[mythtv-users] commercial skipping recorded shows

[Bruce Markey]

>> On Friday 09 May 2003 01:54 am, Craig Longman wrote:
>>  
>>
>>> i'd like some help confirming/refuting one of the problems i'm seeing
>>> with mythtv.  when i record a show in the background and watch it later,
>>> the commercial skipping works quite nicely and is very fast.  however,
>>> if i've watched the show 'live' while its being recorded, then the
>>> commercial skip sucks, taking 10s of seconds to skip through minutes of
>>> video.  at least, i'm getting reasonably confident that watching it live
>>> causes the commercial skipping to suck, but i'd like someone else to get
>>> similar results before i presume thats the issue.
>>>
>>> anyone else notice this?

Yes but it isn't watching it that causes it to suck, it's
the lack of something that isn't added until the end.

> Isaac Richards wrote:
>> With hardware encoding, it can't pre-process the video and look for 
>> commercials while it records.  So in live tv mode, it has to decode 
>> every frame when you tell it to skip the commercial.  Quite naturally, 
>> this takes a bit of time, as you've seen.
>>
> so the answer (right  now at least) is if you hope to be able to skip 
> around a recorded show with any reasonable speed, then don't watch it 
> while its recording?  is this also true if i come in after its started 
> and watch the show 10 seconds behind 'live', will the commecial skipping 
> work on recorded the file then?

While Isaac is correct about decoding hardware encoding,
what you describe is consistent with the lack of a "seektable".
This is used for rapid navigation around the file but is
appended to the end of the file when the recording finishes.
Until the seektable is written, playback needs to search 
through the file without this road map. 

So, if you record a show from 8:00 until 9:00 and start watching
it at 8:30, any seeks (commercial skips, ff/rew, jumps, etc.)
will all be slow and commercial skips on a remote frontend are
no fun at all. You can't Save Position even if it says so on
screen and edit mode doesn't even try to pretend it might work.

However, if you exit playback at 9:01 then start watching it
again, all these features work correctly and your commercial
skips will be instantaneous.

So it's not the fact that you are watching the recording in
progress that's slowing things down, it's the fact that the
recording hasn't finished.

--  bjm