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joe bloe premiere 4,391 posts
Dec 6, 2009
Currently Being Moderated

RAM preview quality vs. render quality

Sep 21, 2011 5:49 AM

Is there any difference in image quality between a targa sequence

output as the result of a saved full resolution RAM preview and

the same comp rendered to a targa sequence at full resolution

via the render queue?

 

I have specified targa sequence as the default format for saving

RAM previews within the output module template.

 

I can see no difference.

 
Replies
  • Currently Being Moderated
    Sep 21, 2011 6:51 AM   in reply to joe bloe premiere

    Just the ability to control the render. You can't change things like the way the alpha is rendered without using the render cue. I don't think it's a very professional workflow and I'd never do it except maybe for a quick, must make the deadline preview for a client.

     

    That would probably be unlikely though because my previews are all web based not and going directly from an AE comp to the Media Encoder to the YouTube of Vimeo HD presets for render would be just as fast if not faster than doing a full project ram preview (even if I had the ram for it), saving the sequence, then compressing it for the web.

     
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    Sep 21, 2011 7:13 AM   in reply to joe bloe premiere

    You're right about setting the options for Ram Preview, which is OK if you remember to do that every time or you always want the same thing. I also never work with targa sequences because it doesn't fit my workflow or delivery pipeline. I think there's better image sequence options.

     

    The biggest reason that I don't use that workflow is that It's too slow. I'll bet that I haven't rendered a full resolution ram preview longer than 10 frames twice in the last 5 years. Most of the time I work at 1/2 or even 1/4 rez in the comp window when previewing because I'm only checking motion. I check the composite a frame at a time most often at 200%. I haven't got time to sit around and wait for 20 or 30 seconds of ram preview at full rez and only a few of the places that I work have a monitor that will show me a full frame full rez preview. Once the project's done I fire it off to the media encoder or cue it up for rendering later and then I start working on something else.

     

    If your workflow is different then that's OK. My workflow is what works best for me and it's only offered as a suggestion. 

     
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    Sep 21, 2011 8:06 AM   in reply to joe bloe premiere

    Unfortunately, I can't find Todd's explanation quickly...

     
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    Sep 21, 2011 8:20 AM   in reply to joe bloe premiere

    As far as I know - No difference.

     
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    Sep 21, 2011 11:30 AM   in reply to joe bloe premiere

    Just to affirm, there is no quality difference, right?

     

    There could be one single deal-breaker:  I believe a rendered targa sequence supports transparency, but a RAM Preview doesn't.  If that's an important consideration, I'd render the targa sequence.

     
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    Sep 21, 2011 12:01 PM   in reply to joe bloe premiere

    As I understand it, the only limitation is that a RAM preview doesn’t generate

    interlaced fields, so this method is only valid for a progressive composition.

     

    That's my understanding, too.  If you haven't done so already, I also recommend double-checking on the type of alpha channel to be delivered: Premultiplied or Straight.  And I learned something new today as well, so thank you.

     
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  • Currently Being Moderated
    Sep 21, 2011 7:51 PM   in reply to joe bloe premiere

    Sorry to chime in so late. Busy day.

     

    If you're rendering a RAM preview at full frame rate and full resolution from your active camera view, then what's stored in the RAM cache is an uncompressed set of frames that represents the same as what you'd be rendering as the first phase in the rendering process through the render queue. (Note all those caveats, though.)

     

    Note that rendering and exporting throught he render queue involves two phases: rendering (controlled by render settings) and encoding/compression/format-conforming (controlled by output module settings). Saving a RAM preview means that you're skipping the first phase and using what's saved in RAM; but you still need to consider the second phase. You can set up any kind of output module settings that you like for saved RAM previews.

     

    Personally, I never use the ability to save RAM previews. I tend to do RAM previews in pieces or at partial resolution or partial frame rate so much that I never have a full green bar for my entire composition just sitting there waiting to be encoded and exported.

     
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    Sep 22, 2011 6:17 PM   in reply to joe bloe premiere

    Select your queued render item, and choose "Add Output Module" from the Composition menu. You can add as many Output Modules as you want to any queued render item. However, I dig what you're saying about freezing pre-processed frames. It could happen with a more successful disk cache strategy in the future, I would imagine.

     

    Overall, by adding multiple Output Modules, it seems it would effectively do what you want (process a frame once, but write it X number of times to X number of files), other than using the existing render data used by generating the RAM preview.

     
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