VIDEO : offset in sound WHY ?

Hi,

i’m getting crazy a bout a project.
i have a video H264 MPEG 4 AVC 720 25fps
when i play the video in VLC the sound is sync
when i import audio from video file nuendo creates a file that has the same lenght as video region on the timeline but when i play it the sound is offset by 5 frames. i can see the lips not sync.

i did a test on an empty session… and it looks synced. so is it that my session is to heavy sound is delayed from video ?
is it a known prblem nuendo poorly handeling video ?

Is this the same with any video / audio you play back? Is it only when audio has been ripped? Is it only for this file or only for H264?

I’ve had experiences where a DAW after upgrades requires a different video offset for audio to be in sync on the monitor I was using.

mm i just realised that so i don’t know for other videos. but editor sent me 3 exports with different setup and i always have the same.
i’m pretty sure it’s nuendo doing this now.
editor exported me his sound that matches his video and when i add my sound that i see in sync inside nuendo the 2 audio files don’t match.
wo what i see is wrong.
i put myself at risk with clients with this thing. spent time asking new exports, delivering mix with offset… this is very bad.

If your file is short enough you can send it to me and I can try it out over here.

Otherwise I’ll try it with other files later. Can you verify the exact container/settings for the embedded video/audio?

It could be that the video is so compressed that it is “off”.
Add too that a not-compensated screen delay calibration, and you might see what you see. (Buy yourself the “Catchinsync” app)
Try converting the video to Dndx of ProRes, and see what gives. Together with Photo Jpeg, these are the only codecs that will guarantee you proper video sync.
And lastly, you can avoid many problems by making a document with your delivery specs.
That should (at least) include proper compressed video (DnDx / ProRes / Photo Jpeg), BITC and 2pop at frons and end.
That’ll allow you to accurately identify any problem.
And avoid so many other problems at a later stage. (Version numbers, miscommunication of Timecodes, etc …)


Just my 2 cents. (Know that we work with video almost 24/7)
Fredo

I,m having this same problem using mp4 videos. It started with Nuendo 8. Unfortunately a lot of clients are using this format because of the small size and NOT having problems with other DAWs. Just have delivered a material mixed with N8.3 and mp4 hoping that it will not be rejected because of this problem.

hi,
thx for your answers,
Mattias sorry i can’t send you this video my client would not want me to share it.
fredo … wow ok i didn’t know that much about video within nuendo and sync and format. i thought it was easier.
i don’t have iphone so i can’t do the catchinsync
i’ll try other video format but as rbresser says… i thought h264 was convinient in size (?) and prores is quite heavy no ?
i’ll look into that.

The matter of fact is that compressed video (easy explenation) “drops” frames along the way, which need to be re-generated by the computer that plays back the video. Best case is that the compression drops one frame out of tree. A-B-C // B is dropped. Which means that upon playback the droppped frame (B) is re-calculated by the computer using the information of A and C. The more a video gets compressed, the more frames are dropped and the more computing power is needed to restore (de-compress) the video. This can result in delays.

What’s more, when nudging video from frame to frame, you inevitably will freeze on a “re-calculated” frame, which is never accurate.
So placing -for example- a doorslam can -and will- result in an inaccrate placement of the impact.
I’ve seen cases where, after receiving a HiRes video, we were 3 frames off versus the mp4 version they send earlier.

The reason why DnDx, ProRes and Photo Jpeg are recommended, is that these are the only codecs which preserve the frame-by frame continuity.
No frames are dropped. Hence why they are “big”.

Everybody working in Audio Post, please make it a habit to send delivery specs to the video people.
Specs that include BITC and 2pop.
It will save your ass on almost every project.

Fredo

Fredo, we need a “like” button for the forum :slight_smile:

All right thx for all.
I don’t those format enough. A production propose to send me Dnx36… that’s not DnDx right ?

Just yesterday, we -again- had an issue with video delivered without BITC & 2pop.
They have delivered to us and the composer a proper video, according our specs, but the director has used a later version with temp-grading to spot the music cues.
The guy who exported the video for the director had not included a logo at the beginning of the movie, and had not put in BITC.
As a result, the movie stared “somewhere” in “black”
So the director spots the music cues using the running time “timecode” in his mediaplayer.
Result: The composer has composed all his music cues according wrong timecodes.
That’s a weeks work down the drain and a furious composer.

Can’t say it enough: BITC and 2pop.

Fredo

yep you’r right.
i just received the Dnx36 file… 25Go ! holly hell… not sure my computer will playback that while nuendo running :stuck_out_tongue:

FYI it is easier for the computer to run a large uncompressed videofile than it is to run a h264.
However it does requière that you have disks that can deliver the video quickly enough.

Power is not a problem with large uncompressed files it’s just shuffling data. It’s pretty much the easiest job of all for a computer.

so that video i’m now working on is:
DNxHD (AVdn) 1920x1080
i bought the DNxHD licence ( :imp:) aaaand i see a delay in the image. i don’t have the sync app you talk about but still… i see a delay in the image that i would have to compensate the same i was doing with h264 = put sounds 4frames later.
i will have and H264 of the same video coming in later so i will be able to compare bothe videos and sound.
but it looks like it’s related to my setup… video card or nuendo ? rather than the compression of movie itself.

We have the problem as well. When importing a video, the corresponding audio from the file is imported with an amount of digital silence at the beginning and the whole sound is moved and not in sync. Not only when playing back, but also when the project is stopped you can see that the audio and video aren’t in sync. For example when going to a Frame with a beep marker, you can see, that the audio-beep is several frames/seconds later on the timeline.
The problem appeared for the first time in the last version of N7 that had the new Video engine and is still there in Nuendo 8.2 and 8.3. It worked perfectly with the old video engine.