Audio and Video only partially syncing.

edited January 2017 in Pro Support

Hi all,

            I am doing some basic tasks in the Hitfilm editor and have come across an interesting situation that I can’t recall ever running into before.

            I'm not sure what info will help with resolving the issue so I'll give some basic info. I received footage from a friend that was shot with I think a Sony HD handicam or something similar. The clips all look and sound fine when I play them on their own and when I play them in Hitfilm. The problem comes into play when I right click the footage and make it a comp shot, the length of the clip grows. Unless I missed something the footage should stay the same length correct? (See attached Picture)

           Finally, The audio syncs and sounds great for each clip until the last 5 minutes or so and then the audio is out of sync by a couple of seconds.

I’m guessing that these two issues are connected but I’m not sure how or how to address it. ANY help would be appreciated. Also I spaced them out on the timeline so you could see that the audio and the video appear to be flush with each other.

Thanks in advance.

https://dl.dropboxusercontent.com/u/36877228/Church master 2017-01-14 09-49-35-459.jpg

 

 

       

Comments

  • There's a frame rate mismatch between your clips and your composite shots. The clip are reporting 29 fps and your comps are @ 29.97 fps. If you can please post a Mediainfo report so we can try and figure out what's causing the mismatch. To use Mediainfo once it's installed, right click on a clip and select Mediainfo. After it opens go to the View menu and select Text. Now you can copy what's in the window and paste it here. 

  • Here is the requested info.

    Looking at this info I'm wondering if the issue is the Variable bit rate, as its the only thing that makes sense to me, at least with my current level of video knowledge.

     

    General
    ID                                       : 0 (0x0)
    Complete name                            : C:\Users\Home\Documents\Projects\The Gifts of Christmas - Copy\00027.MTS
    Format                                   : BDAV
    Format/Info                              : Blu-ray Video
    File size                                : 3.89 GiB
    Duration                                 : 23 min 40 s
    Overall bit rate mode                    : Variable
    Overall bit rate                         : 23.5 Mb/s
    Maximum Overall bit rate                 : 24.0 Mb/s

    Video
    ID                                       : 4113 (0x1011)
    Menu ID                                  : 1 (0x1)
    Format                                   : AVC
    Format/Info                              : Advanced Video Codec
    Format profile                           : High@L4
    Format settings, CABAC                   : Yes
    Format settings, ReFrames                : 2 frames
    Format settings, GOP                     : M=3, N=15
    Codec ID                                 : 27
    Duration                                 : 23 min 40 s
    Bit rate mode                            : Variable
    Bit rate                                 : 22.3 Mb/s
    Maximum bit rate                         : 22.7 Mb/s
    Width                                    : 1 920 pixels
    Height                                   : 1 080 pixels
    Display aspect ratio                     : 16:9
    Frame rate                               : 29.970 (30000/1001) FPS
    Color space                              : YUV
    Chroma subsampling                       : 4:2:0
    Bit depth                                : 8 bits
    Scan type                                : Interlaced
    Scan type, store method                  : Separated fields
    Scan order                               : Top Field First
    Bits/(Pixel*Frame)                       : 0.359
    Stream size                              : 3.69 GiB (95%)

    Audio
    ID                                       : 4352 (0x1100)
    Menu ID                                  : 1 (0x1)
    Format                                   : AC-3
    Format/Info                              : Audio Coding 3
    Mode extension                           : CM (complete main)
    Format settings, Endianness              : Big
    Codec ID                                 : 129
    Duration                                 : 23 min 40 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
    Delay relative to video                  : -67 ms
    Stream size                              : 43.4 MiB (1%)

     

     

     

  • Triem23Triem23 Moderator

    It's not the variable bit rate, it's that the video is a normal 29.97 fps, but, somehow the audio is at 31.25fps.

    You'll need to bounce your source footage through a transcoder to fix that. 

  • I'll give it a go.  Any thought on why that would happen?

     

    Thanks for your time.

  • edited January 2017

    Since I see a video scope on the screenshot so this is HF 2017. Right now 2017 has a bug where a 29.97 media file has its displayed framerate truncated to an integer 29 in the media panel. You have to right click and look at the media properties to verify exactly what framerate Hitfilm thinks of the media file frame rate.

  • @NormanPCN I had forgotten that good catch

  • Great. Thanks.

  • @Hokeb1 Your clips are interlaced and HitFilm prefers progressive so it's probably a good idea to go ahead and transcode no matter what. NormanPCN's latest fast decode AVC settings for Handbrake are in this thread:

    Transcoding to fast decode AVC for timeline performance

    Handbrake has the ability to deinterlace as well and includes Yadif for doing that. You enable it on the Filter tab as pictured below.

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