[mythtv] Ticket #7984: Commercial break detection on H264 progressive recordings off by 2

[Manuel McLure]

I'm seeing a very similar problem with 1080p h.264 recordings - my
commercial breaks are at about 0.78x where they should be (i.e. a
break that should happen at 1000 seconds into the show actually skips
to around 780 seconds.) Here's some numbers for a recent recording:

Real Time      Skipped Time     Ratio
 7:18 (438)     5:37 (337)      1.3
11:19 (679)     8:53 (533)      1.27
16:51 (1011)   13:12 (792)      1.28
18:52 (1132)   14:47 (887)      1.28
24:18 (1458)   19:02 (1142)     1.28
26:20 (1580)   20:37 (1237)     1.28

Real Time is the actual location of the start or end of the commercial
break, skipped time is the place MythTV skipped to. The number in
parenthesis is the time in seconds, and the ratio is the real time in
seconds divided by the skipped time in seconds.

If a developer contacts me directly I can send the 1.3G 1/2 hour show
that gave the above numbers (or at least the first half or so, to
include the whole first commercial break.) The entries in
recordedmarkup for the show are:

mysql> select * from recordedmarkup where chanid = 1647 and starttime
= '2010-02-26 19:30:00';
+--------+---------------------+-------+------+---------+
| chanid | starttime           | mark  | type | data    |
+--------+---------------------+-------+------+---------+
|   1647 | 2010-02-26 19:30:00 |     0 |   -3 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 47374 |    2 |    NULL |
|   1647 | 2010-02-26 19:30:00 |     0 |    4 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 10272 |    4 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 23715 |    4 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 34225 |    4 |    NULL |
|   1647 | 2010-02-26 19:30:00 |    82 |    5 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 15941 |    5 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 26576 |    5 |    NULL |
|   1647 | 2010-02-26 19:30:00 | 37081 |    5 |    NULL |
|   1647 | 2010-02-26 19:30:00 |     1 |   14 | 1764705 |
|   1647 | 2010-02-26 19:30:00 |     1 |   30 |    1920 |
|   1647 | 2010-02-26 19:30:00 |     1 |   31 |    1088 |
+--------+---------------------+-------+------+---------+

The last entry in recordedseek for this show is:

mysql> select * from recordedseek where chanid = 1647 and starttime =
'2010-02-26 19:30:00' and mark = (select max(mark) from recordedseek
where chanid = 1647 and starttime = '2010-02-26 19:30:00');
+--------+---------------------+-------+------------+------+
| chanid | starttime           | mark  | offset     | type |
+--------+---------------------+-------+------------+------+
|   1647 | 2010-02-26 19:30:00 | 53836 | 1334861100 |    9 |
+--------+---------------------+-------+------------+------+

MPEG2 standard definition recordings seem to have no problems with
commercial skip. I am running 0.22-fixes SVN 23069 on 64-bit Gentoo.

Please let me know if there's any other information I can provide. Thanks!
-- 
Manuel A. McLure WW1FA <manuel at mclure.org> <http://www.mclure.org>
...for in Ulthar, according to an ancient and significant law,
no man may kill a cat.                       -- H.P. Lovecraft