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• Live video streaming with Node js ,HTML5, MPEG-DASH, FFMPEG and IP camera/Raspberry Pi

  12 mai 2016, par sparks

  I am a programmer but i am very new in live video streaming concepts.I need help

  What i want to accomplish

  I want to develop an online live video streaming system.The scenario is i would have a device or number of devices(raspberry pi & camera only OR ip camera only ...not sure yet) to capture the video and stream the video live in real time remotely to my web app.Multiple clients can connect to the web app and watch the video live.The key things to note here, is that these devices should be wireless(able to connect to internet and live stream the content) and also i want to eliminate the idea of manually configuring the ip adrress to local WIFI router.So simply i turn on the device and it start streaming right away to the web app.

  Infrastructure, Platforms,Browsers, Streaming methods and formats

  In the beginning i just want to stream though chrome web browser(that’s all i care about).But in the future i would build android and IOS mobile apps.So long term i would expect to be Chrome and mobile(Android & IOS platforms)
  So based on my research i learned that the client should be HTML5, streaming method MPEG-DASH(In the future add HLS), the web app will be in Node Js.I also came across Dash.js for Html5.

  My understanding of streaming based on my research

  I also came across things like FFMPEG,Dash encoder and wowza which i am not clear about.Now correct me if i am wrong, my understanding is that FFMPEG get hold of the device/camera and the content(i am not sure the format of the content at this point)and format it(i am not sure what this means in simple english) and then Dash encoder picks up and re-format the content to MPEG-DASH format, which produces MPD and then Dash.js client uses MPD to display the video to the browser.

  QUESTIONS

  1. First correct me if i am wrong based on my understanding above or
     clarify for me.Also I am not sure of where the wowza streaming
     engine come into play. Do i even need it ?

  2. I am not sure of the devices to use between Raspberry pi with camera
     module/ Or IP Wifi camera by itself.I know with raspberry pi
     connected to internet you can set up all the necessary programs and
     stream the video to web app directly(not sure about quality and
     performance) but I am not sure about Wifi camera.Is it possible to
     connect to the wifi camera remotely from the web app programatically
     without opening the wifi router portal manually or i should stick
     with Raspbery Pi ?

  3. For raspberry Pi would i be able to connect it with high quality
     picture IP camera/web cam ? (The point here to get the best picture
     through raspbery Pi)

     My expectations

     Better performance and quality would be great.But i know live streaming is not easy so i am willing to compromise performance to a point but not quality.

  Thank you in advance, Anything will be appreciated.I know this is a lot so take your time :)

• How to embed subtitles into an mp4 file using gstreamer

  27 août 2021, par Stephen

  My Goal

  


  I'm trying to embed subtitles into an mp4 file using the mp4mux gstreamer element.

  


  What I've tried

  


  The pipeline I would like to use is :

  


  GST_DEBUG=3 gst-launch-1.0 filesrc location=sample-nosub-avc.mp4 ! qtdemux ! queue ! video/x-h264 ! mp4mux name=mux reserved-moov-update-period=1000 ! filesink location=output.mp4 filesrc location=english.srt ! subparse ! queue ! text/x-raw,format=utf8 ! mux.subtitle_0


  


  It just demuxes a sample mp4 file for the h.264 stream and then muxes it together with an srt subtitle file.

  


  The error I get is :

  


  Setting pipeline to PAUSED ...&#xA;0:00:00.009958915 1324869 0x5624a8c7a0a0 WARN                 basesrc gstbasesrc.c:3600:gst_base_src_start_complete:<filesrc0> pad not activated yet&#xA;Pipeline is PREROLLING ...&#xA;0:00:00.010128080 1324869 0x5624a8c53de0 WARN                 basesrc gstbasesrc.c:3072:gst_base_src_loop:<filesrc1> error: Internal data stream error.&#xA;0:00:00.010129102 1324869 0x5624a8c53e40 WARN                 qtdemux qtdemux_types.c:239:qtdemux_type_get: unknown QuickTime node type pasp&#xA;0:00:00.010140810 1324869 0x5624a8c53de0 WARN                 basesrc gstbasesrc.c:3072:gst_base_src_loop:<filesrc1> error: streaming stopped, reason not-negotiated (-4)&#xA;0:00:00.010172990 1324869 0x5624a8c53e40 WARN                 qtdemux qtdemux.c:3237:qtdemux_parse_trex:<qtdemux0> failed to find fragment defaults for stream 1&#xA;ERROR: from element /GstPipeline:pipeline0/GstFileSrc:filesrc1: Internal data stream error.&#xA;Additional debug info:&#xA;gstbasesrc.c(3072): gst_base_src_loop (): /GstPipeline:pipeline0/GstFileSrc:filesrc1:&#xA;streaming stopped, reason not-negotiated (-4)&#xA;ERROR: pipeline doesn&#x27;t want to preroll.&#xA;Setting pipeline to NULL ...&#xA;Freeing pipeline ...&#xA;</qtdemux0></filesrc1></filesrc1></filesrc0>

  


  My Thoughts

  


  I believe the issue is not related to the above warning but rather mp4mux's incompatibility with srt subtitles.

  


  The reason I belive this is because, other debug logs hint at it, but also stealing the subititles from another mp4 file and muxing it back together does work.

  


  gst-launch-1.0  filesrc location=sample-nosub-avc.mp4 ! qtdemux ! mp4mux name=mux ! filesink location=output.mp4 filesrc location=sample-with-subs.mp4 ! qtdemux name=demux demux.subtitle_1 ! text/x-raw,format=utf8 ! queue ! mux.subtitle_0


  


  A major catch 22 I am having is that mp4 files don't typically support srt subtitles, but gstreamer's subparse element doesn't support parsing mp4 subtitle formats (tx3g, ttxt, etc.) so I'm not sure how I'm meant to put it all together.

  


  I'm very sorry for the lengthy question but I've tried many things so it was difficult to condense it. Any hints or help is appreciated. Thank you.

  


• ios video after trimming then play on non ios device audio/video out of sync

  31 août 2015, par gavinHe

  trimming video,then I send the video trimmed to android device and play,I find audio/video out of sync, the audio is several seconds behind the video. but the video can play normal on iOS device.
  1.I trim video with codes like this :

   - (IBAction)showTrimmedVideo:(UIButton *)sender
  
  {
  
  [self deleteTmpFile];
  
  
  
  NSURL *videoFileUrl = [NSURL fileURLWithPath:self.originalVideoPath];
  
  
  
  AVAsset *anAsset = [[AVURLAsset alloc] initWithURL:videoFileUrl options:nil];
  
  NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:anAsset];
  
  if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality]) {
  
  
  
      self.exportSession = [[AVAssetExportSession alloc]
  
                            initWithAsset:anAsset presetName:AVAssetExportPresetHighestQuality];
  
      // Implementation continues.
  
  
  
      NSURL *furl = [NSURL fileURLWithPath:self.tmpVideoPath];
  
  
  
      self.exportSession.outputURL = furl;
  
      self.exportSession.outputFileType = AVFileTypeMPEG4;
  
  
  
      CMTime start = CMTimeMakeWithSeconds(self.startTime, anAsset.duration.timescale);
  
      CMTime duration = CMTimeMakeWithSeconds(self.stopTime-self.startTime, anAsset.duration.timescale);
  
      CMTimeRange range = CMTimeRangeMake(start, duration);
  
      self.exportSession.timeRange = range;
  
  
  
      self.trimBtn.hidden = YES;
  
      self.myActivityIndicator.hidden = NO;
  
      [self.myActivityIndicator startAnimating];
  
      [self.exportSession exportAsynchronouslyWithCompletionHandler:^{
  
  
  
          switch ([self.exportSession status]) {
  
              case AVAssetExportSessionStatusFailed:
  
                  NSLog(@"Export failed: %@", [[self.exportSession error] localizedDescription]);
  
                  break;
  
              case AVAssetExportSessionStatusCancelled:
  
                  NSLog(@"Export canceled");
  
                  break;
  
              default:
  
                  NSLog(@"NONE");
  
                  dispatch_async(dispatch_get_main_queue(), ^{
  
                      [self.myActivityIndicator stopAnimating];
  
                      self.myActivityIndicator.hidden = YES;
  
                      self.trimBtn.hidden = NO;
  
                      [self playMovie:self.tmpVideoPath];
  
                  });
  
                  break;
  
          }
  
      }];
  
  }
  
  }

  2.I send the video trimmed to server,then android device get video from server,but they find audio/video out of sync,at first I consider of server do something wrong,so I just send video to android device with USB,the error still exist.

  3.so I analyze the trimmed video by ffmpeg tools :
  ffmpeg -i trimVideo.mp4
  then I find trimVideo.mp4 start is a negative number.
  here is what ffmpeg print :

  Metadata :
  major_brand : qt
  minor_version : 0
  compatible_brands : qt
  creation_time : 2015-08-29 12:22:13
  encoder : Lavf56.15.102
  Duration : 00:02:21.77, start : -4.692568, bitrate : 359 kb/s
  Stream #0:0(und) : Audio : aac (LC) (mp4a / 0x6134706D), 24000 Hz, stereo, fltp, 69 kb/s (default)
  Metadata :
  creation_time : 2015-08-29 12:22:13
  handler_name : Core Media Data Handler
  Stream #0:1(und) : Video : h264 (High) (avc1 / 0x31637661), yuv420p, 512x288 [SAR 1:1 DAR 16:9], 277 kb/s, 15.16 fps, 15.17 tbr, 12136 tbn, 30.34 tbc (default)
  Metadata :
  creation_time : 2015-08-29 12:22:13
  handler_name : Core Media Data Handler
  encoder : ’avc1’

  I have been puzzled by this bug for several days, I am sorry of my bad english and I really need your help,thanks.