[mythtv] Bugfix: ATSC shouldn't = 25 fps

Brian Foddy bfoddy at visi.com
Mon Jun 6 16:58:46 UTC 2005

On Mon, 6 Jun 2005, Keith Irwin wrote:

> Presently, if someone has a mix of ATSC and NTSC cards installed, in the 
> if/else statement which begins on line 69 in libs/libmythtv/recorderbase.cpp, 
> there is no ATSC case, so it falls through to the PAL case.  Clearly this has 
> not been updated since whenever ATSC was added as an option on the TV Format 
> drop-down in setup/backendsettings.cpp.
> As a result, if you tell it that your TV Format is ATSC, you get 25 fps for 
> any analog capture cards which you have attached.  This would only be 
> desirable, if a user had both ATSC and PAL or SECAM capture cards, which 
> seems highly unlikely.  Because an ATSC capture card does not do frame-rate 
> adjustments since the frame rate is determined by the incoming MPEG stream, 
> these settings do not affect ATSC capture.  But if a user had a mix of ATSC 
> and NTSC cards (as I do), this results in the NTSC cards capturing at 25 fps. 
> The obvious work-around is to switch to NTSC as your listed TV Format, but 
> there are several HOWTO's (including the one from the EFF) which specifically 
> tell people using ATSC cards to switch it to ATSC, so really we should fix it 
> so that 29.97fps is the default when ATSC is selected, especially for people 
> who might use the NTSC mode on their HD2/3000 sometimes.
> As such, I have included a .diff below which is a bug fix for this issue.  It 
> adds one more case to the first if clause to add ATSC in addition to NTSC and 
> NTSC-J.  It also adds comments to that section both about the change and what 
> the code is doing in general.  Hopefully they aren't too verbose for the 
> liking of the code maintainer, but I wanted to make sure that all the bases 
> were covered since the issue may need to be revisited at some point in the 
> future if someone makes a card which can capture HD via component inputs or 
> some other similar method where MPEG-2 streams are not automatically 
> produced.
> Thanks,
> Keith Irwin

Is this what causes my ATSC recordings to show 1:06 for a 1 hour show;
and also mess up the fast forward so the first jump will actually go 
backwards?  If so, this will be great.


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