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• I'm running a process in Java and am getting stuck when I wait for it to finish

  31 juillet 2020, par nottAbott

  I have a Java program that is supposed to make copies of segments of a video and then stitch them back together, using ffmpeg. My "snip" method, the one that makes the segment files, has a problem, it gets stuck when I call "process.waitfor()". When I take it out, the videos load partly, but cannot be accessed until I close the program. When I try to delete them, while the program is running, it says that they cannot be deleted because they are in use. Could anyone lead me in the right direction ? Here is the method :

  


  //snips out all the clips from the main video
public void snip() throws IOException, InterruptedException {
    
    for(int i = 0; i < snippets.size(); i++) {
        //Future reference: https://stackoverflow.com/questions/9885643/ffmpeg-executed-from-javas-processbuilder-does-not-return-under-windows-7/9885717#9885717
        //Example: ffmpeg -i 20sec.mp4 -ss 0:0:1 -to 0:0:5 -c copy foobar.mp4
        String newFile = "foobar" + String.valueOf(i) + ".mp4";
        ProcessBuilder processBuilder = new ProcessBuilder("ffmpeg", "-i", videoName, "-ss",
                snippets.get(i).getStartTime(), "-to", snippets.get(i).getEndTime(), newFile);
        
        //I tried this first and then added in the process/process.waitfor below
        //processBuilder.start();
        
        Process process = processBuilder.start();
        process.waitFor();
        
        System.out.println("Snip " + i + "\n");
        
        //add to the formatted list of files to be concat later
        if(i == snippets.size() - 1) {
            stitchFiles += newFile + "\"";
        }
        
        else {
            stitchFiles += newFile + "|";
        }
    }
}


  


• How to make a batch file wait for all processes of another call to finish before continuing

  1er juillet 2020, par Roman Stadler

  The idea of this script is to take a (lecture) video, split it into smaller pieces, remove the silence for each one, and merge them back together, for increased performance, since the silence-removing script does not scale that well for larger videos.

  


  The 3 batch scripts below work perfectly when started manually after eachother, but when trying to launch them from a single .bat file, I can't prevent them from starting at the same time, which creates errors at the merging stage.

  


  These are the 3 batch files :

  


  

  1. split.bat

  


  2. startall.bat

  


  3. merge.bat

  


  


  Split.bat creates 10 minute long segments, afterwards, startall.bat starts one Video-Remove-Silence task for every segment. At the end, merge.bat creates one single mp4 file with all the segments.

  


  split.bat does the following :

  


  ffmpeg -i in.mp4 -c copy -map 0 -segment_time 00:10:00 -f segment out%%03d.mp4
exit


  


  startall.bat :

  


  start start000.bat
start start001.bat
start start002.bat
start start003.bat
...


  


  The start000.bat call looks like this :

  


  python video-remove-silence out000.mp4 --linear 0.0005
exit


  


  And merge.bat :

  


  :: Create File List
for %%i in (*_result.mp4) do echo file '%%i'>> mylist.txt
:: Concatenate Files
ffmpeg -f concat -safe 0 -i mylist.txt -c copy shortened.mp4

del "C:\Users\Roman\Desktop\download\mylist.txt"
del "C:\Users\Roman\Desktop\download\out*.mp4"
exit


  


  When trying either call, or start /wait, errors occur due to simultaneous execution :

  


  START /wait split.bat
START /wait startall2.bat
START /wait merge.bat


  


  So basically my question is, how can I call these 3 scripts and prevent merge.bat from starting, until all processes inside startall.bat have finished ?

  


• FFmpeg installation on Raspberry Pi Zero W : Undefined references to __atomic

  3 février 2021, par MisterGray

  I'm trying to install ffmpeg on my Raspberry Pi Zero W, but I get several error messages.

  


  OS : Raspberry Pi OS (32-bit) Lite (May 2020)

  


  I have executed the following commands :

  


  sudo apt update
sudo apt full-upgrade
sudo apt install git
git clone https://github.com/FFmpeg/FFmpeg.git
cd FFmpeg
./configure --arch=armel --target-os=linux --enable-gpl --enable-omx --enable-omx-rpi --enable-nonfree
make -j2
sudo make install


  


  Output of last command :

  


  ...
LD      ffmpeg_g
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_init':
/home/pi/FFmpeg/libavformat/fifo.c:519: undefined reference to `__atomic_store_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_write_trailer':
/home/pi/FFmpeg/libavformat/fifo.c:624: undefined reference to `__atomic_fetch_add_8'
/usr/bin/ld: /home/pi/FFmpeg/libavformat/fifo.c:631: undefined reference to `__atomic_store_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_thread_write_packet':
/home/pi/FFmpeg/libavformat/fifo.c:188: undefined reference to `__atomic_fetch_sub_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_consumer_thread':
/home/pi/FFmpeg/libavformat/fifo.c:457: undefined reference to `__atomic_load_8'
/usr/bin/ld: libavformat/libavformat.a(fifo.o): in function `fifo_write_packet':
/home/pi/FFmpeg/libavformat/fifo.c:597: undefined reference to `__atomic_fetch_add_8'
collect2: error: ld returned 1 exit status
make: *** [Makefile:114: ffmpeg_g] Error 1


  


  Maybe another package is missing ? Do I have to change anything in the config ?