Video Audio Lose Sync in Hitfilm

I shoot mpg2 video with ACC audio 48000.

For editing I convert to Prores.  Video and audio still in sync all the way thru. (20 minute clip)

I edit in Hitfilm Pro.  Everything in sync on timeline playback.

Final render starts drifting out of sync half way thru timeline and is a good 3 seconds out of sync by the end.

Computer:

AMD Architecture 8 cores,  Radeon RX-480 Graphics (8 gb mem onboard), 16 gig system memory.

Comments

  • Triem23Triem23 Moderator

    Make certain your footage framerate, project framerate and export framerate all match exactly. Yes, there's a real difference between 29.97 and 30 or 59.96 and 60.

    Make sure audio rates match. If the source audio is 48k and Hitfilm is set to 44.1k (or vice versa) drift will occur. 

    What is the original footage from? It's possible it was variable framerate, and left that way in transcode. Players (like VLC) do fine with VFR footage, but an NLE needs constant framerate footage or synch drift will happen. 

  • I am at a loss...I have spent the better part of a day and a half trying to get my audio (or video) to NOT drift in my 20 minute timeline. The original clip is 720x480 mpg2 SD footage with AAC audio. I have tried converting to Prores, converting to mpg4, converting to .mov, all with Constant Bit Rate...still drifts. I have tried editing the original clip as it came in from the camera...nothing has worked. I make sure all frame rates, in source and project match...that all audio properties in source and project match (i.e. 48,000)...nothing changes...I have tried converting to different audio files as well...no luck. Please...any help?

  • Triem23Triem23 Moderator

    Ok, download Mediainfo (it's free)  and give us the full media info report on your original footage and transcoded footage... We need more information. 

  • Original File:

    General
    Complete name : C:\Users\Desktop\M2U00050.MPG
    Format : MPEG-PS
    File size : 1.41 GiB
    Duration : 21 min 41 s
    Overall bit rate mode : Variable
    Overall bit rate : 9 313 kb/s

    Video
    ID : 224 (0xE0)
    Format : MPEG Video
    Format version : Version 2
    Format profile : Main@Main
    Format settings, BVOP : Yes
    Format settings, Matrix : Custom
    Format settings, GOP : M=3, N=15
    Format settings, picture structure : Frame
    Duration : 21 min 41 s
    Bit rate mode : Variable
    Bit rate : 8 872 kb/s
    Maximum bit rate : 9 100 kb/s
    Width : 720 pixels
    Height : 480 pixels
    Display aspect ratio : 16:9
    Frame rate : 29.970 (30000/1001) FPS
    Standard : NTSC
    Color space : YUV
    Chroma subsampling : 4:2:0
    Bit depth : 8 bits
    Scan type : Interlaced
    Scan order : Top Field First
    Compression mode : Lossy
    Bits/(Pixel*Frame) : 0.857
    Time code of first frame : 00:00:00:00
    Time code source : Group of pictures header
    GOP, Open/Closed : Closed
    Stream size : 1.34 GiB (95%)

    Audio
    ID : 189 (0xBD)-128 (0x80)
    Format : AC-3
    Format/Info : Audio Coding 3
    Mode extension : CM (complete main)
    Format settings, Endianness : Big
    Muxing mode : DVD-Video
    Duration : 21 min 41 s
    Bit rate mode : Constant
    Bit rate : 256 kb/s
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 48.0 kHz
    Frame rate : 31.250 FPS (1536 spf)
    Bit depth : 16 bits
    Compression mode : Lossy
    Stream size : 39.7 MiB (3%)

     

    Transcoded File:

     

    General
    Complete name : C:\Users\Desktop\Desktop\M2U00050.mov
    Format : MPEG-4
    Format profile : QuickTime
    Codec ID : qt 0000.02 (qt )
    File size : 8.54 GiB
    Duration : 21 min 41 s
    Overall bit rate mode : Variable
    Overall bit rate : 56.4 Mb/s
    Writing application : Lavf57.19.100

    Video
    ID : 1
    Format : ProRes
    Format version : Version 0
    Format profile : 422 HQ
    Codec ID : apch
    Duration : 21 min 41 s
    Bit rate mode : Variable
    Bit rate : 56.1 Mb/s
    Width : 720 pixels
    Height : 480 pixels
    Display aspect ratio : 16:9
    Frame rate mode : Constant
    Frame rate : 29.970 (29970/1000) FPS
    Standard : NTSC
    Color space : YUV
    Chroma subsampling : 4:2:2
    Scan type : Interlaced
    Original scan type : Progressive
    Scan type, store method : Interleaved fields
    Scan order : Top Field First
    Bits/(Pixel*Frame) : 5.419
    Stream size : 8.50 GiB (100%)
    Writing library : fmpg
    Language : English
    Matrix coefficients : BT.601

    Audio
    ID : 2
    Format : AAC
    Format/Info : Advanced Audio Codec
    Format profile : LC
    Codec ID : 40
    Duration : 21 min 41 s
    Duration_LastFrame : -11 ms
    Bit rate mode : Variable
    Bit rate : 253 kb/s
    Maximum bit rate : 256 kb/s
    Channel(s) : 2 channels
    Channel positions : Front: L R
    Sampling rate : 48.0 kHz
    Frame rate : 46.875 FPS (1024 spf)
    Compression mode : Lossy
    Stream size : 39.3 MiB (0%)
    Language : English
    Default : Yes
    Alternate group : 1

     

     

  • Triem23Triem23 Moderator

    @NormanPCN @Stargazer54  @Aladdin4d other than his transcoded footage being interlaced, any oddities jumping out at you? 

  • Triem23Triem23 Moderator

    Now, in this thread one of tge developers discusses briefly a known audio bug. It's intended to be patched in the Update #2 release later this month. In the absence of any obvious oddities in the files, this bug may be what's affecting you, in which case you have to wait a week or two for the next Update. 

  • Do you mind if I ask what the "bug" is affecting?  Is it directly related to keeping audio/video in sync?

  • Triem23Triem23 Moderator

    Couldn't tell you. Moderators aren't FxHome staff, we're volunteers. I thought I left a thread link in my last post, but being up for over 60 hours in three days has me a bit loopy. 

    http://hitfilm.com/forum/discussion/comment/85723/#Comment_85723

    Yes, there's an audio bug causing synch issues for some users. 

  • I am having the same problem, at about 8 minutes the sync gets out of wack, even though it is synced in the editor timeline.

  • Nothing jumps out. The source media looks fine. The mpeg-2/AC3 and transcoded Prores/AAC.

  • Not to beat the issue to death (because I believe the developers understand the issue) ... I can play my timeline 20 minutes, 30 minutes, whatever....and video and audio stayed synced.  It's not until I export the timeline does it drift out of sync.

  • A couple of crazy ideas:

    Render out to one of the other format options - Cineform, YouTube, Vimeo, etc.  

    Also, maybe try rendering to variable frame rate instead of constant.

  • I'm not seeing anything obvious either but how about exporting just the video without audio and then export an audio only AVI, import both and see how they line up with the project

  • I'm inclined to go with "this is a bug that should be fixed when Update #2 comes out" at this point. 

  • @HitFilmer220021 @TGamel we've fixed that a few days ago, the new update is coming shortly. For those interested it's to do with the audio sample rate that does not divide with the video frame rate. You can fiddle with the project audio sample rate to get it to work (or wait a little bit to get the update, which would be much easier).

    If this is not fixed for you in Update 2, please let us know. Sorry about the inconvenience.

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