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base repository: FFmpeg/FFV1
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  • 2 commits
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Commits on Jan 12, 2018

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    1d2744d View commit details
  2. change sequential lines to paragraphs

    Github: Closes #85
    dericed authored and michaelni committed Jan 12, 2018
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Showing with 15 additions and 10 deletions.
  1. +15 −10 ffv1.md
25 changes: 15 additions & 10 deletions ffv1.md
Original file line number Diff line number Diff line change
@@ -224,8 +224,7 @@ Positions used for context and median predictor are:
+---+---+---+---+
```

`X` is the current processed Sample.
The identifiers are made of the first letters of the words Top, Left and Right.
`X` is the current processed Sample. The identifiers are made of the first letters of the words Top, Left and Right.

## Median predictor

@@ -266,9 +265,7 @@ If `context >= 0` then `context` is used and the difference between the sample a

## Quantization Table Sets

The FFV1 bitstream contains 1 or more Quantization Table Sets.
Each Quantization Table Set contains exactly 5 Quantization Tables, each Quantization Table corresponding to 1 of the 5 Quantized Sample Differences.
For each Quantization Table, both the number of quantization steps and their distribution are stored in the FFV1 bitstream; each Quantization Table has exactly 256 entries, and the 8 least significant bits of the Quantized Sample Difference are used as index:
The FFV1 bitstream contains 1 or more Quantization Table Sets. Each Quantization Table Set contains exactly 5 Quantization Tables, each Quantization Table corresponding to 1 of the 5 Quantized Sample Differences. For each Quantization Table, both the number of quantization steps and their distribution are stored in the FFV1 bitstream; each Quantization Table has exactly 256 entries, and the 8 least significant bits of the Quantized Sample Difference are used as index:

PDF:$$Q_{j}[k]=quant\_tables[i][j][k\&255]$$
RFC:```
@@ -336,8 +333,7 @@ RFC:```
RFC:b=Cb+g
RFC:```

Exception for the reversible conversions between YCbCr and RGB:
if bits_per_raw_sample is between 9 and 15 inclusive, the following formulae for reversible conversions between YCbCr and RGB MUST be used instead of the ones above:
Exception for the JPEG2000-RCT conversion: if bits_per_raw_sample is between 9 and 15 inclusive, the following formulae for reversible conversions between YCbCr and RGB MUST be used instead of the ones above:

PDF:$$Cb=g-b$$
RFC:```
@@ -1179,9 +1175,18 @@ Inferred to be 0 if not present.
### initial_state_delta
`initial_state_delta` [ i ][ j ][ k ] indicates the initial Range coder state, it is encoded using k as context index and
pred = j ? initial\_states[ i ][j - 1][ k ] : 128
initial\_state[ i ][ j ][ k ] = ( pred + initial\_state\_delta[ i ][ j ][ k ] ) & 255
`initial_state_delta[ i ][ j ][ k ]` indicates the initial Range coder state, it is encoded using `k` as context index and
PDF:$$pred = j ? initial\_states[ i ][j - 1][ k ] : 128$$
RFC:```
RFC:pred = j ? initial_states[ i ][j - 1][ k ] : 128
RFC:```
PDF:initial\_state[ i ][ j ][ k ] = ( pred + initial\_state\_delta[ i ][ j ][ k ] ) & 255
RFC:```
RFC:initial_state[ i ][ j ][ k ] =
RFC: ( pred + initial_state_delta[ i ][ j ][ k ] ) & 255
RFC:```
### ec