void ParseQuant(BitReader br)
{
int base_q0 = br.GetBits (7);
int dqy1_dc = br.GetNextBit() != 0 ? br.GetSignedValue (4) : 0;
int dqy2_dc = br.GetNextBit() != 0 ? br.GetSignedValue (4) : 0;
int dqy2_ac = br.GetNextBit() != 0 ? br.GetSignedValue (4) : 0;
int dquv_dc = br.GetNextBit() != 0 ? br.GetSignedValue (4) : 0;
int dquv_ac = br.GetNextBit() != 0 ? br.GetSignedValue (4) : 0;
for (int i = 0; i < NumMbSegments; ++i)
{
int q;
if (m_segment_hdr.UseSegment)
{
q = m_segment_hdr.Quantizer[i];
if (!m_segment_hdr.AbsoluteDelta)
q += base_q0;
}
else if (i > 0)
{
m_dqm[i] = m_dqm[0];
continue;
}
else
{
q = base_q0;
}
var m = m_dqm[i];
m.y1_mat[0] = kDcTable[Clip (q + dqy1_dc, 127)];
m.y1_mat[1] = kAcTable[Clip (q + 0, 127)];
m.y2_mat[0] = kDcTable[Clip (q + dqy2_dc, 127)] * 2;
// For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16.
// The smallest precision for that is '(x*6349) >> 12' but 16 is a good
// word size.
m.y2_mat[1] = (kAcTable[Clip (q + dqy2_ac, 127)] * 101581) >> 16;
if (m.y2_mat[1] < 8) m.y2_mat[1] = 8;
m.uv_mat[0] = kDcTable[Clip (q + dquv_dc, 117)];
m.uv_mat[1] = kAcTable[Clip (q + dquv_ac, 127)];
m.uv_quant = q + dquv_ac; // for dithering strength evaluation
}
}
bool ParseSegmentHeader(BitReader br)
{
m_segment_hdr.UseSegment = br.GetNextBit() != 0;
if (m_segment_hdr.UseSegment)
{
m_segment_hdr.UpdateMap = br.GetNextBit() != 0;
if (0 != br.GetNextBit())
{ // update data
m_segment_hdr.AbsoluteDelta = br.GetNextBit() != 0;
for (int s = 0; s < NumMbSegments; ++s)
{
m_segment_hdr.Quantizer[s] = (byte)(br.GetNextBit() != 0 ? br.GetSignedValue (7) : 0);
}
for (int s = 0; s < NumMbSegments; ++s)
{
m_segment_hdr.FilterStrength[s] = (byte)(br.GetNextBit() != 0 ? br.GetSignedValue (6) : 0);
}
}
if (m_segment_hdr.UpdateMap)
{
for (int s = 0; s < TreeProbs; ++s)
{
m_proba.Segments[s] = (byte)(br.GetNextBit() != 0 ? br.GetBits (8) : 255);
}
}
}
else
{
m_segment_hdr.UpdateMap = false;
}
return !br.Eof;
}
bool ParseFilterHeader(BitReader br)
{
m_filter_hdr.Simple = br.GetNextBit() != 0;
m_filter_hdr.Level = br.GetBits (6);
m_filter_hdr.Sharpness = br.GetBits (3);
m_filter_hdr.UseLfDelta = br.GetNextBit() != 0;
if (m_filter_hdr.UseLfDelta)
{
if (0 != br.GetNextBit())
{ // update lf-delta?
for (int i = 0; i < NumRefLfDeltas; ++i)
{
if (0 != br.GetNextBit())
m_filter_hdr.RefLfDelta[i] = br.GetSignedValue (6);
}
for (int i = 0; i < NumModeLfDeltas; ++i)
{
if (0 != br.GetNextBit())
m_filter_hdr.ModeLfDelta[i] = br.GetSignedValue (6);
}
}
}
m_filter_type = (0 == m_filter_hdr.Level) ? 0 : m_filter_hdr.Simple ? 1 : 2;
return !br.Eof;
}
