Audio/video sync with the Video Assist 4K

Getting started with a Blackmagic product? Ask questions here about setup and installation.
  • Author
  • Message
Offline

Seymour Clufley

  • Posts: 3
  • Joined: Tue Sep 26, 2017 6:28 pm

Audio/video sync with the Video Assist 4K

PostTue Sep 26, 2017 6:42 pm

I use the Sony RX100 Mk5 and need an external recorder so as to get around the 30min recording limit of the camera. I record in 1080p, 25fps, and use an external microphone, and the continuous shooting can often go for up to 3 hours.

The issue is keeping the video and audio synchronised. I have an external recorder just now (Hauppauge PVR2) which frequently drops frames, resulting in the audio being progressively off-sync. It's a nightmare to fix this in post. So I'm looking for a better recorder that either will not drop frames, or, when it does drop frames, will keep the audio synchronised.

The Video Assist 4K (I only need the 4K because the other model doesn't have external audio input) looks very robust, but I have seen threads about it having audio/video sync issues. Can anyone comment on the wisdom of me buying it? I'd be very grateful for advice.
Offline

Denny Smith

  • Posts: 7092
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Audio/video sync with the Video Assist 4K

PostSun Oct 01, 2017 4:31 pm

The audio sync issue depends on the camera being used, and how much of a delay the video output has.
That said the Sony RX100 is a compact still camera, not sure if the sensor can handle long live video times like 2-3 hrs with out overheating? Also, does the RX100 actually have a clean video output?

Many compact cameras like this, including the excellent Nikon V1 series, do not out put a clean feed (frame guide and screen info gets outputted), which would kill using an external recorder. Try hooking the camera up to a TV monitor, and see if you get a clean feed.

Since you only want to record 1080p, why not get either a BM Pocket camera or the Micro Cinema camera, both are designed for continuous video recording and will give you much better results.
Cheers
Last edited by Denny Smith on Fri Oct 06, 2017 5:33 am, edited 1 time in total.
Denny Smith
SHA Productions
Offline

Seymour Clufley

  • Posts: 3
  • Joined: Tue Sep 26, 2017 6:28 pm

Re: Audio/video sync with the Video Assist 4K

PostThu Oct 05, 2017 9:34 pm

Thanks for replying.

Are those cameras free of the 30-minute recording limit, or do you just mean that they are designed to pass HDMI footage continuously?

My hesitation is because I am very happy with the image quality of the RX100 at low light. It's incredible. If the BM cameras can match that, I would certainly consider switching to them.
Offline

Denny Smith

  • Posts: 7092
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Audio/video sync with the Video Assist 4K

PostFri Oct 06, 2017 5:34 am

The only limit to the BM cameras is the battery life. I have a Micro Cinema camer running 6-days a week, 7 hiurs per day doing a time lapse of a boat building project.
Cheers
Denny
Last edited by Denny Smith on Mon Oct 09, 2017 5:26 pm, edited 1 time in total.
Denny Smith
SHA Productions
Offline

Seymour Clufley

  • Posts: 3
  • Joined: Tue Sep 26, 2017 6:28 pm

Re: Audio/video sync with the Video Assist 4K

PostSun Oct 08, 2017 6:04 pm

But I don't think time-lapse photography is the same thing as video footage. AFAIK the 30-minute limit is imposed for tax reasons, so that the camera doesn't get classed as a camcorder. Can anyone confirm whether BM cameras have this limit?
Offline

Denny Smith

  • Posts: 7092
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Audio/video sync with the Video Assist 4K

PostMon Oct 09, 2017 5:30 pm

Again Seymour, regardless if you are in time lapse or normal video mode, the only limiting factor to the length of a video clip is going to be your recording media and battery. The camera, if powered from a large battery or the mains, will record until the SD card is full. Their is no 20 or 29/30 min. recording limit imposed on it, like the DSLRs have, as BM cameras are full video cameras, not still cameras.

The Micro Cinema/Pocket Camera camera for example can record to its built in media SD card, a 136-min continuous clip on a 128GB SD card. It will also output a continuous video signal out the HDMI as long as the camera is powered on, gainmthe lower source being the only limiting factor. On its internal battery, the Pocket camera is only good for about 30-min, and the Micro Cinema about 45-min., so you will need a larger external bsttery or mains power for longer continuous recording sessions.
Cheers
Denny Smith
SHA Productions

Return to Getting Started

Who is online

Users browsing this forum: No registered users and 6 guests