[mythtv] [Fwd: 0.21 video profiles not working as expected for live TV]
matt.doran at papercut.com
Sat Mar 22 07:18:42 UTC 2008
I didn't get a response on the user's list, it's probably more a
developer question. I think this looks like a bug in the 0.21 video
profiles. All the gory details below.
-------- Original Message --------
Subject: [mythtv-users] 0.21 video profiles not working as expected for
Date: Fri, 21 Mar 2008 12:28:28 +1100
From: Matt Doran <matt.doran at papercut.com>
Reply-To: Discussion about mythtv <mythtv-users at mythtv.org>
To: Discussion about mythtv <mythtv-users at mythtv.org>
I'm using the following version:
MythTV Version : 16733
Library API : 0.21.20080304-1
I've previously been using a basic profile that just used bob
deinterlacing, and wanted to try the new deinterlacers. So I started
with the "high quality" profile, which uses yadif(x2) for SD content,
and reverts back to linearblend for HD (>= 1920x1080).
I'm doing these tests using live TV and a DVB-T. When I use this
profile, it works as expected for SD content, choosing the profile for
SD content with the yadif(x2).
However when I view a HD channel, it chooses the wrong profile (or at
least the wrond deinterlacer). I beleive this has something to do with
the "dummy video" that it sets up which has a resolution of 720x576
while waiting for the channel to tune.
I've got some verbose "playback" logging showing the problem. You can
view the log at the Pastebin URL below.... I've highlighted some of the
* You can see I have a >= 1920x1080 profile that uses linea blend (line 10)
* It seems to start initialising video at resolution 720x576 (line 29)
* Myth picks the video profile based on this dummy resolution (line 40)
* The yadif interlacer is initialized with resolution 720x576 (lines 85
* Once the tuner locks onto the HD channel, the video comes in at
1920x1088 resolution (line 178)
* The Yadif deinterlacer recognizes the change in video resolution
* Video cannot be displayed properly because yadif(x2) requires too
much processing power for HD (lines 231-239).
If I watch a previously recorded show it works as expected, because it
starts playing the content that is 1920x1080 resolution ... so that it
sets up the profile correctly. This problem only seems to appear when
using live TV which sets up the dummy 720x576 stream to start.
This seems like a pretty serious problem with the video profiles for use
with live TV. It means I can't use yadif(x2) because it breaks live TV
for HD content. Is there something I'm doing wrong / missing?
Should I raise an issue for this?
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