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• Why Yuv data readed from ffmpeg is different from original input yuv ?

  13 mai 2021, par sianyi Huang

  I use ffmpeg to make HDR test video, my approach is write a image, converting the image to yuv420p and then use ffmpeg to make the HDR test video.

  



  But I found the yuv data readed from mp4 is different from the original input..
I was stucked in here for a while, does anyone know how to read the correct yuv data from mp4 ?

  



  #ffmpeg encode command
ffmpeg_encode_mp4 = \
"ffmpeg -y -s 100*100 -pix_fmt yuv420p -threads 4 -r 1 -stream_loop -1 -f rawvideo -i write_yuv.yuv -vf \
scale=out_h_chr_pos=0:out_v_chr_pos=0,format=yuv420p10le \
-c:v libx265 -tag:v hvc1 -t 10 -pix_fmt yuv420p10le -preset medium -x265-params \
crf=12:colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:master-display=\"G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)\":max-cll=\"1000,400\" \
-an test.mp4"

#ffmpeg read yuv from mp4 command
ffmpeg_extract_yuv = "ffmpeg -i test.mp4 -vframes 1 -c:v rawvideo -pix_fmt yuv420p read_yuv.yuv"


#make 100*100 yuv raw
w, h = 100, 100
test_gray = 255
test = np.full((100, 100, 3), test_gray, dtype=np.uint8)
yuv_cv = cv.cvtColor(test, cv.COLOR_RGB2YUV_I420)
yuv_cv.tofile("write_yuv.yuv")

#encode yuv raw to mp4 with HDR metadata
print(ffmpeg_encode_mp4)
result = subprocess.check_output(ffmpeg_encode_mp4, shell = True)
print(result)
sleep(0.5)

#extract yuv from mp4
kill_existing_file("read_yuv.yuv")
print(ffmpeg_extract_yuv)
result = subprocess.check_output(ffmpeg_extract_yuv, shell = True)
print(result)
sleep(0.5)

write_yuv = np.fromfile("write_yuv.yuv",dtype='uint8')
read_yuv = np.fromfile("read_yuv.yuv",dtype='uint8')

print("input gray:", test_gray)
print("write_yuv", write_yuv[:10])
print("read_yuv", read_yuv[:10])

reader = imageio.get_reader("test.mp4")
img = reader.get_data(0)
print("imgeio read:", img[50, 50])

'''
ouput result:
input gray: 255
write_yuv [235 235 235 235 235 235 235 235 235 235]
read_yuv [234 235 234 235 234 235 234 235 234 235]
imgeio read: [253 253 253]
'''


  



  I have no idea how to validate the video I made is corret
Any feedback will be very appreciated !

  


• Java does not run command in Linux

  9 août 2017, par Ariana

  I have problems executing this ffmpeg command in my java code :

  ffmpeg -i sample.mp4 -i ad.mp4 -filter_complex "[0:v]trim=0:15,setpts=PTS-STARTPTS[v0]; [1:v]trim=0:5,setpts=PTS-STARTPTS[v1]; [0:v]trim=20:30,setpts=PTS-STARTPTS[v2]; [v0][v1][v2]concat=n=3:v=1:a=0[out]" -map "[out]" output.mp4

  I use this command :

  String command= "ffmpeg -i "+dir+"sample.mp4 -i "+dir+"ad.mp4 -filter_complex [0:v]trim=0:15,setpts=PTS-STARTPTS[v0]; [1:v]trim=0:5,setpts=PTS-STARTPTS[v1]; [0:v]trim=20:30,setpts=PTS-STARTPTS[v2]; [v0][v1][v2]concat=n=3:v=1:a=0[out] -map [out] output.mp4";
  
  final ProcessBuilder pb = new ProcessBuilder("/bin/sh", "-c", command);
  
  System.out.println(command);
  
  final Process p = pb.start();

  I simply remove the ". But still no chance.

  I also used the getRuntime() method, but that also doesn’t work for me.

  String c1=" -i "+dir+"sample.mp4 "+"-i "+dir+"ad.mp4 -fi‌​lter_complex [0:v]‌​trim=0:15,setpts=PTS‌​-STARTPTS[v0]; [1:v]trim=0:5,setpts=PTS-STARTPTS[v1]; [0:v]trim=20:30,setpts=PTS-STARTPTS[v2]; [v0][v1][v2]concat=n=3:v=1:a=0[out] -map [out] "+dir+"output.‌​mp4";
  
  RunCommand("ffmpeg"+c1);

  Using this method :

  private static void RunCommand(String command) throws InterruptedException {
  
      try {
  
          // Execute command
  
          Process proc = Runtime.getRuntime().exec(command);
  
          System.out.println(proc.exitValue());
  
  
  
          // Get output stream to write from it
  
          // Read the output
  
  
  
          BufferedReader reader =  
  
                  new BufferedReader(new InputStreamReader(proc.getInputStream()));
  
          String line = "";
  
          while((line = reader.readLine()) != null) {
  
              System.out.print(line + "\n");
  
              //              System.out.println(ads.get(0));
  
          }
  
          proc.waitFor();  
  
  
  
      } catch (IOException e) {
  
      }
  
  }

  This one doesn’t work also, and printing the exit value shows this :

  Exception in thread "main" java.lang.IllegalThreadStateException: process hasn't exited
  
      at java.lang.UNIXProcess.exitValue(UNIXProcess.java:423)
  
      at parser.Parser.RunCommand(Parser.java:106)
  
      at parser.Parser.commandGenerator2(Parser.java:79)
  
      at parser.Parser.main(Parser.java:44)

  If I move the proc.waitFor(); before printing the exit value, it is 1.

  What is the problem ? Why it doesn’t run in Java code ?

• Setting UseShellExecute = false doesn't work in Process.Start

  5 décembre 2015, par Alex Jolig

  There’s a good Q&A about hiding shell execute when running a process which led me to write my own code using ffmpeg :

  Process proc = new Process();
  
  proc.StartInfo.FileName = "ffmpeg";
  
  proc.StartInfo.Arguments = string.Format("-ss {0} -i \"{1}\" -t {2}{3} DB\\Media\\{4}{5} -y",
  
       TimeSpan.Parse(row.Cells["StartdgvList"].Value.ToString()),
  
       openFileDialog.FileName, _durationTime, quality, newTmpSound,
  
       GetExtension(openFileDialog.FileName));
  
  proc.StartInfo.RedirectStandardError = true;
  
  proc.StartInfo.UseShellExecute = false;
  
  proc.StartInfo.CreateNoWindow = true;
  
  if (!proc.Start()) return;
  
  StreamReader reader = proc.StandardError;
  
  string line;
  
  while ((line = reader.ReadLine()) != null && !_cancel)
  
  {
  
    //Doing something with process line
  
  }
  
  proc.Close();

  This works fine, But when I run it in a few user machines, it just stops working with no error.

  I tried removing lines which hides shell window and turned it to this :

  Process proc = new Process();
  
  proc.StartInfo.FileName = "ffmpeg";
  
  proc.StartInfo.Arguments = string.Format("-ss {0} -i \"{1}\" -t {2}{3} DB\\Media\\{4}{5} -y",
  
       TimeSpan.Parse(row.Cells["StartdgvList"].Value.ToString()),
  
       openFileDialog.FileName, _durationTime, quality, newTmpSound,
  
       GetExtension(openFileDialog.FileName));
  
  if (!proc.Start()) return;
  
  proc.Close();

  and it start working in all the machines.

  I’m wondering if there’s some sort of service or components missing in some machines which makes the process fails when console is hiding.

  I appreciate if anyone has any idea.

  P.S : I installed Visual Studio 2012 on a machine which has problem hiding shell window and it suddenly start working. Maybe VS2012 installed somwthing on the machine which solved the problem.