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@ -1,18 +1,18 @@ |
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============================================= |
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SNOW Video Codec Specification Draft 20080110 |
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Snow Video Codec Specification Draft 20080110 |
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============================================= |
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Introduction: |
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============= |
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This specification describes the SNOW bitstream syntax and semantics as |
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well as the formal SNOW decoding process. |
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This specification describes the Snow bitstream syntax and semantics as |
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well as the formal Snow decoding process. |
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The decoding process is described precisely and any compliant decoder |
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MUST produce the exact same output for a spec-conformant SNOW stream. |
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MUST produce the exact same output for a spec-conformant Snow stream. |
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For encoding, though, any process which generates a stream compliant to |
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the syntactical and semantic requirements and which is decodable by |
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the process described in this spec shall be considered a conformant |
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SNOW encoder. |
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Snow encoder. |
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Definitions: |
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============ |
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@ -315,7 +315,7 @@ Binary Range Coder: |
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The implemented range coder is an adapted version based upon "Range encoding: |
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an algorithm for removing redundancy from a digitised message." by G. N. N. |
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Martin. |
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The symbols encoded by the snow range coder are bits (0|1). The |
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The symbols encoded by the Snow range coder are bits (0|1). The |
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associated probabilities are not fix but change depending on the symbol mix |
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seen so far. |
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@ -486,7 +486,7 @@ the remaining points shall be bilinearly interpolated from the |
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up to 4 surrounding halfpel and fullpel points, again rounding should be to |
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nearest and halfway values rounded up |
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compliant snow decoders MUST support 1-1/8 pel luma and 1/2-1/16 pel chroma |
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compliant Snow decoders MUST support 1-1/8 pel luma and 1/2-1/16 pel chroma |
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interpolation at least |
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@ -562,7 +562,7 @@ s[w ] shall be considered equivalent to s[w-2] |
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| + | + | + | + +1/2 |
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snows 9/7 Integer filter: |
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Snow's 9/7 Integer filter: |
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1. s[i] -= (3*(s[i-1] + s[i+1]) + 4)>>3; for all even i < w |
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2. s[i] -= s[i-1] + s[i+1] ; for all odd i < w |
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3. s[i] += ( s[i-1] + s[i+1] + 4*s[i] + 8)>>4; for all even i < w |
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