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• Retrieving current frame number

  2 avril 2015, par Solidus

  I am doing a project which involves a bit of video recording and editing and I am struggling to find a good C++ library to use. I am using QT as my framework and their video player is not working properly for me to use (seeking crashes some times, e.g.). Also, I need to record video and audio from my camera and QCamera does not work in windows (for recording).

  On my program the user can draw on top of the video and I need to store the start frame and the end frame of those drawings.

  Right now I’ve been testing Libvlc which almost does what I want. From what I can see they don’t have a way to just jump to a certain frame as this can only be done by time or position.

  The first solution that I came up with was to capture the time change event and then calculate the frame using the FPS. The problem is that, as far as I can tell, the interval of this event is around 250ms, which for a 15fps video is almost 4 frames.

  So, the second solution was to use libvlc_video_set_callbacks to make my own "lock, unlock and display" and count the frames there. This works for recording from the camera, as there is no going back and the frames go from 0 until the video stops. The problem is when playing a video. Since there is no timestamp, as far as I can tell, there is no way for me to know in which frame number I am (the user can be seeking for example). My "hacky" solution was to have a "lastTime" and "numTimes" on the struct I pass into these callbacks and this is what I do :

  lastTime represents the "last new time" received and numTimes represents the number of times lastTime was received.

  get_the_current_time
  
  calculate_frame_num_with_fps
  
  if current_time is equal to lastTime: 
  
       frameNum += numTimes
  
       numTimes++
  
  else 
  
       lastTime = current_time
  
       numTimes = 1

  This kinda works but I hate the solution. I’m not sure if when doing seeking the time changes if the difference is less than 250ms. That would maybe be kinda hard for a user to do but I’d prefer not to implement it like that.

  So my question is if there is another solution for this ? If not, any libraries that could help me on this ? I know about FFMPEG which seems would solve me this problem as it’s more low level and I could implement this solution. The problem is my deadline is approaching and that would still me take some time (learning the library and doing all the work). So I was thinking of it as a last resort.

  Thank you for your time.

• RTSP streaming on Android client using FFMpeg

  7 février 2021, par rurtle

  I am working on a hobby project the goal for which is to develop an Android application capable of streaming live feeds captured through web cams in a LAN setting using FFMpeg as the underlying engine. So far, I did the following -

  



  A. Compiling and generating FFMpeg related libraries for the following releases -

  



  FFMpeg version : 2.0
  
NDK version : r8e & r9
  
Android Platform version : android-16 & android-18thisthisthisthis
  
Toolchain version : 4.6 & 4.8
  
Platform built on : Fedora 18 (x86_64)
  

  



  B. Creating the files Android.mk & Application.mk in appropriate path.

  



  However, when it came to writing the native code for accessing appropriate functionality of FFMpeg from the application layer using Java, I'm stuck with following questions -

  



  a) Which all of FFMpeg's features I need to make available from native to app layer for streaming real-time feeds ?
  
b) In order to compile FFMpeg for Android, I followed this link. Whether the compilation options are sufficient for handling *.sdp streams or do I need to modify it ?
  
c) Do I need to make use of live555 ?
  

  



  I am totally new to FFMpeg and Android application development and this is going to be my first serious project for Android platform. I have been searching for relevant tutorials dealing with RTSP streaming using FFMpeg for a while now without much success. Moreover, I tried the latest development build of VLC player and found it to be great for streaming real-time feeds. However, it's a complex beast and the goal for my project is of quite limited nature, mostly learning - in a short time span.

  



  Could you suggest some pointers (e.g. links, documents or sample code) on how can I write the native code for utilizing FFMpeg library and subsequently use those functionality from the app layer for streaming real-time feeds ? Moreover, will really appreciate if you could let me know the kind of background knowledge necessary for this project from a functional standpoint (in a language agnostic sense).

  


• RTSP streaming on Android client using FFMpeg

  10 août 2013, par rurtle

  I am working on a hobby project the goal for which is to develop an Android application capable of streaming live feeds captured through web cams in a LAN setting using FFMpeg as the underlying engine. So far, I did the following -

  A. Compiling and generating FFMpeg related libraries for the following releases -

  FFMpeg version : 2.0
  NDK version : r8e & r9
  Android Platform version : android-16 & android-18thisthisthisthis
  Toolchain version : 4.6 & 4.8
  Platform built on : Fedora 18 (x86_64)
  

  B. Creating the files Android.mk & Application.mk in appropriate path.

  However, when it came to writing the native code for accessing appropriate functionality of FFMpeg from the application layer using Java, I'm stuck with following questions -

  a) Which all of FFMpeg's features I need to make available from native to app layer for streaming real-time feeds ?
  b) In order to compile FFMpeg for Android, I followed this link. Whether the compilation options are sufficient for handling *.sdp streams or do I need to modify it ?
  c) Do I need to make use of live555 ?
  

  I am totally new to FFMpeg and Android application development and this is going to be my first serious project for Android platform. I have been searching for relevant tutorials dealing with RTSP streaming using FFMpeg for a while now without much success. Moreover, I tried the latest development build of VLC player and found it to be great for streaming real-time feeds. However, it's a complex beast and the goal for my project is of quite limited nature, mostly learning - in a short time span.

  Could you suggest some pointers (e.g. links, documents or sample code) on how can I write the native code for utilizing FFMpeg library and subsequently use those functionality from the app layer for streaming real-time feeds ? Moreover, will really appreciate if you could let me know the kind of background knowledge necessary for this project from a functional standpoint (in a language agnostic sense).