Author Topic: H264/TS, frames lost at cut points  (Read 1738 times)

twinsun

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H264/TS, frames lost at cut points
« on: July 12, 2016, 10:20:19 AM »
Hello, dear ADM team.
I encounter a grrr issue.

> Frames are lost before each cut points of TS, kind below.
The same at end of file.
Adm070716-64 (and before)

Sample : Jeumont.ts 5Mb   (source Iref:4, B:8/24)  https://drive.google.com/file/d/0B7UOzqUbGLumU3ZSOHB1THFPSEE/view?usp=sharing

Edit :      Jeumont ( I-frame 4 to 7 cutting).ts.py  https://drive.google.com/file/d/0B7UOzqUbGLumZXZxdDNBeEU4aVU/view?usp=sharing
              Jeumont ( I-frame 4 to 7 cut done).ts.py  https://drive.google.com/file/d/0B7UOzqUbGLumcnRfYVk0SkNYSk0/view?usp=sharing

Result : Jeumont ( I-frame 4 to 7 cut done).ts 4Mb  https://drive.google.com/file/d/0B7UOzqUbGLumZXdoMWQyLXUxZkk/view?usp=sharing

In copy mode (always cutting at I frames) it is a problem, players freeze the result at cut points.
Obviously, reencoding hides the problem, no freeze. But frames are lost.

Jan Gruuthuse

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Re: H264/TS, frames lost at cut points
« Reply #1 on: July 12, 2016, 10:37:33 AM »
Preliminary testing confirms there is an issue.
Have the same result on Ubuntu 14.04.4 64-bit (accelerated and none accelerated) with tested with latest build 8fbbf25.

Is this a DVB-T(2) registration? Could be transmission error(s). Developer(s) probably will pick upon this.

mean

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Re: H264/TS, frames lost at cut points
« Reply #2 on: July 16, 2016, 06:43:33 AM »
This might take a while, it is the worse kind of problems to track down, it could be a lot of thiings

twinsun

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Re: H264/TS, frames lost at cut points
« Reply #3 on: July 18, 2016, 07:20:34 PM »
Sorry for above sample, not so helpful I guess being itself a cutting.

Ach so... I record a short TS from DVB-T, 13Mb :
https://drive.google.com/file/d/0B7UOzqUbGLumbzhkdWZ6SWx1Mkk/view?usp=sharing

This TS is H264 M:8 N:24
You can verify by yourself that wherever you do a cutting between I frames, the saved result (copy_copy.TS) has the last M, before the cut point(s), with only 3 B-frames, 5 B-frames are dropped. It’s a travelling sample : ~ all N are 24.

Same way : if you save parts of the video (instead of cutting them), and then append each parts to do a new copy_copy.ts, you have the same dropped at cut points on the result.

In all cases, players freezes at each cut points (evidence).
So you need to re-encode the whole to have a playable video (knowing that you have frames lost at each cut).
ADM copy mode has to be forgotten for these TS  :(.

Personal context : I mainly always re-encode DVB-T TS (4.2.0) to downscale, except in some cases, when the quality source is good enough. Here for example I would re-encode.

Hope it helps this time.

mean

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Re: H264/TS, frames lost at cut points
« Reply #4 on: July 25, 2016, 03:40:19 PM »
It is actually complicated
The gop is not closed + there are B-Pyramid
I need to rethink it, it cannot cope with that at the moment

mean

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Re: H264/TS, frames lost at cut points
« Reply #5 on: July 25, 2016, 03:43:40 PM »
It looks like that

I A B C D E F G H

with a display order like this

A B C I D E F G H

and D E F G H need A/B/C to be decoded

At the moment, A, B & C are dropped, as they are in the past, so D/E/F/G/H are not decoded properly




mean

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Re: H264/TS, frames lost at cut points
« Reply #6 on: July 26, 2016, 04:37:11 PM »
Should be a little bit better