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• What is this "fixing the build scripts" for compiling x264 ?

  29 mai 2020, par Blake Senftner

  I am trying to compile an all static build of source-customized ffmpeg libraries with the additional codecs from VideoLAN, such as their x264 codec. I am ultimately building for use in Windows with Visual Studio 2015 C++, so I am comparing a few compiling guides for my instructions.

  



  In the guide linked below (I located via Google searches) shows how to compile x264 with the VS2015 toolchain in MSYS2 without any special steps :
https://gist.github.com/RangelReale/3e6392289d8ba1a52b6e70cdd7e10282

  



  While in this other guide, offered by the compiling guide pages from ffmpeg's web site, it includes steps for "fixing the build scripts" for x264 :
https://www.roxlu.com/2019/062/compiling-ffmpeg-with-x264-on-windows-10-using-msvc

  



  Problem being, when I "fix the build scripts" the configure script no longer finds a C compiler. Building with the first guide seems to work, but it was also written nearly 2 years ago, so perhaps the ffmpeg guide is doing some important fix ? I don't know.

  



  I am :

  



  

  1. Running a "VS2015 x64 Native Tools Command Prompt"

  


  2. launching a pacman loaded msys2 shell via "msys2_shell.cmd -mingw64 -use-full-path"

  


  3. git cloning http://git.videolan.org/git/x264.git

  


  



  and at this point the two compiling guides vary, the first guide just cd's into x264 and runs configure while the other guide does some curl download of a config.guess file and then some sed manipulation of ./configure. Considering these instructions are "endorsed" by the ffmpeg site, I am left wondering what that is doing and how critical is it that these "special" steps cause my x264 configure to fail.

  


• There are audio gaps when I join multiple .ts files into a single .mp4 file

  2 juin 2020, par woopwoop399

  After I merge multiple .ts files into a single .mp4 file, when I play this file, I hear short gaps in audio. The gap happens always at same places, but has only about 50% chance of happening, it feels like video player doesn't manage to decode something in time. This gap happens when I play the file with mpc-hc videoplayer, but doesn't happen with vlc player. I'd switch, but mpc-hc worked flawlessly for every file I opened so far for years, so I think the .mp4 file is somehow malformed.

  



  I used this command ffmpeg -f concat -safe 0 -i mylist.txt -c copy sm22413936-ts.mp4, all necessary files are here https://files.catbox.moe/9cl0pm.zip

  



  I asked about this here previously https://superuser.com/questions/1520894/there-are-audio-gaps-when-i-join-multiple-ts-files-into-a-single-mp4-file , but first solution required reencoding, and my solution caused desync really noticeable on long videos.

  



  I suspect that this .mp4 is muxed wrong or something, maybe I need to remux it somehow.

  


• ffmpeg resulting in no audio and unplayble video

  9 juillet 2020, par Chris James Champeau

  I am trying to get ffmpeg to work as expected however I am having all kinds of trouble getting it to work.

  


  I need to output a webm and h264 for web play. However, the command I am using, while it used to work a few years ago, does not work at all now.

  


  Both my webm and h264 do not have audio, and neither will play in any browser.

  


  My command for webm is :

  


  ffmpeg -y -i "$KMVAR_File" -c:v libvpx -crf 24 -b:v 1000k -vf scale=720:-2 -c:a libvorbis "$KMVAR_webmPath"


  


  and my command for mp4 is :

  


  ffmpeg -y -i "$KMVAR_File" -c:v libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -crf 32 -b:v 1M -minrate 1M -maxrate 1M -bufsize 2M -vf scale=720:-2 -c:a aac -strict experimental -movflags +faststart "$KMVAR_mp4Path"