KCE
31st January 2010, 12:17
How much bitrate is needed for subtitles (SUP) on a DVD?
According to http://dvddemystified.com/dvdfaq.html (Section 3.4):
A disc also can have up to 32 subpicture streams that overlay the video for subtitles, captions for the hard of hearing, captions for children, karaoke, menus, simple animation, etc. These are full-screen, run-length-encoded bitmaps with two bits per pixel, giving four color values and four transparency values. For each group of subpictures, four colors are selected from a palette of 16 (from the YCbCr gamut), and four contrast values are selected out of 16 levels from transparent to opaque. Since one of the four values is usually 100% transparency (to let the video show through), only three combinations of colors and transparencies are left, making overlay graphics rather crude. Subpicture display command sequences can be used to create effects such as scroll, move, color/highlight, and fade. The maximum subpicture data rate is 3.36 Mbps, with a maximum size per frame of 53220 bytes.
But that seems too high?...
Or would it be 53220 / 1024 = 51.97 kilobytes = 51.97 * 8 = 415 kilobits
So that would make the max bitrate for subtitles 415 kb/s? (like the 9800 max for videos)
According to http://dvddemystified.com/dvdfaq.html (Section 3.4):
A disc also can have up to 32 subpicture streams that overlay the video for subtitles, captions for the hard of hearing, captions for children, karaoke, menus, simple animation, etc. These are full-screen, run-length-encoded bitmaps with two bits per pixel, giving four color values and four transparency values. For each group of subpictures, four colors are selected from a palette of 16 (from the YCbCr gamut), and four contrast values are selected out of 16 levels from transparent to opaque. Since one of the four values is usually 100% transparency (to let the video show through), only three combinations of colors and transparencies are left, making overlay graphics rather crude. Subpicture display command sequences can be used to create effects such as scroll, move, color/highlight, and fade. The maximum subpicture data rate is 3.36 Mbps, with a maximum size per frame of 53220 bytes.
But that seems too high?...
Or would it be 53220 / 1024 = 51.97 kilobytes = 51.97 * 8 = 415 kilobits
So that would make the max bitrate for subtitles 415 kb/s? (like the 9800 max for videos)