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• Bitrate variation in x264 encode ? [closed]

  21 octobre 2012, par nightcrawler

  Under win732bit
  The following picture is the analysis of bitrateviewer from 2 different encodings :
  
  After learning a great deal I want to ask some basic questions

  • Are the jitters (huge variation of bitrate) in the encoded files
    (relative to original .wmv) usual or they refer to poor results ? (I
    used CBR this should have given me a nice smooth bitrate histogram ?)
  • Am I correct in setting level to 3.1 because this is enough to handle
    the input resolution & bitrate ?
    (http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Levels)
  • Would you recommend me for CBR(currently used at 23) or
    2pass(2500kb/s) or ABR(2500kb/s) for this file ? (I assume that the
    latter of the two will reduce jitters but increase filesize because
    bitrate is kept constant even in those frames where its not needed or
    willlnt produce influential results)
  • Provided that I want good result under 260mb what are the setting I
    have to use ?

• What parameter should use to create adaptive hls videos in different scale using ffmpeg and shaka packager for VOD streaming ?

  25 juin 2019, par Rahul

  I am trying to package HLS with shaka packager in a different scale from 144x256 to 1080x1920 for adaptive streaming using hevc, It is working fine, but Is there some more parameter required to put for good video quality and optimization.

  Below are the command I used :

  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=144:256 144_256_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=360:640 360_640_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=720:1280 720_1280_h265.mp4 -hide_banner
  
  
  
  ffmpeg -i original.mp4 -c:a aac -strict experimental -b:a 128k -c:v libx265 -vf scale=1080:1920 1080_1920_h265.mp4 -hide_banner
  
  
  
  HLS Packaging Using shaka packager.
  
  packager-osx in=144_256_h265.mp4,stream=audio,output=hls/audio.mp4,playlist_name=audio.m3u8,hls_group_id=audio,hls_name=ENGLISH in=144_256_h265.mp4,stream=video,output=hls/h265_144p.mp4,playlist_name=h265_144p.m3u8,iframe_playlist_name=h265_144p_iframe.m3u8 in=360_640_h265.mp4,stream=video,output=hls/h265_360p.mp4,playlist_name=h265_360p.m3u8,iframe_playlist_name=h265_360p_iframe.m3u8 in=720_1280_h265.mp4,stream=video,output=hls/h265_720p.mp4,playlist_name=h265_720p.m3u8,iframe_playlist_name=h265_720p_iframe.m3u8  in=1080_1920_h265.mp4,stream=video,output=hls/h265_1080p.mp4,playlist_name=h265_1080p.m3u8,iframe_playlist_name=h265_1080p_iframe.m3u8 --hls_master_playlist_output hls/h265_master.m3u8

• How can I amplify volume with Audacity and ffmpeg ?

  18 octobre 2019, par Christos Hayward

  I have an MP4 recording where the video is present, but much too quiet. What I’ve done before is :

  ffmpeg -i master.mp4 -i amplified.wav -vcodec copy output.mp4

  I’ve tried various permutations, and the output ffmpeg builds is, as viewed by my browser, at the original overly quiet volume. If I load the Audacity-generated .wav, it plays as loudly as intended. (N.B. I have enabled clipping in Audacity, and I have not noticed it to fail at the amplifications I’ve tried with it.) However, the final result seems to retain unaltered the original audio track along in the video.

  How, with present software or other software, can I assign amplified.wav to be the new audio track to master.mp4 in output.mp4 ?