Hi,

Are you adding the audio and video together as a single input or are you adding audio and video as separate inputs?
If they are separate they will fall out of sync, but if they are added together (DeckLink Video Capture + DeckLink Audio Capture) they should be fine.

Can you provide some information on your system specs? CPU, Memory, Graphics Card etc.

Also check what version of vMix you are running by looking at the version in the title bar. Is it 8.0.0.53?

Thanks,

Martin
vMix

Hi Martin,

I will download the new version today and test it. This might be a similar problem and so similar fix.

It would be good to have some kind of notification about new bug-fixed releases: a mailing list of registered users maybe.

I prefer to use the coupled input so hdmi BM intentity video and audio. Yesterday I switched one computer to seperate hdmi and line out and use the analogue mic input on the computer and the issue was fixed. Since I had the issue on both computers I suspected a bug: one computer is a laptop with BM shuttle USB3 inut and the other a computer with BM intensity capture cards inside.

I record in MPG because I can edit the resulting file (cut the start and end sections of a presentation) without having to render the file again. So I prefer to use MPG. If not stable or reliable I can use any other format and then convert to MPG before editing.

What recording format is recommended for most stable operation?

Greetings Stefan

Hi martin,

I am running tests now and downloaded the upgrade. i was on 8.0.50 and now .53

I will also use TS for recording.

I don't actually edit the output: i just cut it up to individual presentations. The programm I use to do that is part of a simple set of video and audio editing tools called AVS4YOU. one of the tools is AVS Video remaker. This alows me to simply delete the parts I don't want (start and finish of a presentation and save it without rendering.

Anyway: if I need to record in a reliable format first and can do that for a long time (1 - 4 hours in a row) then I can batch convert to MPG and save the individual presentations later.

Just remember: I record a number of presentations in a day, yesterday I recorded 30 presentations in 2 rooms and 6 poster presentations. Just being able to separate the individual presentations without rendering saves me a lot of time and alows me to deliver the product at the place where i am recording.

In video remaker this only works (writes) with specific formats, like (and tested) with MPEG. In this way I can save 4 or 5 presentations in one set within 5 - 10 minutes!

It also works with WMV but only MPEG4 codec and VMIX only has 1 2 and 3 (am I correct).

Anyway: I would like to have your recomendation what format to write to to have absolute reliable video and audio sync and a stable rendering over a long time.

I also wil start - stop the recording in between presentations (when there is the time for it) and open the recording options and press OK to reset the latency if any... Would be great to have that under one button: so on the fly restarting a new file and resetting all accumulated latency and or dropped frames / samples.

Stefan

Hi Martin,

1. I had another recording session with new version 8.0.53. The morning session was OK (no dropped frames, dropped audio samples anything) but in the afternoon I had dropped samples in de audio session. I followed your recomendation to stop recording, opening the recording session settings and press OK to clear the dropped frames and latency on the video part. But the Vmix recorder still had the dropped samples and the delay because of that and I can not get rid of them.

Do you have any idea why I suddenly accumulate dropped audio samples. maybe somthing to do with the BM shuttle getting warm or something? I restarted the computer in the afternoon to be shure that all buffers etc were cleared, and did not change anything else, used the same preset and setup routine!

I also switched to TS format, but the problem is the accumulated dropped samples in the audio section i can not get rid of or reset / clear. So I still have sound off-set.

2. Would it be better to link the BM audio input directly to the recorder in stead of putting it through the vmix mixer? I can do that by not selecting the BM audio input with the video and select that input on the recorder settings. Whould that solve anything?

Hope you can find the cuase of this misterious dropped samples.

Will send you the logfiles of today by mail.

Stefan

Hi Martin:
from the logs:

First recording:
-11-2012 8:28:08, AudioOffset: 24
8-11-2012 8:28:08, AudioEngine
8-11-2012 8:28:08, Running: True
8-11-2012 8:28:08, SampleRate: 48000hz 16 Bit
8-11-2012 8:28:08, MixingErrors: 0
8-11-2012 8:28:08, Streams
8-11-2012 8:28:08, Stream0
8-11-2012 8:28:08, Samples: 32372
8-11-2012 8:28:08, DroppedSamples: 0
8-11-2012 8:28:08, Latency: 2

last recording:
-11-2012 16:31:07, AudioOffset: 19
8-11-2012 16:31:07, AudioEngine
8-11-2012 16:31:07, Running: True
8-11-2012 16:31:07, SampleRate: 48000hz 16 Bit
8-11-2012 16:31:07, MixingErrors: 0
8-11-2012 16:31:07, Streams
8-11-2012 16:31:07, Stream0
8-11-2012 16:31:07, Samples: 283613
8-11-2012 16:31:07, DroppedSamples: 58
8-11-2012 16:31:07, Latency: 2

The problem is in the dropped samples - isn't it!?
Stefan

Thanks for the info.

In the recordings where you see a sync issue, is the audio too early or too late?
If it is too early (hear sound before the video) then it is *possible* it is a Audio Engine issue, but if the audio is delayed then the issue must be somewhere else.

The audio engine works by receiving all of the audio from the various inputs and then mixing it all together.
If an audio input is sending too many audio samples (i.e the BM shuttle sends us 1.1 seconds of audio when only 1 second has elapsed) then it will drop some samples
to ensure that there is no delay. So when you see dropped samples in the log that is actually a good sign as vMix is making sure all audio is arriving when it should be.

So based on that explanation, if the audio is delayed it may be caused somewhere else, such as in the playback or editing program. (which is why I have suggested using TS and trying playback in different programs to see if the issue is there)

Couple of other ideas to try:

1. Try recording using AVI and the DeckLink MJPEG Compressor. Not only is this the highest quality format it is also the most widely supported format for video editing.
2. Are you always recording direct to HD? I've seen some SSDs randomly pause on occasion causing all sort of strange issues.

Regards,

Martin
vMix

The Dropped Samples mentioned in the "Audio Engine" section of the log is unrelated to the recording. It is a total
number of dropped samples since vMix was started and the recording does not use this information to determine how it is recorded.

Hi Stefan,

The information provided in those windows is what is saved to the log file at the end of the recording.
The sound statistics you mention are not applicable to the recording itself.

If you are hearing the delay on the headphones than it does indeed sound like the delay is in the bm shuttle itself in which case if you right click the capture input
and select Reset, this might help. You could also try the "Blackmagic WDM Capture" option with built-in audio selected as this a new alternative BM has provided with the recent drivers.
The resolution for this option is set within the Blackmagic Control Panel. "Set Default Video Standard as"

If the delay in your headphones does not change after resetting the capture device then the problem might be with the camera or audio source.

Regards,

Martin
vMix

Hi Martin,

I have succesfully reprocessed all files using the WDM capture. I have also upgraded the Black magic Design drivers to the latest versions. I will also keep an eye on updates for the NEC Renesses (USB3) drivers.

I still have some issues with black frames once in a while.

I have a new recording this thursday, so hope all will go as planned.

Greetings,
Stefan