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TOPIC: Playback crashing with 120fps AVCHD

Re: Playback crashing with 120fps AVCHD 2 weeks, 2 days ago #239271

  • hugly
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I believe the issue is mixture if multiple problems.

The audio distortion might be a known but apparently not fully fixed bug with high fps media on not so beefed computers. The poor playback performance is very likely to be caused by the demanding compressed video format together with the performance of your laptop and not surprising. The show stopper, however, is the failure when trying to create internal proxies from 119.88 fps material, which forces you to convert the footage prior to import.

I'm still unsure what's the best approach for a workaround.

I converted the file to straight 120fps, encoded with edit-friendly settings, downloadable here: we.tl/t-1z3sOkoO2z

Does it show the same problems as the original file?
Does creating an internal proxy work? (Different from what is shown in the post I linked to above set the bitrate to 'Very High')
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Re: Playback crashing with 120fps AVCHD 2 weeks ago #239323

  • Youssback63
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Hello,
Sorry for late return, yesterday was a busy day.
So i tried the converted file 120p and result for video is good: smooth and not freezing. I have small audio disturbance but it is far better than original one.

I tried to make proxies but it is always a failure.

What is suggestion: conversion before import with different settings?
Thanks for your support.

Re: Playback crashing with 120fps AVCHD 2 weeks ago #239334

  • hugly
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The shared file "GH010045~1080p120.mp4" allows creating proxies on my system flawlessly and that should be the case on your system as well. Would you mind crosschecking your findings?

Make sure that you're running the latest beta release and also that you have selected the right clip. You can double-click to open the clip in the source viewer, crosscheck the title up left on the viewer and start proxy creation from the context menu of the viewer. I'd truly appreciate your feedback on this.

To convert, I used Handbrake with the following settings:

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To get there, start with the preset 'Production Standard' and modifiy the following parameters as shown above: 'Constant Quality', 'Framerate (FPS)', 'Encoder Preset', 'Encoder Profile', 'Fast Decode' and the contents of 'Advanced Options'. For the samples, I lowered the audio bitrate to 160 on the tab 'Audio', but that isn't mandatory.

I attached the settings as loadable preset. If you wish using it, download and unzip the file, then load the resulting json file from 'Options.Import from file' down right. It'll appear as 'H.264 B22-VF' under 'Custom Presets'.

I can provide a FFmpeg command line, which does basically the same, if you prefer using FFmpeg.
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Re: Playback crashing with 120fps AVCHD 2 weeks ago #239339

  • Youssback63
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Hi
Quick precision:
Proxy creation works only with your file "GH010045~1080p120.mp4" . Proxy creation is a failure for my others files.
I am not a user of Handbrake or FFmpeg so i will try both and check which one is user friendly...
Thanks a lot!

Re: Playback crashing with 120fps AVCHD 2 weeks ago #239344

  • hugly
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It won't be possible to use proxies with your footage due to the mentioned bug. That's where all the hassle started. Converting 119.88 to 120 fps fixes the issue. The 60fps file I shared should make no problems when creating proxies. You'll see that the editing performance with proxies is much higher.

Handbrake appears to be more user friendly, because it has a GUI, whereas FFmpeg is a command line tool. I'd suggest starting with Handbrake and the settings explained above.

Since the highest export frame rate is 60 fps, you can use 120 fps material either for slow motion or to just discard half of the frames. I'd suggest converting all 120 fps which you don't intend using for slow motion to 60 fps. Even then, creating proxies from the converted material (e.g. in 480-very high) will give you a better editing experience.
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Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239602

  • Youssback63
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Thanks for your technical support.
This weekend i used Handbrake to convert my videos before imports in Lightworks.
Editing experience was much better.
One question about your custom video settings in Handbrake: what is the purpose of Advance setting "keyint=30" ?

Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239604

  • hugly
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Youssback63 wrote:
One question about your custom video settings in Handbrake: what is the purpose of Advance setting "keyint=30" ?

Practically, compared with the default settings of Handbrake (250 at the given frame rate), it reduces the average time the decoding application (e.g. Lightworks) needs to jump to and decode a random frame.

More detail: AVC (h.264) is a codec which supports interframe compression, with different types of frames. This is efficient compression, but demanding to decode. There are keyframes (aka I-frames), which can be decoded as they are, and other frame types (P-frames, B-frames), which need one or more next neighbours to be decoded. The distance (number of frames) between two keyframes is called GOP (Group of Pictures). It can be variable or constant. Decoders read full GOPs to decode a single frame, not necessarily, but usually. Thus, the distance between two keyframe has direct impact on decoding performance. Handbrake creates keyframes mainly triggered by scene changes with an upper and a lower limit (variable GOP). The parameter "keyint" sets the upper limit.
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Last Edit: 1 week, 1 day ago by hugly.

Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239611

  • schrauber
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In your screenshot, "Production Standard" is set. Is it correct that a low GOP is preset there anyway? Does `keyint = 30` have any influence at all in this case? Can `keyint = 30` maybe even increase the GPO of "Production Standard"?

EDIT: Or was the setting `keyint = 30` not added manually, but automatically entered into this box by Handbrake when clicking on "Production Standard"?
Mainly automatically translated
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Software: Lightworks 2021.2 || Windows 10 Home, 20H2, 64 Bit
Hardware: Intel i5-4440 (3,1 GHz); || RAM: 8 GB; || Intel HD Graphics 4600 (can use max. 2 GB of shared RAM)
Last Edit: 1 week, 1 day ago by schrauber.

Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239612

  • hugly
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The preset Production Standard is (over-)tweaked for quality, i.e to preserve as many details as possible, even if the details are compression or sharpening artifacts. The reason why I suggest it on a regular basis is that it's the most simple setting to get editable results with average footage (at the cost of insane file sizes).

The setting I've posted are based on 2 hours of testing and it isn't only the GOP. The settings are tweaked entirely. Unfortunately the rule "the shorter the GOP the better the performance" doesn't apply for the current implementation of the h.264 decoder, in particular not with high fps footage,

www.lwks.com/index.php?option=com_kunena&func=view&catid=597&id=239353&Itemid=81#239353
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Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239614

  • hugly
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schrauber wrote:
EDIT: Or was the setting `keyint = 30` not added manually, but automatically entered into this box by Handbrake when clicking on "Production Standard"?

Missed the edit. Open Handbrake, select Production Standard and this is what you'll see under Advanced Options:

keyint=12:min-keyint=1:ref=1:bframes=0:qcomp=0.8:aq-strength=0.5:dct-decimate=0:fast-pskip=0:deblock=-2,-2
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Re: Playback crashing with 120fps AVCHD 1 week, 1 day ago #239619

  • schrauber
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I understand, thank you.
Mainly automatically translated
--------------------------------------------
Software: Lightworks 2021.2 || Windows 10 Home, 20H2, 64 Bit
Hardware: Intel i5-4440 (3,1 GHz); || RAM: 8 GB; || Intel HD Graphics 4600 (can use max. 2 GB of shared RAM)
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