Exported video Jerking periodically

Help/How To
#1

I have a file here which I have ripped some bits out of and was wanting to use it for an animated header but for some reason no matter what codec I export with - and I have tried MPEG2/H.264/H.265/and had a really good fiddle with the options for output cycling through them all repeatedly in all possible combinations with no better result.

If I play the source file by itself in VLC - it’s perfect but after cutting it about in shortcut for some reason it will not output smoothly and I’m scratching my head as to why.

I should mention too that I have edited other files in the same manor and they all output fine - it seems to be this one source.

#2

Properties > menu > Convert to edit-friendly… and try with the result.

#3

Ill see if that makes any difference, it didn’t say it was VFR when i load it though or ask me to convert it.

#4

I cant find that Convert to edit-friendly - currently hunting high and low - I do this once the clip can be seen in the edit window right - I don’t have to drag it to timeline or anything like that?
Never mind - found it buried in one of the little icons - not easy to find.

#5

2018-03-06_154323

#6

Thanks - Steve, I did find it, i tend to edit posts to update things if you guys would prefer me to put a new response as it might be easier to follow in thread let me know :slight_smile:

#7

O.K I did the conversion, when the file conversion is done and the converted file played in VLC the jerking in it is almost as bad as when i open an export the source file.

#8

What are your computer’s full specs?

#9

ASUS Rampage V Edition 10 with Intel 6900K + 32 Gig 3000Mhz DDR4 Ram, 1TB PCI3 x4 SSD primary drive, 2 x 480gb SATA 3 SSD’s as secondaries, 1 1TB 2.5 inch for downloads.
Main storage Avago 9361-8i 2G Cache PCIe SAS3 Raid controller with 8 4TB HGST Helium Filled server class drives in a RAID 6 array totaling 18.191TB not counting the hot swap.
Aorus GTX1080Ti and an Viewsonic monitor if I remember rightly an XGS2803 its gsync 28 inch WQHD anyway. I have two source drives atm which are 4tb USB3 WD Passport series with all my material to recompress and create menus for on my raid.

I think it should handle Shotcut - Just.

#10

Well Shotcut may not be the issue really, it’s playback after encoding, right?
I mean I often get jerky video while editing owing to the filters I’ve used, but once I’ve encoded/exported, playback is fine.

#11

Problem is Source playback is fine, Exported playback is not and it only seems to apply to this one film source which is used in a whole series.

I have two film clips ready 11.4m and 55m respectively I’m just trying to find a way for you all to be able to see them.

#12

Here is a link to the source and the exported files so you can see what I am talking about.

https://1drv.ms/f/s!AndEklxBLOSrhxl384utOWhwl9pI

#13

I downloaded both, they both play smoothly here, so the issue is your monster computer somehow?
Have you overclocked?

#14

Only minimally, you didn’t notice any horizontal jumping in the exported file?

Overclocking - logically can’t be the issue - the source file was extracted from DVD on this machine while overclocked. if the source file plays back correctly 100% but a converted version is jerky - it can’t be the overclock, I could turn it off and I guarantee you the result would be identical.

There is something going on in the conversion process which is not quite correct and I have other source material ( 7.5 TB worth ) that does not do this.

So logic would dictate that there is something in the source which is screwing up the conversion.

I’ve worked in IT since I was six. (42 years now) and tend to think these things through quite hard.

** Just had my flat mate test it too, even he noticed that on the converted section as the tail end of the ship passes there is noticeable judder **

#15

None at all.

OK, well there’s none here, both files playback identically (I use POTplayer btw)
I’m sorry but it doesn’t help at all though does it :frowning:
My machine is fairly standard compared to yours.

#16

Maybe try with DaVinci Resolve 14. See if there’s a difference?

#17

Ill have a look at POT player as well, if necessary and there isn’t some fix for Shot cut ill use Avidemux for that one series.

#18

Sounds like a plan. Meanwhile, I’ll keep an interested eye out for Dan or Brian’s experience with your files.

#19

I will too - I think if they look at the source there will be something in there that Shotcut doesn’t like or that simply screws things up - Maybe that series says one thing in it’s encoding and actually has done something funny it just struck me as odd that out of 8TB worth of total video it’s only any video from that particular DVD series that won’t export properly - I randomly tried about 20 of them.

#20

There is one interesting thing that I see with your source file: it uses 3:2 pull-down. That is, the frame rate of the encoded material is 24fps, but the encoding is at 29.97. In order to make up the difference, the codec (mpeg2) includes instructions to repeat some frames.

Here is the output of ffprobe (snipped out the irrelevant parts):

C:\Users\brianm\Downloads>shotcut-win64-180302\Shotcut\ffprobe.exe -show_frames -select_streams v -read_intervals “%+#4” -i "010101 Source.mkv"
Input #0, matroska,webm, from ‘010101 Source.mkv’:
Metadata:
ENCODER : Lavf57.71.100
Duration: 00:00:17.35, start: 0.167000, bitrate: 5633 kb/s
Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, bottom first), 720x480 [SAR 32:27 DAR 16:9], SAR 1:1 DAR 3:2, 30.30 fps, 30.30 tbr, 1k tbn, 59.94 tbc (default)
Metadata:
DURATION : 00:00:17.350000000
Stream #0:1(eng): Audio: ac3, 48000 Hz, 5.1(side), fltp, 448 kb/s (default)
Metadata:
DURATION : 00:00:17.251000000
[FRAME]
top_field_first=0
repeat_pict=1
[/FRAME]
[FRAME]
top_field_first=1
repeat_pict=0
[FRAME]
top_field_first=1
repeat_pict=1
[/FRAME]
[FRAME]
top_field_first=0
repeat_pict=0
[/FRAME]

This cadence of alternating top_field_first and repeat_pic tells the decoder how many times to repeat each frame in order to generate the 29.97fps rate.

This is fine for players that are going to play from the beginning to the end. But it makes it more difficult to seek to a specific frame. Also, it is still a 24fps to 29.97 frame rate conversion - which is always going to feel a little bit un-smooth.

I tried the “Convert to edit friendly” option with your source file and I also still see the ocassional skip.

I also converted the file back to 24fps using an inverse telecine filter in ffmpeg:

C:\Users\brianm\Downloads>shotcut-win64-180302\Shotcut\ffmpeg.exe -i “010101 Source.mkv” -vf “fieldmatch,decimate” output.mov

That seemed to give the best results for me. But again, it is still making a bad frame rate conversion.