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• 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.

• Getting video sped-up with FFmpeg to have the correct duration

  1er septembre 2015, par Vincent Tjeng

  I’ve been speeding up video using ffmpeg by following these instructions. For example, to speed up the video by 4 times, I run the following command :

  ffmpeg -i vid.MP4 -filter:v "setpts=0.25*PTS" vid_fast.MP4

  While the video is sped up by the indicated amount, the duration of the video (as indicated under its properties, and also when I play the video in VLC) remains the same as the original. For example, if vid.MP4 is initially 4 minutes, then vid_fast.MP4 is also 4 minutes, rather than being 1 minute long as expected. (The additional 3 minutes just consist of the video being frozen on the last frame.)

  This is a bit of a hassle, since I need to delete the additional 3 minutes that I’m not interested in. Is there any way to avoid this ?

  Here is a bit more information on the version of ffmpeg I’m using :

  ffmpeg version N-69060-gcd960c8 Copyright (c) 2000-2015 the FFmpeg developers
  
    built on Jan 14 2015 22:13:45 with gcc 4.9.2 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-lib
  
  modplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrw
  
  b --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinge
  
  r --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --en
  
  able-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis
  
   --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-
  
  libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enab
  
  le-zlib
  
    libavutil      54. 16.100 / 54. 16.100
  
    libavcodec     56. 20.100 / 56. 20.100
  
    libavformat    56. 18.101 / 56. 18.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5.  7.101 /  5.  7.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Hyper fast Audio and Video encoder

• RTMPE FFMPEG on Linux [on hold]

  31 août 2015, par user3317118

  I’m getting download on Windows but on Linux can not, gives this error.
  [![enter image description here][1]][1]

  bebetoalves: ~/Web $ ffmpeg -f concat -i ep.txt -codec copy theroyalrangers.mkv  

  ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration : —disable-yasm

  libavutil 54. 27.100 / 54. 27.100
  libavcodec 56. 41.100 / 56. 41.100
  libavformat 56. 36.100 / 56. 36.100
  libavdevice 56. 4.100 / 56. 4.100
  libavfilter 5. 16.101 / 5. 16.101
  libswscale 3. 1.101 / 3. 1.101
  libswresample 1. 2.100 / 1. 2.100

  [concat @ 0x1bf4260] Impossible to open ’rtmpe ://viacomnickstrmfs.fplive.net/viacomnickstrm/gsp.alias/me
  diabus/kids.com/2015/08/26/11/22/23884690/HDXPR510A1_884690_5801915_1280x720_3500_h32.mp4’

  ep.txt : Protocol not found
  bebetoalves : /Web $