Super Video CD
The Super Video CD (SVCD) standard upgrades the Video-CD (VCD) format.
It allows better video and audio quality, including extensions for surround
sound, multi-channel audio and provisioning for PC playback. It's based
on variable bit rate (VBR) MPEG-2 coding for more efficient use of optical
disc capacity.
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Super-VCD standard
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Super-VCD players
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XSVCD format
1. Super-VCD standard
The Super Video-CD is based on the CD-ROM XA disc format. All tracks are
data tracks, the first track is a special DATA track with data retrieval
information and interactive playback MPEG sequences. The MPEG-2 streams
are recorded in the following tracks and are intended to be played sequentially
starting from track #2. A movie could have different coded parts: INTRO,
COPYRIGHT, FILM, CREDITS; each stored on a separate track. The film itself
can be stored on one track with the possibility to be subdivided into chapters
within the one track. The layout will be handle by an SVCD Authoring software
like I-Author.
The DATA track ( #1 ) uses Mode 2, Form 1 data sectors ( 2,048 bytes
) and MPEG files use Mode 2, Form 2 MPEG sectors ( 2,324 bytes ).
The Super Video-CD 1.0 features ( IEC
62107 standard ) are given in the table below:
| |
| Features |
Super Video CD 1.0 |
Video
bit rate
resolution NTSC
resolution PAL |
MPEG-2
variable up to 2.6 Mbps
480x480 interlaced, 29.97Hz
480x576 interlaced, 25Hz |
Still picture (photo)
resolution NTSC
resolution PAL |
MPEG-2 ( I Frame )
480x480, 704x480
480x576, 704x576 |
Audio
sampling
bit rate
audio channels
surround sound |
MPEG-1 layer II
44.1 KHz
from 32 to 384 Kbps
up to 2 stereo or 4 mono
MPEG-2 ( 5+1 ) extension |
Overlay graphics and text
sub-channels
coding |
overlay video plane
<=4
4 color CLUT ( 2bits/pixel ) |
|
|
The Program Stream contains two audio streams, usually for two separate
languages. Audio streams are MPEG-1 audio formats, given in the table below:
| |
| MPEG-1 (ISO 11172-3) audio formats |
| Layer |
layer II only |
| Bit Rate |
may vary from frame to frame |
single channel mode
dual channel mode
stereo mode |
32 to 192 Kbps
64 to 384 Kbps
64 to 384 Kbps |
| Sampling frequency |
44.1 KHz |
|
|
The video MPEG-2 streams are defined by the constraints of Main Profile
at Mail Level ( MP@ML ):
| |
| MPEG-2 video MP@ML profile |
| B-frames |
YES |
| Chroma format |
4:2:0 |
| Scalabilty |
NONE |
| Intra DC precision |
8, 9, 10 bits |
| Buffer size |
1,835,008 bits |
| Luminance sample rate |
10,368,000 |
| Horizontal vector range |
-512..+511.5 |
| Vertical vector range (frame pictures) |
128..+127.5 |
|
|
The interlaced nature of the video signal is preserved. This results
in smoother-looking motion for video footage that was originally shot with
a field-based video camera.
The typical running time of an SVCD disc (with full resolution and quality)
is about 35-45 minutes, although it can be extended to over 70 minutes
by compromising image and sound quality.
For PC playback, the format allows storing applications or setup files
in the EXT directory. The main root can even contain autorun enabling
files.
An SVCD detailed technical explanation is available from Philips
licensing page and a copy is also available from our documentation
at sl00811.zip (86.5KB)
in Acrobat PDF format. Jukka Aho has published a very good Super
Video CD Overview.
2. Super-VCD players
SVCD can be played on PC platforms with a CD-ROM (or DVD-ROM) drive and
appropriate software like WinDVD and STHSVCD (also named STHSDVD sometimes).
In general, people want to play Super-VCD on a TV-set with a standalone
DVD player. Most DVD players sold in Asia can read SVCD but in America
and in Europe only a few players are SVCD compliant.
Because some identical DVD player platforms are used all over the world,
one can sometimes upgrade it's firmware and hack the player to make it
read SVCD. One example is given at Leon's
Lab for the Philips DVD-950 shipped in Europe.
3. XSVCD format
You may see or hear about an extension of the SVCD format called XSVCD.
Because SVCD uses the MPEG-2 decoder of the PC, or the standalone DVD player,
XSVCD
tries to get the maximum from the decoder:
-
Higher resolution up to DVD resolution at 720x480 for NTSC (720x576
for PAL)
-
Higher bit rate up to 9.8Mbps (DVD bit rate) for standalone or 15Mbps
for PC (MP@ML constraint)
For example, the Philips DVD-950 (with firmware 7.12) can play XSVCD at
720x576 and 2.9Mbps .
Bibliography
On labDV.com :
Relevant links:
Author: Jim & Stan (April 6, 2001)
Please visit Leon's
Lab and VCDHelp.com |