This started for me after the update to PMP Version 1.18.0.1846 using the app.plex.tv web player ( Version 4.10.1) in Chrome/75.0 and Chrome/76.0.
Same symptoms described, direct play videos randomly jump 3-5 seconds forward without any errant gaps/noise in video or audio. It’s generally at the same places in a given video but can vary.
Videos play fine transcoded, and in other media players directly.
I have correlated the timing of the jumps with the network requests to the temporary transcoder chunk files in /dev/shm:
-rw-r--r-- 1 plex plex 103681 2019.10.09 02:05:16-0500 chunk-stream1-00043.m4s
-rw-r--r-- 1 plex plex 244364 2019.10.09 02:05:16-0500 chunk-stream1-00044.m4s
-rw-r--r-- 1 plex plex 37666 2019.10.09 02:05:16-0500 chunk-stream1-00045.m4s
-rw-r--r-- 1 plex plex 178574 2019.10.09 02:05:26-0500 chunk-stream1-00046.m4s
-rw-r--r-- 1 plex plex 129610 2019.10.09 02:05:26-0500 chunk-stream1-00047.m4s
-rw-r--r-- 1 plex plex 173035 2019.10.09 02:05:26-0500 chunk-stream1-00048.m4s
-rw-r--r-- 1 plex plex 171965 2019.10.09 02:05:33-0500 chunk-stream1-00049.m4s
-rw-r--r-- 1 plex plex 173590 2019.10.09 02:05:50-0500 chunk-stream1-00050.m4s
-rw-r--r-- 1 plex plex 171536 2019.10.09 02:05:51-0500 chunk-stream1-00051.m4s
-rw-r--r-- 1 plex plex 174138 2019.10.09 02:05:56-0500 chunk-stream1-00052.m4s
-rw-r--r-- 1 plex plex 107388 2019.10.09 02:05:56-0500 chunk-stream1-00053.m4s
-rw-r--r-- 1 plex plex 238409 2019.10.09 02:05:57-0500 chunk-stream1-00054.m4s
-rw-r--r-- 1 plex plex 172406 2019.10.09 02:06:13-0500 chunk-stream1-00055.m4s
-rw-r--r-- 1 plex plex 172372 2019.10.09 02:06:13-0500 chunk-stream1-00056.m4s
-rw-r--r-- 1 plex plex 76664 2019.10.09 02:06:13-0500 chunk-stream1-00057.m4s
-rw-r--r-- 1 plex plex 197304 2019.10.09 02:06:36-0500 chunk-stream1-00058.m4s
-rw-r--r-- 1 plex plex 241927 2019.10.09 02:07:32-0500 chunk-stream1-00059.m4s
-rw-r--r-- 1 plex plex 69276 2019.10.09 02:07:48-0500 chunk-stream1-00060.m4s
-rw-r--r-- 1 plex plex 274780 2019.10.09 02:08:52-0500 chunk-stream1-00061.m4s
-rw-r--r-- 1 plex plex 171474 2019.10.09 02:09:31-0500 chunk-stream1-00062.m4s
-rw-r--r-- 1 plex plex 45582 2019.10.09 02:09:42-0500 chunk-stream1-00063.m4s
-rw-r--r-- 1 plex plex 125977 2019.10.09 02:10:11-0500 chunk-stream1-00064.m4s
The smaller sized chunks (i.e. -rw-r--r-- 1 plex plex 37666 2019.10.09 02:05:16-0500 chunk-stream1-00045.m4s) are where the skips occur presumably at the end of the previous chunk/beginning of the shorter one. That is, watching the video and the network requests, I saw chunks 41-44 come in then skip about 4 seconds as 45-49 came in and continued streaming.
And with this group of chunks, the skipping pattern corresponds directly with the pattern of smaller sized chunks:
-rw-r--r-- 1 plex plex 172372 2019.10.09 02:06:13-0500 chunk-stream1-00056.m4s
-rw-r--r-- 1 plex plex 76664 2019.10.09 02:06:13-0500 chunk-stream1-00057.m4s
-rw-r--r-- 1 plex plex 197304 2019.10.09 02:06:36-0500 chunk-stream1-00058.m4s
-rw-r--r-- 1 plex plex 241927 2019.10.09 02:07:32-0500 chunk-stream1-00059.m4s
-rw-r--r-- 1 plex plex 69276 2019.10.09 02:07:48-0500 chunk-stream1-00060.m4s
-rw-r--r-- 1 plex plex 274780 2019.10.09 02:08:52-0500 chunk-stream1-00061.m4s
-rw-r--r-- 1 plex plex 171474 2019.10.09 02:09:31-0500 chunk-stream1-00062.m4s
-rw-r--r-- 1 plex plex 45582 2019.10.09 02:09:42-0500 chunk-stream1-00063.m4s
-rw-r--r-- 1 plex plex 125977 2019.10.09 02:10:11-0500 chunk-stream1-00064.m4s
-rw-r--r-- 1 plex plex 172427 2019.10.09 02:10:51-0500 chunk-stream1-00065.m4s
