VCD Player

 

VCD PLAYER CIRCUIT DIAGRAM

VCD player Is generally a very useful device which is used to play VCD or CD.

Its full form Is video compact disk

1.     Things which are used in VCD player are

   a.pictures

    b. any audio songs IM mp3,wav,aac

   

Video CDs comply with the CD-i Bridge format, and are authored using tracks in CD-ROM XA mode. The first track of a VCD is in CD-ROM XA Mode 2 Form 1, and stores metadata and menu information inside an ISO 9660 file system. This track may also contain other non-essential files, and is shown by operating systems when loading the disc. This track can be absent from a VCD, which would still work but would not allow it to be properly displayed in computers.[3]

The rest of the tracks are usually in CD-ROM XA Mode 2 Form 2 and contain video and audio multiplexed in an MPEG program stream (MPEG-PS) container, but CD audiotracks are also allowed.[3] Using Mode 2 Form 2 allows roughly 800 megabytes of VCD data to be stored on one 80 minute CD (versus 700 megabytes when using CD-ROM Mode 1). This is achieved by sacrificing the error correction redundancy present in Mode 1. It was considered that small errors in the video and audio stream pass largely unnoticed. This, combined with the net bitrate of VCD video and audio, means that almost exactly 80 minutes of VCD content can be stored on an 80-minute CD, 74 minutes of VCD content on a 74-minute CD, and so on. This was done in part to ensure compatibility with existing CD drive technology, specifically the earliest "1x" speed CD drives.

Video

Video specifications

•         Codec: MPEG-1

•         Resolution:

•         NTSC: 352x240

•         PAL/SECAM: 352x288

•         Aspect Ratio:

•         NTSC: 4:3

•         PAL/SECAM: 4:3

•         Framerate:

•         NTSC: 29.97 or 23.976 frames per second

•         PAL/SECAM: 25 frames per second

•         Bitrate: 1,150 kilobits per second

•         Rate Control: constant bitrate

Although many DVD video players support playback of VCDs, VCD video is only compatible with the DVD-Video standard if encoded at 29.97 frames per second or 25 frames per second.

The 352x240 and 352x288 (or SIF) resolutions were chosen because it is half the horizontal and vertical resolution of NTSC video, and half the horizontal resolution of PAL (the vertical resolution of PAL already being half of the 576 active lines). This is approximately half the resolution of an analog VHS tape which is ~330 horizontal and 480 vertical (NTSC) or 330x576 (PAL).

Audio

Audio specifications

•         Codec: MPEG-1 Audio Layer II

•         Sample Frequency: 44,100 hertz (44.1 kHz)

•         Output: Dual channel or stereo

•         Bitrate: 224 kilobits per second

•         Rate Control: Constant bitrate

As with most CD-based formats, VCD audio is incompatible with the DVD-Video standard due to a difference in sampling frequency; DVDs require 48 kHz, whereas VCDs use 44.1 kHz.

Advantages of compression

By compressing both the video and audio streams, a VCD is able to hold 74 minutes of picture and sound information, nearly the same duration as a standard 74 minute audio CD. The MPEG-1 compression used records mostly the differences between successive video frames, rather than write out each frame individually. Similarly, the audio frequency range is limited to those sounds most clearly heard by the human ear.

Other features

PlayBack Control (PBC) added in VCD 2.0 requires a special 'Return' button

The VCD standard also features the option of DVD-quality still images/slide shows with audio, at resolutions of 704x480 (NTSC) or 704x576 (PAL/SECAM). Version 2.0 also adds the playback control (PBC), featuring a simple menu like DVD-Video.