[mythtv] LiveTV accepts bob 2x even though refresh rate is too low

Billy Macdonald billymacdonald at gmail.com
Wed Apr 9 03:36:54 UTC 2008


On Tue, Dec 18, 2007 at 6:45 PM, Michael T. Dean
<mtdean at thirdcontact.com> wrote:
> I recently noticed that upon startup of LiveTV (playback of recordings
>  is unaffected), the internal player is accepting bobdeint (which my
>  playback profile specified as the primary deinterlacer) even though the
>  refresh rate of my display is too low--which causes all sorts of
>  playback issues (skipped frames, slideshow-like playback, jumpiness,
>  prebuffering pauses, and audio issues).  I don't use LiveTV, so I only
>  noticed it today when testing channels after I rescanned.
>
>  If I use the menu to change "Video Scan" from "Detect" to "Detect"--i.e.
>  just force it to re-check--it realizes the refresh rate is too low and
>  falls back to linearblend (the fallback deinterlacer in my profile).
>  Once this is done, even after changing channels, it continues to use
>  linearblend.  The next time LiveTV starts up, it again uses bob 2x.
>
>  While removing bob (or other 2x deints) from the profile prevents the
>  issue, it seems we should be able to detect this--especially since the
>  default profiles use bob as the primary deinterlacer.  Unfortunately,
>  when I dug into the code, it looked like I would be likely to do more
>  damage than good.  However, it seems that we're just checking whether
>  bob will work just a bit too soon (i.e. before all the video or display
>  information is available), and I'm guessing the fix would be relatively
>  straightforward for someone who knows the player code.  I'll eventually
>  get to looking through the code if someone else doesn't do it first, but
>  I thought I'd mention the issue in case it truly is an easy fix for a
>  knowledgeable developer.
>
>  Thanks,
>  Mike
>

Wow, I've been trying to figure out why HD plays fine in recordings
but not LiveTV and it turns out I was running into a similar issue as
you.  In my case it was picking greedy (Normal profile) based on the
720x576 resolution.  The only solution I found was to have a profile
with one option that works for all resolutions and not use the
features for better de-interlacing at lower resolutions.

Billy


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