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• FFMpeg and max bitrate

  26 septembre 2019, par Aurelien Stride

  For a personal project, using AV1 codec, I have a bitrate constraint for a video to 88kbps, with choosen video bitrate at 66kbps and mono audio bitrate at 22kbps.

  I currently use this command :

  ffmpeg -i input.mp4 -c:v libaom-av1 -strict -2 -b:v 66150 -c:a libfdk_aac -ar 22050 -b:a 22050 -ac 1 -maxrate 66150 -bufsize 66150 -vf scale=720:-1 -movflags +faststart output.mp4

  However, my final video has a 95kbps bitrate :

  Duration : 00:01:09.73, start : 0.000000, bitrate : 95 kb/s

  Stream #0:0(und) : Video : av1 (Main) (av01 / 0x31307661), yuv420p(tv, progressive), 720x302, 69 kb/s, 24 fps, 24 tbr, 12288 tbn, 12288 tbc (default)

  Stream #0:1(und) : Audio : aac (LC) (mp4a / 0x6134706D), 22050 Hz, mono, fltp, 22 kb/s (default)

  Is there a method to validate my need ? Is it normal that 66+22>88kbps ?

  Regards,

  EDIT 1 : as @Gyan suggested, I’ve tried to reduce -bufsize parameter, but I still have a too high bitrate. The most working way is to set video bitrate -b:v to 50kbps, but it gives poorer image...

  ffmpeg -i input.mp4 -c:v libaom-av1 -strict -2 -b:v 50k -c:a libfdk_aac -ar 22050 -b:a 22050 -ac 1 -minrate 33075 -maxrate 66150 -bufsize 44100 -vf scale=-1:360 -movflags +faststart -threads 1 output.mp4

  Any idea to limit overhead, if overhead is in cause ?

• Is it possible to determine if a subtitle track is imaged based or text based with ffprobe

  21 février 2021, par Shex

  I'm writing a script that burns subtitles into video files to prepare them for a personal stream I'm hosting. I'm having a hard time finding which type of subtitle is used in the file. I use ffprobe to get the files' information, and I can get stuff like the codec type, but I was wondering if there is a way to determine if a subtitle track is image based or text based. I can only think of getting a list of all possible codecs and match the codec type with this list but it would be very useful to have an info somewhere that can tell me "OK this is an image-based subtitle track", as when I burn I cannot use the same filters with ffmpeg to burn image vs. text subtitles.

  


• Convert file with any extension to MP4 with ffmpeg

  15 novembre 2019, par not legit

  I am using youtube-dl and ffmpeg to create a youtube downloader and converter (for personal use). I am trying to download a video and convert it to MP4.

  The problem I have, is that youtube-dl downloads the video in a variety of formats. Is there a way that I can download the video and then tell FFMPEG to convert it, not knowing the current file type ?

  I tried using a * wild card but that results in an error.

  @echo off
  
  title youtube downloader
  
  
  
  set /p name= URL: 
  
  echo Select a type. (vid/mp3/mp4)
  
  set /p type=
  
  
  
  IF /i "%type%"=="vid" goto vid
  
  IF /i "%type%"=="mp3" goto mp3
  
  IF /i "%type%"=="mp4" goto mp4
  
  
  
  :vid
  
  youtube-dl %name%
  
  goto commonexit
  
  
  
  :mp3
  
  youtube-dl -x --audio-format mp3 %name%
  
  goto commonexit
  
  
  
  :mp4
  
  youtube-dl -o video %name%
  
  ffmpeg -i video.* video.mp4 -hide_banner
  
  
  
  :commonexit
  
  pause