Sur d’autres sites (9902)

• Changing resolution mid-video with FFMPEG

  16 juillet 2016, par kingrolo

  I have a source video (mpeg2video) which I’m transcoding to x264. The source contains 2 different programs recorded from TV. One is in 4:3 AR and the other 16:9 AR. When I play the source file through VLC the player correctly changes size to show the video at the correct AR. So far so good.

  When I transcode the conversion process auto detects the AR from the first few frames and then transcodes the whole video using this AR. If the 16:9 section comes first then the whole conversion is done in 16:9 and the 4:3 section looks stretch horizontally. If the 4:3 section is at the start of the source file then the whole transcode is done in 4:3 and the 16:9 section looks squashed horizontally.

  No black bars are ever visible.

  Here’s my command :

  nice -n 17 ffmpeg -i source.mpg -acodec libfaac -ar 48000 -ab 192k -async 1 -copyts -vcodec libx264 -b 1250k -threads 2 -level 31 -map 0:0 -map 0:1 -map 0:2 -scodec copy -deinterlace output.mkv

  I don’t fully understand what’s going on. How do I get the same ’change in AR’ mid video in the output file that I have in the input video ?

• FFMPEG : Add a fixed size image on a video, regardless of the video width & height (resolution)

  11 mars 2017, par Drupalist

  This is my code that adds an image to videos, running via PHP :

  exec('ffmpeg -i input.mp4 -i logo.png -filter_complex 
  
  "[0:v][1:v] overlay=10:10"  -pix_fmt yuv420p -c:a copy output.mp4');

  It works well but the problem is, the image is scaled down or up, up on the video resolution. For example in the following images the logo width is 50px but videos resolution are different :

  

  and this one

  

  How can I prevent the image from scaling down/up ?

  ---

  Update

  Thanks to Mulvya, he proposed these codes

  ffmpeg -i input.mp4 -i logo.png -filter_complex 
  
  "[1:v][0:v]scale2ref=(W/H)*ih/8:ih/8[wm][base];[base][wm]overlay=10:10"
  
  -pix_fmt yuv420p -c:a copy output.mp4

  and

  ffmpeg -i input.mp4 -i logo.png -filter_complex 
  
  "[1:v][0:v]scale2ref=(W/H)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];
  
  [base][wmsar]overlay=10:10"
  
  -pix_fmt yuv420p -c:a copy output.mp4

  that works very well, but it doesn’t keep the logo aspect ratio.
  I tried this code on two videos with different resolution and this is the result

  

  and this one

  

  Is it possible to improve this solution ?

• FFMPEG merge two .mp4 videos - resolution distorted

  9 juin 2016, par Misha Moryachok

  I am trying to merge two .mp4 videos, and in some cases the seconds video part is distorted in the output video. Providing an example below :
  https://www.youtube.com/watch?v=wWMNTBWJ37A

  The real video is : https://www.youtube.com/watch?v=ASio-j-Epi8

  As you can see, we added intro before the real content, however, the real content is stretched.
  In my opinion it happens because first video is 1280x720 and the second is 460x720.

  Providing commands for merging videos :

  *1st step (convert the videos from .mp4 to .ts)

   ffmpeg -i videoPathMP4 -c copy -bsf:v h264_mp4toannexb -f mpegts videoPathTS

  *2nd step (merge videos)

  ffmpeg -i "concat:$video1 | $video2" -c copy -bsf:a aac_adtstoasc $meagePathMP4

  Video output is like you saw in provided videolink on youtube.
  I also tried to change the first video resolution to be like the second video :

  ffmpeg -i inputVideo.mp4 -s 460x720 outputVideo.mp4

  However it doesn’t helped.
  Is anyone know how to solve this ?
  Thanks