[LAU] OT - Audio and Video Synch

[Monty Montgomery]

On Fri, Oct 18, 2013 at 5:36 PM, James Stone <jamesmstone at gmail.com> wrote:

> I am wanting to get some audio and video recorded - sample accurately
> - so there is minimal delay between audio and video, and no drift.

Any camera will give you this if you use the audio input on the
camera.  Or do you mean you need to record to some other device and
sync later?  If the latter, you're in for a world of pain.  The clocks
will drift unless you're using a shared clock, and that's a whole
different class of professional equipment....

> Can
> any format do this?

All of them.  The trouble people usually have is software that handles
the sync incorrectly (or doesn't really try to handle it at all.  If
it's based on ffmpeg.... yeah 'all bets are off').

> Do you have recommendations about how to record a
> file which will play back with perfect audio and video sync on all
> players (file size is not an issue)?

Just about any camera made.

> Secondly, I am wanting to intentionally shift the audio timing so it
> may be 5ms/10ms/50ms/100ms or more out of time with the video. Do you
> have any suggestions on software which will do this?

Any NLE will do this.  I use Cinelerra, but I'd urge you not to :-)

> Lastly, do any of you know any research about the limits of human
> perception with these kinds of things?

You'll not hit the limits of human perception in video-- even 10 bit
isn't quite there, and you ca always get closer to see more
resolution.

Audio perception maxes out at around 48k/16 bit, but record to 24 bit
if possible (for production headroom).

However, anything but very high end professional equipment won't
approach these limits in reality no matter how many megapickles they
offer, and the formats being used for recording are low-rate/lossy.

That said, you could do worse than a D7000 or a 5D... depends on what
you're doing.  DSLRs make great video cameras, but the ergonomics are
still better suited to still photography.  Something old/cheap like an
HV40 is easier to use, but the output quality is not current
generation.

Monty