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• FFMPEG two black frames in the beginning when converting mp4 aac to mov pcm [closed]

  12 octobre 2023, par Veikka

  I'm trying to convert mp4 h265 aac file to mov 265 pcm16sle file using ffmpeg withoat touching the video stream. When opening the file in DaVinci Resolve, there is two black frames in beginning.

  


  I used this ffmpeg command :

  


  ffmpeg -i file.mp4 -map_metadata 0 -c:v copy -c:a pcm_s16le file.mov


  


  For some reason this command changes timestamp info :

  


  file.mp4
---
"start_pts": 0,
"start_time": "0.000000",
"duration_ts": 519000,
"duration": "20.760000",
"bit_rate": "80688676",

file.mov
---
"start_pts": 2000,
"start_time": "0.080000",
"duration_ts": 517000,
"duration": "20.680000",
"bit_rate": "81000818",


  


  I also get this error when converting file :

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x565392b65800] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1000


  


  I found this bug report, but there didn't found any fixes to my problem.

  


  file.mp4 edit lists looks like this :

  


  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] track[0].edit_count = 1
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] Processing st: 0, edit list 0 - media time: 1000, duration: 519000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] st: 0 edit list: 1 Missing key frame while searching for timestamp: 1000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] st: 0 edit list 1 Cannot find an index entry before timestamp: 1000.
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] track[1].edit_count = 1
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x561fc98ff800] Processing st: 1, edit list 0 - media time: 0, duration: 996353


  


  AAC timecode and H265 has almost same duration withoat the media time: 1000 starting time :

  


  AAC timebase is 1/48000

  


  996353/48000 = 20.75735416666666666667


  


  H265 timebase is 1/25000

  


  519000/25000 = 20.76


  


• ffmediaplayer playing but screen keeps black

  27 août 2023, par Joergahmann

  I#m coding a video tool for sports with the Windows Template Studio and using the Community Toolkit.MVVM. I finished this with the vlcMediaPlayer and it worked almost fine. I need the Frameback (vlc does not provide) and I like autohiding the controls (which is hard with vlc). So I decided to use the ffmediaelemrnt instead.
Almost everything is ok (I hear sound, i can pause, forward ..), only the Video is not showing !!

  


  I'm using an observable property

  


  `    [ObservableProperty]
     private MediaElement _ffmeMediaElement;`


  


  instead of the original implementation with a complete different basemodel :

  


  public MediaElement MediaElement
        {
            get
            {
                if (m_MediaElement == null)
                    m_MediaElement = (Application.Current.MainWindow as MainWindow)?.Media;

                return m_MediaElement;
            }
        }


  


  —> Could this be the problem ? How do I get the (Application.Current.MainWindow as MainWindow) ? in my case with no mainwindow and a page instead


  


                      



  


  What I tried
When I use a contentcontrol instead : the Video is showing, but the controls are not autohiding anymore

  


  When I compile your WindowsSample, it works completly, but still shows the error Object reference not set to an instance of an object on

  


  I would appreciate any help. Thank you in advance

  


• Is there a way to prevent black frames from appearing at the start of a video when using -c:v copy ?

  11 juillet 2023, par MethanE

  My task seems simple. Using ffmpeg in terminal, I'm trying to pass through the exact video settings minus the audio, and i've been successful, except for the fact that the videos start with a frame of black before the actual video plays.

  


  currently using this :

  


  for i in *.*;do ffmpeg -i "$i" -an -c:v copy "${i%.*}_noaudio.mp4";done


  


  My current thought is it may be related to the error I'm getting (the vid still exports), but I'm not certain :
Missing key frame while searching for timestamp : 1001

  


  Input video metadata :

  


  Metadata :
major_brand : XAVC
minor_version : 16785407
compatible_brands : XAVCmp42iso2
creation_time : 2021-09-12T20:13:46.000000Z
Duration : 00:00:17.52, start : 0.000000, bitrate : 107315 kb/s
Stream #0:0(und) : Video : h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 96798 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)

  


  Googling led me to try not using -c:v copy as there might be a glitch related to h264 keyframes and instead using -c:v libx264 but i really don't want to have to re-encode as I don't want to lose any quality. The file I tried this on went from 135 mb down to 6.

  


  Thanks for your help. Kind of a newb at this.