[vlc-devel] Re: Fixes for HDTV grey line bug

[Derk-Jan Hartman]

Perhaps you could best put a sample of such a stream online  
somewhere, so we can test the patch on all video output modules?

DJ

On 15 okt 2005, at 11:10, Marian Durkovic wrote:

> Hi all,
>
>   in an attempt to fix the annoying HDTV grey line bug (caused by  
> displaying
> 1088 lines instead of only 1080 real lines) I've found the following
> changesets:
>
> https://trac.videolan.org/vlc/changeset/10160
> https://trac.videolan.org/vlc/changeset/10161
>
>   Looking at the video output modules, seems only the ones which  
> deliver
> more than 1 direct buffer are affected (namely xvideo and sdl, are  
> there
> others?). The modules which deliver only 1 direct buffer (e.g.  
> directx)
> and go through memcpy work fine, also indirect rendering works of  
> course.
>
>   For the mentioned ones, the fixes seem to be quite simple:
>
> xvideo:
> -------
>
> make sure that the buffer width/height is aligned to a multiple of 16,
> xvideo handles cropping automatically.
>
> The following code solves the problem, it needs to be put into
> modules/video_output/x11/xcommon.c, functions CreateShmImage() and
> CreateImage() - just under #ifdef MODULE_NAME_IS_xvideo
>
>     /* Make sure the buffer is aligned to multiple of 16 */
>     i_height = ( i_height + 15 ) >> 4 << 4;
>     i_width = ( i_width + 15 ) >> 4 << 4;
>
> sdl:
> ----
>
> unfortunately sdl doesn't seem to be able of cropping the buffer,  
> so the
> only solution seems to be reducing number of direct buffers to 1 in
> modules/video_output/sdl.c:
>
> #define SDL_MAX_DIRECTBUFFERS 1
>
> With the above changes, changeset 10160 could be reapplied, but it  
> needs
> to be enhanced with the following check, since some broadcasters  
> ignore
> the MPEG2 spec:
>
>     if( i_height == 1088 )
>     {
>         i_height = 1080;
>         msg_Warn( p_vout, "Incorrect HDTV stream - reducing height  
> to 1080");
>     }
>
>
>     With kind regards,
>
>
>         M.
>
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> manager         ----
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