[MPEGTS] Special case when unrolled DTS and PTS diverge

[zdanek]

System info

Operating System: all
Shaka Packager Version: 2.4.x

Issue and steps to reproduce the problem

mpeg-ts has 33bit timestamps. After reaching 2^33 it starts from (close to) 0 values. It's known in Shaka so during parsing mpeg-ts unrolling can occur. It happens when PTS and DTS are about to pass 2^33 boudary. Next values read from mpeg-ts are unrolled that is they are continued and incremented beyond 2^33 boundary for DTS to be monotonic increasing.

In very rare case there can be a situation when PTS is very close to 2^33 (right before passing the boudary) and PTS already passed so it has a value a bit above 0. This causes for mpeg-ts parser to unroll only DTS so it next values are very big (and above 2^33) and PTS remain small, right above 0. This causes lot's of problems including:

• PTS - DTS is very big
• PTS < DTS as PTS is close to 0 and DTS is more than 2^33

During mpeg-ts reading, in this special case PTS should be forced to unroll to maintain PTS close to DTS.

I've prepared a PR #1050 fixing this.

Packager Command:

Extra steps to reproduce the problem?
(1) Parse attached bear-640x360_ptszero_dtswraparound.ts

It has set DTS close to 2^33 and PTS a bit above 0. I had to attach zip as you did not enable 'ts' files.

What is the expected result?
Properly parse.

What happens instead?

<Please attach the input files or email to [email protected].>