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List:       mythtv-dev
Subject:    Re: [mythtv] Mythtranscode Segfaulting
From:       "Andy Speagle" <sidrew () gmail ! com>
Date:       2007-04-26 16:45:21
Message-ID: 991ceb870704260945q27f94fb6i805bd60ff9390400 () mail ! gmail ! com
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On 4/25/07, Michael T. Dean <mtdean@thirdcontact.com> wrote:
>
> On 04/25/2007 12:55 AM, Andy Speagle wrote:
> > Ok...
> >
> > So.. let me take another crack at this... I've downgraded my QT to
> > v3.3.4-r8on Gentoo... and my Mythtranscode is continuing to
> > segfault... here's the
> > latest gdb output:
> >
> > mythtv ~ # gdb mythtranscode -x gdbcommands
> ...
> > (no debugging symbols found)
> ...  Really, a backtrace on a build compiled with debugging support is
> much more useful.  (And since you're using Gentoo, it should be easy to
> get one next time.) ...


I guess I'm uncertain how to achieve this... but will research it.

> Program received signal SIGFPE, Arithmetic exception.
> > [Switching to Thread -1258027312 (LWP 9518)]
> > 0xb7afb42e in VideoOutput::ApplySnapToVideoRect () from
> > /usr/lib/libmythtv-
> > 0.20.so.0
>
> However, in this case, it's relatively clear what's likely happening
> even without specifics.  It looks like you're getting a division by zero
> (with "ydiff / display_video_rect.height()" and/or "xdiff /
> display_video_rect.width()").  While it would be possible to just check
> for zero (or add 1 to the width/height, as in the example patch below)
> to prevent the segfault, most of the code in VideoOutput relies on
> non-zero width and height, so you're likely to just get a segfault
> elsewhere if you don't fix the problem (i.e. figure out why
> display_video_rect isn't getting properly initialized).
>
> I haven't looked to see how display_video_rect gets its values, but
> perhaps someone who knows VideoOutput/mythtranscode can chime in with
> reasons yours wouldn't have been initialized properly--giving it 0 for
> height or width.  Guessing... perhaps your transcoding profile is
> misconfigured/corrupt?
>
> Mike


Ok... what would be the best way to recreate my transcoding profiles? .. to
ensure that's not the problem?

Thanks,

Andy

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On 4/25/07, <b class="gmail_sendername">Michael T. Dean</b> &lt;<a \
href="mailto:mtdean@thirdcontact.com">mtdean@thirdcontact.com</a>&gt; \
wrote:<div><span class="gmail_quote"></span><blockquote class="gmail_quote" \
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; \
padding-left: 1ex;"> On 04/25/2007 12:55 AM, Andy Speagle wrote:<br>&gt; \
Ok...<br>&gt;<br>&gt; So.. let me take another crack at this... I&#39;ve downgraded \
my QT to<br>&gt; v3.3.4-r8on Gentoo... and my Mythtranscode is continuing to<br>&gt; \
segfault... here&#39;s the <br>&gt; latest gdb output:<br>&gt;<br>&gt; mythtv ~ # gdb \
mythtranscode -x gdbcommands<br>...<br>&gt; (no debugging symbols \
found)<br>...&nbsp;&nbsp;Really, a backtrace on a build compiled with debugging \
support is<br>much more useful.&nbsp;&nbsp;(And since you&#39;re using Gentoo, it \
should be easy to <br>get one next time.) ...</blockquote><div><br>I guess I&#39;m \
uncertain how to achieve this... but will research it.&nbsp;</div><br><blockquote \
class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt \
0pt 0.8ex; padding-left: 1ex;"> &gt; Program received signal SIGFPE, Arithmetic \
exception.<br>&gt; [Switching to Thread -1258027312 (LWP 9518)]<br>&gt; 0xb7afb42e in \
VideoOutput::ApplySnapToVideoRect () from<br>&gt; /usr/lib/libmythtv-<br>&gt; \
0.20.so.0 <br><br>However, in this case, it&#39;s relatively clear what&#39;s likely \
happening<br>even without specifics.&nbsp;&nbsp;It looks like you&#39;re getting a \
division by zero<br>(with &quot;ydiff / display_video_rect.height()&quot; and/or \
&quot;xdiff / <br>display_video_rect.width()&quot;).&nbsp;&nbsp;While it would be \
possible to just check<br>for zero (or add 1 to the width/height, as in the example \
patch below)<br>to prevent the segfault, most of the code in VideoOutput relies on \
<br>non-zero width and height, so you&#39;re likely to just get a \
segfault<br>elsewhere if you don&#39;t fix the problem (i.e. figure out \
why<br>display_video_rect isn&#39;t getting properly initialized).<br><br>I \
haven&#39;t looked to see how display_video_rect gets its values, but <br>perhaps \
someone who knows VideoOutput/mythtranscode can chime in with<br>reasons yours \
wouldn&#39;t have been initialized properly--giving it 0 for<br>height or \
width.&nbsp;&nbsp;Guessing... perhaps your transcoding profile is<br> \
misconfigured/corrupt?<br><br>Mike</blockquote><div><br>Ok... what would be the best \
way to recreate my transcoding profiles? .. to ensure that&#39;s not the problem?<br> \
<br> Thanks,<br>
<br>
Andy<br></div></div>



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