Steve Anderson wrote:Not wishing to throw a spanner in the works, has any thought been given to sync pulse time? If using 48 pixels during the active video time of a nominal 2.375ms (allowing 5% of 2.5ms for syncs) results in a pixel rate slightly higher than 19.2kHz....around 20.21...kHz...
I'm gonna make a run for it...
Steve A.
Yeah but if you are using the NBTVA standard format the sync forms part of 48 pixels - put it this way, you can use as many pixels as you like along the line but if the signal is bandwidth limited to the NBTVA standard of 9.6kHz you don't achieve any greater resolution by increasing the number of display pixels beyond 48 - sync. I suppose you could in fact save some LEDs by dropping off the LEDs at the bottom of each line that would normally only ever be displaying black if that was all that was ever going to be shown on the display.
I suppose I could have summed all of that up by just saying that the sync is included in the aspect ratio.
Video2NBTV alpha produces video with the full bandwidth of a 48 kHz (24 kHz bandwidth) so that the line of NBTVA video actually has a resolution of 120 pixels - but that is simply because there is no need to limit the bandwidth in the file itself - it should only be limited by the transmission system itself. In the release version of Video2NBTV the video is the Brown/Robers colour format so automatically has half the display bandwidth of a B&W signal, on top of that it is 44.1kHz, and on top of that, the anti-aliasing filter DOES limit the bandwidth to 9.6kHz because it needs a slower roll off to prevent ringing that is clearly evident in the picture (but wouldn't be if it was listened to as audio).