[mythtv] Bug report: MTD passes incorrect framerate info

Anduin Withers awithers at anduin.com
Tue Jul 18 13:36:52 UTC 2006

> When transcoding from an NTSC source using the "Excellent" setting,
> transcode is run with the following option:
> -f 0,1
> This causes transcode to both read and output an incorrect framerate.
> The source material is 29.97 fps, but this option invariably causes
> transcode to treat the video as though it were 23.976 fps.  This
> causes the video to lag behind the audio stream, causing sync
> problems.

Include a failing DVD title in that ticket.

I'm not willing to abandon -f. While your experience with transcode's
auto-detection may be good that is not universal. (In fact, odds are
transcode will make the identical mistake if you let it transcode directly
from the DVD)

Currently mtd uses only the cell time bits to determine the frame rate, what
would normally be 29.97 is set to 23.976. Yes, this is broken, but broken so
it will hit the fewest DVDs.

You can adjust the frc passed to transcode by changing the dvdinput table.
While an frc of 4 may work for this particular disc, it isn't a good general

Anduin Withers

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