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TOPIC: Despite the mp4 being constant framerate, my video (a capture card video) is choppy.

Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182263

MEDIAINFO:
Format : MPEG-4
Codec ID : M4V (M4V /M4A /mp42/isom)
File size : 621 MiB
Duration : 13 min 55 s
Overall bit rate : 6 239 kb/s
Movie name (redacted because privacy)
Description : Description here.
Recorded date : 2018-08-08
Encoded date : UTC 2018-08-07 16:50:25
Tagged date : UTC 2018-08-07 16:50:25

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L3.1
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 2 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 13 min 55 s
Bit rate : 6 000 kb/s
Width : 1 280 pixels
Height : 720 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 (29970/1000) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.217
Stream size : 599 MiB (96%)
Writing library : x264 core 148 r2643
Encoding settings : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x3 / me=dia / subme=1 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=1 / b_pyramid=0 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=12 / keyint_min=7 / scenecut=40 / intra_refresh=0 / rc_lookahead=0 / rc=abr / mbtree=0 / bitrate=6000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=12000 / vbv_bufsize=12000 / nal_hrd=none / filler=0 / ip_ratio=1.40 / pb_ratio=1.30 / aq=1:1.00
Language : English
Encoded date : UTC 2018-08-07 16:50:25
Tagged date : UTC 2018-08-07 16:50:25
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : mp4a-40-2
Duration : 13 min 55 s
Bit rate mode : Constant
Bit rate : 224 kb/s
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 22.0 MiB (4%)
Language : English
Encoded date : UTC 2018-08-07 16:50:25
Tagged date : UTC 2018-08-07 16:50:25

I am attempting to record video footage off a capture card (sorry, don't know specs as it is a friend's card) and the video become choppy towards the final quarter in editing.

I have followed instructions to check whether the framerate is constant, and it would appear so despite the 'framerate' read by LW being 29.95 fps.

Is there any way t0 fix this? And if so, how would I go about fixing this issue?

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182264

  • briandrys
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  • 3 days ago
Welcome to the forum.

Please could you also provide the spec of your computer.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182265

Intel Core i7 2670QM, 500GB SSD, with an NVIDIA GeForce GT 525M GPU

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182266

  • hugly
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  • 3 days ago
Appears the captured video to be choppy in a normal media player as well?
It's better to travel well than to arrive...

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182267

No, it's fine outside LW.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182268

  • hugly
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  • 3 days ago
From technical data it should NOT make trouble in Lightworks on your computer, at least if there isn't any significant additional load on the system.

Please open the video in the viewer, right- click and select "Media.Make proxy". This creates high performance, low resulution files for editing. Wait until proxy creation is finished (watch orange progress bar upper left hand side) and try again.

If that doesn't fix the issue, please explain in detail what "choppy" means.
It's better to travel well than to arrive...
Last Edit: 3 days ago by hugly.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 3 days ago #182269

I can give it a shot now. Will reply results when I can.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 2 days, 23 hours ago #182270

Made the proxy, still choppy.

The choppiness is strange; for periods of videos, the frames are 'out of order', like as if if the pattern of frames normally went '1-2-3-4-5-6-7-8' it would go '1-3-5-7-2-4-6-8'.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 2 days, 22 hours ago #182271

  • hugly
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  • 2 days, 22 hours ago
Oops.

Are you sure?

In compressed mpeg streams with inter frame compression the frame order (in the streams within a Group Of Pictures) can be different from display order, but I've never heard or seen that a decoder isn't able to decode that correctly and mixes frames up. It could be that your capture stream is damaged somehow and one decoder (the media player) can deal with it somehow and another (Lightworks) can't.

Please install Lightworks V14.5 RC10. The MP4 decoder has been changed significantly and might behave differently. You'll find it under Downloads on top of this page.

With V14.5, create a new project with 30 fps (not Auto not Mixed rates) import the file and see what happens.
It's better to travel well than to arrive...
Last Edit: 2 days, 22 hours ago by hugly.

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 2 days, 22 hours ago #182272

Still choppy, unfortunately

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 2 days, 22 hours ago #182273

  • hugly
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  • 2 days, 22 hours ago
Are you really sure that the frame order of some parts is '1-3-5-7-2-4-6-8' and not something like '2-1-4-3-6-5-8-7' (switched pairs). In Lightworks you can nudge frame by frame back and forth with <left-arrow>/<right-arrow> to inspect precisely.

Next would be converting with Handbrake prior to import. Here you'll find some suitable settings: www.lwks.com/index.php?option=com_kunena&func=view&catid=27&id=166802&Itemid=81#167830

You can import the converted file in the just created project. Please check import method, right of the Import button in Local Files it should show Create Link (which is default, but just in case).
It's better to travel well than to arrive...

Re: Despite the mp4 being constant framerate, my video (a capture card video) is choppy. 2 days, 21 hours ago #182274

Works perfectly now. Thanks so much!
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