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• uncertain behaviour of xml parser and ffmpeg streaming

  8 octobre 2013, par user2775836

  I am making an ios application to display live streaming from ip camera using ffmpeg libraries.I am also using http api requests and responses.the response is in xml format ,hence i am using xml parser to parse the response.I have two view controllers(first and second).I am initializing the xml parser at view did disappear function of the first view controller also i am calling the function to stop the streaming in view did disappear after xml parsing function.While navigating from first view controller to second view controller the xml parser gets initiated but the parsing response does not get completed .when i come back from second to first view controller and then navigate again to second view controller ,at that time the full response is parsed.Why the response gets parsed second time not first time and why is it parsing half first time.Please help.
  The code is as follows :

  - (void)viewDidDisappear:(BOOL)animated {
  
  
  
         [self parsing]; //call to parsing function
  
  
  
      [self.h264dec stopDecode]; //call to stop streaming
  
      self.h264dec = nil;
  
   }
  
  
  
  parsing function is:
  
  
  
  -(void)parsing
  
  {
  
      NSString *urlString = [NSString stringWithFormat:@"http://www.example.com"];
  
      NSURL *url = [NSURL URLWithString:urlString];
  
  
  
  
  
      NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];
  
  
  
      [theRequest addValue: @"application/x-www-form-urlencoded; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
  
      [theRequest setHTTPMethod:@"GET"];
  
  
  
      NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
  
  
  
      if( connection )
  
      {
  
          mutableData = [[NSMutableData alloc] init];
  
          NSLog(@"connection successful");
  
      }
  
  
  
  }
  
  
  
  -(void) connection:(NSURLConnection *) connection didReceiveResponse:(NSURLResponse *)response
  
  {
  
      NSLog(@"receive response");
  
  }
  
  -(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
  
  {
  
  
  
      [mutableData appendData:data];
  
      NSLog(@"DIDRECEIVE");
  
      NSLog(@"the mutable data is: %@",mutableData);
  
  
  
  }
  
  
  
  -(void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
  
  {
  
       return;
  
  }
  
  
  
  -(void)connectionDidFinishLoading:(NSURLConnection *)connection
  
  {
  
      NSLog(@"finish loading");
  
  
  
      // You can do your functions here. If your repines is in XML you have to parse the response using NSXMLParser. If your response in JSON you have use SBJSON.
  
      NSXMLParser *parser = [[NSXMLParser alloc] initWithData:mutableData];
  
      [parser setDelegate:self];
  
      [parser parse];
  
  
  
  }
  
  
  
      - (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict
  
      {
  
  
  
          if([elementName isEqualToString:@"Response"]){
  
              NSLog(@"item found");
  
              xmlStringFileObject =[[XMLStringFile alloc]init];
  
          }
  
  
  
      }
  
  
  
      - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
  
      {
  
  
  
            [nodecontent appendString:[string stringByTrimmingCharactersInSet:[NSCharacterSet    whitespaceAndNewlineCharacterSet]]];
  
          NSLog(@"node content = %@",nodecontent);
  
      }
  
  
  
      //bellow delegate method specify when it encounter end tag of specific that tag
  
  
  
      - (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
  
      {
  
          //I am saving my nodecontent data inside the property of XMLString File class
  
           if([elementName isEqualToString:@"test"]){
  
              xmlStringFileObject.test=nodecontent;
  
              NSLog(@"test:%@",xmlStringFileObject.test);
  
          }
  
  
  
          else if([elementName isEqualToString:@"resolution"]){
  
              xmlStringFileObject.resolution=nodecontent;
  
              NSLog(@"resolution:%@",xmlStringFileObject.resolution);
  
              AppDelegate *app = (AppDelegate*) [[UIApplication sharedApplication]delegate];
  
              app.res = xmlStringFileObject.resolution;
  
              NSLog(@"THE APPDELEGATE RES VALUE IS:%@",app.res);
  
          }
  
  
  
              //finally when we reaches the end of tag i am adding data inside the NSMutableArray
  
          if([elementName isEqualToString:@"Response"]){
  
              [rssOutputData addObject:xmlStringFileObject];
  
  
  
              xmlStringFileObject = nil;
  
  
  
          }
  
          //release the data from mutable string variable
  
  
  
  
  
          //reallocate the memory to get new content data from file
  
          nodecontent=[[NSMutableString alloc]init];
  
  
  
      }

• How to play ffmpeg dash ?

  30 janvier 2024, par Roshan Ojha

  I have following code to create chunk of video.

  


  permission_classes=[AllowAny]
video_serializer = serializers.video_serializer

def process_video(self, video_path, video_id):
    # Set the path where the processed videos will be saved
    output_dir = os.path.join(settings.MEDIA_ROOT, 'processed_videos')

     # Create the output directory if it doesn't exist
    os.makedirs(output_dir, exist_ok=True)

    # Add your ffmpeg_streaming code here to process the video
    full_video_path =  os.path.join(settings.MEDIA_ROOT, str(video_path))
    print(video_path)
    video = ffmpeg_streaming.input(full_video_path)
    print(video)

      # Add your ffmpeg_streaming code here to process the video
    _144p  = Representation(Size(256, 144), Bitrate(95 * 1024, 64 * 1024))
    _240p  = Representation(Size(426, 240), Bitrate(150 * 1024, 94 * 1024))
    _360p  = Representation(Size(640, 360), Bitrate(276 * 1024, 128 * 1024))
    _480p  = Representation(Size(854, 480), Bitrate(750 * 1024, 192 * 1024))
    _720p  = Representation(Size(1280, 720), Bitrate(2048 * 1024, 320 * 1024))

    dash = video.dash(Formats.h264())
    dash.representations(_144p, _240p, _360p, _480p, _720p)
    dash.output(os.path.join(output_dir, f'dash-stream-{video_id}.mpd'))


def post(self,request):
    try:
        video_data = self.video_serializer(data=request.data)
        video_data.is_valid(raise_exception=True)
        data = video_data.validated_data

        video_instance = Video.objects.create(
            id = data.get('id'),
            saved_location = data.get('video')
        )
        video_instance.save()

        self.process_video(video_instance.saved_location, video_instance.id)
        return Response({"success":True})
    except Exception as e:
        return Response({"success":False,"message":str(e)})


  


  This code is working well as it has created different chunk files as well as a .mpd file of a video inside media/processed_video folder.

  


  Then I wrote following code to stream that video using that .mpd folder.

  


      def get (self,request,video_id):
    try:
        mpd_path = os.path.join(settings.MEDIA_ROOT, 'processed_videos', f'dash-stream-{video_id}.mpd')
        
        with open(mpd_path, 'rb') as f:
            mpd_content = f.read()
            response = HttpResponse(mpd_content, content_type='application/dash+xml')

            # Set Content-Disposition header to make the response downloadable
            response['Content-Disposition'] = f'attachment; filename="dash-stream-{video_id}.mpd"'
            
            # Optionally set Content-Length header to specify the size of the file
            response['Content-Length'] = len(mpd_content)
            
            return response
        
    except Exception as e:
        return Response({"success":False,"message":str(e)})


  


  When I make get request to the api it returns content of .mpd as it is (i.e xml). When I used that api in vlc network stream, vlc couldn't play the video. But when I dragged .mpd file directly to vlc, the video gets played with 144p only. I don't know where I got wrong in GET. Please help.

  


• Failed to convert web-saved .wemb audio to .wav by using php "shell_exec" and javascript

  30 mai 2022, par Anirbasgnaw

  I'm working on an online experimenter which could record participants' audio from the browser. The audio data I get has an extension of .wemb, so I plan to use ffmpeg to convert it to .wav while I save the data.

  


  I tried to use PHP's shell_exec but nothing happens when I run the scripts. Then I found that my echo and print_r also did not work. I'm new to PHP and javascript, so I''m really confused now.

  


  Below are the relevant codes, I really appreciate it if you could help !

  


  write_data.php :

  


  <?php
  $post_data = json_decode(file_get_contents('php://input'), true); 
  // the directory "data" must be writable by the server
  $name = "../".$post_data['filename'];
  $data = $post_data['filedata'];
   // write the file to disk
  file_put_contents($name, $data);
  
  $INPUT = trim($name) . ".webm";
  $OUTPUT = trim($name) . ".wav";
  echo "start converting...";

  // check if ffmprg is available
  $ffmpeg = trim(shell_exec('which ffmpeg'));
  print_r($ffmpeg);
  // call ffmpeg
  shell_exec("ffmpeg -i '$INPUT' -ac 1 -f wav '$OUTPUT' 2>&1 ");
?>


  


  javascript :

  


    saveData: function(fileName,format){
    // save  as json by default
    if (!format){ format = 'json';}
    // add extension to filename
    fileName = `${fileName}.${format}`
    // create saveData object using fetch
    let saveData = [];
    if (format == 'json') {
        saveData = {
          type: 'call-function',
          async: true,
          func: async function(done) {
            let data = jsPsych.data.get().json();
            const response = await fetch("../write_data.php", {
              method: "POST",
              headers: {
                "content-type": "application/json"
              },
              body: JSON.stringify({ filename: fileName, filedata: data })
            });
            if (response.ok) {
              const responseBody = await response.text();
              done(responseBody);
            }
          }
        }
    } else {
        saveData = {
          type: 'call-function',
          async: true,
          func: async function(done) {
            let data = jsPsych.data.get().csv();
            const response = await fetch("../write_data.php", {
              method: "POST",
              headers: {
                "content-type": "application/json"
              },
              body: JSON.stringify({ filename: fileName, filedata: data })
            });
            if (response.ok) {
              const responseBody = await response.text();
              done(responseBody);
            }
          }
        }
    }
    return saveData;
  },