ATI VCR2

• FourCC: VCR2
• Company: ATI
• Samples: http://www.mplayerhq.hu/MPlayer/samples/V-codecs/ATI-VCR12/

General description

ATI VCR2 is essentially a subset of MPEG-2 video. ATI Video Capture Cards use this format. The Compression is done in the hardware. There is a driver for Win9x that is dedicated to play back VCR2 videos without ATI Hardware.

VCR2 Video frames

VCR2 uses only Intra-frames. Data for each frame consists of the following pieces: optional Sequence header, optional Sequence extension, optional GOP (group of pictures) header, Picture header, Picture header extension and the actual picture data.

To see which header comes as next, just check the bitstream for a start code. The following start codes are defined:

1. SEQ_HEAD_START_CODE 0x000001B3
2. SEQ_EXTENSION_START_CODE 0x000001B5
3. GOP_START_CODE 0x000001B8
4. PIC_START_CODE 0x00000100

Sequence Header

This header is optional. Its presence is indicated by the SEQ_HEAD_START_CODE. It has the following format:

• Horizontal size (12 bits)