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• FFmpeg cutting off exceeded time

  8 mars 2018, par Gvozden Kuzman

  Following ffmpeg command is working fine except it cuts down the exceeded -t duration :

  ffmpeg -ss 00:00:05 -t 49 -i 1.wav -ss 00:00:05 -t 400 -i 2.wav -ss 00:00:05 -t 49 -i 3.wav -filter_complex "[0:0][1:0][2:0]concat=n=3:v=0:a=1[outa]" -map "[outa]" output.mp3

  In this example, 2.wav file is 00:05:09 in length, and we are requesting to get next 400 seconds. Time that exceeded, which is 96 seconds in this example is removed from the output file, and my client doesn’t want that.

  That extra time should be 96 seconds of silence. Does ffmpeg have such capability or will it always remove the extra time ?

• Setting up time triggers on video player

  28 juillet 2022, par gPats

  Background :

  



  I have a some text that I want to display in a textbox whenever the video is playing in a certain interval, say (00:02:00-00:04:00 "Hello there").

  



  These textbox should only be displayed whenever the video is playing in the particular interval. If I rewind, or skip the video to a different time, the textbox should be generated/destroyed depending whether the current time falls within the interval or not.

  



  I have searched the documentation for ffplay and vlc for implementing this functionality.

  



  What I have tried :

  



  ffplay : my strategy would be to keep polling the current time of the video which ffplay dumps in STDERR and check if the current time falls within the interval.

  



  LibVLC :
LibVLC supports asynchronous events, but not the kind which would depend on the time at which video is playing.

  



  My question :

  



  1.Is it advisable to keep polling the current video time or setup callbacks/trigger functions ?

  



  2.Is it possible to get the current playing time of the video as a variable and create callback functions accordingly ?

  



  NOTE : I am aware that subtitles do the same thing, however I want the text to be in a different window. The textbox should be decoupled from the video player I use.

  


• Lossless codec for bayer data

  21 août 2016, par vhdirk

  I’m working with lots of camera’s which capture in BG bayer pattern natively.

  Now, every time I record some data, I save it to the disk in the raw bayer pattern, in an avi container. The problem is, that this really adds up after a while. After one year of research, I have close to 4TB of data...

  So I’m looking for a lossless codec to compress this data. I know I could use libx264 (with —qp 0), or huffYUV, dirac or jpeg2000, but they all assume you have RGB or YUV data. It’s easy enough to convert the bayered data to RGB, and then compress it, but it kind of defeats the purpose of compression if you first triple the data. This would also mean that the demoasicing artefacts introduced by debayering would also be in my source data, which is also not too great. It would be nice to have a codec that can work on the bayered data directly.

  Even more nice would be that the solution would involve a codec that is already supported by gstreamer (or ffmpeg), since that’s what I am already using.