Level 1

8 points

Lossless MJPEG exports?

We've just finished shooting a feature in MJPEG at the resolution of 4096 x 2160 with a Canon 1DC and are about to start cutting with FCPX on a Retina Macbook Pro with 16GB of RAM - so far viewing the rushes and making preliminary cuts has posed no problems and we're particularly pleased there is no lag or slowing down of the footage which simply plays like it was any other smaller format…

I have a question about MJPEG and FCPX and my own cutting methodology. When cutting, I like to copy quite a bit, so to speak. For instance, I will focus on a particular scene, cut it together and render it. Then will take the rendered file and design its sound, lay it all down, then render that. I will do this, individually for each scene in the film. Then I will dump the fifty or so scenes into a fresh timeline and render that also. Subsequently, I will lay in the score and re-render. So, as you can see, there are many generations of copying / rendering / exporting.

In the old days, I would have been going back to the neg or in analog video using a timecode and go back to the masters… but I prefer not to go through a similar process here. Therefore, what I need to know is whether the duplication I have outlined above will cause any degradation to my image whatsoever. To be totally clear, it's all MJPEG files at 4096 x 2160 and every single time I export something I am religiously doing it with all the best, highest, slowest settings and outputting at 4444 and so on - with so much reverence that it's almost as if I am handling a negative.

But is it possible I will lose anything from the image, even the slightest bit of quality, doing what I have described? If so, I will have to find another way. I would really appreciate any advice (or reassurance?) you experienced FCPX folks can throw my way, thank you for it deeply in advance and ask you to please remember this is not a request for help with cutting methodologies and so on (I have that part figured out over the years) but rather a straightforward technical query about whether repeatedly exporting MJPEG will cause the image to slowly, even slightly degrade, thus making my methodology a faulty one!

Is there, for instance, a particular setting or settings that will ensure the MJPEG remains as MJPEG until such time as I want to create various versions of the master later on?

I need to be darn sure that my master is 100% for many obvious reasons, not least of all that we'll be premiering in 4K cinemas.

MacBook Pro with Retina display, OS X Mountain Lion (10.8.3), FCPX

Posted on May 30, 2013 2:43 AM

24 replies

Tom Wolsky

Level 10

152,809 points

May 31, 2013 8:07 AM in response to Jemappelle

I am sorry but it is not false. When I say completely transparent, I meant completely transparent without any loss at all.

There is nothing that will do what you want the way you describe in copying a file. No video editing or encoding application can do that.

But you can believe whatever you want.

Jemappelle Author

Level 1

8 points

May 31, 2013 8:15 AM in response to Tom Wolsky

Tom, each of the 24 frames we shot with every second can be extracted as an independent JPEG.

If I take 500 consecutive JPEGS from one shot and 500 consecutive JPEGS from another shot and place one of these groups of frames after the other, giving me 1000 new consecutive JPEGS... it will subsequently be possible to export them from an NLE with mere data duplication occurring and and a total lack of further compression beyonf that which exists within each individual frame.

So when you say "No video editing or encoding application can do that" you're wrong because I just designed one in theory.

Thankfully, I don't think I will have to actually build it because I am fairly sure it probably already exists.

Tom Wolsky

Level 10

152,809 points

May 31, 2013 8:20 AM in response to Jemappelle

it will subsequently be possible to export them from an NLE with mere data duplication

No, you can't. Did you see Meg's message? Export = Recompression. A file duplication is not a frame by frame duplication. Even if you export a JPEG image sequence, each frame is recompressed.

Jemappelle Author

Level 1

8 points

May 31, 2013 8:27 AM in response to Tom Wolsky

If you export a JPEG image sequence, each frame is recompressed, unless the option not to recompress each frame is offered and chosen which it sometimes is.

I'll link to the NLE or plugin that I end up using to do this.

You can believe what you want, to use a phrase you keep repeating... 🙂

Tom Wolsky

Level 10

152,809 points

May 31, 2013 8:34 AM in response to Jemappelle

JPEG is always recompressed, even if the option is offered.

Jemappelle Author

Level 1

8 points

May 31, 2013 8:40 AM in response to Tom Wolsky

Not always, Tom. You admitted upstream that if I simply copy and paste a JPEG on my desktop, so that I now have two JPEGS on my desktop, that no recompression occurs. It's a simple data transfer of 1s and 0s. You admitted that, if you'd like to scroll upwards to refresh your memory.

I expanded on that admission by saying it would be possible to do that frame by frame for every single frame in the film and place them together and play them with no further compression - hence in theory what I am proposing is clearly technically possible... and not in a complicated sense I might add.

I'm proposing a NLE or Plugin will allow this and of course it will.

Over and out!

Tom Wolsky

Level 10

152,809 points

May 31, 2013 9:03 AM in response to Jemappelle

I did a little experiment. This is a 4K RED RAW image. Underneath it in After Effects is an exported ProRes 4444 file of the same clip.

The RED RAW image on top has a difference matte applied to it. When you switch AE to show you matte view you get this

The white pixels show the difference in pixels between the two files. This is a single generation.

Over and out.

Tom Wolsky

Level 10

152,809 points

May 31, 2013 9:08 AM in response to Jemappelle

hence in theory what I am proposing is clearly technically possible

No, it isn't, because there is no single, separate file for each frame. You can create a single file for each frame by exporting an image sequence, but in so doing you are recompressing each frame.

Jemappelle Author

Level 1

8 points

May 31, 2013 9:18 AM in response to Tom Wolsky

Excuse me, but I thought we already agreed ProRes 4444 recompresses? This is reactionary, Tom! The point is that digital images, even compressed ones, are basically a gallon of 1s and 0s and it's technically possible to duplicate every single one of them, whether for an individual image or a carnival of such individual images.

Proving ProRes 4444 does what you say, doesn't mean it cannot possibly be done by any NLE or plug in, and is very revealing.

It shows you don't get what I am saying at all!

I am opting out of this now.

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Lossless MJPEG exports?