DV Info Net

DV Info Net (https://www.dvinfo.net/forum/)
-   All Things Audio (https://www.dvinfo.net/forum/all-things-audio/)
-   -   Frame Rate of 702 (https://www.dvinfo.net/forum/all-things-audio/114268-frame-rate-702-a.html)

Roshdi Alkadri February 7th, 2008 11:11 PM

Frame Rate of 702
 
Does anyone know what frame rate the audio runs at in the 702 not the 702TC

is it 30 nd? will it sync with 23.976?

Jeffery Magat February 7th, 2008 11:30 PM

Quote:

Originally Posted by Roshdi Alkadri (Post 822399)
Does anyone know what frame rate the audio runs at in the 702 not the 702TC

is it 30 nd? will it sync with 23.976?

The 702 does not stamp timecode to the BWF files. The 702T does though.

Steve House February 8th, 2008 02:19 AM

Adding a bit to Jeffrey's note ... audio doesn't have "frames" as such so there is no such thing as an audio frame rate. It does have a sample rate and the 702 is capable of running at a number of different sample rates, including the 44.1 kHz sample rate used for CDs and so for recording music destined for CD and the 48kHz sample rate used for video. But there is no relationship between the video frame rate, hence the elasped time associated with each frame of video which is what timecode is dealing with, and audio sample rate.

Roshdi Alkadri February 8th, 2008 08:51 AM

i see, so obviously it would be easier to sync audio from a TC capable recorder and a camera running at the same frame or sampling rate.

Jeffery Magat February 8th, 2008 09:13 AM

Quote:

Originally Posted by Roshdi Alkadri (Post 822565)
i see, so obviously it would be easier to sync audio from a TC capable recorder and a camera running at the same frame or sampling rate.

Well not entirely true here, you need to do some research on timecode and audio sample rates. Cameras do not run at 'sample rates'.. For instance, if I'm using an external recorder and the production is using a film camera.. The camera isn't going to run at 48kHz, 44.1kHz or the like.

Wayne Brissette February 8th, 2008 09:18 AM

Timecode, timecode, timecode.... it's a topic that often confuses pro mixers. Yes it matters, if everybody is using it. However, that said, people used audio for years without it, and so can you. Be aware however that you should at least use a slate to help sync up audio later.

The biggest issue with timecode is that it is stamped on the header of the BWAV file and it's not something that is stripped during the entire audio. By that I mean the timecode states when you pressed record, but it is up to the playback equipment or software to determine what the timecode is once you move away from the beginning of the file.

Some things to think about.
* Who keeps the master clock?
* Do you own a timecode slate?
* Are you using a camera that supports timecode?
* Are you doing real film? -- there are special considerations here....
If you're working on 35mm there is no audio or timecode that gets jammed to the camera, it's all based on the master clock jamming the slate and using the slate, telecine will sync picture and audio for dailies.

I bring all of these up, because it's not simply a matter of spending the extra money for timecode in your recorder. You have to know what to do with it and how it works for it to be of any real value to you. If you're working on a lot of small productions, most won't even know what to do with the timecode and most won't want to use it. It really isn't as critical as people make it sound, just use a dumb slate with a clapper and you'll be fine. If you don't own a time code slate, devices to jam the timecode to cameras, have a camera that supports timecode, then it's all a moot point.

Now don't get me wrong, I love timecode, but you have to have people who understand it to use it properly.

Wayne

Steve House February 8th, 2008 09:37 AM

I agree with Wayne. People think that timecode will align both audio and video files to each other and keep them in sync over the duration of the shot. It doesn't. Film going through telecine is another story. But with video TC does exactly what a dumb slate does - sets a single point where the audio and video files line up. But once you move away from that lineup point towards the end of the shot, TC does nothing to prevent them from drifitng apart. The video camera's and the audio recorder's sample clocks have to be slaved to each other or otherwise driven to insure they run at exactly the same rate in order to insure there's no drift in the audio versus the video. Most of the time timecode is generated by a totally separate clock from the sample clock and does not lock the files together over their complete length - it only locks them together at one single point.

Roshdi Alkadri February 8th, 2008 07:58 PM

I returned the 702 and went with the 702TC for a better future investment.
My HVX does not support timecode, but i do figure for the extra $600, its worth to get the TC version for future camera purposes that may support TC in/out

Dont get me wrong, i owned the 702T with the denecke TC slate but didnt help much as my camera does not support other than time of day code. so i went back to the 702, then realized that in three months, i may purchase a TC capable camera and i can jam sync the recorder/camera

what threw me off is that the 702T has all different frame rates to choose from, i just wondered what the 702 would be as a standard (30 ND etc.)

i was given a brief lesson six years ago in film school, but i will revisit and research more about this. i have been doing the manual line up of slate sound and picture, but Timecode (if done well) well save a few headaches.

thanks everyone

Steve House February 8th, 2008 08:36 PM

Quote:

Originally Posted by Roshdi Alkadri (Post 822958)
I returned the 702 and went with the 702TC for a better future investment.
My HVX does not support timecode, but i do figure for the extra $600, its worth to get the TC version for future camera purposes that may support TC in/out

Dont get me wrong, i owned the 702T with the denecke TC slate but didnt help much as my camera does not support other than time of day code. so i went back to the 702, then realized that in three months, i may purchase a TC capable camera and i can jam sync the recorder/camera

what threw me off is that the 702T has all different frame rates to choose from, i just wondered what the 702 would be as a standard (30 ND etc.)

i was given a brief lesson six years ago in film school, but i will revisit and research more about this. i have been doing the manual line up of slate sound and picture, but Timecode (if done well) well save a few headaches.

thanks everyone

Timecode won't help with your present camera unless you use a smart slate jammed from it. Even then it will only be a convenience, nothing more. That being said, I would have made the same choice as you did in getting the 702T model. When you're spending this much money it only makes sense to buy with an eye to the future. Let's say you make a jump up to a Canon XL-H1 with full timecode I/O and genlock capabilities - it's going to be nice not to have to replace your audio recording tools at the same time in order to be able to take advantage of its full capabilities.

Wayne Brissette February 8th, 2008 09:05 PM

Quote:

Originally Posted by Roshdi Alkadri (Post 822958)
what threw me off is that the 702T has all different frame rates to choose from, i just wondered what the 702 would be as a standard (30 ND etc.)

NTSC video is typically 29.97 NDF
PAL video is typically 25 frames
24P video is typically 24 frames
Film is typically 30 NDF


I say typical here because there are cases where your settings may vary depending on what post production wants or what a director, etc. wants.

Wayne

Roshdi Alkadri February 8th, 2008 10:43 PM

Quote:

Originally Posted by Steve House (Post 822974)
Timecode won't help with your present camera unless you use a smart slate jammed from it. Even then it will only be a convenience, nothing more. That being said, I would have made the same choice as you did in getting the 702T model. When you're spending this much money it only makes sense to buy with an eye to the future. Let's say you make a jump up to a Canon XL-H1 with full timecode I/O and genlock capabilities - it's going to be nice not to have to replace your audio recording tools at the same time in order to be able to take advantage of its full capabilities.

exactly steve

Steve Oakley February 9th, 2008 12:58 AM

You can send TC to the camera's AUDIO input then use a 3rd party plugin in in FCP to read TC from the audio track as if it was from the normal TC track. Yes you will most likely get bleed in the camera from one channel to the other with the TC rendering the other audio track useless but you can still get TC onto the audio track for sync in post. I do think some flavors of Avid may do the same thing. so if you know you can read the TC from the audio track in post, its possible. I supposed the trick is to record the TC low enough it doesn't bleed to you can still possibly use the other audio track.

all that said, many cameras have gotten decent audio handling, so you could also just feed them from the mixer in the first place and skip the external recorder. you have to know your camera and its performance in audio.

Roshdi Alkadri February 9th, 2008 01:35 AM

Quote:

Originally Posted by Steve Oakley (Post 823041)
You can send TC to the camera's AUDIO input then use a 3rd party plugin in in FCP to read TC from the audio track as if it was from the normal TC track. Yes you will most likely get bleed in the camera from one channel to the other with the TC rendering the other audio track useless but you can still get TC onto the audio track for sync in post. I do think some flavors of Avid may do the same thing. so if you know you can read the TC from the audio track in post, its possible. I supposed the trick is to record the TC low enough it doesn't bleed to you can still possibly use the other audio track.

all that said, many cameras have gotten decent audio handling, so you could also just feed them from the mixer in the first place and skip the external recorder. you have to know your camera and its performance in audio.

I use premiere and not final cut. i would have to say thats an interesting workaround but i still prefer using an external recorder as its preamps are better than any camera's amps, plus i get those extra bits to work with at 24 bit, more processing power and low noise when blending tracks in post.

i also prefer the seperate recorder for collecting fx, foley, room tones, ambiences, V.O., wild lines.

Bill Ravens February 9th, 2008 08:46 AM

One more time...
TC won't help you sync a seperate audio recording to your camera.

The 7xx series SD recorders are timed with WORDCLOCK. The fact that the 7xxT has a TC generator is almost an artifact, it still syncs itself to its internal WORDCLOCK. The problem is how to convert the wordclock pulse into something the camera can use and lock its TC generator to. Unlike LTC, Wordclock is simply a pulse with no absolute start or stop value.

Once again, the easiest thing to do is use a clapboard at the start, line up the audio and the video to the clapboard in post, and stretch/shrink the audio in post to account for drift.

Roshdi Alkadri February 9th, 2008 09:23 AM

Quote:

Originally Posted by Bill Ravens (Post 823129)
One more time...
TC won't help you sync a seperate audio recording to your camera.

The 7xx series SD recorders are timed with WORDCLOCK. The fact that the 7xxT has a TC generator is almost an artifact, it still syncs itself to its internal WORDCLOCK. The problem is how to convert the wordclock pulse into something the camera can use and lock its TC generator to. Unlike LTC, Wordclock is simply a pulse with no absolute start or stop value.

Once again, the easiest thing to do is use a clapboard at the start, line up the audio and the video to the clapboard in post, and stretch/shrink the audio in post to account for drift.

Good points, but isnt different when the recorder is acting as the master to feed both the recorder and slate?

taken from sound devices website
"The full-featured time code implementation of the 702T is designed specifically for dual-system film and video productions where audio needs to be master"

the frame rates will come in handy eh, 23.976, 29.97, 24, 25, 30 nd

Its internal generator should do the trick at 23.976 with an HD camera

and i will still use a slate just in case


All times are GMT -6. The time now is 08:12 PM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2020 The Digital Video Information Network