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• how to prevent FFMPEG from increasing the video size ?

  28 juin 2018, par drexdelta

  My aim is to compress the video and reduce its file size.

  ffmpeg -i input.mp4 -crf 28 output.mp4

  Now, this command, increases the size of the given input file. And on the otherside, quality of the video is same as earlier. So, it’s increasing the space for nothing.

  How can I stop this from happening .

  This is original video (size 9.5 MB) , and this is the compressed video (size 13.2 MB) .

  So, I want to know, if it is possible to detect using ffmpeg, whether the size of the final video will increase or not ?

  FYI : I am writing script. I am not planning to change the CRF factor. Because that will damage quality of other good videos.

  These are the details on my ffmpeg version :

  ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with Apple LLVM version 9.1.0 (clang-902.0.39.1)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/4.0 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-ffplay --enable-frei0r --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-librtmp --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-libopenjpeg --disable-decoder=jpeg2000 --extra-cflags=-I/usr/local/Cellar/openjpeg/2.3.0/include/openjpeg-2.3 --enable-nonfree
  
    libavutil      56. 14.100 / 56. 14.100
  
    libavcodec     58. 18.100 / 58. 18.100
  
    libavformat    58. 12.100 / 58. 12.100
  
    libavdevice    58.  3.100 / 58.  3.100
  
    libavfilter     7. 16.100 /  7. 16.100
  
    libavresample   4.  0.  0 /  4.  0.  0
  
    libswscale      5.  1.100 /  5.  1.100
  
    libswresample   3.  1.100 /  3.  1.100
  
    libpostproc    55.  1.100 / 55.  1.100

  ---

  Found something here :

  "The only downside with this mode is that you don’t know what the resulting file size or the fluctuation of the bitrate will be." . checkout here

• How to livestream a webcam to YouTube with FFmpeg ?

  6 juillet 2023, par pkok

  I want to send the livestream of my webcam to YouTube. I can follow YouTube's guide up to step 8. "Stream Connection" tells me there is "No data" and the button "Go Live" remains unclickable. A screenshot of this situation can be seen at

  



  

  



  As encoding software, I was planning on using FFmpeg because it can run from the target platform, a Raspberry Pi with Raspbian. A USB webcam supported by video4linux2 is used.

  



  FFmpeg's wiki shows that streaming a file can be done with the following :

  



  ffmpeg -re -i input.mkv \&#xA;-c:v libx264 -preset veryfast -maxrate 3000k \&#xA;-bufsize 6000k -pix_fmt yuv420p -g 50 -c:a aac -b:a 160k -ac 2 \&#xA;-ar 44100 -f flv rtmp://live.twitch.tv/app/<stream key="key">&#xA;</stream>

  



  I modified this command in the following ways :
1. It takes the video stream from the webcam with -f v4l2 -i /dev/video0.
2. It does not broadcast any audio with -an.
3. It broadcasts to YouTube's RTMP server, rtmp://a.rtmp.youtube.com/live2/<stream key="key"></stream>

  



  The final version of the command is now :

  



  RTMP_URL="rtmp://a.rtmp.youtube.com/live2"
STREAM_KEY="secr-etse-cret-secr"
OUTPUT=$RTMP_URL/$STREAM_KEY
ffmpeg -re -f v4l2 -i /dev/video0 \
-c:v libx264 -preset veryfast -maxrate 3000k \
-bufsize 6000k -pix_fmt yuv420p -g 50 -an \
-f flv $OUTPUT


  



  When I run this command, I would expect that "Stream connection" would change to something else than "No data" after a few seconds, but that does not happen.

  



  I have tried recording the stream to a local file with :

  



  ffmpeg -re -f v4l2 -i /dev/video0 \
-c:v libx264 -preset veryfast -maxrate 3000k \
-bufsize 6000k -pix_fmt yuv420p -g 50 -an \
-f flv test.flv


  



  This worked fine. That demonstrates to me that the issue is with getting the video stream accepted by YouTube.

  


• Revision 87599 : $GLOBALS[’visiteur_session’] au lieu de global $auteur_session ; et ...

  22 février 2015, par kent1@… — Log

  $GLOBALSvisiteur_session ? au lieu de global $auteur_session ; et $auteur_session
  Indentation / Formatage