Recherche avancée

Sur d’autres sites (9943)

• 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.

  


• Android and JNI, pipe data to FFmpeg

  2 décembre 2014, par William Seemann

  I’m trying to create a metadata retriever based on FFmpeg. Since raw Android application resources are often only accessible using a file descriptor I need a way to pipe this data to FFmpeg via JNI. I know FFmpeg supports a "pipe" protocol :

  UNIX pipe access protocol.
  
  
  
  Allow to read and write from UNIX pipes.
  
  
  
  The accepted syntax is: 
  
  
  
      pipe:[number]
  
  
  
  number is the number corresponding to the file descriptor of the pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number is not specified, by default the stdout file descriptor will be used for writing, stdin for reading.
  
  
  
  For example: cat test.wav | ffmpeg -i pipe:0

  My question is, how do I programmatically emulate cat test.wav | ffmpeg -i pipe:0 using JNI and avformat_open_input using a FileDescriptor ? Is this possible ?

• Does AVFrame store AV_PIX_FMT_YUV420P data as YVU ?

  28 juin 2017, par Peter

  I am decoding raw H.265 data using avcodec_decode_video2 api. When I examine the resulting instance pictYUV of type AVFrame, I see that pictYUV->format is AV_PIX_FMT_YUV420P and pictYUV->data[0] points to Y-plane. Both of these are expected. However, it appears pictYUV->data[1] seem to contain V-plane data and pictYUV->data[2]seem to contain U-plane data. My intuition was that pictYUV->data would store YUV planes in that order and not YVU planes. Wondering if the data is always ordered as YVU or is there some flag I failed to look at. Regards.