Navigation bar main page key to sysmbols

DVD basic terms and notes

[tech: dvd]

NTSC || Hz / kHz || refresh rate || ES / PS || PGC

NTSC (vs. PAL): this refers to the (non-digital) video standard used in the United States (and elsewhere). It is important in that it differs from PAL, which is used in the United Kingdom and much of Europe. Because the transmission standards are different, you can not, for example, play a PAL video-cassette (VHS) on a VCR and television made to play NTSC video, and you can not play a PAL DVD on an NTSC television (without doing some sort of conversion).

Note that Japan uses NTSC (technically "NTSC-J") as well: I know from personal experience you can record a video cassette in Japan using Japanese equiptment, and then play that video cassette on US equipment (player and TV).

standard NTSC video:

Number of horizontal lines per picture (no. of lines per frame) = 525
Field frequency, nominal value (fields per second) = 59.94
(note: 59.94 Hz is only a conventional approximation)

BUT, NTSC (standard TV) has only 480 horizontal lines of visible resolution!

So our NTSC system can be summarized as "525 lines, 480 visible, interlaced scan".

NOTE: NTSC is sometime abbreviated as 525/60 based on the values above (525 lines at approximately 60 Hz), and PAL is similarly abbreviated as 625/50 (625 lines at approximately 50 Hz).

The DVD-Video specifications for NTSC are as follows (not a complete list):

- MPEG2 video with a bitrate of up to 9.8 Megabits per second (Mbps) [9,800 kilobits per second (kbps)]*
- MPEG1 video with a bitrate of up to 1.856 Mbps (1856 kbps)

Resolution options (pixel depth; more pixels means more detail), width by height:
- 720 x 480 pixels (720 pixels wide by 480 pixels tall) MPEG2 (Called Full-D1)
- 704 x 480 pixels MPEG2
- 352 x 480 pixels MPEG2 (Called Half-D1, same as the CVD Standard)
- 352 x 240 pixels MPEG2
- 352 x 240 pixels MPEG1 (Same as the VCD Standard)

29.97 frames per second (fps)

Note: the SVCD (Super Video CD) pixel depth is 480x480.

Further description of why more pixels mean better clarity, in the context of HDTV, can be found here.
Click here to compare 352x480 pixels to 720x480 pixels.
Note that the ratio of 720 to 480 is not exactly 4:3 (4 to 3).
[if 480 is divided by 3, you get 160. 160 times 4 is 640. So a 4 to 3 ratio based on a height of 480 would be 640x480.]

Command DVD Aspect Ratio: 1.33 : 1

Modern digital video applications such as DV, DVD and digital television (HDTV, DVB, ATSC) often use MPEG-1 or MPEG-2 formats (or their derivatives), which are all based on 16×16 pixel macroblocks. So is it important to have the height and width of the raster image divisible by 16 (e.g. 720×480 / 16×16 = 45×30 [345600/16^2=1350]).

Hz / kHz :Hz - Hertz is "cycles per second", it is a unit for frequency. kHz - Kilohertz is a thousand cycles per second (kilo- means thousand).
The standard US electrical power frequency is 60 Hz, which is why NTSC video uses 60 Hz, but you should not confuse electical Hz with Hz as an expression of video refresh/redraw rate.

Q: What is a refresh rate? What is field frequency? Why do monitors have different Hz settings?

refresh rate
: This term is seen most often in the context of computer monitors, but, with the introduction of digital television monitors and HDTV, is seen in the discussion of television as well.

The "refresh rate" (scan rate) is the rate, expressed as Hz (cycles per second), that a monitor (or tv or video) redraws the screen (from top to bottom).
If you use a video camera to record a video of a television or monitor (or if you take a photo of a television or PC monitor), the lines you see are the screen refreshing itself.

The refresh rate used for analog NTSC television is 60 Hz (60 redraw cycles per second).
A refresh rate of 60 Hz means that 60 images are drawn on the screen every second. But it's not as simple as that: for "interlaced" scanning a complete image (called a "frame") is only produced 30 times per second. Please read this article for details about "Interlaced vs. Progressive Scanning and Refresh Rate".

Movies (film) as shown in the movie theater are recorded at a rate of 24 images (frames) per second (this could be expressed as "24 Hz"). Each image is actually projected twice in the theater, however, resulting in an effective refresh rate of 48 Hz.

For computer monitors, a refresh rate of 85 Hz is virtually flicker-free to the most discerning eye, but a rate as low as 72 Hz is perfectly acceptable for most of us.
Most TVs have a refresh rate of about 30 Hz; no monitor has a rate below 60 Hz.
If you set the refresh rate too high, the image quality can appear to degrade. Also, reportedly, if you set the refresh rate to high, you can damage your monitor.
You can experiment with different refresh settings -- keep your eye just above or to the side of your screen, and lower the refresh rate until any perceptible flicker you can detect out of the corner of your eye is gone. (I've found that setting the refresh rate too high does strange things to your eyes, and can give you a headache. I'm not sure why this is, but I'm sure it's explained somewhere online.)


DVD Record Rates: 2.4x (3,324 KB/s); 4x ....

4x = 5,xxx KB/s
4.2x = 5,888 KB/s
4.3x: 6080
4.4x: 6208
4.5x: 6336
4.6x: 6464
4.7x: 6592
5x: 6,912 KB/s
5.1x: 7040-7104-7168
5.2x: 7232
5.3x: 7360 7424
5.4x: 7552
5.5x: 7616 7680
5.6x: 7808
5.7x: 7872 7936 8000
5.8x: 8128
5.9x: 8192 8256
6x: 8,320 - 8,384 KB/s
6.1x: 8512 8448
6.2x: 8576 8640
6.3x: 8704 8768
6.4x: 8832 8896
6.5x: 9088
6.6x: 9216
6.7x: 9280
6.8x: 9408 9472
6.9x: 9600 9536
7x: 9,664 - 9,792 KB/s
7.1x: 9920 9856
7.2x: 9984
7.3x: 10112 10176
7.4x: 10240 10304
7.5x: 10368 10432
7.6x: 10560 10496
7.7x: 10752 10688
7.8x: 10816 10880
7.9x:10944 11008
8x: 11,072 - 11,136 KB/s


ES / PS : ES means elementary stream, that is audio and video will be separate. PS means program stream and will results in a multiplexed audio/video stream. You often have to chose this when re-encoding a file (for example, input=DivX, output=MPEG).


PGC : This corresponds to an "episode" on a DVD. For example, a documentary DVD may have 3 episodes on the disk. DVD Decrypter, if "IFO" mode is selected, will display the Episodes (and extra content) as follows:

Here, you can see Episode 1 as "PGC 2 (58 minutes)", Episode 2 as "PGC 3 (58 minutes)" and Episode 3 as "PGC 4 (59 minutes)".

This allows you to, for example, just rip a single episode from the disk; to do so, just uncheck all of the chapters in the other PGCs. (So, for example, I wanted to re-rip Episode 2 of that disk due to an encoding error. So I leave all Chapters of PGC 3 checked, and uncheck all other chapters in the other PGCs.)
Note that IFO mode also allows you to rip certain chapters, if you want to back up only certain chapters (or even a single chapter).

Note also that by right clicking on a PGC, you can select the File Splitting method. Be default, this is "split file into 2 GB chunks", but if you're doing a certain chapter, or want to apply further processing to an episode, you might want to choose "File Splitting > By Chapter" or "File Splitting > By Vob ID"




A Conversion Table for Digital Video Formats