDA® is a parallel computing platform and programming model invented
  by NVIDIA. It enables dramatic increases in computing performance by
  harnessing the power of the graphics processing unit (GPU). With
  millions of CUDA-enabled GPUs sold to date, software developers,
  scientists and researchers are finding broad-ranging uses for GPU
  computing with CUDA. Here are a few examples : - See more at :
  http://www.nvidia.com/object/cuda_home_new.html#sthash.dEYaqae7.dpuf

  isn’t cuda the programming model that a theoretical ffmpeg library should support to handle GPU encoding on nvidia cards like the gtx 970 ?? like the badaboom software http://www.geforce.com/games-applications/pc-applications/badaboom-media-converter.

• automatically run script recording video at interval using command line and ffmpg

  29 décembre 2014, par arrie

  I’m really a beginner noob newbie command line noob. But. I’m trying to create a script that automatically starts my isight camera when turning on my mac laptop. It should create clips of about 5 seconds at an interval of 5 hours or so. (These numbers I can change of course later on if I have the basis for my script).

  So what I in fact need is (i think) a launch script, that launches a video recording script.

  Right now I’m as far as my video recording script, which is not finished : camera.sh

  #!/bin/bash
  
  
  
  FNAME=videocapture_`date +"%F_%H_%M"`.mpg
  
  echo $FNAME
  
  
  
  ffmpeg -f -t "0.20avfoundation -i "" $FNAME

  ---

  This in fact records a video when I play the script in the command line, until I tell it to quit. These videos are then named according to the date etc. But of course I want it to automatically record videos, in an already determined duration. And I just can’t seem to figure out how to make it happen. I come back to different kind of scripts using isight capture, which in fact doesn’t seem to exist anymore, and even so, I would like to stay with my own basis script just because I understand it haha.

  Hopefully someone here can help me figure this out ! Much appreciated :) Thanks !

• Generating random thumbnails with PHP+FFMPEG

  30 décembre 2014, par MrGhost

  I’m trying to generate thumbnails from random points in a movie using FFMPEG and FFMPEG-PHP extension.

  My script works OK.. however takes 20 minutes just to generate 5-10 thumbnails !!

  The script works by generating random numbers which are used as frame numbers later. All numbers generated are within the movies frame count.

  Can you work out why this script is taking 20 mins to finish ?
  If not, a better solution ?

  <?php
  
  
  
  //Dont' timeout
  
  set_time_limit(0);
  
  
  
  //Load the file (This can be any file - still takes ages) 
  
  $mov = new ffmpeg_movie('1486460.mp4');
  
  
  
  //Get the total frames within the movie
  
  $total_frames = $mov->getFrameCount();
  
  
  
  //Loop 5-10 times to generate random frames 5-10 times
  
  for ($i = 1; $i <= 5; ) {
  
      // Generate a number within 200 and the total number of frames.
  
   $frame = mt_rand(200,$total_frames);
  
   $getframe = $mov->getFrame($frame);
  
   // Check if the frame exists within the movie
  
   // If it does, place the frame number inside an array and break the current loop
  
   if($getframe){
  
    $frames[$frame] = $getframe ;
  
    $i++;
  
   }
  
  }
  
  
  
  //For each frame found generate a thumbnail
  
  foreach ($frames as $key => $getframe) {
  
   $gd_image = $getframe->toGDImage();
  
   imagejpeg($gd_image, "images/shot_".$key.'.jpeg');
  
   imagedestroy($gd_image);
  
   echo $key.'<br />';
  
  }
  
  
  
  ?>

  The script SHOULD be generating frame numbers which are valid ? Anything within START - END should be valid frame numbers ? Yet the loop takes ages !