Lossless export issue

Alan_R

I have a project consisting of a number of mp4 files produced from all the segments of a large project, produced in pieces for manageability, but the task to join all as one mp4 using lossless export failed to work.

So I then did the following...

Took two mp4 files exported by VP to combine into one mp4.

Had assumed lossless export would be the way to go.

Dragging both into VP, then doing a lossless export seemed to result in rendering taking place, many minutes of 100% PC processing, I gave up.

Using a competitors editor to do the same, I loaded the same two mp4 files, and it subsequently took 12 seconds to make a combined mp4.

Reading VP manual it is suggested that if any Visual Effects are used Lossless export does not work! Not sure I understand that - its just an mp4 irrespective of any fancy name used in its creation.

So - does it do what I want?

I have not examined the parameters in detail of the two mp4 files, but they are both mp4, fixed 25fps, HD resolution, and no editing has been done on them. In that both editors are trying to reuse already rendered footage without rerendering unless necessary, I assume input parameters would be the same. But VP seems to need to re-render whereas competitor does not.

Have I misunderstood something?

Am running VP 8.95 and cannot find any of the settings referred to in online documentation, so assume docs are not up to date with how 8.95 works today.

----------- time passes as I experiment ------------------------

I think I can see why VP fails Lossless export.

Here's what I do - select Export Video and select Lossless Video from the drop down.

Select destination Local Computer

Export File Settings window opens.

I set filename and destination folder,

resolution is greyed out and matches source items, frame rate is greyed out but DOES NOT match source file frame rate, hence why I believe that's the reason VP always decides to re-render. Why does VP not pick up on the source file frame rate and use it as default?

My frame rate of the 2 smaller mp4 files was rendered fixed at 25fps PAL. Why? Because before I understood VP did lossless, I planned to use my old editor to do the bolting together job. Now VP seems to have issues, looks like my old editor may yet "be the chosen one"!

Am I doing something wrong?

borate

Using version 8.95, took two twelve-second mp4 25fps clips, placed them on the timeline and chose Export | Video.

VP automatically detected that they were lossless eligible and dispatched them in about two seconds.

Please upload your two files so others can test them. Use a free server, such as Google Drive, get a shareable (public) link, copy that link and post it here or privately in a Personal Message to me (folder at top of this forum). With Google, be sure to click on "restricted" and change that to "anyone with this link can view."

Alan_R

Ah right - not quite the way I went, but will try your route first to see if "auto" mode actually works! If not I'll upload them for others to try!

Taken to a PM.

Alan_R

After many experiments I now have 2 clips rendered as mp4, dragged into VP, and then exported but did not go lossless as expected.

Also taken 2 clips direct from video camera, unedited and they will not export lossless either.

Input clips are mp4, export is set to mp4, and everything is 25fps..

The clips are available on GoogleDrive and the links are:

File1

File2

Both are approx 15s long and take just under 30s to export (so clearly not lossless).

My system is Windows 7 64bit and I'm running VP v 8.95

Would be interested if you run Windows7 64bit - do you see x264enc execute as native 64 bit or 32bit?

Apart from time - does unnecessarily rendering actually degrade the final quality???

TIA

Alan

borate

Test 1 (left) used default Video settings, and appeared to export losslessly. No "converting file" message.

Test 2 used the Lossless button, and appeared to re-encode. There was a "converting file" message briefly at the start of export.

No clue as to the disparity. Both were quick: test 1 about 5 seconds, test 2 about 8.

Degradation of quality re-encoding likely wouldn't be spotted by most folks, depending upon the nature of content and export settings.

This on Windows 10 (Pro) PC. No reference to x264enc was spotted in the task manager, but perhaps it was missed.

Alan_R

Thanks Borate - and these were with the 2 files I left on GoogleDrive?

I think how long probably reflects on hardware being, and that is very much 'it is what it is' - its more about how long in comparison.

Those 2 clips take around 27s for VP to export (render), whereas my 'other' VE not only confirms no need to render, but produces same combined clip in just under 7s.

borate wrote:

No reference to x264enc was spotted in the task manager, but perhaps it was missed.

No chance of missing it on my pile!!!

Thanks for your help - await with interest for developer feedback!

I certainly see no degradation. It's just nice to get it done quicker, but as this process is likely to be done just once per project the overhead is not too unacceptable. Shame that VP is not able to perform at the moment. VP is far nicer to create with, especially as I now 'chop-up' large projects and deal with subject related sections, combining all mp4's only at the end.

Regards

Alan

borate

Here's the skinny on lossless, from a developer...

1 Only one file of the whole project can be lossless. others have to be re-encoded.
2 When exporting lossless, the re-encoding part is slow because of the complexity of mixing different packets.
3 When choosing auto, if lossless region is 85% and more, we will do lossless, so it is better to always choose auto.

If no success, suspect hardware.

Though your other editor dealt with the files in twelve seconds, it may have re-encoded them?? It took only five seconds for VP to combine them..

Alan_R

Thank you - but....

1) "Only one file can be lossless". What is meant by that? A file is not lossless or otherwise, the process of creating that file is either lossless or not. My understanding is that rendering a new output file can benefit (quality and speed) from a lossless procedure if the input file(s) do not need rendering (because nothing has changed that requires re-rendering).

Stage 1 - edit clips and pics - cropped blended transitioned etc and render to make one file.

Stage 2 - collect all the files from stage 1 and make a bigger file - no changes - no render.

2) "When exporting lossless, the re-encoding part is slow because of the complexity of mixing different packets." What are different packets? This lossless exercise (as far as I see) is just taking a number of mp4's created earlier, and making a larger mp4 that meets all the criteria to qualify for lossless proocessing. So where's the difference(s) that fail this criteria requirement?

3) I guess this point is obvious.

I may not seem to fully understand the feedback we got, and would appreciate an explanation to my points above as I cannot see how any of the data involved fail the criteria checks for lossless processing.

Thank you for bearing with me.

Alan.

borate

To illustrate what my take is on #1...

A single lossless-eligible :15 file was repeatedly placed on the timeline until the sequence length was :45. Export re-encoded.

Then the result of that export was placed - alone - on the timeline and exported again. Lossless. So it seems lossless applies to a single clip. If you exported Stage 1, then imported it alone, exporting again should have been lossless.

Finally, the export result was again placed on the timeline, but this time the raw clip was added several times to the end. Now, pressing the LOSSLESS button, export was lossless for the previously exported segment, then slowed for the added files, which were apparently being re-encoded.

That may explain #2. Not a programmer, so can't elaborate. Apparently a reference to the difference of data in the clips.

For quality, the point may be moot in most cases, but re-encoding will be slower.

Alan_R

borate wrote:

To illustrate what my take is on #1...

A single :15 file that qualified to be exported losslessly was repeatedly placed on the timeline until the sequence length was :45. Export re-encoded.

I understand - but am surprised that's what VP does. Tried my old editor loaded one clip (:15), dragged it to the timeline 4 times (total length 1:02), performed render necessity test, all four instances passed requiring no further rendering, exported taking 19s and interesting slowing as it passed the three joins so obviously a little bit of work required. I would say 1 sec per piece plus around 5s per join so 3 joins and 4 pieces approx 19s.

borate wrote:

As to #2, not a programmer, so can't elaborate. Apparently a reference to the nature of the data in the clips.

Yeah I just do not understand that either.

borate wrote:

As for quality, as noted earlier, the point may be moot in most cases, but re-encoding is bound to be slower.

Totally agree!!

Thank you for your persistence in helping me understand whats going on, much appreciated.

Alan.

borate

Tacked together four :15 files which exported (854x480) in about :07.

Brought that result in - alone - and exported twice - first at video defaults then by pressing LOSSLESS. Both took less than :02.

Added a few of the same raw files and exported at video defaults. Fast overall, but it appeared to re-encode. Total about :08.

Then exported by pressing LOSSLESS. The prior export segment was lightning quick, the added files were re-encoded. Total about :06.

You get the picture. ^_

Alan_R

I do indeed and thank you.