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• Decode h264 video

  27 juillet 2020, par john bowring

  I am looking for a way to decode h264 (or indeed any video format) using c#. The ultimate goal is to be able to decode the images and very strictly control the playback in real time. The project I am working on is a non-linear video art piece where the HD footage is required to loop and edit itself on the fly, playing back certain frame ranges and then jumping to the next randomly selected frame range seamlessly.

  



  I have created an app which reads image files (jpegs) in from the disk and plays them on screen in order, I have total control over which frame is loaded and when it is displayed but at full HD res it takes slightly longer than I want to load the images from hard drive (which are about 500k each), I am thinking that using a compressed video format would be smaller and therefore faster to read and decode into a particular frame however I cannot find any readily available way to do this.

  



  Are there any libraries which can do this ? i.e. extract an arbitrary frame from a video file and serve it to my app in less time than it takes to show the frame (running at 25fps), I have looked into the vlc libraries and wrappers for ffmpeg but I don't know which would be better or if there would be another even better option. Also I don't know which codec would be the best choice as some are key frame based making arbitrary frame extraction probably very difficult.

  



  Any advice welcome, thanks

  


• Decode h264 video

  29 août 2011, par john bowring

  I am looking for a way to decode h264 (or indeed any video format) using c#. The ultimate goal is to be able to decode the images and very strictly control the playback in real time. The project I am working on is a non-linear video art piece where the HD footage is required to loop and edit itself on the fly, playing back certain frame ranges and then jumping to the next randomly selected frame range seamlessly.

  I have created an app which reads image files (jpegs) in from the disk and plays them on screen in order, I have total control over which frame is loaded and when it is displayed but at full HD res it takes slightly longer than I want to load the images from hard drive (which are about 500k each), I am thinking that using a compressed video format would be smaller and therefore faster to read and decode into a particular frame however I cannot find any readily available way to do this.

  Are there any libraries which can do this ? i.e. extract an arbitrary frame from a video file and serve it to my app in less time than it takes to show the frame (running at 25fps), I have looked into the vlc libraries and wrappers for ffmpeg but I don't know which would be better or if there would be another even better option. Also I don't know which codec would be the best choice as some are key frame based making arbitrary frame extraction probably very difficult.

  Any advice welcome, thanks

• How to bash-script or simplify ffmpeg commands for resizing the watermark, adding it to the video and adding subtitle.ass to the video ?

  25 décembre 2018, par Wai Gyi

  I would like to create hard-subbed video with watermark by using ffmpeg. And I’d like to know how to combine and simplify multiple commands or how to create a bash-script for this purpose.

  I’ve tried searching in stackflow and tested some commands but they didn’t work. Here are the comands I’m using.

  1. To detect video width & height :

     ffprobe -v quiet -show_entries stream=width,height -of default=noprint_wrappers=1 video_in.mp4

  2. To resize the watermark image : (video width = 1280)

     ffmpeg -i watermark.png -y -v quiet -vf scale=1280*0.15:-1 watermark_scaled.png

  3. To add watermark to the video :

     ffmpeg -i video_in.mp4 -i watermark_scaled.png -filter_complex "overlay=W-w-5:5" video_marked.mp4

  4. To add .ass subtitle to the video : (it need to be ’.ass’)

     ffmpeg -i video_marked.mp4 -vf ass=subtitle.ass video_final.mp4