[mythtv-commits] Ticket #6203: Comment describing rtfileheader.aspect is inconsistent with how it is used

MythTV mythtv at cvs.mythtv.org
Fri Jan 30 23:37:47 UTC 2009


#6203: Comment describing rtfileheader.aspect is inconsistent with how it is used
------------------------------+---------------------------------------------
 Reporter:  jrgreen at mit.edu   |       Owner:  ijr    
     Type:  patch             |      Status:  new    
 Priority:  trivial           |   Milestone:  unknown
Component:  MythTV - General  |     Version:  head   
 Severity:  low               |     Mlocked:  0      
------------------------------+---------------------------------------------
 In format.h, the definition of struct rtfileheader includes the following:

 22        double aspect;      // 1.0 .. square pixel (1.5 .. e.g.
 width=480: width*1.5=720[[BR]]
 23                            // for capturing for svcd material

 This describes the aspect ratio of a single pixel, whereas in
 NuppelVideoRecorder.cpp, it is used as a frame aspect ratio (video_aspect
 defaults to 1.33333 as of Changeset
 [http://svn.mythtv.org/trac/changeset/5627 5627]):

 1914        fileheader.aspect = video_aspect;

 There is similar behavior in nuppeldecoder.cpp, except a special case for
 aspect 1.0:

 208         if (fileheader.aspect > .999 && fileheader.aspect <
 1.001)[[BR]]
 209             fileheader.aspect = 4.0 / 3;[[BR]]
 210         current_aspect = fileheader.aspect;

 This causes problems when a nuv file generated by MythTV is played in
 MPlayer, for example, since the result is a 640x480 4:3 video is
 interpreted by MPlayer as being 16:9, and a 720x480 4:3 video is
 interpreted as 2:1.

 Seeing as this has been the behavior for 4 years, I can understand that
 changing MythTV's behavior is undesirable. In fact, it looks like
 libavformat in FFmpeg svn has been modified to match MythTV's behaviour as
 of last July. Because of this, the attached patch simply modifies the
 comment to make it describe how this variable is actually used.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/6203>
MythTV <http://www.mythtv.org/>
MythTV


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