Apple ProRes

• FourCCs used to indicate different ProRes flavours in the QuickTime container:
  • Apple ProRes 422 High Quality: 'apch' ('hcpa' in little-endian)
  • Apple ProRes 422 Standard Definition: 'apcn' ('ncpa' in little-endian)
  • Apple ProRes 422 LT: 'apcs' ('scpa' in little-endian)
  • Apple ProRes 422 Proxy: 'apco' ('ocpa' in little-endian)
  • Apple ProRes 4444: 'ap4h' ('h4pa' in little-endian)
• Company: Apple
• Whitepaper: http://images.apple.com/finalcutstudio/resources/white_papers/L342568A_ProRes_WP.pdf
• New Whitepaper introducing ProRes LT/Proxy/4444: http://images.apple.com/finalcutstudio/docs/Apple_ProRes_White_Paper_July_2009.pdf
• Samples: http://samples.mplayerhq.hu/V-codecs/HCPA/

ProRes Introduction

Apple ProRes is a family of video codecs used for storing and editing high definition video data in Apple's Final Cut Pro. Apple's official whitepaper lists the codec's key features as being:

• intra-only codecs
• 4:2:2 / 4:4:4:4 source material
• 10-bit (12-bit for ProRes 4444) sample depth
• variable bitrate

Technical documentation on ProRes 422 Standard Definition / High Quality codec

ProRes 422 SD/HQ is the same codec operating on two different bitrates (flavours). Two different FOURCCs are used in order to indicate each flavour:

Flavour name	FOURCC	Bitrate
Standard Definition (SD)	'apcn'	145 Mbps
High Quality (HQ)	'apch'	220 Mbps

ProRes algorithm is based on the Discrete cosine transform (further DCT) and utilizes the following compression techniques:

• custom hybrid Golomb-Rice / Exponential Golomb coding for DCT coefficients
• run-lenght coding
• differential coding
• scalar quantization