Fix for PES packets with too much padding

[Sergio Ammirata, Ph.D.]

Summary of the bug:
PES packet with too much padding trigger unlimited error messages "PES packet size mismatch" because the code that corrects the length is wrong.
Here is a sample file: ​http://99.93.62.129/smpte2038.ts
PID 300 is the one triggering the errors.
I am attaching a patch that fixes the problem.

[Sergio Ammirata, Ph.D.]

proposed patch

[Balling]

What is #2392? That one has nothing to do with above.

[Sergio Ammirata, Ph.D.]

Replying to Balling:

What is #2392? That one has nothing to do with above.

I do not know what #2392 is ... that comment was there from before.

[Balling]

Replying to Sergio Ammirata, Ph.D.:

Replying to Balling:

What is #2392? That one has nothing to do with above.

I do not know what #2392 is ... that comment was there from before.

Yet that comment should be deleted after your change or better clarified. Also, there are other bugs that often have this PES warning, maybe they should be checked too.

[Balling]

For example, does it fix that warning sample in #3309? What about my issue #8108? Also samples in #6152. And in #6026.

[Balling]

Also this is a duplicate of #5860. P.S. Apparently not.

[Balling]

Replying to Sergio Ammirata, Ph.D.:

Replying to Balling:

What is #2392? That one has nothing to do with above.

I do not know what #2392 is ... that comment was there from before.

I found it! It is this issue, ​https://ffmpeg-issues.lscube.narkive.com/s0jecfqy/issue2392-memory-leak-in-mpegts-demuxer-on-samples-with-too-large-pes-packets so a different bug tracker. WTF.

[Balling]

What is even in that PID 0x012c in PES data?

[Balling]

Insane series of patches to fix this: ​https://patchwork.ffmpeg.org/project/ffmpeg/patch/20210922172914.17914-4-cus@passwd.hu/

[Marton Balint]

Fixed in 9420f7e09560d82ebdb96ddc6724a734f4fe0b95.

[Balling]

Yet it does not fix any other issues above, interesting!