[mythtv-commits] Ticket #7874: nvidia refresh rate detection uses locale-aware strtod() function

[MythTV]

#7874: nvidia refresh rate detection uses locale-aware strtod() function
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 Reporter:  René H. Larsen <rhl@…>           |       Owner:  janne     
     Type:  defect                           |      Status:  new       
 Priority:  minor                            |   Milestone:  unknown   
Component:  MythTV - Video Playback          |     Version:  0.22-fixes
 Severity:  low                              |     Mlocked:  0         
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 I'm using MythTV 0.22-fixes with VDPAU on a GT 220 GPU connected via HDMI
 to a Samsung UE46B7070 TV.

 I've noticed that MythTV reports inaccurate refresh rates for the modes
 supported by my TV. For instance, the refresh rate of the 1920x1080_50
 mode is reported as 49.832Hz. This causes MythTV to choose the wrong
 display mode in some cases (eg. 720p50 material displayed at 60Hz).

 I've tracked down the problem to the use of `strtod()` for parsing the
 `dcl` value of the modeline in `libmythui/util-nvctrl.cpp`.

 I'm in a part of the world (Denmark) that uses "," as the decimal point,
 while the modeline reported by the nvidia driver uses ".". The locale-
 aware `strtod()` function mis-parses the value, effectively rounding it
 down to the nearest integer.

 My solution is to use a C++ `stringstream` imbued with the "C" locale for
 parsing that part of the modeline. See the attached patch.

 I believe this fix may make [changeset:23023] redundant.

 A workaround for those affected, who don't want to recompile MythTV, is to
 set `LC_NUMERIC=C` when starting the frontend, thus overriding the default
 locale with respect to parsing and displaying numeric values:
 {{{
 LC_NUMERIC=C mythfrontend
 }}}

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Ticket URL: <http://svn.mythtv.org/trac/ticket/7874>
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