Black/Blank Frames Appear in Imported Video

edited November 16 in Express Support

When I import 1080 30 FPS AVI file intermittent blank frames appear in the playback in Hitfilm 4 Express. It appears randomly as a series of 1-3 black flashes. It's in the original media, carries over through compositing and becomes part of the final rendered video export.

When I play the original source AVI file in VLC or Media Player or VideoPad, and go frame by frame, the blank frames are not present. They only appear in Hitfilm. However, after Hitfilm exports the video, it becomes permanently part of the file and it can be seen in all the other video players.

Anybody have a clue what this is?

Comments

  • Triem23Triem23 Moderator

    Ok, the above video covers transcoding, but there's also a section on using MediaInfo to analyze files. Can you install MediaInfo (free), generate a Tree Report and copy/paste it here? That will show us the details of the source video and help debug the issue. 

  •  General
    Complete name                            : R:\MOVI0001.avi
    Format                                   : AVI
    Format/Info                              : Audio Video Interleave
    File size                                : 676 MiB
    Duration                                 : 10 min 1 s
    Overall bit rate                         : 9 433 kb/s
    Director                                 : Generplus
    Original source form/Distributed by      : Generplus
    Recorded date                            : 2010-06-29
    Copyright                                : Generplus

    Video
    ID                                       : 0
    Format                                   : JPEG
    Codec ID                                 : MJPG
    Duration                                 : 10 min 0 s
    Bit rate                                 : 8 462 kb/s
    Width                                    : 1 920 pixels
    Height                                   : 1 080 pixels
    Display aspect ratio                     : 16:9
    Frame rate                               : 30.000 FPS
    Color space                              : YUV
    Chroma subsampling                       : 4:2:0
    Bit depth                                : 8 bits
    Compression mode                         : Lossy
    Bits/(Pixel*Frame)                       : 0.136
    Stream size                              : 606 MiB (90%)

    Audio
    ID                                       : 1
    Format                                   : PCM
    Format settings                          : Little / Signed
    Codec ID                                 : 1
    Duration                                 : 10 min 1 s
    Bit rate mode                            : Constant
    Bit rate                                 : 512 kb/s
    Channel(s)                               : 1 channel
    Sampling rate                            : 32.0 kHz
    Bit depth                                : 16 bits
    Stream size                              : 36.7 MiB (5%)
    Alignment                                : Aligned on interleaves
    Interleave, duration                     : 999  ms (29.97 video frames)

  • edited November 17

    I transcoded the original AVI to MP4 using Handbrake using the recommended settings. The MP4 output file does not seem to have the blank flashing frames.

  • edited November 17

    What created the original AVI file? Was it a screen capture program?

    If yes, I wonder if the file is variable frame rate. The AVI format does not really support variable frame rate. It (VFR) can be faked by inserting null/empty (not blank/black) frames where the decoder is supposed to repeat a previous frame for the null frame. This is as I understand it (which may not be worth a lot). So what if a decoder gave a black frame for a null/empty frame in the data stream. All big time speculation of course.

    One thing I can say is that you really do not want to be using media where Hitfilm uses Video for Windows to decode the file. The performance is not so good relative to all others. Anything in any AVI file goes through VfW except Cineform in Hitfilm 2017. Cineform performs better than all others in Hitfilm.

    edit: So a transcode really can help in a couple of ways.

  • @NormanPCN I'm going to guess it's a problem with Motion JPEG instead of being variable frame rate. I've had problems with MJPEG in general since the Windows 10 Anniversary update. The Windows MJPEG decoder is  a Media Foundation Transform(?) and I suspect even simple playback has been affected by the changes made to enable camera sharing across applications. 

  •  @NormanPCN I have a hunch your speculation re: the null-to-black frame issue with AVI files is correct.  I remember encountering black frames in a project involving screen capture footage that I'd acquired from a Windows user.  Haven't thought about it much since then, but my gut tells me that if I'd known about transcoding then, I wouldn't have had those black frames.

  • The AVI files are from a cheap action camera. All I'm doing is editing together some home videos. Why do these blank frames only appear in Hitfilm but not in any other video player or editor I've tried?

  • Triem23Triem23 Moderator

    The action camera might still be VFR, in which case Norman and Aladdin's analysis applies. 

    Video players are more forgiving than any editor and Hitfilm is very strict in codec implementation. Any kind of non standard implementation will cause issues. 

     

  • @CloudMonkey As @NormanPCN already pointed out, with the exception of Cineform encoded clips, HitFilm relies on Video for Windows for handling AVI files. Microsoft's own MJPEG implementation is pretty shoddy and really meant to be used in a capture stream like with a webcam rather than decoding in an editing app. Because of that there are third party MJPEG VfW codecs out there with most of them (LEAD Tools, Morgan, PicVideo)  being pay to play. Other free options don't do a whole lot better than Microsoft's own implementation because they aren't really VfW codecs. Instead they are DirectShow filters with their own problems. 

    What a lot of other programs do for MJPEG instead of relying on a VfW codec is incorporate a "native" decoder usually using FFMpeg libraries. Since it's native, it bypasses the whole VfW nightmare.

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