2024-06-07 00:47:07 +02:00

627 lines
23 KiB
C#

using System;
namespace NAudio.Codecs
{
/// <summary>
/// SpanDSP - a series of DSP components for telephony
///
/// g722_decode.c - The ITU G.722 codec, decode part.
///
/// Written by Steve Underwood &lt;steveu@coppice.org&gt;
///
/// Copyright (C) 2005 Steve Underwood
/// Ported to C# by Mark Heath 2011
///
/// Despite my general liking of the GPL, I place my own contributions
/// to this code in the public domain for the benefit of all mankind -
/// even the slimy ones who might try to proprietize my work and use it
/// to my detriment.
///
/// Based in part on a single channel G.722 codec which is:
/// Copyright (c) CMU 1993
/// Computer Science, Speech Group
/// Chengxiang Lu and Alex Hauptmann
/// </summary>
public class G722Codec
{
/// <summary>
/// hard limits to 16 bit samples
/// </summary>
static short Saturate(int amp)
{
short amp16;
// Hopefully this is optimised for the common case - not clipping
amp16 = (short)amp;
if (amp == amp16)
return amp16;
if (amp > Int16.MaxValue)
return Int16.MaxValue;
return Int16.MinValue;
}
static void Block4(G722CodecState s, int band, int d)
{
int wd1;
int wd2;
int wd3;
int i;
// Block 4, RECONS
s.Band[band].d[0] = d;
s.Band[band].r[0] = Saturate(s.Band[band].s + d);
// Block 4, PARREC
s.Band[band].p[0] = Saturate(s.Band[band].sz + d);
// Block 4, UPPOL2
for (i = 0; i < 3; i++)
s.Band[band].sg[i] = s.Band[band].p[i] >> 15;
wd1 = Saturate(s.Band[band].a[1] << 2);
wd2 = (s.Band[band].sg[0] == s.Band[band].sg[1]) ? -wd1 : wd1;
if (wd2 > 32767)
wd2 = 32767;
wd3 = (s.Band[band].sg[0] == s.Band[band].sg[2]) ? 128 : -128;
wd3 += (wd2 >> 7);
wd3 += (s.Band[band].a[2] * 32512) >> 15;
if (wd3 > 12288)
wd3 = 12288;
else if (wd3 < -12288)
wd3 = -12288;
s.Band[band].ap[2] = wd3;
// Block 4, UPPOL1
s.Band[band].sg[0] = s.Band[band].p[0] >> 15;
s.Band[band].sg[1] = s.Band[band].p[1] >> 15;
wd1 = (s.Band[band].sg[0] == s.Band[band].sg[1]) ? 192 : -192;
wd2 = (s.Band[band].a[1] * 32640) >> 15;
s.Band[band].ap[1] = Saturate(wd1 + wd2);
wd3 = Saturate(15360 - s.Band[band].ap[2]);
if (s.Band[band].ap[1] > wd3)
s.Band[band].ap[1] = wd3;
else if (s.Band[band].ap[1] < -wd3)
s.Band[band].ap[1] = -wd3;
// Block 4, UPZERO
wd1 = (d == 0) ? 0 : 128;
s.Band[band].sg[0] = d >> 15;
for (i = 1; i < 7; i++)
{
s.Band[band].sg[i] = s.Band[band].d[i] >> 15;
wd2 = (s.Band[band].sg[i] == s.Band[band].sg[0]) ? wd1 : -wd1;
wd3 = (s.Band[band].b[i] * 32640) >> 15;
s.Band[band].bp[i] = Saturate(wd2 + wd3);
}
// Block 4, DELAYA
for (i = 6; i > 0; i--)
{
s.Band[band].d[i] = s.Band[band].d[i - 1];
s.Band[band].b[i] = s.Band[band].bp[i];
}
for (i = 2; i > 0; i--)
{
s.Band[band].r[i] = s.Band[band].r[i - 1];
s.Band[band].p[i] = s.Band[band].p[i - 1];
s.Band[band].a[i] = s.Band[band].ap[i];
}
// Block 4, FILTEP
wd1 = Saturate(s.Band[band].r[1] + s.Band[band].r[1]);
wd1 = (s.Band[band].a[1] * wd1) >> 15;
wd2 = Saturate(s.Band[band].r[2] + s.Band[band].r[2]);
wd2 = (s.Band[band].a[2] * wd2) >> 15;
s.Band[band].sp = Saturate(wd1 + wd2);
// Block 4, FILTEZ
s.Band[band].sz = 0;
for (i = 6; i > 0; i--)
{
wd1 = Saturate(s.Band[band].d[i] + s.Band[band].d[i]);
s.Band[band].sz += (s.Band[band].b[i] * wd1) >> 15;
}
s.Band[band].sz = Saturate(s.Band[band].sz);
// Block 4, PREDIC
s.Band[band].s = Saturate(s.Band[band].sp + s.Band[band].sz);
}
static readonly int[] wl = { -60, -30, 58, 172, 334, 538, 1198, 3042 };
static readonly int[] rl42 = { 0, 7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 0 };
static readonly int[] ilb = { 2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383, 2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834, 2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371, 3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008 };
static readonly int[] wh = { 0, -214, 798 };
static readonly int[] rh2 = { 2, 1, 2, 1 };
static readonly int[] qm2 = { -7408, -1616, 7408, 1616 };
static readonly int[] qm4 = { 0, -20456, -12896, -8968, -6288, -4240, -2584, -1200, 20456, 12896, 8968, 6288, 4240, 2584, 1200, 0 };
static readonly int[] qm5 = { -280, -280, -23352, -17560, -14120, -11664, -9752, -8184, -6864, -5712, -4696, -3784, -2960, -2208, -1520, -880, 23352, 17560, 14120, 11664, 9752, 8184, 6864, 5712, 4696, 3784, 2960, 2208, 1520, 880, 280, -280 };
static readonly int[] qm6 = { -136, -136, -136, -136, -24808, -21904, -19008, -16704, -14984, -13512, -12280, -11192, -10232, -9360, -8576, -7856, -7192, -6576, -6000, -5456, -4944, -4464, -4008, -3576, -3168, -2776, -2400, -2032, -1688, -1360, -1040, -728, 24808, 21904, 19008, 16704, 14984, 13512, 12280, 11192, 10232, 9360, 8576, 7856, 7192, 6576, 6000, 5456, 4944, 4464, 4008, 3576, 3168, 2776, 2400, 2032, 1688, 1360, 1040, 728, 432, 136, -432, -136 };
static readonly int[] qmf_coeffs = { 3, -11, 12, 32, -210, 951, 3876, -805, 362, -156, 53, -11, };
static readonly int[] q6 = { 0, 35, 72, 110, 150, 190, 233, 276, 323, 370, 422, 473, 530, 587, 650, 714, 786, 858, 940, 1023, 1121, 1219, 1339, 1458, 1612, 1765, 1980, 2195, 2557, 2919, 0, 0 };
static readonly int[] iln = { 0, 63, 62, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 0 };
static readonly int[] ilp = { 0, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 0 };
static readonly int[] ihn = { 0, 1, 0 };
static readonly int[] ihp = { 0, 3, 2 };
/// <summary>
/// Decodes a buffer of G722
/// </summary>
/// <param name="state">Codec state</param>
/// <param name="outputBuffer">Output buffer (to contain decompressed PCM samples)</param>
/// <param name="inputG722Data"></param>
/// <param name="inputLength">Number of bytes in input G722 data to decode</param>
/// <returns>Number of samples written into output buffer</returns>
public int Decode(G722CodecState state, short[] outputBuffer, byte[] inputG722Data, int inputLength)
{
int dlowt;
int rlow;
int ihigh;
int dhigh;
int rhigh;
int xout1;
int xout2;
int wd1;
int wd2;
int wd3;
int code;
int outlen;
int i;
int j;
outlen = 0;
rhigh = 0;
for (j = 0; j < inputLength; )
{
if (state.Packed)
{
// Unpack the code bits
if (state.InBits < state.BitsPerSample)
{
state.InBuffer |= (uint)(inputG722Data[j++] << state.InBits);
state.InBits += 8;
}
code = (int)state.InBuffer & ((1 << state.BitsPerSample) - 1);
state.InBuffer >>= state.BitsPerSample;
state.InBits -= state.BitsPerSample;
}
else
{
code = inputG722Data[j++];
}
switch (state.BitsPerSample)
{
default:
case 8:
wd1 = code & 0x3F;
ihigh = (code >> 6) & 0x03;
wd2 = qm6[wd1];
wd1 >>= 2;
break;
case 7:
wd1 = code & 0x1F;
ihigh = (code >> 5) & 0x03;
wd2 = qm5[wd1];
wd1 >>= 1;
break;
case 6:
wd1 = code & 0x0F;
ihigh = (code >> 4) & 0x03;
wd2 = qm4[wd1];
break;
}
// Block 5L, LOW BAND INVQBL
wd2 = (state.Band[0].det * wd2) >> 15;
// Block 5L, RECONS
rlow = state.Band[0].s + wd2;
// Block 6L, LIMIT
if (rlow > 16383)
rlow = 16383;
else if (rlow < -16384)
rlow = -16384;
// Block 2L, INVQAL
wd2 = qm4[wd1];
dlowt = (state.Band[0].det * wd2) >> 15;
// Block 3L, LOGSCL
wd2 = rl42[wd1];
wd1 = (state.Band[0].nb * 127) >> 7;
wd1 += wl[wd2];
if (wd1 < 0)
wd1 = 0;
else if (wd1 > 18432)
wd1 = 18432;
state.Band[0].nb = wd1;
// Block 3L, SCALEL
wd1 = (state.Band[0].nb >> 6) & 31;
wd2 = 8 - (state.Band[0].nb >> 11);
wd3 = (wd2 < 0) ? (ilb[wd1] << -wd2) : (ilb[wd1] >> wd2);
state.Band[0].det = wd3 << 2;
Block4(state, 0, dlowt);
if (!state.EncodeFrom8000Hz)
{
// Block 2H, INVQAH
wd2 = qm2[ihigh];
dhigh = (state.Band[1].det * wd2) >> 15;
// Block 5H, RECONS
rhigh = dhigh + state.Band[1].s;
// Block 6H, LIMIT
if (rhigh > 16383)
rhigh = 16383;
else if (rhigh < -16384)
rhigh = -16384;
// Block 2H, INVQAH
wd2 = rh2[ihigh];
wd1 = (state.Band[1].nb * 127) >> 7;
wd1 += wh[wd2];
if (wd1 < 0)
wd1 = 0;
else if (wd1 > 22528)
wd1 = 22528;
state.Band[1].nb = wd1;
// Block 3H, SCALEH
wd1 = (state.Band[1].nb >> 6) & 31;
wd2 = 10 - (state.Band[1].nb >> 11);
wd3 = (wd2 < 0) ? (ilb[wd1] << -wd2) : (ilb[wd1] >> wd2);
state.Band[1].det = wd3 << 2;
Block4(state, 1, dhigh);
}
if (state.ItuTestMode)
{
outputBuffer[outlen++] = (short)(rlow << 1);
outputBuffer[outlen++] = (short)(rhigh << 1);
}
else
{
if (state.EncodeFrom8000Hz)
{
outputBuffer[outlen++] = (short)(rlow << 1);
}
else
{
// Apply the receive QMF
for (i = 0; i < 22; i++)
state.QmfSignalHistory[i] = state.QmfSignalHistory[i + 2];
state.QmfSignalHistory[22] = rlow + rhigh;
state.QmfSignalHistory[23] = rlow - rhigh;
xout1 = 0;
xout2 = 0;
for (i = 0; i < 12; i++)
{
xout2 += state.QmfSignalHistory[2 * i] * qmf_coeffs[i];
xout1 += state.QmfSignalHistory[2 * i + 1] * qmf_coeffs[11 - i];
}
outputBuffer[outlen++] = (short)(xout1 >> 11);
outputBuffer[outlen++] = (short)(xout2 >> 11);
}
}
}
return outlen;
}
/// <summary>
/// Encodes a buffer of G722
/// </summary>
/// <param name="state">Codec state</param>
/// <param name="outputBuffer">Output buffer (to contain encoded G722)</param>
/// <param name="inputBuffer">PCM 16 bit samples to encode</param>
/// <param name="inputBufferCount">Number of samples in the input buffer to encode</param>
/// <returns>Number of encoded bytes written into output buffer</returns>
public int Encode(G722CodecState state, byte[] outputBuffer, short[] inputBuffer, int inputBufferCount)
{
int dlow;
int dhigh;
int el;
int wd;
int wd1;
int ril;
int wd2;
int il4;
int ih2;
int wd3;
int eh;
int mih;
int i;
int j;
// Low and high band PCM from the QMF
int xlow;
int xhigh;
int g722_bytes;
// Even and odd tap accumulators
int sumeven;
int sumodd;
int ihigh;
int ilow;
int code;
g722_bytes = 0;
xhigh = 0;
for (j = 0; j < inputBufferCount; )
{
if (state.ItuTestMode)
{
xlow =
xhigh = inputBuffer[j++] >> 1;
}
else
{
if (state.EncodeFrom8000Hz)
{
xlow = inputBuffer[j++] >> 1;
}
else
{
// Apply the transmit QMF
// Shuffle the buffer down
for (i = 0; i < 22; i++)
state.QmfSignalHistory[i] = state.QmfSignalHistory[i + 2];
state.QmfSignalHistory[22] = inputBuffer[j++];
state.QmfSignalHistory[23] = inputBuffer[j++];
// Discard every other QMF output
sumeven = 0;
sumodd = 0;
for (i = 0; i < 12; i++)
{
sumodd += state.QmfSignalHistory[2 * i] * qmf_coeffs[i];
sumeven += state.QmfSignalHistory[2 * i + 1] * qmf_coeffs[11 - i];
}
xlow = (sumeven + sumodd) >> 14;
xhigh = (sumeven - sumodd) >> 14;
}
}
// Block 1L, SUBTRA
el = Saturate(xlow - state.Band[0].s);
// Block 1L, QUANTL
wd = (el >= 0) ? el : -(el + 1);
for (i = 1; i < 30; i++)
{
wd1 = (q6[i] * state.Band[0].det) >> 12;
if (wd < wd1)
break;
}
ilow = (el < 0) ? iln[i] : ilp[i];
// Block 2L, INVQAL
ril = ilow >> 2;
wd2 = qm4[ril];
dlow = (state.Band[0].det * wd2) >> 15;
// Block 3L, LOGSCL
il4 = rl42[ril];
wd = (state.Band[0].nb * 127) >> 7;
state.Band[0].nb = wd + wl[il4];
if (state.Band[0].nb < 0)
state.Band[0].nb = 0;
else if (state.Band[0].nb > 18432)
state.Band[0].nb = 18432;
// Block 3L, SCALEL
wd1 = (state.Band[0].nb >> 6) & 31;
wd2 = 8 - (state.Band[0].nb >> 11);
wd3 = (wd2 < 0) ? (ilb[wd1] << -wd2) : (ilb[wd1] >> wd2);
state.Band[0].det = wd3 << 2;
Block4(state, 0, dlow);
if (state.EncodeFrom8000Hz)
{
// Just leave the high bits as zero
code = (0xC0 | ilow) >> (8 - state.BitsPerSample);
}
else
{
// Block 1H, SUBTRA
eh = Saturate(xhigh - state.Band[1].s);
// Block 1H, QUANTH
wd = (eh >= 0) ? eh : -(eh + 1);
wd1 = (564 * state.Band[1].det) >> 12;
mih = (wd >= wd1) ? 2 : 1;
ihigh = (eh < 0) ? ihn[mih] : ihp[mih];
// Block 2H, INVQAH
wd2 = qm2[ihigh];
dhigh = (state.Band[1].det * wd2) >> 15;
// Block 3H, LOGSCH
ih2 = rh2[ihigh];
wd = (state.Band[1].nb * 127) >> 7;
state.Band[1].nb = wd + wh[ih2];
if (state.Band[1].nb < 0)
state.Band[1].nb = 0;
else if (state.Band[1].nb > 22528)
state.Band[1].nb = 22528;
// Block 3H, SCALEH
wd1 = (state.Band[1].nb >> 6) & 31;
wd2 = 10 - (state.Band[1].nb >> 11);
wd3 = (wd2 < 0) ? (ilb[wd1] << -wd2) : (ilb[wd1] >> wd2);
state.Band[1].det = wd3 << 2;
Block4(state, 1, dhigh);
code = ((ihigh << 6) | ilow) >> (8 - state.BitsPerSample);
}
if (state.Packed)
{
// Pack the code bits
state.OutBuffer |= (uint)(code << state.OutBits);
state.OutBits += state.BitsPerSample;
if (state.OutBits >= 8)
{
outputBuffer[g722_bytes++] = (byte)(state.OutBuffer & 0xFF);
state.OutBits -= 8;
state.OutBuffer >>= 8;
}
}
else
{
outputBuffer[g722_bytes++] = (byte)code;
}
}
return g722_bytes;
}
}
/// <summary>
/// Stores state to be used between calls to Encode or Decode
/// </summary>
public class G722CodecState
{
/// <summary>
/// ITU Test Mode
/// TRUE if the operating in the special ITU test mode, with the band split filters disabled.
/// </summary>
public bool ItuTestMode { get; set; }
/// <summary>
/// TRUE if the G.722 data is packed
/// </summary>
public bool Packed { get; private set; }
/// <summary>
/// 8kHz Sampling
/// TRUE if encode from 8k samples/second
/// </summary>
public bool EncodeFrom8000Hz { get; private set; }
/// <summary>
/// Bits Per Sample
/// 6 for 48000kbps, 7 for 56000kbps, or 8 for 64000kbps.
/// </summary>
public int BitsPerSample { get; private set; }
/// <summary>
/// Signal history for the QMF (x)
/// </summary>
public int[] QmfSignalHistory { get; private set; }
/// <summary>
/// Band
/// </summary>
public Band[] Band { get; private set; }
/// <summary>
/// In bit buffer
/// </summary>
public uint InBuffer { get; internal set; }
/// <summary>
/// Number of bits in InBuffer
/// </summary>
public int InBits { get; internal set; }
/// <summary>
/// Out bit buffer
/// </summary>
public uint OutBuffer { get; internal set; }
/// <summary>
/// Number of bits in OutBuffer
/// </summary>
public int OutBits { get; internal set; }
/// <summary>
/// Creates a new instance of G722 Codec State for a
/// new encode or decode session
/// </summary>
/// <param name="rate">Bitrate (typically 64000)</param>
/// <param name="options">Special options</param>
public G722CodecState(int rate, G722Flags options)
{
this.Band = new Band[2] { new Band(), new Band() };
this.QmfSignalHistory = new int[24];
this.ItuTestMode = false;
if (rate == 48000)
this.BitsPerSample = 6;
else if (rate == 56000)
this.BitsPerSample = 7;
else if (rate == 64000)
this.BitsPerSample = 8;
else
throw new ArgumentException("Invalid rate, should be 48000, 56000 or 64000");
if ((options & G722Flags.SampleRate8000) == G722Flags.SampleRate8000)
this.EncodeFrom8000Hz = true;
if (((options & G722Flags.Packed) == G722Flags.Packed) && this.BitsPerSample != 8)
this.Packed = true;
else
this.Packed = false;
this.Band[0].det = 32;
this.Band[1].det = 8;
}
}
/// <summary>
/// Band data for G722 Codec
/// </summary>
public class Band
{
/// <summary>s</summary>
public int s;
/// <summary>sp</summary>
public int sp;
/// <summary>sz</summary>
public int sz;
/// <summary>r</summary>
public int[] r = new int[3];
/// <summary>a</summary>
public int[] a = new int[3];
/// <summary>ap</summary>
public int[] ap = new int[3];
/// <summary>p</summary>
public int[] p = new int[3];
/// <summary>d</summary>
public int[] d = new int[7];
/// <summary>b</summary>
public int[] b = new int[7];
/// <summary>bp</summary>
public int[] bp = new int[7];
/// <summary>sg</summary>
public int[] sg = new int[7];
/// <summary>nb</summary>
public int nb;
/// <summary>det</summary>
public int det;
}
/// <summary>
/// G722 Flags
/// </summary>
[Flags]
public enum G722Flags
{
/// <summary>
/// None
/// </summary>
None = 0,
/// <summary>
/// Using a G722 sample rate of 8000
/// </summary>
SampleRate8000 = 0x0001,
/// <summary>
/// Packed
/// </summary>
Packed = 0x0002
}
}