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Avid & non-standard frame rates (problems)

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Paul Dougherty
Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 6:10:46 pm

I'm working with 720p h.264 web cam interviews shot in a mixed bag of non-standard frame rates.

I did try to edit a (bizarre) 24.33 Qt in a 23.97 timeline and it played poorly and exported with a random stutter frame every second to two.

Then thought it best to edit in software that can mirror the source file, so as to avoid any frame rate interpolation and artifacts. This is standard in Premiere & FCP, has this ability come up as an Avid feature request?

For this job and ones like it, are my instincts right to want to maintain native frame-rates if this is meant for computer playback only? It seems retro for Avid to only offer projects that conform to broadcast frame rates.

Thanks,

Paul


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Michael Phillips
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 6:15:47 pm

23.976, 24, 47.972, and 48 are not typically "broadcast" rates and are all supported with the latest version of Media Composer 8.3. I see no reason why you would want to work at 24.33 if that is what you're asking?

What version are you on? If 8.3. For this example, I would created a 24.000 project, AMA link to the 24.33 file and in "source settings" select project rate. This will play the file back, frame for frame, at 24.000. Any audio will be sample rate converte to match project rate.


Michael


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Shane Ross
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 7:21:03 pm

This also begs the question...where will this be delivered and played from? What is the intended delivery? Played from YouTube or similar, or TV, DVD? Avid is designed to work only with TV and film frame rates. What you have is simply not that...and yes, that odd frame rate will show repeated frames in a 29.97 or 23.98 project...because it's like between 24 and 25.

Either do what Michael says...or if you want to work with the native frame rate, use Adobe. Although I'm not sure HOW a frame rate can be a decimal...how do you have .33 of a frame?

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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Paul Dougherty
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 7:40:49 pm

Hi Michael,

Can't beat getting a frame rate answer from you! :-) I'm on MC 8.2 and don't see the ability to select project rate in "source settings" I can upgrade to 8.3 and try again. Since this is 720 size I will make a 23.97 proj (instead of 24)

Shane I had mentioned this job is for computer playback only (mobile app). The is no good reason for the dopey frame rate of the file I was given but you say "I'm not sure HOW a frame rate can be a decimal" aren't these standards also 29.97 or 23.98 decimal?

Finally once I have been supplied with the original with the strange frame rate, that is meant for computer playback only (on a mobile app) doing the content edit and giving it back in the native frame rate seems like a good practice or "insurance", not to introduce any unnecessary frame rate artifacts. But I'm guessing you guys don't think this is a winning argument.

Paul


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Michael Phillips
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 7:56:31 pm

There's a difference between frame rate for editing and a playback frame rate. For example, 23.976 is a playback rate, but EDLs, edits and such have 24 frame. They're just playing back slower. The same goes for 30 and 29.97, and because of that slower play back rate, drop frame was created to keep the count accurate relative to wall time. In theory the same could be done for 23.976 to have a drop frame count following the same rules of 29.97DF, it just seems no one is in a hurry to do so. Once you get into OTT type delivery specs who want the programs delivered in their original shooting rate, 23.976, 24.000, 25.000, 29.97, etc. but they don't have to keep to a broadcast schedule based on set times. So no real need (yet).

The issue with 24.33 is that is is a recording device that wanted to either do 24 or 25 and failed at both for whatever reason. But I've seen these rates from cell phones and such. For best quality, you will want to do a frame for frame, as you said 23.976 which will only be a 1.45% change in speed, so won't be noticeable from a slowness perspective, but will not have blended or dropped frames.

That will require an update to 8.3 to get that feature.


Michael


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Paul Dougherty
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 8:06:37 pm

As to why I would get such a crazy mix of frame-rates, Ht Davis suggested this in my original Premiere post…

You have fallen into the OIS trap.

This type of image stabilizer is on by default on some cameras and will either speed up the frame rate or slow it down to stabilize an image. If you are on a rig or tripod, turn this off and make damned sure you check that before shooting. After shooting, if you are experiencing frame rate problems, the missing frames will be marked and the frame rate change will be as well, but only in the bitstream, not in the header. SO.... ...You'll have to transcode to a useable format. Find the base frame rate for the cameras, looks like a 25p on the 24.03, and a 24p setting on the 23.xx (25 frames and 23.9x in media encoder). You should transcode them with "USE FRAME BLENDING" so that the frame rates are filled in. This will fix any problems with the videos themselves.

Next, you'll have to import those into premiere. I also advise you to right click the clip in project panel and Interpret the Footage to your sequence frame rate. This will flag it and play it as if at that frame rate, but conforming it to seconds instead of frames. WARNING: you may drop some frames (though not many, and usually not enough to degrade the quality unless in areas of high motion).


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Shane Ross
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 8:09:40 pm

AH...yes, touché on the decimal point. I did mean odd frame decimals like .33. The 29.97 and 23.976 means they play slower than one second. I guess 24.33 plays one third faster than a second.

But yes, if you want to maintain the frame rate, and delivery is for computer or web only...I suggest using the best tool for that job, and that is Adobe Premiere. You can edit the codec natively too. Avid is meant for broadcast and film work...and it conforms to those standards. Not saying it isn't good for web delivery, but when given the odd frame rate you are...Adobe is best suited for that.

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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Paul Dougherty
Re: Avid & non-standard frame rates (problems)
on Apr 6, 2015 at 11:45:32 pm

Thanks Shane! Michael I did the upgrade to 8.3 and changed the frame rate setting for the clip and it seems the weirdness has subsided. Don't want to pop champagne yet but the 'point" release feature really seems to make a difference

Paul


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