title: "Non-monotonous DTS in output stream 0:0 This may result in incorrect timestamps in the output file." error
body: <p>I'm trying to go from .mkv to .mp4 through ffmpeg. Normally I would use </p>
  
  <pre><code>ffmpeg -i $1 -codec copy -strict -2 $2
  </code></pre>
  
  <p>But on this particular file, I get this error, like, A LOT :</p>
  
  <pre><code>Non-monotonous DTS in output stream 0:0; previous: 49189232, current: 49189232; changing to 49189233. This may result in incorrect timestamps in the output file.
  </code></pre>
  
  <p>I guess it has something to do with the DTS :</p>
  
  <pre><code>[mp4 @ 0x7f8b14001200] Invalid DTS: 14832 PTS: 13552 in output stream 0:0, replacing by guess
  [mp4 @ 0x7f8b14001200] Invalid DTS: 15472 PTS: 12272 in output stream 0:0, replacing by guess
  </code></pre>
  
  <p>I would not care if the result was ok, but the sound is out of sync, and the video is "stuttering". Feels like everything is out of sync. </p>
  
  <p>I've tried a lot of things, including -async 1 -vsync 1 , but nothing seems to work. </p>
  
  <p>Here's some mediainfo : </p>
  
  <pre><code>Complete name                            : /Users/petaire/Desktop/CNEWS-2019-07-23_16-00-00h.mkv
  Format                                   : Matroska
  Format version                           : Version 2
  File size                                : 1.19 GiB
  Movie name                               : Time-2019-07-23_16:00
  Writing application                      : Tvheadend 4.3-1801~g7f952c2ed
  Writing library                          : Tvheadend Matroska muxer
  Original source form                     : TV
  Comment                                  : Time recording
  IsTruncated                              : Yes
  DATE_BROADCASTED                         : 2019-07-23 16:00:00
  
  Video
  ID                                       : 1
  Format                                   : AVC
  Format/Info                              : Advanced Video Codec
  Format profile                           : High@L4
  Format settings                          : CABAC / 4 Ref Frames
  Format settings, CABAC                   : Yes
  Format settings, ReFrames                : 4 frames
  Codec ID                                 : V_MPEG4/ISO/AVC
  Width                                    : 1 920 pixels
  Height                                   : 1 080 pixels
  Display aspect ratio                     : 16:9
  Frame rate mode                          : Constant
  Frame rate                               : 25.000 fps
  Standard                                 : Component
  Color space                              : YUV
  Chroma subsampling                       : 4:2:0
  Bit depth                                : 8 bits
  Scan type                                : MBAFF
  Scan type, store method                  : Interleaved fields
  Scan order                               : Top Field First
  Language                                 : English
  Default                                  : Yes
  Forced                                   : No
  Color range                              : Limited
  Color primaries                          : BT.709
  Transfer characteristics                 : BT.709
  Matrix coefficients                      : BT.709
  
  Audio
  ID                                       : 2
  Format                                   : E-AC-3
  Format/Info                              : Enhanced AC-3
  Commercial name                          : Dolby Digital Plus
  Codec ID                                 : A_EAC3
  Bit rate mode                            : Constant
  Bit rate                                 : 128 Kbps
  Channel(s)                               : 2 channels
  Channel layout                           : L R
  Sampling rate                            : 48.0 KHz
  Frame rate                               : 31.250 fps (1536 SPF)
  Compression mode                         : Lossy
  Delay relative to video                  : -757ms
  Language                                 : French
  Service kind                             : Complete Main
  Default                                  : Yes
  Forced                                   : No
  
  Text
  ID                                       : 3
  Format                                   : DVB Subtitle
  Codec ID                                 : S_DVBSUB
  Codec ID/Info                            : Picture based subtitle format used on DVBs
  Language                                 : French
  Default                                  : Yes
  Forced                                   : No
  </code></pre>
  
  <p>Any idea ?</p>