“Bitmap” subtitles can appear in the wrong position

[almvtb@…]

“Bitmap” subtitles appear in the wrong position for 24 fps film that has been slowed to 23.976 for NTSC television and transcoded to a lower resolution.

I do not have any examples of this that I am willing to post, but it should not be hard to find or create an example of the issues. You can play the video with the Internal Player, and then enable the subtitles. Finally, you can compare the position of the subtitles to the original source.

The list of standard frame rates on Wikipedia leads me to believe this patch will not break anything else. ​http://en.wikipedia.org/wiki/Frame_rate#Film_and_television

[Jim Stichnoth]

I will look at this as part of #10402 ("Implement DVD subtitle zoom"). It would be very helpful if you had a sample to upload.

[almvtb@…]

small sample video clip

[Jim Stichnoth]

Thanks for providing the sample.

[almtvb <almvtb@…>]

In 53f7a1d2aa38a0343f33e91760ac88ffc6d596e9/mythtv:

Subtitles: Adjust AVSub scaling in some cases.

Tweaks the heuristic for determining when the video was resized
without correspondingly rescaling the AV subtitles. Fixes #10688.

Signed-off-by: Jim Stichnoth <jstichnoth@…>