Lossless video cutting

[Ron P.]

Geesh I forgot about that one, "Save Trimmed...." command. Yes that does allow for no reencoding.

[RafaelLVX]

Correct me if I'm wrong, but we seem to be talking about what I have been doing for the past twelve or so years with Video Studio. And I just reconfirmed it now with a little experiment. I put a random .mts file in the X9 timeline (though it could have been any version of VS -- I started back with VS7 and that's 7 without an X!) I chose a random spot in the clip and cut it with the scissors icon below the preview screen. Then I highlighted one part of the part clip. Then I went to File > Save Trimmed Video. And a totally real, totally new clip with exactly the same properties as the original, was created. And I could then do the same with the remaining part of the original clip.

And I repeat, these are completely new and separate clips, not just virtual ones. And the original clip remains intact as well. One thing to note if you try this yourself is that the Save Trimmed Video process does not ask where you want the new clip(s) to be stored. By default it stores them in C:\Users\[YourName]\Documents\Corel VideoStudio Pro\19.0 -- but of course once created you can move them wherever you want.

So from my point of view VS can certainly cut a video clip into real pieces with no re-encoding at all!

I been fiddling with the demo for only a few days. I'll try what you said. I does sound like that's what I need. I'll report back. Thanks!

[RafaelLVX]

Correct me if I'm wrong, but we seem to be talking about what I have been doing for the past twelve or so years with Video Studio. And I just reconfirmed it now with a little experiment. I put a random .mts file in the X9 timeline (though it could have been any version of VS -- I started back with VS7 and that's 7 without an X!) I chose a random spot in the clip and cut it with the scissors icon below the preview screen. Then I highlighted one part of the part clip. Then I went to File > Save Trimmed Video. And a totally real, totally new clip with exactly the same properties as the original, was created. And I could then do the same with the remaining part of the original clip.

And I repeat, these are completely new and separate clips, not just virtual ones. And the original clip remains intact as well. One thing to note if you try this yourself is that the Save Trimmed Video process does not ask where you want the new clip(s) to be stored. By default it stores them in C:\Users\[YourName]\Documents\Corel VideoStudio Pro\19.0 -- but of course once created you can move them wherever you want.

So from my point of view VS can certainly cut a video clip into real pieces with no re-encoding at all!

Oh, the demo doesn't have that option to save trimmed, I'm gonna have to take your word for it.

[ConsumerDV]

We are not talking about joining videos but only about cutting/trimming

Yes, I understand that. However if you cut or trim a video file, it will need to be rendered, which would be a new video file. That rendering does require the usage of codecs correct? It does require (re)encoding. Reencoding seems to scare or worry people, and they need not be. Simple edits do not have serious impact on video quality. Mixing several different formats, complex projects may.

Intra video can be cut with straight cuts completely losless.

For inter-frame video, a certain number of frames, depending on the format, will have to be re-encoded. AFAIK, it is up to 15 frames for popular 30p/60i/60p formats and up to 12 frames for 24p or something like that, because the complete GOP has to be re-encoded.

It was the main reason I bought the X8 to do straight cuts of AVCHD Progressive, but the app simply does not work, throws an error. What a mess.

[lata]

Hi ConsumerDV

You say “but the app simply does not work, throws an error”

What error?

Errors are nothing to do with Lossless Video Cutting but certainly a problem with the program or a compatibility issue between the program and the video file.
I would advise you start a new post regarding the crashes,

Oh I see you have done that, I will comment there.

[ConsumerDV]

Hi ConsumerDV

You say “but the app simply does not work, throws an error”

What error?

Errors are nothing to do with Lossless Video Cutting but certainly a problem with the program or a compatibility issue between the program and the video file.
I would advise you start a new post regarding the crashes,

Oh I see you have done that, I will comment there.

Fixed by installing a bunch of updates. Thanks.

[Nick Mirro]

So from my point of view VS can certainly cut a video clip into real pieces with no re-encoding at all!

So "saving trimmed video" renders but does not re-encode. Just learning this now. Hope this is right... Rendering is just the process of re-writing frames, which is lossless. Encoding is compressing, which is lossy. ?

[MrJohnny]

Nick
This is from the VS manual:

Corel VideoStudio combines the video, titles, sounds, and effects in a
process called rendering. Project settings determine how your movie
project is rendered when you preview it. The output video can then be
played back on your computer, burned to disc, or uploaded to the
Internet.

I take this to mean VS assembles (renders) the timeline into one file, encoded or re-encoded as necessary, depending on the project settings and the original clip properties. So if the project setting calls for uncompressed video (large file!) the file will be encoded without compression.

John

[lata]

Hi Guys

It is general practice to set our project properties to match the video properties.
The Show Messages will do that for compliant video (for want of a better description.)
By compliant video I mean the video properties can be used to set project properties.

If we are using different formats then the project properties could be set to match the longest footage, may not always be the case. Otherwise the project properties can be set to our output settings.

Rendering will use some form of compression to create that output video.

To achieve a format with no compression I think the only option would be AVI where we can indeed set the compression type to None, file size will be approx. 65 Gb per hour of footage.
Any other format will use some form of codec. There is no point in converting MP4, Mov , MTS, in fact any format to AVI no compression.

Share – “Same as first clip” would use the clips properties to render the project, this is probably the fastest render option, rendering like for like. Smart Render would be used, so unedited portions will render fast and edited sections slower, the encoder having to combine clips / filters etc.

As we match the project properties to Video clips properties, Share Same as Project Properties would be identical to Same as First Clip.

[Ken Berry]

Rendering is just the process of re-writing frames, which is lossless. Encoding is compressing, which is lossy. ?

As the two previous posts by lata (Trevor) and Mr Johnny I think will by now have made clear, this is not correct. As the quote from the VS manual has it, rendering is just the process of converting a project in the timeline -- which can be made up of a variety of videos in the same or different formats, photos, music, voiceovers, titles, transitions, and filters -- into a single new video which has a single format. And while the whole project is being rendered, some or all of the individual elements of the project will be encoded depending on the output format that has been chosen.

And further, depending on the output format (apart from uncompressed .avi), some element of compression will be involved affecting some or all of the video/photos/audio in the project.

This is where SmartRender comes in. If your project has a lot of video in it (or all of it) in a particular format, and you are rendering to exactly the same format (Share > Same As Project Settings or Same As First Clip), then there is really no need to re-encode the existing video. So with SmartRender enabled, during the rendering process, only those parts of the project which are different from the chosen output format, or those parts of the project which have had something done to them (like filters) will be encoded or re-encoded.

So getting back to your original question in a "clear as mud" sort of way, rendering is just the process of converting a project into a new video. But it will involve encoding or re-encoding at least some parts of the project, and in turn this will also involve some form of compression or, in the case of uncompressed avi, decompression. Note here that even with uncompressed avi as the chosen output format, encoding will happen if the project does not contain any such avi.

And finally, the only lossless part of the rendering process will be for those bits which are SmartRendered. If SmartRender is not used, or for those parts of the project which need encoding or re-encoding, then using a lossy codec (which includes just about everything except uncompressed avi) will mean that the encoding which occurs as part of the rendering process will involve some loss of quality. The amount of loss might be tiny depending on what codec is chosen, and perhaps not detectable by the naked eye, but it will be there nonetheless.

So to re-write your question in a way which gives the answers (I hope):

Rendering is the process of converting a project into a video. SmartRendering is just the process of re-writing frames, which is lossless. Encoding, apart from uncompressed avi, is compressing, which is lossy -- though even the process of conversion to uncompressed avi involves encoding and decompressing.

[MrJohnny]

Hi Trevor (lata) and Ken

Happy New Year.

Thanks for the clarifications. The “Save Trimmed...” command is very useful. This appears to copy the trimmed clip information in the original format, regardless of project settings. Although it does not ask where to save, it will redirect the saved trimmed clip to the Working Folder named under Preferences.

As far as I know, all rendering uses some form of encoding (codec) to produce the video file for replay.

https://en.wikipedia.org/wiki/Codec

The use of a codec to encode the information does not necessarily equate to compression or “lossy”. Uncompressed video is encoded and decoded on replay.

https://en.wikipedia.org/wiki/Uncompressed_video

The use of a codec to compress video information does not necessarily equate to “lossy”, there are lossless compression codecs available at the expense of file size.

VideoStudio allows “None” for compression under the AVI and Mov file types for output. This may be useful when trying to preserve quality. Previously lost data (quality) will not be recovered by doing so.

John