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• 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

• 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 ?

• 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 !