Adam (adam@xxxxxxxxxxxx): > I need to make some VHS-tape quality recording. thus I have two > questions. > > 1) what is resolution/frame rate of VHS-NTSC (USA) recording. I could > not find conclusive information on web, but it seems to me that it is > 320x240 @ 30 fps. (32bit color?). For vertical resolution, there are 486 scanlines recorded to VHS tape. These are in two separate 'fields', so each field has a vertical resolution of 243 lines. The standard sampling for broadcast TV of vertical resolution gives 720 pixels per scanline. However, on a VHS tape you really only get about half that, so sampling between 360 and 400 will probably give you about as much information as is on the tape. The colour data is sent as a composite signal with the luminance, and the best you could get out of it is about one chrominance sample per two luma samples, so, you want to use a Y'CbCr format at 4:2:2 sampling. So my recommendation, for highest quality, sample from your analog capture card as 360x480 (most cards don't give you all 486 scanlines) at a framerate of 29.97 frames per second, or at 360x240 at 59.94 fields per second. Using 4:2:2 Y'CbCr, that's at an average of 16 bits per pixel. Lots of data to sample.... > 2) what kind of web cam would be recommended. it seems to me that it > should be either one which connects to bttv or USB cam. I don't have > any experience with either, so not sure which is prefered. In the linux world, everyone likes to plug things into a bttv card. -- Billy Biggs vektor@xxxxxxxxxxxx
