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• Play Raspberry Pi h264 stream in C# app

  29 octobre 2016, par CoreMeltdown

  I have a Raspberry Pi board with dedicated camera that records video only in h264. I am looking for the best method to stream and play recorded video in real-time (as in, less than 1 sec delay) in c# windows forms app. The additional requirement is that such stream can be easily processed before displaying, for example for searching for objects on the image.

  Stuff I tried :

  - VLC server on raspi and VLC control in c# forms app <- simple solution, with RTSP, but has a serious flaw, which is a 3sec delay in image displayed. I couldn’t fix it with buffor size/options etc.

  - creating a socket on raspi with nc, receiving raw h264 data in c# and passing it to mplayer frontend <- If I simply start raspivid | nc and on the laptop nc | mplayer, i get exactly the results i want, the video i get is pretty much realtime, but the problem arises when i try to create mplayer frontend in c# and simulate the nc.exe. Maybe I’m passing the h264 data wrong (simply write them to stdin) or maybe something else.

  - using https://github.com/cisco/openh264 <- I compiled everything, but i can’t even get to decode sample vid.h264 i recorded on raspi with h264dec.exe, not to mention using it in c#.

  h264dec.exe vid.h264 out.yuv

  This produces 0bytes out.yuv file, while :

  h264dec.exe  vid.h264

  Gives me error message : "No input file specified in configuration file."

  - ffmpeg <- I implemented ffplay.exe playback in c# app but the lack of easy method to take screencaps etc. discouraged me to further investigate and develop.

  I’m not even sure whether I’m properly approaching the subject, so I’d be really thankful for every piece of advice I can get.

  EDIT
  Here is my ’working’ solution I am trying to implement in c#

  raspivid --width 400 --height 300 -t 9999999 --framerate 25 --output - | nc -l 5884
  
  
  
  nc ip_addr 5884 | mplayer -nosound -fps 100 -demuxer +h264es -cache 1024 -

  The key here is FPS 100, becuase then mplayer skips lag and plays the video it immediately receives with normal speed.
  The issue here is that I don’t know how to pass video data from socket into mplayer via c#, because I guess it is not done via stdin (already tried that).

• mp4 is not playing on changing the name of mp4 file

  7 juillet 2014, par user2301309

  I am using below code to generate file name-

          File imagefile = new File(path);
  
          int imageCount = 0;
  
          if (!imagefile.exists()) {
  
              imagefile.mkdirs();
  
          }else{
  
              String[] files = imagefile.list();
  
              for(String file : files){
  
                  if(file.contains("mp4")){
  
                      String fileName = file.replace(".mp4","");
  
                      String[] parts = fileName.split("_");
  
                      String count  = parts[parts.length-1].replaceAll("\\D+","");
  
                      int i = Integer.parseInt(count);
  
                      if(i+1>imageCount){
  
                          imageCount = i+1;
  
                      }
  
                  }
  
              }
  
          }
  
          String video_id = "VID"+ "_" + imageCount;
  
          String video_info = (Lat_Lon_CellID.lat+"#"+Lat_Lon_CellID.lon+"#"+Lat_Lon_CellID.datetimestamp+"#"+Home.imei+"#").replaceAll("\\.", "@");
  
          newVideoPath = path + File.separator +video_info+ video_id + ".mp4";

  videofile name generated here is 0@0#0@0#null#354961053417767#VID_0.mp4

  but when i try to play this video, i got error MediaPlayer error (1, -2147483648) while if i change newVideoPath to-

      String video_id = "VID"+ "_" + imageCount;
  
          newVideoPath = path + File.separator + video_id + ".mp4";

  videofile name generated here is VID_0.mp4

  then it plays the video.
  Can anyone tell me that what could be the reason ?

• WebRTC Experiment : Chrome windows audio not sync

  10 juillet 2014, par putoshop

  I tried to make the audio work for Chrome using this Git Repo, but I’m having a sync problem with video and audio. The audio finished playing earlier. The video seems to be correct. I noticed that when I play the blob, the audio is playing fast.

  I was able to make the audio work by commenting the line the throws error in the condition that check if sampleRate is less than 22050 or greater than 96000 in RecordRTC.js.

  I tried to adjust the sampleRate other values and noticed that If the sampleRate is low, the audio plays slow and if the sampleRate is high, the audio plays fast. I was able to make the audio and video somewhat sync but it seems the pitch of the audio becomes noticeable lower than the expected pitch.

  I’ve also tried FFMPEG to adjust the length of the audio to match the video length, but didn’t been able to make it work.

  the extensions of the files that are uploaded to the server for Chrome are .webm(video) and .wav(audio).