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• How to force "full range" flag on export

  28 janvier 2019, par Emanuele Vissani

  I have an ffmpeg command to remap audio tracks to descrete channels in a ProRes 4444 quicktime file. Even if the input video is copied to the output, the exported file is interpreted by a professional video player software as video range (16-234 values) instead of the original full range (0-255 values), making it look more contrasted.
  The content is actually correct, changing manually the range setting in the player software gives back the right light range, so I think the output file just lose some kind of range flag.

  I already tried the following options without results :

  -colorspace bt709 -movflags +write_colr

  -dst_range 1 -color_range 2

  -vf scale=out_range=full

  -vf scale=in_range=full:out_range=full

  Original command is :

  ffmpeg -i F:\_IMPORT\TST_ProRes4444_4k.mov -map 0:0 -c copy -map 0:1 -c copy -map_channel 0.2.0:0.2 -c:a pcm_s24le F:\_EXPORT\TEST\test.mov

  Thank you for your help.

• Node.js Stream Mp3 to http without having to save file

  10 janvier 2019, par user2758113

  I am trying to stream just audio from a youtube link straight to http with node.js.

  My code looks like this, I am using express 4.0.

  var express = require('express');
  
  var router = express.Router();
  
  var ytdl = require('ytdl');
  
  var ffmpeg = require('fluent-ffmpeg');
  
  var fs = require('fs');
  
  
  
  router.get('/', function(req, res) {
  
  
  
    var url = 'https://www.youtube.com/watch?v=GgcHlZsOgQo';
  
    var video = ytdl(url)
  
  
  
    res.set({
  
        "Content-Type": "audio/mpeg"
  
    })
  
  
  
    new ffmpeg({source: video})
  
        .toFormat('mp3')
  
        .writeToStream(res, function(data, err) {
  
          if (err) console.log(err)
  
        })
  
  
  
  });
  
  
  
  module.exports = router;

  Now, I’m able to stream the video’s audio to the response if I save the file then pipe it to the response, but I’d rather try to figure out some way to go from downloading to ffmpeg to response.

  Not sure if this is possible. The main goal is to keep it as light weight as possible, and not have to read from files.

  I’ve seen this code which is essentially what I’d like to do minus the saving to a file part.

  

• FFMPEG - What are some recommended parameters for x265 (libx265) ?

  7 janvier 2019, par dd_code

  I am working on re-encoding some footage (x264), including some grainy footage. I am interested in CRF-only bitrate management (I want to avoid artifacts during demanding scenes).
  What are recommended parameters to be set instead of leaving them at their defaults ?

  Here is what I got so far, pretty simple :

  ffmpeg -i in.mkv -vf unsharp=3:3:1 -c:v libx265 -tune:v grain -crf 24 -c:a copy out.mkv

  (this example has grain tune as many files are grainy, and without it it washes it out and all the "detail by noise" is lost + I am applying a light sharpening filter, I find there is always a room to sharpen a bit without causing noticeable sharpening artifacts)

  If I am not mistaken all the params one does consider are ones contained in the presets, but is there some other or one of those which is a good practice to adjust manually to achieve a better result ? I was wondering specifically about P,I,B-frames and AQ (but I guess there are some other as well).