what exactly is happening when i ask fcp to re-compress all frames?


i has some drop frames in a qtsc that carried to a flv. the jumps was not happing in the tl.
the 1st qtsc was exported without the option. and it had jumps in 3 spots.

this one is qtsc re-comp and the jumps are gone.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

It forces a render on all the footage. Do the jumps occur in the timeline before rendering?



www.strypesinpost.com

It adds a layer of compression to the footage. So instead of just copying the data as it exists on the timeline to another file, it COMPRESSES it to the same compression.

At least that was my understanding.


www.shanerosseditor.com

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Not really that much of difference between the two terms. The render process means that footage is decompressed for signal processing, then recompressed back to your sequence codec (essentially you lose a generation). With "recompress all frames" checked, all frames are decompressed, then recompressed, similar to the rendering process.

If you run a test, and export a clip with a blink filter as a control (or a 3 way CC with settings unchanged) and another set to "recompress all frames" but without filters applied, you should find that similar frames from the two exported videos should produce a completely black image when both frames are passed through a differential matte.

Usually, there shouldn't be a noticeable visual difference between having it checked or unchecked, however there are some peculiarities. A P2 clip (at least a DvcproHD 720p25 clip), cannot be conformed in Cinema Tools, which will list the clip as "temporally compressed". It doesn't conform even if you export a SCQT movie of that clip, unless you select "recompress all frames".

Also, I couldn't get an example of an interlaced frame, but I posted this a few weeks ago on field dominance settings in an FCP sequence.

[www.lafcpug.org]



www.strypesinpost.com

Quote
strypes
If you run a test, and export a clip with a blink filter as a control (or a 3 way CC with settings unchanged) and another set to "recompress all frames" but without filters applied, you should find that similar frames from the two exported videos should produce a completely black image when both frames are passed through a differential matte.

What the. i had to read that 4 times. But i guess you are saying its like making sure everything is rendered. ? .

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

Not really. It's an option, like many of the options. Some we use more often, some we use less. This is one that I hardly use.



www.strypesinpost.com

This isn't actually as complicated as it sounds. "Recompress all frames" does just what it says on the tin: All frames are recompressed during the output process.

If you're working in an I-frame-only compressed format, like DV (ugh) or DVCPRO or ProRes, Final Cut doesn't have to do anything, computationally, to frames that have not been subject to changes like a repo or an effect. When you export an I-frame-only timeline, Final Cut can just take those frames that weren't changed in any way and copy them, bit-for-bit, to the output Quicktime.

When you tell Final Cut to recompress all frames, you're telling it to fully decode every frame of your timeline and re-encode it to your output format, even if Final Cut technically doesn't have to. If you're working with compressed footage, this will always degrade your image. It's analogous to doing a tape-to-tape dub from one HDCAM SR deck to another, but through the analog outputs and inputs. Generational loss, and all that. How much of a degradation you see depends on your compressor. With ProRes, it won't be noticeable at all. With DV, it'll make you want to stab yourself in your eyes with a Wacom stylus. Either that, or you won't notice at all, in which case there's clearly something wrong with your eyes already, and you should see a doctor as soon as possible.

Doing this is not the same as "making sure everything is rendered," because when you force a "recompress all frames," you're telling Final Cut to decode and re-encode all frames whether they needed rendering or not.

"Making sure everything is rendered" is kind of a dumb way of talking about Final Cut anyway, because if you understand the internals of the system, you know that Final Cut cannot export unrendered footage. It's physically impossible. You can lay an unrendered shot off to tape, if your system can play that shot in real time without rendering it, but exporting is an entirely different operation. Before Final Cut can write down the correct numbers, it has to do all the math to get those numbers.

Imagine you're editing the manuscript of a book. You made changes to the text on pages 3, 6 and 7, but you didn't change any of the text on the other pages. Instead of re-typing all the pages, you can just re-type pages 3, 6 and 7, and bind them with the other, original, unchanged pages. "Recompress all frames" is like telling Final Cut to re-type the whole manuscript, even those pages that didn't have any changes at all and could just have been reused without touching them.

That might be the best explanation I've seen for that option. FAQ time?

> if you understand the internals of the system, you know that Final Cut cannot export
> unrendered footage.

This is the reason why so many of us -- even experienced ones -- don't know why that pesky option is there!


www.derekmok.com

I've gotta concur. I don't know why that option exists. The obvious guess, to me, is that it's a legacy bit, left over from antiquity, maybe even from back when it was called KeyGrip.

If that's the case ? then frankly, it's possible that option has no genuine purpose. It might be one of those features that was just stuck in there because it was possible to add it, rather than based on some rational use case for it.

But that's all just speculation on my part. Does anybody have the manual handy?

Yes, Jeff...the Manual is an oft ignored - very handy piece of software that, oddly enough, is built right into the Final Cut Pro application so no need to "crack a book". Checking the manual BEFORE POSTING could eliminate many redundant inquiries. Here's a short tutorial on "cracking the digital manual":

? Launch Final Cut Pro
? Menu Bar / Help / Final Cut Pro User Manual
? Left Panel - Index (twirl down) and select "R" for "Recompress All Frames"
? Recompress All Frames option IV-239, IV-241, IV-298
? Start on page 237 & read the entire section.

That's all there is to it. The manual is our friend. Please check it before posting.

When life gives you dilemmas...make dilemmanade.

the final cut manual did not always give me a clear under stand of a lot of things. Maybe jeff should wrote it so it could be easier to understand.

thanx all.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

The big question, is why is the option there? You generally do not want to subject your footage to recompression (unless you're running a codec comparison test). Recompression is inevitable when shots require a render. However, why would you want to recompress or render footage when rendering is not required?

But then again, there are rare cases where recompression produces a different result (other than a generation loss and extended exporting time) from exporting without recompression. That's the only reason I can think of.



www.strypesinpost.com

Actually strypes...you DO want to recompress your footage if you are going to the internet with the video. Still...you bring up a good point with "why is the option there?". It really doesn't have to be with the other options available.

When life gives you dilemmas...make dilemmanade.

as i said in the 1st of the post.

Quote
corbett
has some drop frames in a qtsc that carried to a flv. the jumps was not happing in the tl.
the 1st qtsc was exported without the option. and it had jumps in 3 spots.

with the option chosen those jumps disappeared. look at this.

no-compress



re-compress



but then.....

no-compress



re-compress


""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

>you DO want to recompress your footage if you are going to the internet with the video.

Yes, but usually we export "current settings" for encoding in Compressor or Squeeze. Recompressing all frames when you're doing SCQT in ProRes HQ defeats it's own purpose.

I can only see that it's a handy option in those 2 situations I highlighted above (to conform P2 acquired DvcproHD footage in Cinema Tools, and to run a quick deinterlace on interlaced footage).



www.strypesinpost.com

check out the luma and contrast on example 2. it seems that the re-comp looks slightly clearer.

oh by the way, it is going to the web.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

But Corbett, it sounds like you took an anomalous situation and "fixed" it by clicking things at random just to see what they do.

I'm sure one of us would have been more inclined to help you figure out what your problem was if you'd described it in a way that could be understood. As it is, all we have is "something wasn't okay, and then I clicked this button and now it's okay." That doesn't add up to "therefore this button exists to fix that other thing."

Quote
jeff
" That doesn't add up to "therefore this button exists to fix that other thing."

Normally when i do that i get the "THATS BAD ADVICE."

so since i didn't know, i just posted what was happening, and asked what is the option for.

Quote
jeff
it sounds like you took an anomalous situation and "fixed" it by clicking things at random just to see what they do.

yep, but not quite as random. I saw a problem in my output file that was not in my TL. I reproduce the problem using the same method 3x with some slight adjustments to the TL. As far as exporting QTSC there was only one option unexplored. The re-compress.

When it fixed my problem with the re-compress option, i wanted to know how it done it and what the option was for.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

Quote

Yes, but usually we export "current settings" for encoding in Compressor or Squeeze. Recompressing all frames when you're doing SCQT in ProRes HQ defeats it's own purpose.

I don't use it to export to a high quality codec - that would be dumb. I am talking about exporting a high quality timeline to H.264 & skip Compressor altogether...which works out well for me. Otherwise, I use "Current Settings" which is the same as "Same As Source".

When life gives you dilemmas...make dilemmanade.

That's fine and all, Joey, except for two things. First, if you're in a situation where you want to keep file-based masters around ? which you may not be; it depends entirely on the workflow ? then exporting a Quicktime without additional processing is the way to go. And if you're in a situation where you've got an Episode Pro or Qmaster cluster for file-based format conversion, then exporting a Quicktime without additional processing is an important part of the production pipeline.

But if Apple is reading this, I really don't mind them keeping this option around, as I mentioned, there are times (although rare), that it serves a purpose.

The H.264 option is not available in the export mode (Export> Quicktime Movie) where the option to recompress all frames is (which is why it's strange that it is there).

Back to the topic, J.Corbett, if you're going to run frame comparisons, you need to export both stills properly. The aspect ratio of both pictures are outta whack.



www.strypesinpost.com

I know that Jeff...never said anything to the contrary regarding digital master files. Strypes made it sound earlier like the option was a bit useless and my point was it is not.

Maybe I misread.

When life gives you dilemmas...make dilemmanade.

screenshots of the same frames. maybe not good enough nut i can see the same differences.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

i'm not getting what you think the point is.

is you select a different output format, either by choosing somethings other than "Current Settings" n a QT Movie export, or by choosing "QT Conversion" you will be re-compressing all the frames by default.


nm

if its my point nick, what i was trying to figure out is....

why i got the stutter without re-compression.
It wasn't in the tl at all but no matter what i did, stutter came out in the qtsc.

so re-comp did something i just don't know what other than add a layer of compression.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"

What happens if you trash your render files and re-render?



www.strypesinpost.com

same thing when render file are deleted. its in the qtsc process it seems. h264 doesn't stutter either. new seq same also.

in order to get rid of the stutter it has to be compressed for some odd reason.

""" What you do with what you have, is more important than what you could do, with what you don't have."

> > > Knowledge + Action = Wisdom - J. Corbett 1992 """"