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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.

  



  

  


• 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.

• What video format will allow Android MediaPlayer.seekTo() to reliably provide frame-accurate scrubbing ?

  8 juillet 2015, par Tim Closs

  We have an iOS app that we are currently rebuilding for Android. The app relies on being able to scrub video with frame accuracy. We have 3D animations that are rendered out as single frames ; we build subsets of frames into lots of small (1-2 second) videos ; and the app provides the ability to scrub those videos and see each individual frame.

  The MP4 videos we initially created work fine on iOS. When we tried to get them working on Android (using the MediaPlayer class), we entered a world of pain ! What we need to do is find a video format that will play and allow frame-accurate scrubbing across all Android devices, using MediaPlayer.seekTo(). Initially we are targetting Android 3.0 and above, but we probably want to stretch back to 2.3.3 after our initial release. Here’s what I’ve discovered so far :

  (A) Android claims that H264 "baseline profile" should be supported everywhere : (URL). However, within that, there are dozens of other settings that may or may not be supported. Is there a more fine-grained list anywhere ? Currently we are converting to H264 within an MP4 container.

  (B) I haven’t yet seen an Android device that will accurately scrub H264 files without inserting keyframes ("intra frames"). iOS will happily take H264 files without keyframes and provide accurate scrubbing. It seems that, to allow accurate scrubbing, we need to insert a keyframe for every frame of the video (the relevant ffmpeg setting is "-g 1"). This significantly increases the file size.

  (C) However, inserting a keyframe for every frame results in a video that will not play at all on the Samsung Galaxy Note 3 (Snapdragon chipset I believe). Reducing the keyframes to every second frame or above seems to work (ffmpeg setting "-g 2").

  To summarise :
  MediaPlayer.seekTo() seems very dependent on the video format, and varies across devices. Is this the intention ? Is there a base level of behaviour that seekTo() is supposed to provide, regardless of format ?

  What video format that will allow frame-accurate scrubbing (using MediaPlayer.seekTo()) across all Android devices (at least for 3.0 and above ?)