Selur's Little Message Board

I found a way to reproduce the issue.
Will try look at it during the week, but not sure if I find the time.

Cu Selur

yeah, I'm not wrong, there must be something wrong.

Question is what.
Unlike what you wrote remuxing the file without chapters does not fix the problem here.

-> Does it make a difference for you if you disable 'x264->Main->Automatically->Create qp file chapters' ?

Okay, remuxing to mkv does resolve the problem.
So the video stream itself is okay, the chapter times are okay.
And it's likely a bug in MP4Box, will have to do more testing to be sure.

Cu Selur

-> Does it make a difference for you if you disable 'x264->Main->Automatically->Create qp file chapters' ?

under x264 - base, there is no Automatically. And i found x264 - Misc - Main - Automatically, there is a "Create qp file chapters", it's checked by default.


remuxing to mkv does resolve the problem?

no, it's impossible, after remuxing, it's still the same.

Sorry, meant:
'x264->Misc->Main->Automatically->Create qp file chapters'

Opening the laggy file in Hybrid, setting audio&video to passthrough all and saving the file as a .mkv file does fix the issue here.

Cu Selur

good news! after uncheck "Create qp file chapters", then encode, everything is OK now. So what's "Create qp file chapters" is use for?

okay, no clue why that helps.

Try also keeping 'Create qp file chapters' enabled while making sure that 'x264->Frames->Advanced Frame Settings->Open GOP' is disabled.

Quote: So what's "Create qp file chapters" is use for?

It makes sure that at each chapter point an I frame is created to make sure that jumping to the chapter point properly works.

Cu Selur

Ps.: Using ffmpeg instead of MP4Box for muxing also works.

this option can't check, it's always unenabled state no matter 'Create qp file chapters' checked or not.

Ah okay, it's a side effect of the 'ultrafast' preset, to be precise it can't be used when b-frames aren't used.