Vegas Pro: Audio Shift in rendered video

1. offizieller Beitrag

    When I render from Vegas Pro 17 with Voukoder/x264/AAC I see that in resulting file audio stream is ahead of video stream.

    If I render simple wav or using internal encoder audio and video are in sync.

    People in Vegas Pro forum mentioned that this is known issue and they have the same issue while rendering through frameserver + handbrake/x264/AAC: audio stream is 44ms ahead.

    Another option for render from Vegas using x264/AAC is Happy Otter Scripts and autor added workaround (ffmpeg option -itsofffset 0.0444) to deal with the issue.

    Is it possible to add option into Vegas connector to add audio offset (defaulted to 44ms) that can be used to deal with the issue?

    Thanks.

    • Offizieller Beitrag

    I've already investigated this some months ago, and yes, if you extract the streams it looks exactly like this, but ...

    Each stream (audio, video and subtitles) has a timestamp associated with each frame, sample, sub, ... These timestamps are set during the encoding process. So when you extract all the streams (timestamps are ignored) and compare them, they might have different offsets, but once you are playing the file in a media player the demuxer "realigns" the streams and makes sure all timestamps are perfectly in sync. That's why it is perfectly okay for streams to have different offsets and it is fully within the specification - if the timestamps are correct, of course. (And if the demuxer is working correctly).

    So you can only compare and check this using a proper player (hardware or software). Like with the good old clapperboard.

    But I agree, when importing such a file in an NLE it should look correct, yes.

  • Vouk 6. Februar 2020 um 10:53

    Hat das Label In Bearbeitung hinzugefügt.

  • Vouk 6. März 2020 um 11:30

    Hat das Label von In Bearbeitung auf Behoben geändert.

    Could you advice, how the filter can be used for fix the described issue when audio is ahead of video?

    If I specify Start (in s), the audio will be further ahead. Negative values not accepted.

    Stare/End samples do not work ar all: as soon as I finished enter value it reset to 0.

    P.S. Voukoder 4.1 and Vegas Connector 7.0

    Could you please have a look at this:

    https://www.dropbox.com/s/9vp35vgfle35…Shift2.zip?dl=1

    In archive:

    - Source m2ts file

    - Simple project where I just dropped single file on timeline and delete all audio tracks but front one

    - Wav file that I rendered from the project

    - Two mp4 files rendered with Voukoder. One without atrim and one with atrim 0.044

    - Comparison project in which I dropped all these files

    =>

    atrim 0.044 audio shifted more ahead. This is predictable as if I understand correctly, atrim stand for Audio TRIM and so it is trimming a bit of audio at start and the rest of audio shifting ahead.

    For the project I need option to shift audio behind.

    Thanks.

    • Offizieller Beitrag

    So you basically need to opposite of what i've shown above?

    Unfortunately this is a different filter "adelay". They could've really combined this in one filter.

    Maybe it doesn't really make sense to pass through FFmpegs filter 1:1. Maybe I need to put more logic in voukoder to make this more user friendly.

    That is sad.

    The audio shift I currently have with my footage from Panasonic X920 does not allow me to do final renders using Voukoder.

    Should I post the same in Feature Request forum or you can move this thread there?

    Any chance the -itsofffset option will be implemented one day?

    I'm aware about another thread related to the issue and that you've already made it much better in version 0.7.1.

    However, I'm forced to disable so4compoundplug in VP15-17 as it has issues with my 5.1 sources so I still have 1 frame audio shift :(