[mythtv-users] mythcommflag logo detection does not work

Daryl McDonald darylangela at gmail.com
Tue Dec 24 13:53:11 UTC 2013


On Tue, Dec 24, 2013 at 7:11 AM, Brian J. Murrell <brian at interlinx.bc.ca> wrote:
> On Mon, 2013-12-23 at 22:34 -0500, Michael T. Dean wrote:
>
>> The best I can tell you is that commercial detection worked extremely
>> well in the US when it was developed (back in the days of SDTV) because
>> it was developed by a developer from the US.  It has progressively
>> gotten less reliable in the US because of changes to how broadcasters
>> send out the video--with different broadcasters doing things differently
>> resulting in varied success across different channels.
>
> You know, everyone has this feeling that the commercial detection has
> gotten worse over time, through different versions.  I'm in that boat.
>
> I suspect that it's only related to time/versions in-so-much as how
> things have changed since commflagging worked really well.  My gut tells
> me that the most significant change over that time is move away from
> encoding to MPEG2 from analog signals on capture cards such as the
> Hauppage PVR-{{1,2}50,500) series cards towards what a lot of us do now
> and that's direct capture of MPEG2 from the broadcaster.
>
> When all that mythcommflag had to deal with was the MPEG2 that those
> Hauppage cards produced, it was a very well known quantity.  Now
> mythcommflag (well, ffmpeg, I suppose) has to deal with whatever funky
> encoding might be coming from the provider directly and I suspect it's
> not doing so well at that -- understandably.
>
> The reason I have this feeling in my gut is because I have both types of
> encodings here.  I have the QAM that my cableco sends me and I also have
> a couple of those Hauppage encoder cards and I get recordings from both.
> The commflagging on recordings from the Hauppage cards is still pretty
> damn good, whereas the commflagging on the QAM recordings is not nearly
> as good.
>
> It's strange though, given that ffmpeg can decode these QAM captures
> well enough to display them for our eyes but something about them makes
> commflagging less accurate.  It would seem that if it could do one it
> could do the other.  Which is why I just call this a "gut feeling".  I
> have no science whatsoever beyond the anecdotal evidence gathered here.
>
> I have had a long-time desire to break into the commflagging code to
> debug this particular issue, but as Gary later posts -- life happens,
> and seems to take up more and more of your (non-leisure) time the older
> you get.
>
> But I'd kill for accurate commercial detection since that's probably the
> one deal-breaker that's preventing me from using XBMC as my FE over
> MythTV[1].  XBMC only has two commercial detection handling modes: none
> and automatic.  It doesn't have the middle-ground "skip commercial
> buttons" handling that MythTV's FE does and using automatic with XBMC
> and inaccurate detection is just frustrating and using none is a
> non-starter, around these parts at least.
>
> Cheers,
> b.
>
> [1] I still believe that if all of the MythFE development effort were
> moved into XBMC, we'd have an overall better FE given that the overall
> FE effort would be bigger where regular XBMC devs can concentrate on
> their parts (regular videos, network streaming, etc.) and the MythFE
> developers can focus their effort on purely playing Myth recordings and
> things associated -- like adding commercial skip button handling --
> instead of also having to handle video, network streaming, a browser,
> weather plugin, etc.  But that's just my uninformed, outsider view of
> things.  :-)
>
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My experience puts the blame on the redistributers. I record from a
STB and from an antenna (FTA), commflagging is near flawless from the
latter and 40%ish from the former

Daryl
>


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