Newest 'ffmpeg' Questions - Stack Overflow

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  • FFMEG multiple frames extraction

    28 janvier 2017, par Yevgeni Burshtein

    I need a command (if there is any) that will allow me to extract frames at different time offsets. Currently I'm able to extract them one by one using ss command.

    Example of current command:

    C:\ffmpeg\bin\ffmpeg.exe -i %1 -ss %2  -vframes 1 -s %3x%4 -f image2 %5 -hide_banner -loglevel panic
    

    This works very slowly on large number of time offsets.

  • FFMPEG, Netbeans and C++ [duplicate]

    28 janvier 2017, par Murtadha

    This question already has an answer here:

    I used to work on C++ project on Netbeans and I would like to use ffmpeg libraries / include files all the stuff inside my program. I don't know how to install ffmpeg in there and integrate it with Netbeans have installed also the latest mingw? I have surfed the net for such a topic then I have found one but to be honest I understand a very little.

    System info:

    Windows 8 64bit
    Netbeans 7.3 32.b
    mingw 32bit
    opencv 4.4 32.bit

  • Create time lapse video from other video

    27 janvier 2017, par Orlando

    Using avconv (or even ffmpeg, so I can use as a reference), how can I create a time lapse video by taking only anchor/reference frames from another video? Most information I find is on how to create a time lapse video by combining images, and I'd like to do it by extracting frames from a video. Say, if a video is 30 seconds long at 30 FPS, I'd like to take 60 out of those 900 frames (900/60 = every 15 seconds) to produce a 2 second video.

  • How to cut and concatenate the file so it is not off-beat when the file I got the bpm from is being muxed ?

    27 janvier 2017, par P. Dee

    I am cutting files with ffmpeg based on the bpm I found in a music file. So let's assume, the file's bpm = 120. That means, there are 2 bps and 1 beat every 500ms.

    So I cut a video file with multiples of 500ms length, ie 500ms, 1500ms, 3000ms etc. length. But cutting it using

    ffmpeg -ss start -i fileorig.mp4 -t duration part_number.mp4
    

    and finally creating a mylist.txt with

    file 'part_1.mp4'
    file 'part_2.mp4'
    ...
    

    and adding them via

    ffmpeg -f concat -i mylist.txt -c copy output.mp4
    

    and replacing the audio track with the music file, makes the video be off-beat after some time.

    How to cut and concatenate the file so it is not off-beat when the file I got the bpm from is being muxed?

  • FCNTL File IO errors using FFmpeg on iOS

    27 janvier 2017, par ebeis051

    I have an application that leverages FFmpeg libraries to play video (modeled after FFplay). It works on every platform except iOS, where I experience a strange file IO issue that I cannot figure out.

    I am able to stream two videos successfully, but on the third stream attempt the calls to av_read_frame() fail and the AVIOContext shows error 9, E_BADF. To investigate, I added some logging messages to try to see where the error originated and I found that the error was coming from the read() call inside the file_read() function in libavformat/file.c.

    I then looked into how the video files were being opened and I found that on the third run, the open() call (inside avpriv_open() in libavutil/file_open.c) was returning 0 as the file descriptor, whereas the first two were returning more normal positive values. After a few successful attempts to read from 0, the read calls proceeded to fail indefinitely with E_BADF.

    The 0 file descriptor is usually reserved for stdin, and I am confident my application is not closing stdin at any point. Having open() return 0 as the file descriptor isn't inherently wrong, but in this case it eventually results in a read failure every time. I am able to work around this by artificially using up 0 in the table by opening something but not operating on it, and then restarting the open process to get back to a positive value. When I do this, my videos are able to play again. My only theory to explain this behaviour is that something somewhere is repeatedly closing the 0 file descriptor underneath my feet, which causes the read attempts to start failing.

    I can't say for sure yet if this is a problem in FFmpeg or possibly the operating system, but I am unable to reproduce this issue in a simple program that doesn't use FFmpeg, nor does it occur on any other platform as I mentioned above. I have also tried many different versions of the FFmpeg source running on iOS versions 9 and 10 and they all demonstrate the issue. I realize iOS is not a high runner platform for FFmpeg use, but I am wondering if anyone has attempted to build and use FFmpeg for iOS and recognizes any of these issues. Any pointers in the right direction would be greatly appreciated.