Grateful for a reality check (recording separate video and audio)

[John Rofrano]

[Scott Matthews] “For example, am I correct to think that the MP4 or MTS/AVCHD files will have 48KHz audio? Does it matter if Ableton on the PC is recording audio at 44KHz?”

Yes the MP4 or MTS/AVCHD use 48K audio as do all video files. You should also record at 48K with your PC if you don’t want it to be resampled because Movie Studio will have to resample it to make it compliant for use in video.

In general, you should not be recording at 44K. 44K is a delivery format for CD. You should be recording your source at a higher sample rate to improve your audio quality.

[Scott Matthews] “(One thing I’m worried about is drifting sync.)”

You will have sync problems regardless. The clock in your camera will never keep time with the clock in your PC unless they are GenLock synced together. So plan for sync problems and correcting them. That is just the reality of using an external audio recorder without GenLock.

[Scott Matthews] “When saving from Movie Studio, is there a way to simply “replace the audio” without needing to recompress the video?”

No. You will need to use some other tool to demux and remux the video and audio. Movie Studio is a video “editor” not a demuxer.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Bob Peterson]

Your camera still must record the audio. It can use its own mic if necessary, but it must capture audio. You will need this in camera audio so that you can accurately synch the external audio to the video. Once synched, you simply null the camera’s audio track. If the external audio drifts out of synch, simply split the file at a quiet spot and move the audio back into synch.

[Scott Matthews]

Thank you, that was tremendously helpful!

If my goal is mostly to align the clips, and render a new one (with some trimming at either end) would I be better off with some sort of muxing application?

Or, assuming I stick with Movie Studio, am I correct to output with: MainConcept/Internet HD 1080p? (I mostly plan on keeping the files and uploading some to YouTube.)

Thanks again, I’m happy to be making progress!

[Scott Matthews]

Yes, thanks — I’m still recording audio in the camera — either via the built-in mic (if my speakers are on) or via the line input (if I’m using headphones), so that I can align the two.

Just curious: roughly how “mis-aligned” can something like speech (with video of a mouth) be before it feels wrong?

Thanks also for the alignment tip — it hadn’t occurred to splice and shift (I assumed I would have to ‘strech’ somehow) — the splice is obviously a much better way to go about it!

Thanks again! -Scott

[John Rofrano]

[Scott Matthews] “If my goal is mostly to align the clips, and render a new one (with some trimming at either end) would I be better off with some sort of muxing application?”

Muxing applications usually don’t allow you to align anything. What you might be able to do is align the audio in Movie Studio, then render the audio to a WAV file and use a muxing application to mix the aligned audio with the video.

[Scott Matthews] “Or, assuming I stick with Movie Studio, am I correct to output with: MainConcept/Internet HD 1080p? (I mostly plan on keeping the files and uploading some to YouTube.)”

Yes, if you are uploading to YouTube that is the render template to use. Your quality should be fine; no need to remux. I would not stress out over having to render. You’re eyes are not going to see a quality difference once YouTube gets done processing it.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[John Rofrano]

[Scott Matthews] “Just curious: roughly how “mis-aligned” can something like speech (with video of a mouth) be before it feels wrong?”

I never measured. I usually watch until it feels wrong, then back up a bit and correct before that spot.

[Scott Matthews] “Thanks also for the alignment tip — it hadn’t occurred to splice and shift (I assumed I would have to ‘strech’ somehow) — the splice is obviously a much better way to go about it!”

Yea, I usually split my audio every 10 minutes and shift it left a frame or two. It’s not that big a deal and only takes a few minutes of editing to get it all synced.

~jr

http://www.johnrofrano.com
http://www.vasst.com

[Scott Matthews]

Thank you again for taking time to help.

fwiw, I was partly thinking about muxing not just because of the quality — but I also assumed it would be faster than recompressing — but that seems moot if I can’t do it in one place.

Thanks kindly for all, -Scott

[Bob Peterson]

I listen to both audio sources simultaneously via headphones. If I hear even a slight echo, I know that they are out of synch and can adjust accordingly. When adjusting, I zoom in very close on the sound tracks (probably to the frame level), and widen the track width displayed so that I can see the waveform very clearly.