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• GoPro (MP4) video timestamp sync with precision of milliseconds

  3 février 2021, par Raphael Ottoni

  I need your help with a data sync problem... I m currently trying to sync my GoPro video with real world time (a.k.a my notebook). I manage to sync date and time of my notebook and my GoPro 3+ black perfectly. The problem is that when the GoPro save the files in disk it round up the milliseconds on the creation_time (the milliseconds is always 000000) . Thus, turning the perfect sync impossible. In attachment is a picture of the meta information (extracted by ffprobe) of the MP4 video.

  



  My question is : What I have to do, so the GoPro actually save the creation_time with precision of milliseconds ?

  



  Another small question : Looking at the attachment figure, we see the "timecode" which is a time synchronization data in the format of hours:minuts:seconds:frame. I was thinking that I could use the "frame" value to calculate the missing milliseconds value. If we take this attachment, as a example, we can see that the frame value is "36". Meaning that the millisecond that it started to record was the one associated with the 36th frame of the FPS (in this video : 60fps) value : Some thing like 1000/60 * 36 which is 600 milliseconds, thus the actual creation_time of this video would be : 2017-07-19T18:10:34.600

  



  Is this logic right ? it didn't work ! I don't know what else to do.

  



  P.S : I need this kind of time precision because I will sync the video frames with a external sensor data that is recorded at 11hz.

  



  Please Help

  



  

  



  update

  



  I forgot to mention, even if you check the original raw file information, inside the GoPro SSD card, using "stats" to read the creation time (see attachment) it still has the same timestamp without milliseconds.

  



  

  


• Metadata disappears when hevc_nvenc is used in ffmpeg (Estimated to be overwrite with null value.)

  30 janvier 2020, par Dashhh

  disappear metadata using at heve_nvenc

  • When using h264_cuvid and hevc_nvenc through ffmpeg on my server, the metadata of the files that come out of the encoding output is lost.
    There was no such thing in h264_nvenc. Also, the libx265 encoding result has metadata.

  • The ffmpeg command I used is as follows.

  ffmpeg -v debug -vsync 0 -hwaccel cuvid -hwaccel_device 2 -c:v h264_cuvid \
  
  -i ./intputfile.mp4 -map_metadata 0 -map_metadata 0:s:0 -map_metadata:s:v 0:s:v -map_metadata:s:a 0:s:a \
  
  -map 0:v -vf hwdownload,format=nv12,format=yuv420p,scale=iw*2:ih*2 \
  
  -c:v nvenc_hevc -preset slow -rc vbr_hq -pix_fmt yuv420p -b:v 5M -maxrate:v 8M -gpu 2 \
  
  -map 0:a -c:a copy \
  
  -color_range tv -colorspace bt709 -color_trc bt709 -color_primaries bt709 \
  
  hevc_output_test.mp4

  ---

  • Refer to the image below for property information on the generated file.

  

  • In the image in the link, the left pane is a playable h264_nvenc encoding deliverable file.
  • In the image in the link, the right pane is a non-replayable hevc_nvenc encoding deliverable
    file.
    • Program available for play : VLC
    • Unable to play : Ubuntu 18.04 Base Video Player, Samsung Smart TV (h264_nvenc and libx265 encoded deliverables files can be played).
  • Please refer to the image below for an error message displayed in the Player when it is not possible to play. (This is the default video player for ubuntu 18.04.)

  

  • I added ‘-f matroska’ option to the command written above and made a result.(The result file extension has also been changed to "mkv")
    Unusually, metadata exists in the process in which images are made as follows :
    

  • However, at the end of encoding, this metadata disappears again. (It looks exactly like the first image in the right pane.)

  • The path to which this information was obtained was identified by right-clicking the file in Ubuntu (18.04) to the category "Properties" - "video/audio".
    Can you tell me why this is happening ?
    If not, please advise me where I should look.

  CUDA : 10.2

  Video SDK Version (Nvenc version) : 9.1

  GPU : GeForce GTX 1080 Ti

  Driver Version : 440.33.01

• Need to extract text from any audio file

  20 novembre 2018, par mystack flow

  I am trying to extract the text from audio file. I tried with FreeTTS, but i can able to do Text to Speech.

  here is my code,

  package video_audio_text.project;
  
  
  
  import javax.sound.sampled.AudioFileFormat.Type;
  
  import com.sun.speech.freetts.FreeTTS;
  
  import com.sun.speech.freetts.Voice;
  
  import com.sun.speech.freetts.VoiceManager;
  
  import com.sun.speech.freetts.audio.AudioPlayer;
  
  import com.sun.speech.freetts.audio.SingleFileAudioPlayer;
  
  
  
  public class AudioToText {
  
  
  
      /**
  
       * Example of how to list all the known voices.
  
       */
  
  
  
  
  
      public static void main(String[] args) {
  
  
  
         // listAllVoices();
  
          System.setProperty("freetts.voices", "com.sun.speech.freetts.en.us.cmu_us_kal.KevinVoiceDirectory");
  
  
  
          FreeTTS freetts;
  
          AudioPlayer audioPlayer = null;
  
          String voiceName = "kevin16";
  
  
  
          System.out.println();
  
          System.out.println("Using voice: " + voiceName);
  
  
  
          /* The VoiceManager manages all the voices for FreeTTS.
  
           */
  
          VoiceManager voiceManager = VoiceManager.getInstance();
  
          Voice helloVoice = voiceManager.getVoice(voiceName);
  
  
  
          if (helloVoice == null) {
  
              System.err.println(
  
                  "Cannot find a voice named "
  
                  + voiceName + ".  Please specify a different voice.");
  
              System.exit(1);
  
          }
  
  
  
          /* Allocates the resources for the voice.
  
           */
  
          helloVoice.allocate();
  
  
  
          /* Synthesize speech.
  
           */
  
  //create a audioplayer to dump the output file
  
         audioPlayer = new SingleFileAudioPlayer("/Users/user/Documents/test",Type.WAVE);
  
  //attach the audioplayer 
  
         helloVoice.setAudioPlayer(audioPlayer);
  
  
  
  
  
          helloVoice.speak("Thank you for giving me a voice. "
  
                           + "I'm so glad to say hello to this world." + 
  
                          + "here you go good way");
  
  
  
  
  
  
  
          /* Clean up and leave.
  
           */
  
          helloVoice.deallocate();
  
          audioPlayer.close();
  
          System.exit(0);
  
      }
  
  
  
  }

  But i need to give the audio file and extract text from the audio file.

  Please suggest me how can I achieve.

  please suggest which library like FFMPEG or any other library which can help me to achieve this.