Each time the render file is heavier

[Walter Soyka]

[Giuliana Bergamin] “I’m rendering the same composition several times, I’m using quicktime photo-JPEG, each new render is heavier than the others and I want to know how to stop this.”

If you are rendering to a lossy codec like PhotoJPEG, each generation introduces compression artifacts. When you encode that render again, the codec doesn’t know they are compression artifacts; it thinks they are details and attempts to preserve (but of course also generates more compression artifacts in the process).

If you are adding additional effects to those renders, you may be making more complex imagery that’s harder to compress, and you will lose compression efficiency as a result.

If you must work in a multi-generation workflow, you should consider using lossless intermediates (they will be big, but they will be pristine), then compressing only at the end of the workflow.

Of course, if you can avoid multiple generations altogether (perhaps through precomposing), you can save yourself the disk space.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Giuliana Bergamin]

Thanks for your reply.

There is no way to keep using the same codec and composition without getting the increasement?

Maybe I can make a script to pre-compose the final render for every render, would that help me to solve the problem?

[Walter Soyka]

[Giuliana Bergamin] “There is no way to keep using the same codec and composition without getting the increasement?”

Effects processing can only happen on pixels. Compressed video files do not actually store the values of pixels themselves; they store a mathematically reduced representation of an image that can be reconstituted into pixels.

So what does that mean? After Effects has to decompress your compressed frames into memory for processing. At that point, the original compression data itself is gone, but any artifacts that the compression process introduced into the image are irreversible and are preserved in the uncompressed frame in RAM. After processing, the new frame must be recompressed from scratch, so the original compression cannot pass through.

It’s like making a copy of a copy of a copy of a VHS tape. Each time, the signal is read off the tape, demodulated, remodulated as an NTSC or PAL signal, then demodulated and remodulated for recording back to tape. With each generation, you get further and further away from the original.

Let me turn the question around: why does file size matter? If you try to keep the file size small, you’ll decrease quality. Disk space is cheap.

[Giuliana Bergamin] “Maybe I can make a script to pre-compose the final render for every render, would that help me to solve the problem?”

What is it exactly that you are trying to accomplish? If you describe your problem instead of your proposed solutions, we might be able to offer other suggestions, too.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Giuliana Bergamin]

I need to keep all the rendered files at the same size, it’s not about disk space, is about bandwidth, I need to upload all the files and the files should be very small because the limited bandwidth.

[Walter Soyka]

[Giuliana Bergamin] “I need to keep all the rendered files at the same size, it’s not about disk space, is about bandwidth, I need to upload all the files and the files should be very small because the limited bandwidth.”

I would render everything to a lossless intermediate file, then compress it for final delivery.

If you can deliver H.264 files, you can get pretty good quality at very small file sizes — but the delivery format is really driven by the needs of the next user in the chain.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Giuliana Bergamin]

I must use .MOV / Photo-JPEG.

I can’t render in lossless, it would take twice the render time or more and I really need several renders.

There is something I don’t understand… this info which makes a difference on the weight of the files should be saved somewhere, in the RAM, in the project file, in the AE settings files… if I could just know where then I can fix the problem by just restoring to the previous state.

[Walter Soyka]

[Giuliana Bergamin] “I must use .MOV / Photo-JPEG.”

Ok.

[Giuliana Bergamin] “There is something I don’t understand… this info which makes a difference on the weight of the files should be saved somewhere, in the RAM, in the project file, in the AE settings files… if I could just know where then I can fix the problem by just restoring to the previous state.”

Maybe I’m confused. What exactly are you rendering?

Are you rendering literally the same composition over and over? Are you rendering, importing the render, then re-rendering? Have you added effects or changed the footage since your first render?

The file size of PhotoJPEG will be driven by the image complexity and the PhotoJPEG quality slider. If you want smaller files, you can get it by making your images simpler or by dialing down the compression quality.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Giuliana Bergamin]

I will explain, I have a project with a composition with a text, I’m using a jsx script to change that text, then render, then again, change text, render, and again, and again.

It works great, except because every new .mov file is heavier than the previous one.

[Walter Soyka]

[Giuliana Bergamin] “It works great, except because every new .mov file is heavier than the previous one.”

They will not all be the same size, because PhotoJPEG does not work on fixed bitrates but rather a specific level of quality per frame. In other words, PhotoJPEG compression’s efficiency is dependent on the content itself, not on its length.

It is normal for comps of the same length with different content to have different file sizes. If you render the same exact comp twice, however, the results should be the same size. If they are not, something is amiss.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Giuliana Bergamin]

Each render is heavier than the previous, if I render now with the first render text it’s like 200% heavier with exactly the same text.