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• Prevent ffmpeg from changing the intensity of colors while downscaling the resolution of the video

  29 août 2022, par dravit

  I have a use case where I need to downscale a 716x1280 mp4 video to 358x640 (half of the original). Command that I used is

  


  ffmpeg -i ./input.mp4 -vf "scale=640:640:force_original_aspect_ratio=decrease,pad=ceil(iw/2)*2:ceil(ih/2)*2" ./output.mp4


  


  Out of 10 sample videos, 2 of the them suffered impact on colors. Below I have attached a comparison from the one which was impacted the most.

  


  

  


  NOTE : The one on the right is a frame from the original video and the frame on the left is the one from the processed (down scaled) video. Notice the colors red and green in the image (even the skin color and hair color were changed).

  


  What I am looking for is

  


  

  • Is there any way I can prevent changes like these happening ? Probably some flag on saturation, brightness, contrast or any other parameter.

  


  • I am assuming that ffmpeg uses some default settings while downscaling a video. What made ffmpeg change colors only for these two videos ? If it made similar changes for the rest of the videos as well, how to predict this behaviour before hand ?

  


  


  EDIT :

  


  What I already have Tried ?

  


  

  • -crf with values 0 and 18.

  


  • -preset veryslow as mentioned here

  


  


  None helped

  


  Mediainfo input V/S output

  


  





  


  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  param	input	output
  color range	Limited	NA (attribute not in description)
  color primaries	BT.2020	NA (attribute not in description)
  transfer characteristics	HLG	NA (attribute not in description)
  matrix coefficients	BT.2020 non-constant	NA (attribute not in description)
  bit deapth	8	8

  


  


  Logs of the ffmpeg command

  


  ffmpeg -i ./input.mp4 -vf "scale=640:640:force_original_aspect_ratio=decrease,pad=ceil(iw/2)*2:ceil(ih/2)*2" -movflags +faststart ./output.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.28)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './input.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
  Duration: 00:00:30.05, start: 0.000000, bitrate: 10366 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt2020nc/bt2020/arib-std-b67), 716x1280, 10116 kb/s, 30 fps, 30 tbr, 19200 tbn, 38400 tbc (default)
    Metadata:
      handler_name    : Core Media Video
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 245 kb/s (default)
    Metadata:
      handler_name    : Core Media Audio
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x7faab4808800] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7faab4808800] profile High, level 3.0, 4:2:0, 8-bit
[libx264 @ 0x7faab4808800] 264 - core 161 r3027 4121277 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to './output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 358x640, q=-1--1, 30 fps, 15360 tbn, 30 tbc (default)
    Metadata:
      handler_name    : Core Media Video
      encoder         : Lavc58.91.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : Core Media Audio
      encoder         : Lavc58.91.100 aac
[mp4 @ 0x7faab5808800] Starting second pass: moving the moov atom to the beginning of the file
frame=  901 fps=210 q=-1.0 Lsize=    3438kB time=00:00:30.02 bitrate= 938.0kbits/s speed=7.01x
video:2933kB audio:472kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.974633%
[libx264 @ 0x7faab4808800] frame I:6     Avg QP:22.60  size: 20769
[libx264 @ 0x7faab4808800] frame P:228   Avg QP:24.84  size:  7657
[libx264 @ 0x7faab4808800] frame B:667   Avg QP:27.59  size:  1697
[libx264 @ 0x7faab4808800] consecutive B-frames:  0.9%  0.9%  1.0% 97.2%
[libx264 @ 0x7faab4808800] mb I  I16..4:  9.5% 64.6% 26.0%
[libx264 @ 0x7faab4808800] mb P  I16..4:  2.5% 12.2%  2.5%  P16..4: 37.2% 20.6% 11.2%  0.0%  0.0%    skip:13.7%
[libx264 @ 0x7faab4808800] mb B  I16..4:  0.4%  2.1%  0.2%  B16..8: 42.2%  7.1%  1.2%  direct: 1.8%  skip:44.9%  L0:39.4% L1:52.8% BI: 7.8%
[libx264 @ 0x7faab4808800] 8x8 transform intra:72.2% inter:74.2%
[libx264 @ 0x7faab4808800] coded y,uvDC,uvAC intra: 61.8% 67.2% 20.2% inter: 16.7% 13.9% 1.3%
[libx264 @ 0x7faab4808800] i16 v,h,dc,p: 24% 19%  7% 50%
[libx264 @ 0x7faab4808800] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 16% 15%  6%  9% 11%  7% 10%  6%
[libx264 @ 0x7faab4808800] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 16% 13%  7%  9% 10%  7%  9%  4%
[libx264 @ 0x7faab4808800] i8c dc,h,v,p: 53% 16% 26%  5%
[libx264 @ 0x7faab4808800] Weighted P-Frames: Y:3.9% UV:1.8%
[libx264 @ 0x7faab4808800] ref P L0: 57.8% 19.5% 14.8%  7.8%  0.1%
[libx264 @ 0x7faab4808800] ref B L0: 90.7%  7.2%  2.1%
[libx264 @ 0x7faab4808800] ref B L1: 95.3%  4.7%
[libx264 @ 0x7faab4808800] kb/s:799.80
[aac @ 0x7faab2036a00] Qavg: 189.523


  


• arm : vp9itxfm : Do a simpler half/quarter idct16/idct32 when possible

  22 novembre 2016, par Martin Storsjö

  arm : vp9itxfm : Do a simpler half/quarter idct16/idct32 when possible
  This work is sponsored by, and copyright, Google.
  This avoids loading and calculating coefficients that we know will
  
  be zero, and avoids filling the temp buffer with zeros in places
  
  where we know the second pass won’t read.
  This gives a pretty substantial speedup for the smaller subpartitions.
  The code size increases from 12388 bytes to 19784 bytes.
  The idct16/32_end macros are moved above the individual functions ; the
  
  instructions themselves are unchanged, but since new functions are added
  
  at the same place where the code is moved from, the diff looks rather
  
  messy.
  Before :                              Cortex A7       A8       A9      A53
  
  vp9_inv_dct_dct_16x16_sub1_add_neon :     273.0    189.5    212.0    235.8
  
  vp9_inv_dct_dct_16x16_sub2_add_neon :    2102.1   1521.7   1736.2   1265.8
  
  vp9_inv_dct_dct_16x16_sub4_add_neon :    2104.5   1533.0   1736.6   1265.5
  
  vp9_inv_dct_dct_16x16_sub8_add_neon :    2484.8   1828.7   2014.4   1506.5
  
  vp9_inv_dct_dct_16x16_sub12_add_neon :   2851.2   2117.8   2294.8   1753.2
  
  vp9_inv_dct_dct_16x16_sub16_add_neon :   3239.4   2408.3   2543.5   1994.9
  
  vp9_inv_dct_dct_32x32_sub1_add_neon :     758.3    456.7    864.5    553.9
  
  vp9_inv_dct_dct_32x32_sub2_add_neon :   10776.7   7949.8   8567.7   6819.7
  
  vp9_inv_dct_dct_32x32_sub4_add_neon :   10865.6   8131.5   8589.6   6816.3
  
  vp9_inv_dct_dct_32x32_sub8_add_neon :   12053.9   9271.3   9387.7   7564.0
  
  vp9_inv_dct_dct_32x32_sub12_add_neon :  13328.3  10463.2  10217.0   8321.3
  
  vp9_inv_dct_dct_32x32_sub16_add_neon :  14176.4  11509.5  11018.7   9062.3
  
  vp9_inv_dct_dct_32x32_sub20_add_neon :  15301.5  12999.9  11855.1   9828.2
  
  vp9_inv_dct_dct_32x32_sub24_add_neon :  16482.7  14931.5  12650.1  10575.0
  
  vp9_inv_dct_dct_32x32_sub28_add_neon :  17589.5  15811.9  13482.8  11333.4
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :  18696.2  17049.2  14355.6  12089.7
  After :
  
  vp9_inv_dct_dct_16x16_sub1_add_neon :     273.0    189.5    211.7    235.8
  
  vp9_inv_dct_dct_16x16_sub2_add_neon :    1203.5    998.2   1035.3    763.0
  
  vp9_inv_dct_dct_16x16_sub4_add_neon :    1203.5    998.1   1035.5    760.8
  
  vp9_inv_dct_dct_16x16_sub8_add_neon :    1926.1   1610.6   1722.1   1271.7
  
  vp9_inv_dct_dct_16x16_sub12_add_neon :   2873.2   2129.7   2285.1   1757.3
  
  vp9_inv_dct_dct_16x16_sub16_add_neon :   3221.4   2520.3   2557.6   2002.1
  
  vp9_inv_dct_dct_32x32_sub1_add_neon :     753.0    457.5    866.6    554.6
  
  vp9_inv_dct_dct_32x32_sub2_add_neon :    7554.6   5652.4   6048.4   4920.2
  
  vp9_inv_dct_dct_32x32_sub4_add_neon :    7549.9   5685.0   6046.9   4925.7
  
  vp9_inv_dct_dct_32x32_sub8_add_neon :    8336.9   6704.5   6604.0   5478.0
  
  vp9_inv_dct_dct_32x32_sub12_add_neon :  10914.0   9777.2   9240.4   7416.9
  
  vp9_inv_dct_dct_32x32_sub16_add_neon :  11859.2  11223.3   9966.3   8095.1
  
  vp9_inv_dct_dct_32x32_sub20_add_neon :  15237.1  13029.4  11838.3   9829.4
  
  vp9_inv_dct_dct_32x32_sub24_add_neon :  16293.2  14379.8  12644.9  10572.0
  
  vp9_inv_dct_dct_32x32_sub28_add_neon :  17424.3  15734.7  13473.0  11326.9
  
  vp9_inv_dct_dct_32x32_sub32_add_neon :  18531.3  17457.0  14298.6  12080.0
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavcodec/arm/vp9itxfm_neon.S

• 400 Bad Request Error uploading paperclip videos

  5 mars 2017, par jalen201

  Im trying to upload videos with paperclip. When i hit the submit button i receive.

  RSolr::Error::Http - 400 Bad Request Error: 

  this is the migration

  class AddAttachmentVideoToPins < ActiveRecord::Migration
  
    def self.up
  
      change_table :pins do |t|
  
        t.attachment :video
  
      end
  
    end
  
  
  
    def self.down
  
      remove_attachment :pins, :video
  
    end
  
  end

  Heres the model

  class Pin < ApplicationRecord
  
    acts_as_votable
  
    belongs_to :user
  
    has_many :comments
  
  
  
    searchable do
  
      text :title, :boost => 5
  
      text :description
  
    end
  
  
  
    has_attached_file :image, styles: {medium: "300x300>" }
  
    validates_attachment_content_type :image, content_type: /\Aimage\/.*\z/
  
  
  
    has_attached_file :video, styles: {
  
      :medium => {
  
        :geometry => "640x480",
  
        :format => 'mp4'
  
      },
  
      :thumb => { 
  
        :geometry => "160x120", :format => 'jpeg', :time => 10 
  
      }
  
    },
  
    :processors => [:transcoder]
  
  
  
    validates_attachment_content_type :video, content_type:  /\Avideo\/.*\Z/

  also i added these 4 gems, and installed ffmpeg with homebrew

      gem 'paperclip', '~> 5.1'
  
  
  
      gem 'aws-sdk', '~> 2.8'
  
  
  
      gem 'paperclip-av-transcoder', '~> 0.6.4'
  
  
  
      gem 'paperclip-ffmpeg', '~> 1.2'

  lastly this is my controller, i added :video as a strong parameter.

  class PinsController < ApplicationController
  
  
  
    before_action :find_pin, only: [:show,:edit,:update,:destroy, :upvote]
  
    before_action :authenticate_user!, except: [:index,:show]
  
  
  
    def index
  
      @search = Pin.search do
  
        fulltext params[:search]
  
      end
  
      @pins = @search.results
  
    end
  
  
  
    def new
  
      @pin = current_user.pins.build
  
    end
  
  
  
    def show
  
      @comments = Comment.where(pin_id: @pin).order('created_at DESC')
  
    end
  
  
  
    def edit
  
      @lookup = User.all
  
    end
  
  
  
    def profile
  
      @users = User.all
  
      if User.find_by_username(params[:id])
  
        @username = params[:id]
  
        @user = User.find_by_username(params[:id])
  
      else
  
        redirect_to root_path
  
      end
  
      @user_pin = Pin.all.where('user_id = ?',       User.find_by_username(params[:id]).id)
  
    end
  
  
  
    def update
  
      if @pin.update(pin_params)
  
        redirect_to @pin, notice: "Pin was succesfully updated"
  
      else
  
        render 'edit'
  
      end
  
    end
  
  
  
    def destroy
  
      @pin.destroy
  
      redirect_to root_path       
  
    end
  
  
  
    def upvote
  
      @pin.upvote_by current_user
  
      redirect_to :back
  
    end
  
  
  
    def create
  
      @pin = current_user.pins.build (pin_params)
  
  
  
      if @pin.save
  
        redirect_to @pin , notice: "Succesfully created new pin"
  
      else
  
        render 'new'
  
      end
  
    end
  
  
  
    private
  
  
  
    def pin_params
  
      params.require(:pin).permit(:title, :description, :image, :video)
  
    end
  
  
  
    def find_pin
  
      @pin = Pin.find(params[:id])
  
    end
  
  end

  i added this in the view

  <%= video_tag @pin.video.url(:medium), controls: true, style: "max-width: 100%;" %>

  If anyone could help that would be greatly appreciated