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Revision as of 08:01, 19 November 2005 by Gumboot (talk | contribs) (→‎Field rates and timebase: Shutter rate distinction.)
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  • At very low resolutions it's possible to encode a video that has incomplete timing information because more than one frame could fit into an Ogg page. This represents data loss in the case of variable frame rate video (a common case in devices that are limited to such low resolutions). libogg's default limit of 4kB isn't meaningful; the actual limit is ~64kB. Are people really willing to impose a rule that no more than one field can finish within a page? --Gumboot 06:34, 19 Nov 2005 (PST)

Field rates and timebase

The combination of field rate and timebase information amounts to only two scalars. The field rate can be expressed as the number of time steps between each frame. If this is imprecise then the timebase should be increased, or it can be specified that the step rate varies between k and k+1. Multiplying the timebase by the Frame Rate Numerator will have all the original precision. --Gumboot 06:44, 19 Nov 2005 (PST)

The distinction between shutter rate and field rate has not been made clear. It is possible, and not uncommon, to issue two fields from the same sample interval separately. It is also possible to have no shutter at all, and for every pixel to be sampled in a different time interval. Be careful to note the common case where the actual shutter is 24Hz, but the effective shutter rate needs to be declared as 25Hz to be consistent with the audio track and the field rate. --Gumboot 07:01, 19 Nov 2005 (PST)