View Bug Details

IDProjectCategoryView StatusLast Update
0001887DCP-o-maticBugspublic2021-03-01 15:40
Reporteroverlookmotel Assigned Tocarl  
PrioritynormalSeverityminorReproducibilityhave not tried
Status confirmedResolutionopen 
PlatformMacOSOS XOS Version10.14
Product Version2.14.37 
Summary0001887: Unable to seek in preview with 4K H265 file
Description

Usually in DCP-o-matic preview you can skip around the length of a file to preview the output.

I've encountered an inability to do this with a 4K (3840x2160) H265 file (NB H265 not H264).

When you drop drag the "playhead" slider forwards, it has no effect. When inputting a timecode to go to directly, or using the forward/back a frame buttons the interface hangs. It does come back eventually, but it takes a very long time - perhaps DCP-o-matic has to read the entire file from the start again to find the right frame.

This is on DCP-o-matic 2.14.38.

Steps To Reproduce

Carl, I'll email you a link to the file.

TagsNo tags attached.
Branch
Estimated weeks required
Estimated work requiredUnknown

Activities

overlookmotel

2020-12-15 19:14

reporter   ~0004061

Problem also replicated in DOM 2.15.102.

carl

2021-02-27 21:54

administrator   ~0004135

This file also doesn't play back properly; after a while every frame is late in SimpleVideoView::update. vlc will play it but it uses a lot of CPU (2-300%).

Carsten

2021-02-28 12:42

manager   ~0004136

Where does it come from?

carl

2021-02-28 19:31

administrator   ~0004140

Last edited: 2021-02-28 19:31

OP sent it, I don't know what it was made with.

carl

2021-02-28 20:25

administrator   ~0004141

avcodec_decode_video2 starts taking 50, 60, 70ms.

carl

2021-02-28 20:51

administrator   ~0004142

It appears FFmpeg wasn't enabled for multi-threaded decoding; added this in 981f76a38547b30e67b94eb1c98308edf65d76ef and the file can now be played back.

carl

2021-02-28 21:09

administrator   ~0004143

Last edited: 2021-02-28 21:12

Seeking is better with that threading change; it looks like there are only a couple of I frames in the whole thing. VLC struggles to seek in it as well.

overlookmotel

2021-03-01 14:40

reporter   ~0004144

Thanks for investigating Carl. I have no idea how this file was created. We get sent some pretty weird stuff!

Carsten

2021-03-01 15:08

manager   ~0004145

Last edited: 2021-03-01 15:40

I understand there are some tools like screen recorders, slideshow converters, animation tools, etc. that expect very small local and temporal content changes and configure their encoders to get away with as few I frames as possible. So, playing is very relaxed, but seeking becomes nearly impossible.

Bug History

Date Modified Username Field Change
2020-12-15 15:15 overlookmotel New Bug
2020-12-15 19:14 overlookmotel Note Added: 0004061
2020-12-16 00:17 carl Priority normal => immediate
2020-12-16 00:17 carl Status new => acknowledged
2020-12-16 00:17 carl Target Version => 2.16.0
2020-12-16 00:17 carl Estimated work required => Undecided
2020-12-16 00:19 carl Assigned To => carl
2020-12-16 00:19 carl Status acknowledged => confirmed
2021-01-07 23:54 carl Estimated work required Undecided => Unknown
2021-02-27 21:54 carl Note Added: 0004135
2021-02-28 12:42 Carsten Note Added: 0004136
2021-02-28 19:31 carl Note Added: 0004140
2021-02-28 19:31 carl Note Edited: 0004140
2021-02-28 20:25 carl Note Added: 0004141
2021-02-28 20:51 carl Note Added: 0004142
2021-02-28 21:09 carl Note Added: 0004143
2021-02-28 21:12 carl Note Edited: 0004143
2021-02-28 21:12 carl Priority immediate => normal
2021-02-28 21:12 carl Target Version 2.16.0 =>
2021-03-01 14:40 overlookmotel Note Added: 0004144
2021-03-01 15:08 Carsten Note Added: 0004145
2021-03-01 15:08 Carsten Note Edited: 0004145
2021-03-01 15:40 Carsten Note Edited: 0004145