How to use extended framerate and pan&scan in MPEG2?

[unixfs]

Hi,
reading the specs of mpeg2video I found some description,
that I don't fully understand, of extended framerate mode
(in the sequece_display_extension) and pan&scan display
coordinates (in picture_display_extension).

Does it mean that I can encode an mpeg2 with
- a non-standard framerate (e.g. 15 fps)?
- a non {4/3 | 16/9 | 1.1 | 2.21} A/R using
custom coordinated + the pan&scan width and height?

If so, can someone explain in detail how those fields work, please?
That part of the specs is not clear to me.

Thanks.

[mpucoder]

To the first part, yes, you can use framerates that are ratios of the standard ones, provided the numerator is in the range of 1 to 4 and the denominator is in the range of 1 to 32. So for 15fps you would set the framerate to 5 (30 fps), the frame_rate_extension_n to 0 (1 less than the actual numerator) and frame_rate_extension_d to 1 (again, 1 less than the denominator, for a ratio of 1/2)

The sequence_display_extension can define a window in the frame, but the DAR applies to that window, and not the full frame. (see section 6.3.3 of ISO 13818-2)

You should also know that DAR has nothing to do with the ratio of the display or frame dimensions. In mpeg-2 you specify the display aspect ratio.

[unixfs]

Originally posted by mpucoder
To the first part, yes, you can use framerates that are ratios of the standard ones, provided the numerator is in the range of 1 to 4 and the denominator is in the range of 1 to 32. So for 15fps you would set the framerate to 5 (30 fps), the frame_rate_extension_n to 0 (1 less than the actual numerator) and frame_rate_extension_d to 1 (again, 1 less than the denominator, for a ratio of 1/2)
[/i]

good :)


The sequence_display_extension can define a window in the frame, but the DAR applies to that window, and not the full frame. (see section 6.3.3 of ISO 13818-2)


sounds like a cropping region


You should also know that DAR has nothing to do with the ratio of the display or frame dimensions. In mpeg-2 you specify the display aspect ratio.

Thanks for you answer!