Sur d’autres sites (10978)

• Can x264 be used from Java code via JNI to decrease the resolution of RTMP streams ? [on hold]

  5 septembre 2016, par Orr151

  I would like to implement a custom RTMP transcoder to HLS format in Java. As the repackaging itself seems to be relatively clear and doable in Java, then I found the modification of the video resolution a bit challenging in Java. My plan is to avoid using existing solutions like FFmpeg or at least minimize the amount of 3rd party frameworks/tools integrated with my component.

  After some research it seems that reusage of JCodec and Xuggler can be challenging as both project are idle for a while. Also I’m not sure if their performance is acceptable. That’s why I would like to integrate directly with x264 library via JNI from Java code.

  Is integration with x264/libx264 from Java code to decrease resolution/bitrate doable and is it a good idea ? Could you please suggest any other solutions ?

  Thanks !

• 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 ?