Recherche avancée

Sur d’autres sites (5597)

• Trim / Cut video on Android using FFMpeg's Copy

  6 août 2012, par Kevin P

  We're trying to replicate the functionality of this command line ffmpeg directive using the FFMpeg c api through JNI calls on Android.

  ffmpeg -ss 2 -t 120 -vcodec copy -acodec copy -i input.file output.file

  Basically, given a start and end time, we wish to copy (not re-encode) a small(er) segment of video from the larger (input) video source.

  We've been using the wonderful JavaCv wrapper to openCv and FFMpeg, but we just cannot figure out how to do this simple bit of work. We've been scouring the ffmpeg.c and related sources and while I now understand that it switches to stream_copy and remuxing rather than re-encoding when the codec is specified as copy I cannot for the life of me identify what series of method calls to make to replicate this through the C api. Does anyone have an example JNI file for doing this ? Or are there rockstar C types that can explain how I get from that command line to api calls ? We've spent the better part of two weeks working on this (we're not native C guys) and we're at the point where we just need to ship some code. Any example code, especially JNI code or method call maps etc. would be greatly appreciated !

• Output a video to a file

  3 novembre 2011, par EagleEye

  I am working on a very CPU intensive legacy application on windows which captures video frames from camera and displays it on the screen. Now I need to add a feature to it to save this video feed to an output file. And I have a raw image data as an input. I need to make this process as efficient as possible so that it doesn't affect the performance of my application.

  So what are the best available API's in C++ that I can use to create an output video file. And moreover what should be the most efficient encoding format that I must use so that I get the maximum throughput. Also I may have to use some compression techniques. So what should be the best approach.

  Moreover can I use GPU acceleration for this process and how ?

  Uptil now I have encountered following tools that I may use :

  1. OpenCV
  2. Microsoft Media Foundation LIbrary or DirectShow
  3. ffmpeg

• Tailing last frame of a growing video file

  9 janvier 2012, par ebayindir

  On windows, I have a dynamically created uncompressed avi video file which grows overtime. The application which generates the video file can only write to a physical file. I can start/stop generation of video file and delete the old video file easily.

  I would like to analyze the changing last frame of the growing video file to make some decision depending on the content of the current/latest image in real time. If I can achieve more than 10fps it should be enough.
  I would like to get uncompressed images whenever a new frame available in the video file.

  As a file format I think png could be the best options in that case but I am open to alternatives.
  I wonder if such a thing is possible with ffmpeg or with a similar tool.

  I prefer to analyze the image and make decisions by using a perl+Imager module.
  Tha analyisis requirements are not complicated. Basically I just need to find existence of a few small images in certain locations inside the last frame.
  I would also appreciate if you can suggest an efficient way to get this information in to my application from ffmpeg.
  For example piping directly to my code or reading from saved png files.

  I know perl already has an ffmpeg interface module but as far as I understand that module can't provide the functionality I need.