Export HD to NTSC Widescreen -- not truly 16:9

Question

If you export HD footage, 1080x1920 for example, to NTSC Widescreen, you end up with 720x480 with rectangular pixels that have a 1.2121 pixel aspect ratio. That means, the display is effectively 873x480 pixels, which is a a screen aspect ratio of about 16.4:9 instead of 16:9. What you end up with is the original video image squashed between thin, vertical black bars on the right and left sides (not the thick black bars you get when you display a 4:3 video in a 16:9 display).
If you open the video in an NTSC Widescreen Sequence, you'll see those black bars. The video image does not fill the screen.
This is easily fixed: change the Scale Width value to 102.3 (uncheck Uniform Scale). That puts the image portion of the clip into the proper aspect ratio (and shoves the black bars off the left and right sides of the screen). But I'd rather change the scale of all the clips in a project.
Since NTSC has to be 720x480 pixels, if you want to display something at a 16:9 ratio, the pixel aspect ratio should be 1.185 instead of 1.2121.
Perhaps an Adobe engineer can explain why exporting HD to NTSC Widescreen creates a video with black vertical bars and how a 720x480 (with rectangular pixels with a 1.2121 aspect ratio) clip can be considered as having a 16:9 aspect ratio.
Thanks,
Jeff Sengstack

Answer 1

you have to do your frame aspect ratio calculations based on the image  area (clean aperture) not the production aperture.
page 4...this link
http://www.panavision.com/publish/2007/12/10/GenesisFAQs20071207.pdf
My take on this is that CCD's that are full size for 35mm film ( beginning of aspect ratios for a lot of stuff ) there is less fudging re: transforming a smaller chip size to the correct exact image size, that the image size derrived from the real camera recording may not be exactly the "production" aspect ratio sizes...or something like that... It is confusing to me also, as I have no video cameras, digital or otherwise, and don't shoot anything but still film.
I think ( not sure but think I read ) that the red camera actually has a CCD "larger" than the genesis, so it actually is capable of recording higher resolutions than typical 4.4.4 production dimensions....but how that works into "clean" image area and aspect ratio is confusing to me also...
To further confuse me, this article has info on exact number of lines broadcast for pal and ntsc...
note THIS in the article ===------------------------------------------------------
NTSC Video
525 scan lines per frame,  30      frames per second (or be exact, 29.97 fps, 33.37 msec/frame)
Interlaced, each frame is      divided into 2 fields, 262.5 lines/field
20 lines reserved for control      information at the beginning of each fieldSo a maximum of 485       lines of visible data
Basics of Video
Analog video is represented      as a continuous (time varying) signal.
Digital video is represented      as a sequence of digital images.
    Types of Color Video Signals
Component video --      each primary is sent as a separate video signal.
The primaries can       either be RGB or a luminance-chrominance transformation of them (e.g.,       YIQ, YUV).
Best color       reproduction
Requires more       bandwidth and good synchronization of the three components
Composite video --      color (chrominance) and luminance signals are mixed into a single carrier      wave. Some interference between the two signals is inevitable.
S-Video (Separated      video, e.g., in S-VHS) -- a compromise between component analog video and      the composite video. It uses two lines, one for luminance and another for      composite chrominance signal.
    Analog Video
The following figures are from A.M. Tekalp, "Digital video processing", Prentice Hall PTR, 1995, NTSC.
NTSC Video
525 scan lines per frame, 30      frames per second (or be exact, 29.97 fps, 33.37 msec/frame)
Interlaced, each frame is      divided into 2 fields, 262.5 lines/field
20 lines reserved for control      information at the beginning of each field
So a maximum of 485       lines of visible data
Laserdisc and S-VHS       have actual resolution of ~420 lines
Ordinary TV -- ~320       lines
Each line takes 63.5      microseconds to scan. Horizontal retrace takes 10 microseconds (with 5      microseconds horizontal synch pulse embedded), so the active line time is      53.5 microseconds.
Digital Video Rasters
Color representation:
NTSC uses YIQ color       model.
composite = Y + I cos(Fsc       t) + Q sin(Fsc t), where Fsc is the frequency of color subcarrier
PAL Video
625 scan lines per frame, 25      frames per second (40 msec/frame)
Interlaced, each frame is      divided into 2 fields, 312.5 lines/field
Uses YUV color model
    Digital Video
Advantages:
Direct random access       --> good for nonlinear video editing
No problem for       repeated recording
No need for blanking       and sync pulse
Almost all digital video uses      component video
Chroma Subsampling
How to decimate for      chrominance?
4:4:4 --> No chroma      subsampling, each pixel has Y, Cr and Cb values.
4:2:2 --> Horizontally subsample Cr, Cb signals by a factor of 2.
4:1:1 --> Horizontally subsampled by a factor of 4.
4:2:0 --> Subsampled in both the horizontal and vertical dimensions by a factor of 2. Theoretically, the chroma pixel is positioned between the rows and columns as shown in the figure.
4:1:1 and 4:2:0 are mostly      used in JPEG and MPEG (see Chapter 4).
CCIR Standards for Digital Video
(CCIR -- Consultative Committee for International Radio)
                       CCIR 601       CCIR 601         CIF         QCIF
                        525/60         625/50  
                         NTSC         PAL/SECAM      
Luminance resolution   720 x 485      720 x 576     352 x 288    176 x 144
Chrominance resolut.   360 x 485      360 x 576     176 x 144     88 x 72
Color Subsampling        4:2:2          4:2:2         4:2:0        4:2:0
Fields/sec                60             50            30           30
Interlacing               Yes            Yes           No           No
CCIR 601 uses interlaced      scan, so each field only has half as much vertical resolution (e.g., 243      lines in NTSC). The CCIR 601 (NTSC) data rate is ~165 Mbps.
CIF (Common Intermediate      Format) -- an acceptable temporary standard
Approximately the VHS       quality
Uses progressive       (non-interlaced) scan
Uses NTSC frame rate,       and half the active lines of PAL signals --> To play on existing TVs,       PAL systems need to do frame rate conversion, and NTSC systems need to do       line-number conversion.
QCIF -- Quarter-CIF
ATSC Digital Television Standard
(ATSC -- Advanced Television Systems Committee) The ATSC Digital Television Standard was recommended to be adopted as the Advanced TV broadcasting standard by the FCC Advisory Committee on Advanced Television Service on November 28, 1995. It covers the standard for HDTV (High Definition TV).
Video Format
The video scanning formats supported by the ATSC Digital Television Standard are shown in the following table.
Vertical Lines
Horizontal   Pixels
Aspect Ratio
Picture Rate
1080
1920
16:9
60I 30P 24P
720
1280
16:9
60P 30P 24P
480
704
16:9 &   4:3
60I 60P 30P   24P
480
640
4:3
60I 60P 30P   24P
The aspect ratio for HDTV is      16:9 as opposed to 4:3 in NTSC, PAL, and SECAM. (A 33% increase in      horizontal dimension.)
In the picture rate column,      the "I" means interlaced scan, and the "P" means      progressive (non-interlaced) scan.
Both NTSC rates and integer      rates are supported (i.e., 60.00, 59.94, 30.00, 29.97, 24.00, and 23.98).
At 1920 x 1080, 60I (which      CBS and NBC have selected), there will be 1920 x 1080 x 30 = 62.2 millions      pixels per second. Considering 4:2:2 chroma subsampling, each pixel needs      16 bits to represent, the bit rate is 62.2 x 16 = 995 Mb/sec.
Homepage of the Advanced Television Systems Committee (ATSC)