683 lines
23 KiB
Go
683 lines
23 KiB
Go
|
// Copyright 2017 Hajime Hoshi
|
||
|
|
//
|
||
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
|
|
// you may not use this file except in compliance with the License.
|
||
|
|
// You may obtain a copy of the License at
|
||
|
|
//
|
||
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
//
|
||
|
|
// Unless required by applicable law or agreed to in writing, software
|
||
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
|
|
// See the License for the specific language governing permissions and
|
||
|
|
// limitations under the License.
|
||
|
|
|
||
|
|
package frame
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"io"
|
||
|
|
"math"
|
||
|
|
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/bits"
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/consts"
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/frameheader"
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/imdct"
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/maindata"
|
||
|
|
"github.com/hajimehoshi/go-mp3/internal/sideinfo"
|
||
|
|
)
|
||
|
|
|
||
|
|
var (
|
||
|
|
powtab34 = make([]float64, 8207)
|
||
|
|
pretab = []float64{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 2, 0}
|
||
|
|
)
|
||
|
|
|
||
|
|
func init() {
|
||
|
|
for i := range powtab34 {
|
||
|
|
powtab34[i] = math.Pow(float64(i), 4.0/3.0)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
type Frame struct {
|
||
|
|
header frameheader.FrameHeader
|
||
|
|
sideInfo *sideinfo.SideInfo
|
||
|
|
mainData *maindata.MainData
|
||
|
|
|
||
|
|
mainDataBits *bits.Bits
|
||
|
|
store [2][32][18]float32
|
||
|
|
v_vec [2][1024]float32
|
||
|
|
}
|
||
|
|
|
||
|
|
type FullReader interface {
|
||
|
|
ReadFull([]byte) (int, error)
|
||
|
|
}
|
||
|
|
|
||
|
|
func readCRC(source FullReader) error {
|
||
|
|
buf := make([]byte, 2)
|
||
|
|
if n, err := source.ReadFull(buf); n < 2 {
|
||
|
|
if err == io.EOF {
|
||
|
|
return &consts.UnexpectedEOF{"readCRC"}
|
||
|
|
}
|
||
|
|
return fmt.Errorf("mp3: error at readCRC: %v", err)
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func Read(source FullReader, position int64, prev *Frame) (frame *Frame, startPosition int64, err error) {
|
||
|
|
h, pos, err := frameheader.Read(source, position)
|
||
|
|
if err != nil {
|
||
|
|
return nil, 0, err
|
||
|
|
}
|
||
|
|
|
||
|
|
if h.ProtectionBit() == 0 {
|
||
|
|
if err := readCRC(source); err != nil {
|
||
|
|
return nil, 0, err
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if h.ID() == consts.Version2_5 {
|
||
|
|
return nil, 0, fmt.Errorf("mp3: MPEG version 2.5 is not supported")
|
||
|
|
}
|
||
|
|
if h.Layer() != consts.Layer3 {
|
||
|
|
return nil, 0, fmt.Errorf("mp3: only layer3 (want %d; got %d) is supported", consts.Layer3, h.Layer())
|
||
|
|
}
|
||
|
|
|
||
|
|
si, err := sideinfo.Read(source, h)
|
||
|
|
if err != nil {
|
||
|
|
return nil, 0, err
|
||
|
|
}
|
||
|
|
|
||
|
|
// If there's not enough main data in the bit reservoir,
|
||
|
|
// signal to calling function so that decoding isn't done!
|
||
|
|
// Get main data (scalefactors and Huffman coded frequency data)
|
||
|
|
var prevM *bits.Bits
|
||
|
|
if prev != nil {
|
||
|
|
prevM = prev.mainDataBits
|
||
|
|
}
|
||
|
|
md, mdb, err := maindata.Read(source, prevM, h, si)
|
||
|
|
if err != nil {
|
||
|
|
return nil, 0, err
|
||
|
|
}
|
||
|
|
nf := &Frame{
|
||
|
|
header: h,
|
||
|
|
sideInfo: si,
|
||
|
|
mainData: md,
|
||
|
|
mainDataBits: mdb,
|
||
|
|
}
|
||
|
|
if prev != nil {
|
||
|
|
nf.store = prev.store
|
||
|
|
nf.v_vec = prev.v_vec
|
||
|
|
}
|
||
|
|
return nf, pos, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) SamplingFrequency() (int, error) {
|
||
|
|
return f.header.SamplingFrequencyValue()
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) Decode() []byte {
|
||
|
|
out := make([]byte, f.header.BytesPerFrame())
|
||
|
|
nch := f.header.NumberOfChannels()
|
||
|
|
for gr := 0; gr < f.header.Granules(); gr++ {
|
||
|
|
for ch := 0; ch < nch; ch++ {
|
||
|
|
f.requantize(gr, ch)
|
||
|
|
f.reorder(gr, ch)
|
||
|
|
}
|
||
|
|
f.stereo(gr)
|
||
|
|
for ch := 0; ch < nch; ch++ {
|
||
|
|
f.antialias(gr, ch)
|
||
|
|
f.hybridSynthesis(gr, ch)
|
||
|
|
f.frequencyInversion(gr, ch)
|
||
|
|
f.subbandSynthesis(gr, ch, out[consts.SamplesPerGr*4*gr:])
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return out
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) requantizeProcessLong(gr, ch, is_pos, sfb int) {
|
||
|
|
sf_mult := 0.5
|
||
|
|
if f.sideInfo.ScalefacScale[gr][ch] != 0 {
|
||
|
|
sf_mult = 1.0
|
||
|
|
}
|
||
|
|
pf_x_pt := float64(f.sideInfo.Preflag[gr][ch]) * pretab[sfb]
|
||
|
|
idx := -(sf_mult * (float64(f.mainData.ScalefacL[gr][ch][sfb]) + pf_x_pt)) +
|
||
|
|
0.25*(float64(f.sideInfo.GlobalGain[gr][ch])-210)
|
||
|
|
tmp1 := math.Pow(2.0, idx)
|
||
|
|
tmp2 := 0.0
|
||
|
|
if f.mainData.Is[gr][ch][is_pos] < 0.0 {
|
||
|
|
tmp2 = -powtab34[int(-f.mainData.Is[gr][ch][is_pos])]
|
||
|
|
} else {
|
||
|
|
tmp2 = powtab34[int(f.mainData.Is[gr][ch][is_pos])]
|
||
|
|
}
|
||
|
|
f.mainData.Is[gr][ch][is_pos] = float32(tmp1 * tmp2)
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) requantizeProcessShort(gr, ch, is_pos, sfb, win int) {
|
||
|
|
sf_mult := 0.5
|
||
|
|
if f.sideInfo.ScalefacScale[gr][ch] != 0 {
|
||
|
|
sf_mult = 1.0
|
||
|
|
}
|
||
|
|
idx := -(sf_mult * float64(f.mainData.ScalefacS[gr][ch][sfb][win])) +
|
||
|
|
0.25*(float64(f.sideInfo.GlobalGain[gr][ch])-210.0-
|
||
|
|
8.0*float64(f.sideInfo.SubblockGain[gr][ch][win]))
|
||
|
|
tmp1 := math.Pow(2.0, idx)
|
||
|
|
tmp2 := 0.0
|
||
|
|
if f.mainData.Is[gr][ch][is_pos] < 0 {
|
||
|
|
tmp2 = -powtab34[int(-f.mainData.Is[gr][ch][is_pos])]
|
||
|
|
} else {
|
||
|
|
tmp2 = powtab34[int(f.mainData.Is[gr][ch][is_pos])]
|
||
|
|
}
|
||
|
|
f.mainData.Is[gr][ch][is_pos] = float32(tmp1 * tmp2)
|
||
|
|
}
|
||
|
|
|
||
|
|
func getSfBandIndicesArray(header *frameheader.FrameHeader) ([]int, []int) {
|
||
|
|
sfreq := header.SamplingFrequency() // Setup sampling frequency index
|
||
|
|
lsf := header.LowSamplingFrequency()
|
||
|
|
sfBandIndicesShort := consts.SfBandIndices[lsf][sfreq][consts.SfBandIndicesShort]
|
||
|
|
sfBandIndicesLong := consts.SfBandIndices[lsf][sfreq][consts.SfBandIndicesLong]
|
||
|
|
return sfBandIndicesLong, sfBandIndicesShort
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) requantize(gr int, ch int) {
|
||
|
|
sfBandIndicesLong, sfBandIndicesShort := getSfBandIndicesArray(&f.header)
|
||
|
|
// Determine type of block to process
|
||
|
|
if f.sideInfo.WinSwitchFlag[gr][ch] == 1 && f.sideInfo.BlockType[gr][ch] == 2 { // Short blocks
|
||
|
|
// Check if the first two subbands
|
||
|
|
// (=2*18 samples = 8 long or 3 short sfb's) uses long blocks
|
||
|
|
if f.sideInfo.MixedBlockFlag[gr][ch] != 0 { // 2 longbl. sb first
|
||
|
|
// First process the 2 long block subbands at the start
|
||
|
|
sfb := 0
|
||
|
|
next_sfb := sfBandIndicesLong[sfb+1]
|
||
|
|
for i := 0; i < 36; i++ {
|
||
|
|
if i == next_sfb {
|
||
|
|
sfb++
|
||
|
|
next_sfb = sfBandIndicesLong[sfb+1]
|
||
|
|
}
|
||
|
|
f.requantizeProcessLong(gr, ch, i, sfb)
|
||
|
|
}
|
||
|
|
// And next the remaining,non-zero,bands which uses short blocks
|
||
|
|
sfb = 3
|
||
|
|
next_sfb = sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len := sfBandIndicesShort[sfb+1] -
|
||
|
|
sfBandIndicesShort[sfb]
|
||
|
|
|
||
|
|
for i := 36; i < int(f.sideInfo.Count1[gr][ch]); /* i++ done below! */ {
|
||
|
|
// Check if we're into the next scalefac band
|
||
|
|
if i == next_sfb {
|
||
|
|
sfb++
|
||
|
|
next_sfb = sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len = sfBandIndicesShort[sfb+1] -
|
||
|
|
sfBandIndicesShort[sfb]
|
||
|
|
}
|
||
|
|
for win := 0; win < 3; win++ {
|
||
|
|
for j := 0; j < win_len; j++ {
|
||
|
|
f.requantizeProcessShort(gr, ch, i, sfb, win)
|
||
|
|
i++
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
} else { // Only short blocks
|
||
|
|
sfb := 0
|
||
|
|
next_sfb := sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len := sfBandIndicesShort[sfb+1] -
|
||
|
|
sfBandIndicesShort[sfb]
|
||
|
|
for i := 0; i < int(f.sideInfo.Count1[gr][ch]); /* i++ done below! */ {
|
||
|
|
// Check if we're into the next scalefac band
|
||
|
|
if i == next_sfb {
|
||
|
|
sfb++
|
||
|
|
next_sfb = sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len = sfBandIndicesShort[sfb+1] -
|
||
|
|
sfBandIndicesShort[sfb]
|
||
|
|
}
|
||
|
|
for win := 0; win < 3; win++ {
|
||
|
|
for j := 0; j < win_len; j++ {
|
||
|
|
f.requantizeProcessShort(gr, ch, i, sfb, win)
|
||
|
|
i++
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} else { // Only long blocks
|
||
|
|
sfb := 0
|
||
|
|
next_sfb := sfBandIndicesLong[sfb+1]
|
||
|
|
for i := 0; i < int(f.sideInfo.Count1[gr][ch]); i++ {
|
||
|
|
if i == next_sfb {
|
||
|
|
sfb++
|
||
|
|
next_sfb = sfBandIndicesLong[sfb+1]
|
||
|
|
}
|
||
|
|
f.requantizeProcessLong(gr, ch, i, sfb)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) reorder(gr int, ch int) {
|
||
|
|
re := make([]float32, consts.SamplesPerGr)
|
||
|
|
|
||
|
|
_, sfBandIndicesShort := getSfBandIndicesArray(&f.header)
|
||
|
|
|
||
|
|
// Only reorder short blocks
|
||
|
|
if (f.sideInfo.WinSwitchFlag[gr][ch] == 1) && (f.sideInfo.BlockType[gr][ch] == 2) { // Short blocks
|
||
|
|
// Check if the first two subbands
|
||
|
|
// (=2*18 samples = 8 long or 3 short sfb's) uses long blocks
|
||
|
|
sfb := 0
|
||
|
|
// 2 longbl. sb first
|
||
|
|
if f.sideInfo.MixedBlockFlag[gr][ch] != 0 {
|
||
|
|
sfb = 3
|
||
|
|
}
|
||
|
|
next_sfb := sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len := sfBandIndicesShort[sfb+1] - sfBandIndicesShort[sfb]
|
||
|
|
i := 36
|
||
|
|
if sfb == 0 {
|
||
|
|
i = 0
|
||
|
|
}
|
||
|
|
for i < consts.SamplesPerGr {
|
||
|
|
// Check if we're into the next scalefac band
|
||
|
|
if i == next_sfb {
|
||
|
|
// Copy reordered data back to the original vector
|
||
|
|
j := 3 * sfBandIndicesShort[sfb]
|
||
|
|
copy(f.mainData.Is[gr][ch][j:j+3*win_len], re[0:3*win_len])
|
||
|
|
// Check if this band is above the rzero region,if so we're done
|
||
|
|
if i >= f.sideInfo.Count1[gr][ch] {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
sfb++
|
||
|
|
next_sfb = sfBandIndicesShort[sfb+1] * 3
|
||
|
|
win_len = sfBandIndicesShort[sfb+1] - sfBandIndicesShort[sfb]
|
||
|
|
}
|
||
|
|
for win := 0; win < 3; win++ { // Do the actual reordering
|
||
|
|
for j := 0; j < win_len; j++ {
|
||
|
|
re[j*3+win] = f.mainData.Is[gr][ch][i]
|
||
|
|
i++
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// Copy reordered data of last band back to original vector
|
||
|
|
j := 3 * sfBandIndicesShort[12]
|
||
|
|
copy(f.mainData.Is[gr][ch][j:j+3*win_len], re[0:3*win_len])
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
var (
|
||
|
|
isRatios = []float32{0.000000, 0.267949, 0.577350, 1.000000, 1.732051, 3.732051}
|
||
|
|
)
|
||
|
|
|
||
|
|
func (f *Frame) stereoProcessIntensityLong(gr int, sfb int) {
|
||
|
|
is_ratio_l := float32(0)
|
||
|
|
is_ratio_r := float32(0)
|
||
|
|
// Check that((is_pos[sfb]=scalefac) < 7) => no intensity stereo
|
||
|
|
if is_pos := f.mainData.ScalefacL[gr][0][sfb]; is_pos < 7 {
|
||
|
|
sfBandIndicesLong, _ := getSfBandIndicesArray(&f.header)
|
||
|
|
sfb_start := sfBandIndicesLong[sfb]
|
||
|
|
sfb_stop := sfBandIndicesLong[sfb+1]
|
||
|
|
if is_pos == 6 { // tan((6*PI)/12 = PI/2) needs special treatment!
|
||
|
|
is_ratio_l = 1.0
|
||
|
|
is_ratio_r = 0.0
|
||
|
|
} else {
|
||
|
|
is_ratio_l = isRatios[is_pos] / (1.0 + isRatios[is_pos])
|
||
|
|
is_ratio_r = 1.0 / (1.0 + isRatios[is_pos])
|
||
|
|
}
|
||
|
|
// Now decode all samples in this scale factor band
|
||
|
|
for i := sfb_start; i < sfb_stop; i++ {
|
||
|
|
f.mainData.Is[gr][0][i] *= is_ratio_l
|
||
|
|
f.mainData.Is[gr][1][i] *= is_ratio_r
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) stereoProcessIntensityShort(gr int, sfb int) {
|
||
|
|
is_ratio_l := float32(0)
|
||
|
|
is_ratio_r := float32(0)
|
||
|
|
_, sfBandIndicesShort := getSfBandIndicesArray(&f.header)
|
||
|
|
// The window length
|
||
|
|
win_len := sfBandIndicesShort[sfb+1] - sfBandIndicesShort[sfb]
|
||
|
|
// The three windows within the band has different scalefactors
|
||
|
|
for win := 0; win < 3; win++ {
|
||
|
|
// Check that((is_pos[sfb]=scalefac) < 7) => no intensity stereo
|
||
|
|
is_pos := f.mainData.ScalefacS[gr][0][sfb][win]
|
||
|
|
if is_pos < 7 {
|
||
|
|
sfb_start := sfBandIndicesShort[sfb]*3 + win_len*win
|
||
|
|
sfb_stop := sfb_start + win_len
|
||
|
|
if is_pos == 6 { // tan((6*PI)/12 = PI/2) needs special treatment!
|
||
|
|
is_ratio_l = 1.0
|
||
|
|
is_ratio_r = 0.0
|
||
|
|
} else {
|
||
|
|
is_ratio_l = isRatios[is_pos] / (1.0 + isRatios[is_pos])
|
||
|
|
is_ratio_r = 1.0 / (1.0 + isRatios[is_pos])
|
||
|
|
}
|
||
|
|
// Now decode all samples in this scale factor band
|
||
|
|
for i := sfb_start; i < sfb_stop; i++ {
|
||
|
|
// https://github.com/technosaurus/PDMP3/issues/3
|
||
|
|
f.mainData.Is[gr][0][i] *= is_ratio_l
|
||
|
|
f.mainData.Is[gr][1][i] *= is_ratio_r
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) stereo(gr int) {
|
||
|
|
if f.header.UseMSStereo() {
|
||
|
|
// Determine how many frequency lines to transform
|
||
|
|
i := 1
|
||
|
|
if f.sideInfo.Count1[gr][0] > f.sideInfo.Count1[gr][1] {
|
||
|
|
i = 0
|
||
|
|
}
|
||
|
|
max_pos := int(f.sideInfo.Count1[gr][i])
|
||
|
|
// Do the actual processing
|
||
|
|
const invSqrt2 = math.Sqrt2 / 2
|
||
|
|
for i := 0; i < max_pos; i++ {
|
||
|
|
left := (f.mainData.Is[gr][0][i] + f.mainData.Is[gr][1][i]) * invSqrt2
|
||
|
|
right := (f.mainData.Is[gr][0][i] - f.mainData.Is[gr][1][i]) * invSqrt2
|
||
|
|
f.mainData.Is[gr][0][i] = left
|
||
|
|
f.mainData.Is[gr][1][i] = right
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if f.header.UseIntensityStereo() {
|
||
|
|
sfBandIndicesLong, sfBandIndicesShort := getSfBandIndicesArray(&f.header)
|
||
|
|
// First band that is intensity stereo encoded is first band scale factor
|
||
|
|
// band on or above count1 frequency line. N.B.: Intensity stereo coding is
|
||
|
|
// only done for higher subbands, but logic is here for lower subbands.
|
||
|
|
// Determine type of block to process
|
||
|
|
if (f.sideInfo.WinSwitchFlag[gr][0] == 1) &&
|
||
|
|
(f.sideInfo.BlockType[gr][0] == 2) { // Short blocks
|
||
|
|
// Check if the first two subbands
|
||
|
|
// (=2*18 samples = 8 long or 3 short sfb's) uses long blocks
|
||
|
|
if f.sideInfo.MixedBlockFlag[gr][0] != 0 { // 2 longbl. sb first
|
||
|
|
for sfb := 0; sfb < 8; sfb++ { // First process 8 sfb's at start
|
||
|
|
// Is this scale factor band above count1 for the right channel?
|
||
|
|
if sfBandIndicesLong[sfb] >= f.sideInfo.Count1[gr][1] {
|
||
|
|
f.stereoProcessIntensityLong(gr, sfb)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
// And next the remaining bands which uses short blocks
|
||
|
|
for sfb := 3; sfb < 12; sfb++ {
|
||
|
|
// Is this scale factor band above count1 for the right channel?
|
||
|
|
if sfBandIndicesShort[sfb]*3 >= f.sideInfo.Count1[gr][1] {
|
||
|
|
f.stereoProcessIntensityShort(gr, sfb)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} else { // Only short blocks
|
||
|
|
for sfb := 0; sfb < 12; sfb++ {
|
||
|
|
// Is this scale factor band above count1 for the right channel?
|
||
|
|
if sfBandIndicesShort[sfb]*3 >= f.sideInfo.Count1[gr][1] {
|
||
|
|
f.stereoProcessIntensityShort(gr, sfb)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} else { // Only long blocks
|
||
|
|
for sfb := 0; sfb < 21; sfb++ {
|
||
|
|
// Is this scale factor band above count1 for the right channel?
|
||
|
|
if sfBandIndicesLong[sfb] >= f.sideInfo.Count1[gr][1] {
|
||
|
|
f.stereoProcessIntensityLong(gr, sfb)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
var (
|
||
|
|
cs = []float32{0.857493, 0.881742, 0.949629, 0.983315, 0.995518, 0.999161, 0.999899, 0.999993}
|
||
|
|
ca = []float32{-0.514496, -0.471732, -0.313377, -0.181913, -0.094574, -0.040966, -0.014199, -0.003700}
|
||
|
|
)
|
||
|
|
|
||
|
|
func (f *Frame) antialias(gr int, ch int) {
|
||
|
|
// No antialiasing is done for short blocks
|
||
|
|
if (f.sideInfo.WinSwitchFlag[gr][ch] == 1) &&
|
||
|
|
(f.sideInfo.BlockType[gr][ch] == 2) &&
|
||
|
|
(f.sideInfo.MixedBlockFlag[gr][ch]) == 0 {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
// Setup the limit for how many subbands to transform
|
||
|
|
sblim := 32
|
||
|
|
if (f.sideInfo.WinSwitchFlag[gr][ch] == 1) &&
|
||
|
|
(f.sideInfo.BlockType[gr][ch] == 2) &&
|
||
|
|
(f.sideInfo.MixedBlockFlag[gr][ch] == 1) {
|
||
|
|
sblim = 2
|
||
|
|
}
|
||
|
|
// Do the actual antialiasing
|
||
|
|
for sb := 1; sb < sblim; sb++ {
|
||
|
|
for i := 0; i < 8; i++ {
|
||
|
|
li := 18*sb - 1 - i
|
||
|
|
ui := 18*sb + i
|
||
|
|
lb := f.mainData.Is[gr][ch][li]*cs[i] - f.mainData.Is[gr][ch][ui]*ca[i]
|
||
|
|
ub := f.mainData.Is[gr][ch][ui]*cs[i] + f.mainData.Is[gr][ch][li]*ca[i]
|
||
|
|
f.mainData.Is[gr][ch][li] = lb
|
||
|
|
f.mainData.Is[gr][ch][ui] = ub
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) hybridSynthesis(gr int, ch int) {
|
||
|
|
// Loop through all 32 subbands
|
||
|
|
for sb := 0; sb < 32; sb++ {
|
||
|
|
// Determine blocktype for this subband
|
||
|
|
bt := int(f.sideInfo.BlockType[gr][ch])
|
||
|
|
if (f.sideInfo.WinSwitchFlag[gr][ch] == 1) &&
|
||
|
|
(f.sideInfo.MixedBlockFlag[gr][ch] == 1) && (sb < 2) {
|
||
|
|
bt = 0
|
||
|
|
}
|
||
|
|
// Do the inverse modified DCT and windowing
|
||
|
|
in := make([]float32, 18)
|
||
|
|
for i := range in {
|
||
|
|
in[i] = f.mainData.Is[gr][ch][sb*18+i]
|
||
|
|
}
|
||
|
|
rawout := imdct.Win(in, bt)
|
||
|
|
// Overlapp add with stored vector into main_data vector
|
||
|
|
for i := 0; i < 18; i++ {
|
||
|
|
f.mainData.Is[gr][ch][sb*18+i] = rawout[i] + f.store[ch][sb][i]
|
||
|
|
f.store[ch][sb][i] = rawout[i+18]
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) frequencyInversion(gr int, ch int) {
|
||
|
|
for sb := 1; sb < 32; sb += 2 {
|
||
|
|
for i := 1; i < 18; i += 2 {
|
||
|
|
f.mainData.Is[gr][ch][sb*18+i] = -f.mainData.Is[gr][ch][sb*18+i]
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
var synthNWin = [64][32]float32{}
|
||
|
|
|
||
|
|
func init() {
|
||
|
|
for i := 0; i < 64; i++ {
|
||
|
|
for j := 0; j < 32; j++ {
|
||
|
|
synthNWin[i][j] =
|
||
|
|
float32(math.Cos(float64((16+i)*(2*j+1)) * (math.Pi / 64.0)))
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
var synthDtbl = [512]float32{
|
||
|
|
0.000000000, -0.000015259, -0.000015259, -0.000015259,
|
||
|
|
-0.000015259, -0.000015259, -0.000015259, -0.000030518,
|
||
|
|
-0.000030518, -0.000030518, -0.000030518, -0.000045776,
|
||
|
|
-0.000045776, -0.000061035, -0.000061035, -0.000076294,
|
||
|
|
-0.000076294, -0.000091553, -0.000106812, -0.000106812,
|
||
|
|
-0.000122070, -0.000137329, -0.000152588, -0.000167847,
|
||
|
|
-0.000198364, -0.000213623, -0.000244141, -0.000259399,
|
||
|
|
-0.000289917, -0.000320435, -0.000366211, -0.000396729,
|
||
|
|
-0.000442505, -0.000473022, -0.000534058, -0.000579834,
|
||
|
|
-0.000625610, -0.000686646, -0.000747681, -0.000808716,
|
||
|
|
-0.000885010, -0.000961304, -0.001037598, -0.001113892,
|
||
|
|
-0.001205444, -0.001296997, -0.001388550, -0.001480103,
|
||
|
|
-0.001586914, -0.001693726, -0.001785278, -0.001907349,
|
||
|
|
-0.002014160, -0.002120972, -0.002243042, -0.002349854,
|
||
|
|
-0.002456665, -0.002578735, -0.002685547, -0.002792358,
|
||
|
|
-0.002899170, -0.002990723, -0.003082275, -0.003173828,
|
||
|
|
0.003250122, 0.003326416, 0.003387451, 0.003433228,
|
||
|
|
0.003463745, 0.003479004, 0.003479004, 0.003463745,
|
||
|
|
0.003417969, 0.003372192, 0.003280640, 0.003173828,
|
||
|
|
0.003051758, 0.002883911, 0.002700806, 0.002487183,
|
||
|
|
0.002227783, 0.001937866, 0.001617432, 0.001266479,
|
||
|
|
0.000869751, 0.000442505, -0.000030518, -0.000549316,
|
||
|
|
-0.001098633, -0.001693726, -0.002334595, -0.003005981,
|
||
|
|
-0.003723145, -0.004486084, -0.005294800, -0.006118774,
|
||
|
|
-0.007003784, -0.007919312, -0.008865356, -0.009841919,
|
||
|
|
-0.010848999, -0.011886597, -0.012939453, -0.014022827,
|
||
|
|
-0.015121460, -0.016235352, -0.017349243, -0.018463135,
|
||
|
|
-0.019577026, -0.020690918, -0.021789551, -0.022857666,
|
||
|
|
-0.023910522, -0.024932861, -0.025909424, -0.026840210,
|
||
|
|
-0.027725220, -0.028533936, -0.029281616, -0.029937744,
|
||
|
|
-0.030532837, -0.031005859, -0.031387329, -0.031661987,
|
||
|
|
-0.031814575, -0.031845093, -0.031738281, -0.031478882,
|
||
|
|
0.031082153, 0.030517578, 0.029785156, 0.028884888,
|
||
|
|
0.027801514, 0.026535034, 0.025085449, 0.023422241,
|
||
|
|
0.021575928, 0.019531250, 0.017257690, 0.014801025,
|
||
|
|
0.012115479, 0.009231567, 0.006134033, 0.002822876,
|
||
|
|
-0.000686646, -0.004394531, -0.008316040, -0.012420654,
|
||
|
|
-0.016708374, -0.021179199, -0.025817871, -0.030609131,
|
||
|
|
-0.035552979, -0.040634155, -0.045837402, -0.051132202,
|
||
|
|
-0.056533813, -0.061996460, -0.067520142, -0.073059082,
|
||
|
|
-0.078628540, -0.084182739, -0.089706421, -0.095169067,
|
||
|
|
-0.100540161, -0.105819702, -0.110946655, -0.115921021,
|
||
|
|
-0.120697021, -0.125259399, -0.129562378, -0.133590698,
|
||
|
|
-0.137298584, -0.140670776, -0.143676758, -0.146255493,
|
||
|
|
-0.148422241, -0.150115967, -0.151306152, -0.151962280,
|
||
|
|
-0.152069092, -0.151596069, -0.150497437, -0.148773193,
|
||
|
|
-0.146362305, -0.143264771, -0.139450073, -0.134887695,
|
||
|
|
-0.129577637, -0.123474121, -0.116577148, -0.108856201,
|
||
|
|
0.100311279, 0.090927124, 0.080688477, 0.069595337,
|
||
|
|
0.057617188, 0.044784546, 0.031082153, 0.016510010,
|
||
|
|
0.001068115, -0.015228271, -0.032379150, -0.050354004,
|
||
|
|
-0.069168091, -0.088775635, -0.109161377, -0.130310059,
|
||
|
|
-0.152206421, -0.174789429, -0.198059082, -0.221984863,
|
||
|
|
-0.246505737, -0.271591187, -0.297210693, -0.323318481,
|
||
|
|
-0.349868774, -0.376800537, -0.404083252, -0.431655884,
|
||
|
|
-0.459472656, -0.487472534, -0.515609741, -0.543823242,
|
||
|
|
-0.572036743, -0.600219727, -0.628295898, -0.656219482,
|
||
|
|
-0.683914185, -0.711318970, -0.738372803, -0.765029907,
|
||
|
|
-0.791213989, -0.816864014, -0.841949463, -0.866363525,
|
||
|
|
-0.890090942, -0.913055420, -0.935195923, -0.956481934,
|
||
|
|
-0.976852417, -0.996246338, -1.014617920, -1.031936646,
|
||
|
|
-1.048156738, -1.063217163, -1.077117920, -1.089782715,
|
||
|
|
-1.101211548, -1.111373901, -1.120223999, -1.127746582,
|
||
|
|
-1.133926392, -1.138763428, -1.142211914, -1.144287109,
|
||
|
|
1.144989014, 1.144287109, 1.142211914, 1.138763428,
|
||
|
|
1.133926392, 1.127746582, 1.120223999, 1.111373901,
|
||
|
|
1.101211548, 1.089782715, 1.077117920, 1.063217163,
|
||
|
|
1.048156738, 1.031936646, 1.014617920, 0.996246338,
|
||
|
|
0.976852417, 0.956481934, 0.935195923, 0.913055420,
|
||
|
|
0.890090942, 0.866363525, 0.841949463, 0.816864014,
|
||
|
|
0.791213989, 0.765029907, 0.738372803, 0.711318970,
|
||
|
|
0.683914185, 0.656219482, 0.628295898, 0.600219727,
|
||
|
|
0.572036743, 0.543823242, 0.515609741, 0.487472534,
|
||
|
|
0.459472656, 0.431655884, 0.404083252, 0.376800537,
|
||
|
|
0.349868774, 0.323318481, 0.297210693, 0.271591187,
|
||
|
|
0.246505737, 0.221984863, 0.198059082, 0.174789429,
|
||
|
|
0.152206421, 0.130310059, 0.109161377, 0.088775635,
|
||
|
|
0.069168091, 0.050354004, 0.032379150, 0.015228271,
|
||
|
|
-0.001068115, -0.016510010, -0.031082153, -0.044784546,
|
||
|
|
-0.057617188, -0.069595337, -0.080688477, -0.090927124,
|
||
|
|
0.100311279, 0.108856201, 0.116577148, 0.123474121,
|
||
|
|
0.129577637, 0.134887695, 0.139450073, 0.143264771,
|
||
|
|
0.146362305, 0.148773193, 0.150497437, 0.151596069,
|
||
|
|
0.152069092, 0.151962280, 0.151306152, 0.150115967,
|
||
|
|
0.148422241, 0.146255493, 0.143676758, 0.140670776,
|
||
|
|
0.137298584, 0.133590698, 0.129562378, 0.125259399,
|
||
|
|
0.120697021, 0.115921021, 0.110946655, 0.105819702,
|
||
|
|
0.100540161, 0.095169067, 0.089706421, 0.084182739,
|
||
|
|
0.078628540, 0.073059082, 0.067520142, 0.061996460,
|
||
|
|
0.056533813, 0.051132202, 0.045837402, 0.040634155,
|
||
|
|
0.035552979, 0.030609131, 0.025817871, 0.021179199,
|
||
|
|
0.016708374, 0.012420654, 0.008316040, 0.004394531,
|
||
|
|
0.000686646, -0.002822876, -0.006134033, -0.009231567,
|
||
|
|
-0.012115479, -0.014801025, -0.017257690, -0.019531250,
|
||
|
|
-0.021575928, -0.023422241, -0.025085449, -0.026535034,
|
||
|
|
-0.027801514, -0.028884888, -0.029785156, -0.030517578,
|
||
|
|
0.031082153, 0.031478882, 0.031738281, 0.031845093,
|
||
|
|
0.031814575, 0.031661987, 0.031387329, 0.031005859,
|
||
|
|
0.030532837, 0.029937744, 0.029281616, 0.028533936,
|
||
|
|
0.027725220, 0.026840210, 0.025909424, 0.024932861,
|
||
|
|
0.023910522, 0.022857666, 0.021789551, 0.020690918,
|
||
|
|
0.019577026, 0.018463135, 0.017349243, 0.016235352,
|
||
|
|
0.015121460, 0.014022827, 0.012939453, 0.011886597,
|
||
|
|
0.010848999, 0.009841919, 0.008865356, 0.007919312,
|
||
|
|
0.007003784, 0.006118774, 0.005294800, 0.004486084,
|
||
|
|
0.003723145, 0.003005981, 0.002334595, 0.001693726,
|
||
|
|
0.001098633, 0.000549316, 0.000030518, -0.000442505,
|
||
|
|
-0.000869751, -0.001266479, -0.001617432, -0.001937866,
|
||
|
|
-0.002227783, -0.002487183, -0.002700806, -0.002883911,
|
||
|
|
-0.003051758, -0.003173828, -0.003280640, -0.003372192,
|
||
|
|
-0.003417969, -0.003463745, -0.003479004, -0.003479004,
|
||
|
|
-0.003463745, -0.003433228, -0.003387451, -0.003326416,
|
||
|
|
0.003250122, 0.003173828, 0.003082275, 0.002990723,
|
||
|
|
0.002899170, 0.002792358, 0.002685547, 0.002578735,
|
||
|
|
0.002456665, 0.002349854, 0.002243042, 0.002120972,
|
||
|
|
0.002014160, 0.001907349, 0.001785278, 0.001693726,
|
||
|
|
0.001586914, 0.001480103, 0.001388550, 0.001296997,
|
||
|
|
0.001205444, 0.001113892, 0.001037598, 0.000961304,
|
||
|
|
0.000885010, 0.000808716, 0.000747681, 0.000686646,
|
||
|
|
0.000625610, 0.000579834, 0.000534058, 0.000473022,
|
||
|
|
0.000442505, 0.000396729, 0.000366211, 0.000320435,
|
||
|
|
0.000289917, 0.000259399, 0.000244141, 0.000213623,
|
||
|
|
0.000198364, 0.000167847, 0.000152588, 0.000137329,
|
||
|
|
0.000122070, 0.000106812, 0.000106812, 0.000091553,
|
||
|
|
0.000076294, 0.000076294, 0.000061035, 0.000061035,
|
||
|
|
0.000045776, 0.000045776, 0.000030518, 0.000030518,
|
||
|
|
0.000030518, 0.000030518, 0.000015259, 0.000015259,
|
||
|
|
0.000015259, 0.000015259, 0.000015259, 0.000015259,
|
||
|
|
}
|
||
|
|
|
||
|
|
func (f *Frame) subbandSynthesis(gr int, ch int, out []byte) {
|
||
|
|
u_vec := make([]float32, 512)
|
||
|
|
s_vec := make([]float32, 32)
|
||
|
|
|
||
|
|
nch := f.header.NumberOfChannels()
|
||
|
|
// Setup the n_win windowing vector and the v_vec intermediate vector
|
||
|
|
for ss := 0; ss < 18; ss++ { // Loop through 18 samples in 32 subbands
|
||
|
|
copy(f.v_vec[ch][64:1024], f.v_vec[ch][0:1024-64])
|
||
|
|
d := f.mainData.Is[gr][ch]
|
||
|
|
for i := 0; i < 32; i++ { // Copy next 32 time samples to a temp vector
|
||
|
|
s_vec[i] = d[i*18+ss]
|
||
|
|
}
|
||
|
|
for i := 0; i < 64; i++ { // Matrix multiply input with n_win[][] matrix
|
||
|
|
sum := float32(0)
|
||
|
|
for j := 0; j < 32; j++ {
|
||
|
|
sum += synthNWin[i][j] * s_vec[j]
|
||
|
|
}
|
||
|
|
f.v_vec[ch][i] = sum
|
||
|
|
}
|
||
|
|
v := f.v_vec[ch]
|
||
|
|
for i := 0; i < 512; i += 64 { // Build the U vector
|
||
|
|
copy(u_vec[i:i+32], v[(i<<1):(i<<1)+32])
|
||
|
|
copy(u_vec[i+32:i+64], v[(i<<1)+96:(i<<1)+128])
|
||
|
|
}
|
||
|
|
for i := 0; i < 512; i++ { // Window by u_vec[i] with synthDtbl[i]
|
||
|
|
u_vec[i] *= synthDtbl[i]
|
||
|
|
}
|
||
|
|
for i := 0; i < 32; i++ { // Calc 32 samples,store in outdata vector
|
||
|
|
sum := float32(0)
|
||
|
|
for j := 0; j < 512; j += 32 {
|
||
|
|
sum += u_vec[j+i]
|
||
|
|
}
|
||
|
|
// sum now contains time sample 32*ss+i. Convert to 16-bit signed int
|
||
|
|
samp := int(sum * 32767)
|
||
|
|
if samp > 32767 {
|
||
|
|
samp = 32767
|
||
|
|
} else if samp < -32767 {
|
||
|
|
samp = -32767
|
||
|
|
}
|
||
|
|
s := int16(samp)
|
||
|
|
idx := 4 * (32*ss + i)
|
||
|
|
if nch == 1 {
|
||
|
|
// We always run in stereo mode and duplicate channels here for mono.
|
||
|
|
out[idx] = byte(s)
|
||
|
|
out[idx+1] = byte(s >> 8)
|
||
|
|
out[idx+2] = byte(s)
|
||
|
|
out[idx+3] = byte(s >> 8)
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
if ch == 0 {
|
||
|
|
out[idx] = byte(s)
|
||
|
|
out[idx+1] = byte(s >> 8)
|
||
|
|
} else {
|
||
|
|
out[idx+2] = byte(s)
|
||
|
|
out[idx+3] = byte(s >> 8)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|