Quantcast Rendering material to an external disk? - digitalFAQ Forum
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08-01-2019, 05:03 AM
dima dima is offline
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Can anything happen for the quality, stability, fluidity of a given movie if we render it to an external drive, eg HDD (USB 3.0), not an internal disk of computer ? [Ex. render after simple editing; in and to lossless codec].
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  #2  
08-01-2019, 05:10 AM
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If by render you mean encode, then no. It's just slower.
If you mean capture, then yes, dropped frames, maybe even software lock-up.

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  #3  
08-01-2019, 05:20 AM
dima dima is offline
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I don't mean capturing.
I mean saving the material(for example after some editing) in/by some software program.

It's good in the light of what you wrote that the external disk does not bother (except for the slower action than the internal disk).
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  #4  
08-08-2019, 01:55 PM
Koreth Koreth is offline
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Once digitized, where you store the digital data should have no impact upon the information contained in the digitial data, so long as the storage device is doing its job correctly. That's one of the main point's of digital. A digital sequence of "00110101" will be "00110101" whether on an SSD, USB hard drive, burned DVD, or piece of paper taped to a carrier pigeon's leg.

The only thing that will really matter is when trying to play back said encoded/edited video from some external media is the media's speed. Some external media will be too slow to play back smoothly. But, that is not damage to your digital video data, that's just the media being too slow to present the digital video data fast enough that you can watch it.
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  #5  
08-08-2019, 02:26 PM
sanlyn sanlyn is online now
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Quote:
Originally Posted by dima View Post
Can anything happen for the quality, stability, fluidity of a given movie if we render it to an external drive, eg HDD (USB 3.0), not an internal disk of computer ? [Ex. render after simple editing; in and to lossless codec].
Tell is what you mean by "render".
Tell us what you mean by "edit".
Here is what it means to most users:

"Render" usually means to re-encode a video to a different codec, with or without modification to the original image. This has a quality cost, the extent depending on how it's done and on the condition of the source. In editors, "render" carries the connotation of lossy re-encoding, especially in several stages of loss. However, if you render a new version to a lossless codec (huffyuv, Lagaritrh, etc.), there is no data loss.

"Render" also carries with it the connotation of encoding to a final delivery format after all other project work is completed. Final delivery formats are almost always encoded with MPEG or h.264, which are are lossy codecs. If the previous processing used lossless methods, the quality of the final encode depends on how the compressor is configured -- low bitrates mean lesser quality, higher bitrates mean better quality. If the previous processing used lossy methods, the final encode will look awful.

"Edit" means to cut or add various segments to a video, then save the new new copy. If you are using a lossless copy and lossless codec, there is no quality loss even if the editing means compressing and re-compressing several times losslessly. If you encode to a lossy codec (MPEG, h.264, etc.) there is a quality cost. "Lossy" always means "you lose". Lossy compression data and quality losses are cumulative and cannot be recovered. "Lossless" means that 100% of what goes into the compressor is what you get back.

If you mean to "copy" a video from one place to another making no changes, there is no quality change.

Last edited by sanlyn; 08-08-2019 at 02:52 PM.
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  #6  
08-08-2019, 10:35 PM
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jwillis84 jwillis84 is offline
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I would guess he's coming from the standpoint of using software that (always) "renders". When I was new to this, Sony Vegas and Camtasia or other like software offered no simple option like (save to disk) you always had to "publish" or "render" or "upload" to Youtube after editing source clips together.

So the OP may be asking if saving to lossless or other any other method is "truly" like saving a file, or asking if is really only a different form of "render". It messes with your head after unlearning there is "no lossless" save to file option from most editing programs.

If that is the case..

Then the answer is complicated.

First (yes) when we say save to "lossless" we really mean save your file as a bit for bit identical copy of your edit stream.

The difference is we are talking about clips that are not compressed at all.. they are really uncompressed frames on the edit stream, when they are saved to disk, they are saved exactly as they are.. only they are compressed "losslessly" which is more akin to saving the uncompressed stream to a file, then running zip or winrar on the result so the uncompressed file gets smaller.. but looses no detail. That's why its called "lossless". The Huffyuv or Lagarith "codec" is not really compressing the bits within the frames, but the frames themselves after the fact.. when they are uncompressed (file is opened) then they are restored to their exact original condition with no losses at all.

Editing Uncompressed video is not like editing Compressed video. Once the clips are put together there is no "discontinuity" between groups of frames that share bits between frames.. so you do not have to "sync" them up as it were. Its more like cutting full frames of movie film together.. there is no reconciliation between the clips during "render" to recompress the stream so that it plays back smoothly on a lower power decoder program or decoder device.

Normally if your edited Compressed stream of clips were just smushed together into a stream and saved, then tried to play that back on a program or device it would "choke" the stream would not be in a form that the decoder could smoothly process.

This trade off.. is why most Compressed (aka most video Editors) must "Recompressed" or "Re-encode" or "Render" a stream of clips of Compressed video.. to smooth out the transitions and fixup various things like indexing depending on the output type of the video file.

Uncompressed editing doesn't need any of that, its ready to be played back immediately, so it can be saved straight to a file. then you can run zip on it or winrar to compress that file "losslessly" (or) you can choose to "render" (miss-use of the term) in some editors using the Huffyuv or Lagarith "codec" to a lossless output file.

It gets complicated where some editors can't use the "lossless" codecs, or they have alternatives like Apple ProRes which are not quite lossless, but along the same ideas.. that is.. a codec that is intended for "editing" that retains as much detail as possible, even when re-encoded.. until such time as you render to a "publication" type like DVD compliant MPEG2-PS or other formats.

The long story is that computers have not been practically capable of capturing, editing and saving in Uncompressed format until relatively recently, it was simply astronomically expensive and even TV and Movie studios (Professionals) used Compressed capture, edit and save of their projects.

That has rapidly changed in the last ten years.. and people can now reach for much better capture output and do ("amazing") things with very poor video.. as long as its captured in Uncompressed format. But Uncompressed format normally eats disk space rapidly and one hour of video is Gigantic in size. To help with this Huffyuv and Lagarith were created and compress the "frames" losslessly on the fly during capture and make the Gigantic files smaller.. while still making them editable in many popular video Editor programs.

When you edit Uncompressed clips together and save back to disk, those frames are not "rendered" they are literally "transformed" 100 percent as they originally were into a compressed "zip file" like format which is smaller.. but retains all the resolution and details of the original video. When you re-open those "lossless" files in a video editor, they come back 100 percent as they were when they were put into the "lossless" codec for saving to a file (even if the program says its is "rendering" them.. which in this context means its only "saving them").

Last edited by jwillis84; 08-08-2019 at 10:50 PM.
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  #7  
08-09-2019, 01:24 AM
dima dima is offline
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Thank you all for help. I think I understand everything I needed to know about this matter.
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  #8  
08-12-2019, 10:00 PM
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Quote:
Originally Posted by sanlyn View Post
"Render" usually means
As is the case with "capturing" DV, the word "render" is misused a lot.

To render means to create something new from nothing. You render CG to make special effects. After Effects renders.

Inputting video, and outputting to a different format, is simply re-encoding. Even if importing, editing/restoring, and outputting to a different codec, it's still just re-encoding. There is an argument to be made that editing creates new material, thus render, but it's a weak argument. Premiere/Vegas/NLE does not render. Encoders do not render.

You know this, so my post most for benefit of others reading.

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