| Microsoft DirectX 8.1 (C++) |
The TV Tuner support shipped with Windows 98 and Windows 98 SE operating systems was suitable only for TV Tuning in the U.S. market. Although the general framework for International tuning was in place, there were some problems that prevented its use outside the U.S.
The TV Tuner filter (kstvtune.ax) includes internal tables for mapping channel numbers to frequencies. Fixed channel numbers are not appropriate for all markets. For instance, the European channel numbers are not actually used by consumers. Instead, the consumer is expecting to choose and assign their own channel numbers for the frequencies used by the broadcast or cable operators in their area.
This problem has been addressed by changing the notion of channel numbers to that of frequency indexes. Ordinal numbers are still used to select frequencies, but they are now treated more as indexes into tables of frequencies, than as channel numbers. In areas where channel numbers make sense (especially the US markets or markets using the US channel lineup), the indexes continue to correspond directly with the channel numbers.
Since the frequency tables were built into the TV Tuner filter, it wasn't possible to update the frequencies if they were incorrect or had become obsolete. It was also not possible to add new frequencies. This was less of a problem with broadcast frequencies, although errors in these tables could not be fixed without shipping a new binary. However, this was a very big problem with cable frequencies. Most non-US cable operators are free to broadcast on frequencies of their choosing, often mixing frequencies from different standards into the same channel lineup. This problem has been addressed in two ways. One, by providing a "Unicable" frequency table for any country/region lacking a standard cable channel standards authority; and two, by providing a Windows Registry-based mechanism to override one or more frequencies in the frequency tables.
The data encapsulated by the TV Tuner filter includes frequency tables, color standards, and the frequency and color standard assignments for each country/region. Errors in these tables and assignments could not be corrected without shipping a new TV Tuner filter. This problem has been addressed via a combination of the steps described above, as well as exhaustive research leading to updates to the internal tables and assignments. A significant amount of effort was spent to ensure that the broadcast frequencies and color standard assignments are correct for each country/region.
This document describes how to use the new features, and includes the frequency tables and country/region assignments.