Video Encoding

Encoding DVD video assets is the process of digitizing video from tape to hard disk, and compressing the information using either the MPEG-1 or MPEG-2 compression algorithm. This results is a relatively small file.

The main advantage of using a high-end system like Sonic Creator is that the Sonic SD-2000 MPEG video encoder is regarded throughout the industry as being second to none.

MPEG-2 encoding was designed to encode full CCIR 601 digital signal at the full resolution of 720 x 480 (NTSC) or 720 x 576 (PAL/SECAM). MPEG-2 provides for both VBR (see below) and interlaced display as used for broadcast television signals and allows a compression ratio of up to 40:1.

MPEG-1, also used for Video CD, gives even longer playing time but at a lower quality. Since MPEG-1 does not allow for interlaced display, the image resolution available is reduced to 352 x 240 (NTSC) or 352 x 288 (PAL/SECAM). MPEG-1 is also restricted to constant bit rate (CBR).


Here is a summary:

	MPEG-2	MPEG-1
NTSC resolutions (height x width)	720 x 480 704 x 480 352 x 480 352 x 240	352 X 480 351 x 240
PAL/SECAM  resolutions (height x width)	720 x 576 704 x 576 352 x 576 352 x 288	352 x 576 352 x 288
Variable Bit Rate (VBR*), Constant Bit Rate(CBR**)	VBR or CBR	CBR
PAL/SECAM Frame rate	25 fps
NTSC frame rate (on disc)	24 or 30 fps

*VBR, or variable bit rate encoding allows higher image quality at a lower average bit rate by using more data to encode those parts of a video sequence which are more complex and do not compress well, for example scenes with a lot of movement, and less data for those parts that do compress well, such as static scenes, talking heads etc.

**Using CBR, or constant bit rate encoding, a high enough data rate is chosen to encode all the video well. For short videos where disc capacity is not an issue CBR, at as high a bit rate as possible, is the way to go.

MPEG-2 is generally used for maximum quality. MPEG-1 is available where playing time is more important than quality.