Arachnotron
28th December 2004, 13:49
One thing that comes to mind is the following. If both chips give about the same quality, why was it only Philips ADC used in professional boards such as Fast AV Master, Pinnacle Pro-One, Pinnacle DV500. Some even say Canopus used Philips ADCs. Why BTs were only used in PCI TV Tuner cards exclusively?
Could simply be price, features, driver support, support in general, availability of good reference designs, easier interfacing to other hardware, availability of custom features (there is an enormous range of video-related chips from Philips) etc. etc.
There have been various improvements for working with ACPI, improved FIFO sizes, better combfilters, better interfaces to hardware MPEG2 encoders, better sound decoding and whatnot since the bt848 and bt878. These improvements matter. However, they are not intended to improve the amount of detail simply because the BT878 already had enough to deal with the maximum amount of detail available in TV broadcasts.
A good example of this is the fusion 878: it is the same as the old BT878, only the interface has been brought up to date to deal with PCI 2.2 and ACPI.
The point is this: the BT878 already had a high enough sampling rate to deal with capturing PAL TV (5.5 MHz bandwidth) at 768x576. The CX kept the same raw PAL sampling rate as the BT878 (35.5 MHz), the Philips series is actually a bit lower. (27 MHz). There simply is not that much detail available in broadcast and certainly not in VHS (only 3 MHz luma bandwidth), and the BT878 already reached the point where it could deal with all of it long ago. Newer chips have improvements on many other points, but not there.
Could simply be price, features, driver support, support in general, availability of good reference designs, easier interfacing to other hardware, availability of custom features (there is an enormous range of video-related chips from Philips) etc. etc.
There have been various improvements for working with ACPI, improved FIFO sizes, better combfilters, better interfaces to hardware MPEG2 encoders, better sound decoding and whatnot since the bt848 and bt878. These improvements matter. However, they are not intended to improve the amount of detail simply because the BT878 already had enough to deal with the maximum amount of detail available in TV broadcasts.
A good example of this is the fusion 878: it is the same as the old BT878, only the interface has been brought up to date to deal with PCI 2.2 and ACPI.
The point is this: the BT878 already had a high enough sampling rate to deal with capturing PAL TV (5.5 MHz bandwidth) at 768x576. The CX kept the same raw PAL sampling rate as the BT878 (35.5 MHz), the Philips series is actually a bit lower. (27 MHz). There simply is not that much detail available in broadcast and certainly not in VHS (only 3 MHz luma bandwidth), and the BT878 already reached the point where it could deal with all of it long ago. Newer chips have improvements on many other points, but not there.