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• FFmpeg on Android

  26 décembre 2016, par Jag

  I have got FFmpeg compiled (libffmpeg.so) on Android. Now I have to build either an application like RockPlayer or use existing Android multimedia framework to invoke FFmpeg.

  1. Do you have steps / procedures / code / example on integrating FFmpeg on Android / StageFright ?

  2. Can you please guide me on how can I use this library for multimedia playback ?

  3. I have a requirement where I have already audio and video transport streams, which I need to feed to FFmpeg and get it decoded / rendered. How can I do this on Android, since IOMX APIs are OMX based and cannot plug-in FFmpeg here ?

  4. Also I could not find documentation on the FFmpeg APIs which need to be used for playback.

• Please help ! Now having sound issues on 14.04

  21 avril 2015, par Nobody Atall

  Please help ! Today I was trying to edit some home video with KDENLive and when I’d try to preview my videos, they’d play for about a second then lock up the program.

  In troubleshooting, I discovered :

  If I reboot the computer, most multimedia files play fine : MP3, MP4, FLV, AVI, WMV, etc. But as soon as I try playing an MPEG-2 file, the video freezes. (Using SMPlayer. With VLC it plays, but has no sound.) After that, I have no sound on any format, though they still play. However, trying to play Flash videos on Facebook then lock up after a second or so, as well.

  If I reboot the computer and go directly to Sound Settings | Test Sound, I get no sound. Then my video files also have no sound (MP3, MP4, etc.), just like when I try playing an MPEG-2.

  Is there some commonality there ? Like, does KDENLive, the Test Sound function, and the MPEG-2 files use FFMPEG or something ? Because it seems like as soon as I execute any of those three things, I’m screwed.

  Are there any diagnostics I can run ? I’m kinda dead in the water on editing our home videos until I find out what happened !

  Thanks.

• Ghost image issues with ffmpeg -filter_complex displace

  5 juillet 2022, par raul.vila

  I've (almost) been able to apply a displacement based on 2 animated gaussian noise videos, but I'm having issues with a ghost image. A picture is worth a thousand words.

  


  Here you have a script to replicate the issue :

  


  ffmpeg -y -t 2 -f lavfi -i color=c=blue:s=160x120 -c:v libx264 -tune stillimage -pix_fmt rgb24 00_empty.mp4
ffmpeg -y -i 00_empty.mp4 -vf "drawtext=text=string1:y=h/2:x=w-t*w/2:fontcolor=white:fontsize=60" 01_text.mp4
ffmpeg -y -t 2 -f lavfi -i color=c=gray:s=160x120 -c:v libx264 -tune stillimage -pix_fmt rgb24 02_gray.mp4
ffmpeg -y -i 01_text.mp4 -i 02_gray.mp4 -i 02_gray.mp4 -filter_complex "[0][1][2]displace=edge=mirror" 03_displaced_text.mp4


  


  It creates a test video with a scrolling text and a gray dummy video. Then it applies a displacement based on the gray video. If I understand correctly, because the gray video is 100% gray, it should leave the video unchanged (or maybe displace everything by a fixed ammount of pixels), but it creates a "shadow". I tried with 3 different pixel formats (yuv420p, yuv444p, rgb24) because I found this question on stackoverflow talking about that :

  


  

  • Why are Cb and Cr planes displaced differently from lum by the displace complex filter in ffmpeg ?

  


  


  ffmpeg version 5.0.1-full_build-www.gyan.dev

  


  Any idea will be welcome.
  
Thanks !