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• Extracting programs from dvb mux which begin later in stream

  28 novembre 2016, par John Allsup

  On DVB-T, some channels do not run 24h/day. If I save the entire mux using e.g. vlc (I do this on Windows due to Linux not liking my TV stick), I can play back the resulting .ts file with vlc, and select programs, and if I skip, say, 1hr in, and switch to the program (once started), I can watch it ok. If, however, I run ffmpeg on the file, it reports the program as having only one stream, of type ’Unknown : none’, and cannot extract the stream.

  The reasoning is that if I wish to capture the first program from a channel which comes on at, say, 7pm, I want the dump of the mux to begin before 7pm.

  Any thoughts on how to extract the program stream ?

• Displaying text on video while recording and if saved then also (add text to video when start recording)

  25 novembre 2017, par J4GD33P 51NGH

  i’m using this android project from git hub and now want to add text to video when start recording. text should also there if we watch saved video later. can anyone suggest me an idea to do this.

• How to do Slow Motion video in IOS

  17 janvier 2017, par 2vision2

  I have to do "slow motion" in a video file along with audio, in-between some frames and need to store the ramped video as a new video.

  Ref : http://www.youtube.com/watch?v=BJ3_xMGzauk (watch from 0 to 10s)

  From my analysis, I’ve found that AVFoundation framework can be helpful.

  Ref :
  http://developer.apple.com/library/ios/#documentation/AudioVideo/Conceptual/AVFoundationPG/Articles/00_Introduction.html

  Copy and pasted from the above link :

  "
  Editing
  AV Foundation uses compositions to create new assets from existing pieces of media (typically, one or more video and audio tracks). You use a mutable composition to add and remove tracks, and adjust their temporal orderings. You can also set the relative volumes and ramping of audio tracks ; and set the opacity, and opacity ramps, of video tracks. A composition is an assemblage of pieces of media held in memory. When you export a composition using an export session, it’s collapsed to a file.
  On iOS 4.1 and later, you can also create an asset from media such as sample buffers or still images using an asset writer.

  "

  Questions :
  Can I do " slow motion " the video/audio file using the AVFoundation framework ? Or Is there any other package available ? If i want to handle audio and video separately, please guide me how to do ?

  Update : : Code For AV Export Session :

   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  
      NSString *outputURL = paths[0];
  
      NSFileManager *manager = [NSFileManager defaultManager];
  
      [manager createDirectoryAtPath:outputURL withIntermediateDirectories:YES attributes:nil error:nil];
  
      outputURL = [outputURL stringByAppendingPathComponent:@"output.mp4"];
  
      // Remove Existing File
  
      [manager removeItemAtPath:outputURL error:nil];
  
      AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:self.inputAsset presetName:AVAssetExportPresetLowQuality];
  
      exportSession.outputURL = [NSURL fileURLWithPath:outputURL]; // output path;
  
      exportSession.outputFileType = AVFileTypeQuickTimeMovie;
  
      [exportSession exportAsynchronouslyWithCompletionHandler:^(void) {
  
          if (exportSession.status == AVAssetExportSessionStatusCompleted) {
  
              [self writeVideoToPhotoLibrary:[NSURL fileURLWithPath:outputURL]];
  
              ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
  
              [library writeVideoAtPathToSavedPhotosAlbum:[NSURL fileURLWithPath:outputURL] completionBlock:^(NSURL *assetURL, NSError *error){
  
                  if (error) {
  
                      NSLog(@"Video could not be saved");
  
                  }
  
              }];
  
          } else {
  
              NSLog(@"error: %@", [exportSession error]);
  
          }
  
      }];