Here are some handy pre-computed statistics to give you a sense of how big video is.
(Rec. 601 Digital)
|ANSI/SMPTE 125M, 259M|
(Rec. 601 Digital)
If you want just the visible picture, no VITC, not all of the closed captioning, and no other ancillary data of any kind, then you want the "active" region. For NTSC and PAL, the part of the signal which is "active" is a little ill-defined. We use the same definition adopted by all SGI VL devices (see Definitions: F1/F2, Interleave, Field Dominance, and More for the vertical definitions of active region). For the 525-line 601 digital format, the concept of active region is well-defined: we choose the "Active Video" region from 125M, not including the "Optional Blanking." For the 625-line digital format, we choose the same set of lines as with the 625-analog format.
If you want VITC or other data which lives in the vertical blanking interval (that data is called VANC (vertical ancillary data) when dealing with a 601 digital signal), you have to capture more lines of data than active video. If you have a digital signal, then ancillary data such as audio can also be stuck in the horizontal blank (this is called HANC), so to get this you will have to capture more pixels per line.
What if you want all the data? For the digital formats, this is well-defined: an image which represents every single bit of data transferred over a Rec. 601 digital video link (including the timing reference signals (called EAV and SAV)) is a "full-raster" image. If you really want all the data, you'll also have to capture at 10 bits (which ends up being 4 bytes per pixel due to padding) rather than 8 bits (which is 2 bytes per pixel). Nitpick: for the digital formats, the size of the two fields is not the same: one field has one more line than the other, and lasts one line time longer than the other. We use the average size for the "field" quantities below.
Sorted by video standard:
|x size||y size||total pixels|
The exact field rate of drop-frame timecode (which is a hack that was invented to get around the bizzarre field rate of 525-line video) is 59.94 fields per second, which is not equal to (60000.0/1001.0). This oddity is explained in "Time Code: A User's Guide" by John Ratcliff (Oxford: Butterworth-Heinemann, 1993).
The exact field rate of PAL and 625-line digital video is 50 fields per second.
|NTSC and 525-dig||29.97||33.3667ms||59.9401||16.6833ms|
|PAL and 625-dig||25||40ms||50||20ms|
|total bytes per second|
A few of these "pixels" are reserved for use as timing reference signals (EAV and SAV).
The reason you don't see "27MB/sec" as the data rate for 2-bytes-per-pixel full-raster digital video above is that we have defined a MB as (1024*1024) bytes (as the computer memory geeks do) rather than (1000*1000) bytes, as the communications people do. Gotta love standards!
Some notes about those specifications:
"Video Demystified" by Keith Jack (United States: Brooktree, 1993) comes in a very distant third.