edit then convert or convert then edit?

jchh

Hi,

Apologies if this is a dumb question, but is there any difference in cutting/trimming TS flies (from my HDHomeRun) before converting to MP4, or is it better the other way around?

The only thing that I can imagine might influence this are I-frames?

I am on a Mac and ma using Movavi Split Movie 2 to remove the adverts and trim the ends followed by Handbrake to convert.  I know Handbrake is good, but not so sure about Movavi - I am not quite sure how it handles cutting between the I-frames.  Does anyone have any experience of the right apps to use on a Mac for this?

jchh

no takers?

LV426

I know that Handbrake's primary purpose is to convert.  And re-rendering of compressed video is inherently degrading.  Therefore the Handbrake conversion is degrading.

What I don't know is whether the editing tool you are using always fully re-renders (even if the file format is unchanged) or if it can "smart render" (which means - only re-render those parts where changes/edits have been made and simply copy data for the rest).

IF it fully re-renders always then that, plus the handbrake conversion, is two degrading re-renders.  Ideally you don't want to degrade twice.  It wouldn't matter which you did first; they will both degrade.

IF it smart renders then, again, they are equal - one full re-render and one "smart" (partial).

What I equally don't know is whether the editing software is able to produce a mp4 output directly.  IF it can then that is the optimal approach - assuming its algorithms are equal to those of Handbrake.

jchh

Hi,

I don't think it doesn't smart re-renders as it saves the edited file very quickly.

I guess my follow-up question (to all) is whether the is a decent Mac edit/convert app out there that I should be using instead.

LV426

A quick "save" (or export) of a fully recreated video file is actually indicative of a smart render - because copying data (unchanged) is quicker than re-encoding it.

HOWEVER bear in mind that many video editors work like this:  when you "save", what you are actually saving is a project file which is nothing more than a set of instructions, usable only by that same program to recreate your editing commands when you reload the project.  That's a small file and a trivial process - so, quick.  It's not (usually) a usable video file.

In order to produce a usable video file as output, the command is often "export" (or similar terms) and it is typically here that you may choose from various output formats.  I'd expect an export to take (possibly much) longer.

I haven't used your proposed app as I say, but it appears from the website (which isn't entirely clear) that it can produce outputs from various and mixed sources in various formats.

So my suggestion is to experiment with the app, but look for options to "export" as your chosen format - mp4 - directly from that app.  You won't then need a further conversion, and rendering will be done just once - which (all other things equal) is optimal.

Use a short segment first (as a test) to save time, and use something like VLC to play it afterwards - VLC has a menu item that describes the file format, encoding, audio channels, and so on, so you can see technical details of what you made.  Once you know how to use it, then do the whole thing.

jchh

Thanks!
Movavi Video Editor cuts, trims and converts.Movavi Split Movie only cuts and trims.  There is no export function, only "save"The website says this:
Split Movie processes multimedia files without re-encoding and post-conversion, which lets you preserve the original quality and cut video on your Mac up to 20x faster!
Read more: Trim Videos on Mac with Movavi | Video Splitter for Mac​
So I am wondering how it handles the cut frame as it implies it doesn't do smart re-rendering.  I did try emailing them a while back but there was something lost in translation.

LV426

My best understanding:  it will re-render in the immediate area surrounding the edit/s but not elsewhere.  I can't speak specifically for the GOP structure that results, except to say that (based on results from another editor that does the same thing) it appears to work.

jchh

cheers, LV246