mirror of
https://github.com/wader/fq.git
synced 2024-11-27 14:14:58 +03:00
661 lines
22 KiB
Go
661 lines
22 KiB
Go
package flac
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
"math/bits"
|
|
|
|
"github.com/wader/fq/format"
|
|
"github.com/wader/fq/format/registry"
|
|
"github.com/wader/fq/internal/num"
|
|
"github.com/wader/fq/pkg/crc"
|
|
"github.com/wader/fq/pkg/decode"
|
|
)
|
|
|
|
func init() {
|
|
registry.MustRegister(&decode.Format{
|
|
Name: format.FLAC_FRAME,
|
|
Description: "FLAC frame",
|
|
DecodeFn: frameDecode,
|
|
})
|
|
}
|
|
|
|
const (
|
|
BlockingStrategyFixed = iota
|
|
BlockingStrategyVariable
|
|
)
|
|
|
|
var BlockingStrategyNames = map[uint]string{
|
|
BlockingStrategyFixed: "Fixed",
|
|
BlockingStrategyVariable: "Variable",
|
|
}
|
|
|
|
const (
|
|
SubframeConstant = iota
|
|
SubframeVerbatim
|
|
SubframeFixed
|
|
SubframeLPC
|
|
)
|
|
|
|
var SubframeTypeNames = map[uint]string{
|
|
SubframeConstant: "Constant",
|
|
SubframeVerbatim: "Verbatim",
|
|
SubframeFixed: "Fixed",
|
|
SubframeLPC: "LPC",
|
|
}
|
|
|
|
const (
|
|
ChannelLeftSide = 0b1000
|
|
ChannelSideRight = 0b1001
|
|
ChannelMidSide = 0b1010
|
|
)
|
|
|
|
// TODO: generic enough?
|
|
func utf8Uint(d *decode.D) uint64 {
|
|
n := d.U8()
|
|
// leading ones, bit negate and count zeroes
|
|
c := bits.LeadingZeros8(^uint8(n))
|
|
switch c {
|
|
case 0:
|
|
// nop
|
|
case 1:
|
|
// TODO: error
|
|
panic("invalid UTF8Uint")
|
|
default:
|
|
n = n & ((1 << (8 - c - 1)) - 1)
|
|
for i := 1; i < c; i++ {
|
|
n = n<<6 | d.U8()&0x3f
|
|
}
|
|
}
|
|
return n
|
|
}
|
|
|
|
// in argument is an optional FlacFrameIn struct with stream info
|
|
func frameDecode(d *decode.D, in interface{}) interface{} {
|
|
var inStreamInfo *format.FlacMetadatablockStreamInfo
|
|
ffi, ok := in.(format.FlacFrameIn)
|
|
if ok {
|
|
inStreamInfo = &ffi.StreamInfo
|
|
}
|
|
|
|
frameStart := d.Pos()
|
|
|
|
var channels uint64
|
|
sampleSize := 0
|
|
blockSize := 0
|
|
channelAssignment := -1
|
|
sideChannelIndex := -1
|
|
|
|
d.FieldStructFn("header", func(d *decode.D) {
|
|
// <14> 11111111111110
|
|
d.FieldValidateUFn("sync", 0b11111111111110, d.U14)
|
|
|
|
// <1> Reserved
|
|
// 0 : mandatory value
|
|
// 1 : reserved for future use
|
|
d.FieldValidateUFn("reserved0", 0, d.U1)
|
|
|
|
// <1> Blocking strategy:
|
|
// 0 : fixed-blocksize stream; frame header encodes the frame number
|
|
// 1 : variable-blocksize stream; frame header encodes the sample number
|
|
blockingStrategy := d.FieldUFn("blocking_strategy", func() (uint64, decode.DisplayFormat, string) {
|
|
switch d.U1() {
|
|
case 0:
|
|
return BlockingStrategyFixed, decode.NumberDecimal, BlockingStrategyNames[BlockingStrategyFixed]
|
|
default:
|
|
return BlockingStrategyVariable, decode.NumberDecimal, BlockingStrategyNames[BlockingStrategyVariable]
|
|
}
|
|
})
|
|
|
|
// <4> Block size in inter-channel samples:
|
|
// 0000 : reserved
|
|
// 0001 : 192 samples
|
|
// 0010-0101 : 576 * (2^(n-2)) samples, i.e. 576/1152/2304/4608
|
|
// 0110 : get 8 bit (blocksize-1) from end of header
|
|
// 0111 : get 16 bit (blocksize-1) from end of header
|
|
// 1000-1111 : 256 * (2^(n-8)) samples, i.e. 256/512/1024/2048/4096/8192/16384/32768
|
|
var blockSizeBits uint64
|
|
blockSize = int(d.FieldUFn("block_size", func() (uint64, decode.DisplayFormat, string) {
|
|
blockSizeBits = d.U4()
|
|
switch blockSizeBits {
|
|
case 0b0000:
|
|
return 0, decode.NumberDecimal, "reserved"
|
|
case 0b0001:
|
|
return 192, decode.NumberDecimal, ""
|
|
case 0b0010, 0b0011, 0b0100, 0b0101:
|
|
return 576 * (1 << (blockSizeBits - 2)), decode.NumberDecimal, ""
|
|
case 0b0110:
|
|
return 0, decode.NumberDecimal, "end of header (8 bit)"
|
|
case 0b0111:
|
|
return 0, decode.NumberDecimal, "end of header (16 bit)"
|
|
default:
|
|
return 256 * (1 << (blockSizeBits - 8)), decode.NumberDecimal, ""
|
|
}
|
|
}))
|
|
|
|
// <4> Sample rate:
|
|
// 0000 : get from STREAMINFO metadata block
|
|
// 0001 : 88.2kHz
|
|
// 0010 : 176.4kHz
|
|
// 0011 : 192kHz
|
|
// 0100 : 8kHz
|
|
// 0101 : 16kHz
|
|
// 0110 : 22.05kHz
|
|
// 0111 : 24kHz
|
|
// 1000 : 32kHz
|
|
// 1001 : 44.1kHz
|
|
// 1010 : 48kHz
|
|
// 1011 : 96kHz
|
|
// 1100 : get 8 bit sample rate (in kHz) from end of header
|
|
// 1101 : get 16 bit sample rate (in Hz) from end of header
|
|
// 1110 : get 16 bit sample rate (in tens of Hz) from end of header
|
|
// 1111 : invalid, to prevent sync-fooling string of 1s
|
|
var sampleRateBits uint64
|
|
d.FieldUFn("sample_rate", func() (uint64, decode.DisplayFormat, string) {
|
|
sampleRateBits = d.U4()
|
|
switch sampleRateBits {
|
|
case 0:
|
|
if inStreamInfo == nil {
|
|
d.Invalid("streaminfo required for sample rate")
|
|
}
|
|
return inStreamInfo.SampleRate, decode.NumberDecimal, "streaminfo"
|
|
case 0b0001:
|
|
return 88200, decode.NumberDecimal, ""
|
|
case 0b0010:
|
|
return 176000, decode.NumberDecimal, ""
|
|
case 0b0011:
|
|
return 19200, decode.NumberDecimal, ""
|
|
case 0b0100:
|
|
return 800, decode.NumberDecimal, ""
|
|
case 0b0101:
|
|
return 1600, decode.NumberDecimal, ""
|
|
case 0b0110:
|
|
return 22050, decode.NumberDecimal, ""
|
|
case 0b0111:
|
|
return 44100, decode.NumberDecimal, ""
|
|
case 0b1000:
|
|
return 32000, decode.NumberDecimal, ""
|
|
case 0b1001:
|
|
return 44100, decode.NumberDecimal, ""
|
|
case 0b1010:
|
|
return 48000, decode.NumberDecimal, ""
|
|
case 0b1011:
|
|
return 96000, decode.NumberDecimal, ""
|
|
case 0b1100:
|
|
return 0, decode.NumberDecimal, "end of header (8 bit*1000)"
|
|
case 0b1101:
|
|
return 0, decode.NumberDecimal, "end of header (16 bit)"
|
|
case 0b1110:
|
|
return 0, decode.NumberDecimal, "end of header (16 bit*10)"
|
|
default:
|
|
return 0, decode.NumberDecimal, "invalid"
|
|
}
|
|
})
|
|
|
|
// <4> Channel assignment
|
|
// 0000-0111 : (number of independent channels)-1. Where defined, the channel order follows SMPTE/ITU-R recommendations. The assignments are as follows:
|
|
// 1 channel: mono
|
|
// 2 channels: left, right
|
|
// 3 channels: left, right, center
|
|
// 4 channels: front left, front right, back left, back right
|
|
// 5 channels: front left, front right, front center, back/surround left, back/surround right
|
|
// 6 channels: front left, front right, front center, LFE, back/surround left, back/surround right
|
|
// 7 channels: front left, front right, front center, LFE, back center, side left, side right
|
|
// 8 channels: front left, front right, front center, LFE, back left, back right, side left, side right
|
|
// 1000 : left/side stereo: channel 0 is the left channel, channel 1 is the side(difference) channel
|
|
// 1001 : right/side stereo: channel 0 is the side(difference) channel, channel 1 is the right channel
|
|
// 1010 : mid/side stereo: channel 0 is the mid(average) channel, channel 1 is the side(difference) channel
|
|
// 1011-1111 : reserved
|
|
channels = d.FieldUFn("channel_assignment", func() (uint64, decode.DisplayFormat, string) {
|
|
ca, u, disp := func() (uint64, uint64, string) {
|
|
v := d.U4()
|
|
switch v {
|
|
case 0:
|
|
return v, 1, "mono"
|
|
case 1:
|
|
return v, 2, "left, right"
|
|
case 2:
|
|
return v, 3, "left, right, center"
|
|
case 3:
|
|
return v, 4, "front left, front right, back left, back right"
|
|
case 4:
|
|
return v, 5, "front left, front right, front center, back/surround left, back/surround right"
|
|
case 5:
|
|
return v, 6, "front left, front right, front center, LFE, back/surround left, back/surround right"
|
|
case 6:
|
|
return v, 7, "front left, front right, front center, LFE, back center, side left, side right"
|
|
case 7:
|
|
return v, 8, "front left, front right, front center, LFE, back left, back right, side left, side right"
|
|
case 0b1000:
|
|
sideChannelIndex = 1
|
|
return v, 2, "left/side"
|
|
case 0b1001:
|
|
sideChannelIndex = 0
|
|
return v, 2, "side/right"
|
|
case 0b1010:
|
|
sideChannelIndex = 1
|
|
return v, 2, "mid/side"
|
|
default:
|
|
return v, 0, "reserved"
|
|
}
|
|
}()
|
|
channelAssignment = int(ca)
|
|
if sideChannelIndex != -1 {
|
|
d.FieldUFn("side_channel_index", func() (uint64, decode.DisplayFormat, string) {
|
|
return uint64(sideChannelIndex), decode.NumberDecimal, ""
|
|
})
|
|
}
|
|
return u, decode.NumberDecimal, disp
|
|
})
|
|
|
|
// <3> Sample size in bits:
|
|
// 000 : get from STREAMINFO metadata block
|
|
// 001 : 8 bits per sample
|
|
// 010 : 12 bits per sample
|
|
// 011 : reserved
|
|
// 100 : 16 bits per sample
|
|
// 101 : 20 bits per sample
|
|
// 110 : 24 bits per sample
|
|
// 111 : reserved
|
|
sampleSize = int(d.FieldUFn("sample_size", func() (uint64, decode.DisplayFormat, string) {
|
|
switch d.U3() {
|
|
case 0b000:
|
|
if inStreamInfo == nil {
|
|
d.Invalid("streaminfo required for bit per sample")
|
|
}
|
|
return inStreamInfo.BitPerSample, decode.NumberDecimal, "streaminfo"
|
|
case 0b001:
|
|
return 8, decode.NumberDecimal, ""
|
|
case 0b010:
|
|
return 12, decode.NumberDecimal, ""
|
|
case 0b011:
|
|
return 0, decode.NumberDecimal, "reserved"
|
|
case 0b100:
|
|
return 16, decode.NumberDecimal, ""
|
|
case 0b101:
|
|
return 20, decode.NumberDecimal, ""
|
|
case 0b110:
|
|
return 24, decode.NumberDecimal, ""
|
|
case 0b111:
|
|
return 0, decode.NumberDecimal, "reserved"
|
|
}
|
|
panic("unreachable")
|
|
}))
|
|
|
|
// <1> Reserved:
|
|
// 0 : mandatory value
|
|
// 1 : reserved for future use
|
|
d.FieldValidateUFn("reserved1", 0, d.U1)
|
|
|
|
d.FieldStructFn("end_of_header", func(d *decode.D) {
|
|
// if(variable blocksize)
|
|
// <8-56>:"UTF-8" coded sample number (decoded number is 36 bits) [4]
|
|
// else
|
|
// <8-48>:"UTF-8" coded frame number (decoded number is 31 bits) [4]
|
|
switch blockingStrategy {
|
|
case BlockingStrategyVariable:
|
|
d.FieldUFn("sample_number", func() (uint64, decode.DisplayFormat, string) {
|
|
return utf8Uint(d), decode.NumberDecimal, ""
|
|
})
|
|
case BlockingStrategyFixed:
|
|
d.FieldUFn("frame_number", func() (uint64, decode.DisplayFormat, string) {
|
|
return utf8Uint(d), decode.NumberDecimal, ""
|
|
})
|
|
}
|
|
|
|
// if(blocksize bits == 011x)
|
|
// 8/16 bit (blocksize-1)
|
|
switch blockSizeBits {
|
|
case 0b0110:
|
|
blockSize = int(d.FieldUFn("block_size", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U8() + 1, decode.NumberDecimal, ""
|
|
}))
|
|
case 0b0111:
|
|
blockSize = int(d.FieldUFn("block_size", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U16() + 1, decode.NumberDecimal, ""
|
|
}))
|
|
}
|
|
|
|
// if(sample rate bits == 11xx)
|
|
// 8/16 bit sample rate
|
|
switch sampleRateBits {
|
|
case 0b1100:
|
|
d.FieldUFn("sample_rate", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U8() * 1000, decode.NumberDecimal, ""
|
|
})
|
|
case 0b1101:
|
|
d.FieldUFn("sample_rate", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U16(), decode.NumberDecimal, ""
|
|
})
|
|
case 0b1110:
|
|
d.FieldUFn("sample_rate", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U16() * 10, decode.NumberDecimal, ""
|
|
})
|
|
case 0b1111:
|
|
// TODO: reserved?
|
|
}
|
|
})
|
|
|
|
headerCRC := &crc.CRC{Bits: 8, Table: crc.ATM8Table}
|
|
decode.MustCopy(d, headerCRC, d.BitBufRange(frameStart, d.Pos()-frameStart))
|
|
d.FieldChecksumLen("crc", 8, headerCRC.Sum(nil), decode.BigEndian)
|
|
|
|
})
|
|
|
|
var channelSamples [][]int64
|
|
rs := make([]int64, 0, blockSize)
|
|
d.FieldArrayFn("subframes", func(d *decode.D) {
|
|
for channelIndex := 0; channelIndex < int(channels); channelIndex++ {
|
|
d.FieldStructFn("subframe", func(d *decode.D) {
|
|
// <1> Zero bit padding, to prevent sync-fooling string of 1s
|
|
d.FieldValidateUFn("zero_bit", 0, d.U1)
|
|
|
|
// <6> Subframe type:
|
|
// 000000 : SUBFRAME_CONSTANT
|
|
// 000001 : SUBFRAME_VERBATIM
|
|
// 00001x : reserved
|
|
// 0001xx : reserved
|
|
// 001xxx : if(xxx <= 4) SUBFRAME_FIXED, xxx=order ; else reserved
|
|
// 01xxxx : reserved
|
|
// 1xxxxx : SUBFRAME_LPC, xxxxx=order-1
|
|
var lpcOrder int
|
|
subframeType := d.FieldUFn("subframe_type", func() (uint64, decode.DisplayFormat, string) {
|
|
u, disp := func() (uint64, string) {
|
|
bits := d.U6()
|
|
switch bits {
|
|
case 0b000000:
|
|
return SubframeConstant, SubframeTypeNames[SubframeConstant]
|
|
case 0b000001:
|
|
return SubframeVerbatim, SubframeTypeNames[SubframeVerbatim]
|
|
case 0b001000, 0b001001, 0b001010, 0b001011, 0b001100:
|
|
lpcOrder = int(bits & 0x7)
|
|
return SubframeFixed, SubframeTypeNames[SubframeFixed]
|
|
default:
|
|
if bits&0x20 > 0 {
|
|
lpcOrder = int((bits & 0x1f) + 1)
|
|
} else {
|
|
return 0, "reserved"
|
|
}
|
|
return SubframeLPC, SubframeTypeNames[SubframeLPC]
|
|
}
|
|
}()
|
|
d.FieldUFn("lpc_order", func() (uint64, decode.DisplayFormat, string) {
|
|
return uint64(lpcOrder), decode.NumberDecimal, ""
|
|
})
|
|
return u, decode.NumberDecimal, disp
|
|
})
|
|
|
|
// 'Wasted bits-per-sample' flag:
|
|
// 0 : no wasted bits-per-sample in source subblock, k=0
|
|
// 1 : k wasted bits-per-sample in source subblock, k-1 follows, unary coded; e.g. k=3 => 001 follows, k=7 => 0000001 follows.
|
|
wastedBitsFlag := d.FieldU1("wasted_bits_flag")
|
|
var wastedBitsK int
|
|
if wastedBitsFlag != 0 {
|
|
wastedBitsK = int(d.FieldUFn("wasted_bits_k", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.Unary(0) + 1, decode.NumberDecimal, ""
|
|
}))
|
|
}
|
|
|
|
subframeSampleSize := sampleSize - wastedBitsK
|
|
if subframeSampleSize < 0 {
|
|
d.Invalid(fmt.Sprintf("negative subframeSampleSize %d", subframeSampleSize))
|
|
}
|
|
// if channel is side, add en extra sample bit
|
|
// https://github.com/xiph/flac/blob/37e675b777d4e0de53ac9ff69e2aea10d92e729c/src/libFLAC/stream_decoder.c#L2040
|
|
if channelIndex == sideChannelIndex {
|
|
subframeSampleSize++
|
|
}
|
|
d.FieldValueU("subframe_sample_size", uint64(subframeSampleSize), "")
|
|
|
|
decodeWarmupSamples := func(n int, sampleSize int) []int64 {
|
|
var ss []int64
|
|
d.FieldArrayFn("warmup_samples", func(d *decode.D) {
|
|
for i := 0; i < n; i++ {
|
|
ss = append(ss, d.FieldS("value", sampleSize))
|
|
}
|
|
})
|
|
return ss
|
|
}
|
|
|
|
decodeResiduals := func() []int64 {
|
|
// is less than blockSize
|
|
// reset array
|
|
rs = rs[:0]
|
|
|
|
// <2> Residual coding method:
|
|
// 00 : partitioned Rice coding with 4-bit Rice parameter; RESIDUAL_CODING_METHOD_PARTITIONED_RICE follows
|
|
// 01 : partitioned Rice coding with 5-bit Rice parameter; RESIDUAL_CODING_METHOD_PARTITIONED_RICE2 follows
|
|
// 10-11 : reserved
|
|
var riceEscape int
|
|
riceBits := int(d.FieldUFn("residual_coding_method", func() (uint64, decode.DisplayFormat, string) {
|
|
switch d.U2() {
|
|
case 0:
|
|
riceEscape = 15
|
|
return 4, decode.NumberDecimal, "rice"
|
|
case 1:
|
|
riceEscape = 31
|
|
return 5, decode.NumberDecimal, "rice2"
|
|
default:
|
|
return 0, decode.NumberDecimal, "reserved"
|
|
}
|
|
}))
|
|
|
|
// <4> Partition order.
|
|
partitionOrder := int(d.FieldU4("partition_order"))
|
|
// There will be 2^order partitions.
|
|
ricePartitions := 1 << partitionOrder
|
|
d.FieldValueU("rice_partitions", uint64(ricePartitions), "")
|
|
|
|
d.FieldArrayFn("partitions", func(d *decode.D) {
|
|
for i := 0; i < ricePartitions; i++ {
|
|
d.FieldStructFn("partition", func(d *decode.D) {
|
|
// Encoding parameter:
|
|
// <4(+5)> Encoding parameter:
|
|
// 0000-1110 : Rice parameter.
|
|
// 1111 : Escape code, meaning the partition is in unencoded binary form using n bits per sample; n follows as a 5-bit number.
|
|
// Or:
|
|
// <5(+5)> Encoding parameter:
|
|
// 00000-11110 : Rice parameter.
|
|
// 11111 : Escape code, meaning the partition is in unencoded binary form using n bits per sample; n follows as a 5-bit number.
|
|
// Encoded residual. The number of samples (n) in the partition is determined as follows:
|
|
// if the partition order is zero, n = frame's blocksize - predictor order
|
|
// else if this is not the first partition of the subframe, n = (frame's blocksize / (2^partition order))
|
|
// else n = (frame's blocksize / (2^partition order)) - predictor order
|
|
var count int
|
|
if partitionOrder == 0 {
|
|
count = blockSize - lpcOrder
|
|
} else if i != 0 {
|
|
count = blockSize / ricePartitions
|
|
} else {
|
|
count = (blockSize / ricePartitions) - lpcOrder
|
|
}
|
|
|
|
d.FieldValueU("count", uint64(count), "")
|
|
|
|
riceParameter := int(d.FieldU("rice_parameter", riceBits))
|
|
if riceParameter == riceEscape {
|
|
escapeSampleSize := int(d.FieldU5("escape_sample_size"))
|
|
d.FieldBitBufLen("samples", int64(count*escapeSampleSize*8))
|
|
} else {
|
|
samplesStart := d.Pos()
|
|
for j := 0; j < count; j++ {
|
|
high := d.Unary(0)
|
|
_ = high
|
|
low := d.U(riceParameter)
|
|
_ = low
|
|
rs = append(rs, num.ZigZag(high<<riceParameter|low))
|
|
}
|
|
samplesStop := d.Pos()
|
|
d.FieldBitBufRange("samples", samplesStart, samplesStop-samplesStart)
|
|
}
|
|
})
|
|
}
|
|
})
|
|
return rs
|
|
}
|
|
|
|
// modifies input samples slice and returns it
|
|
decodeLPC := func(lpcOrder int, samples []int64, coeffs []int64, shift int64) []int64 {
|
|
for i := lpcOrder; i < len(samples); i++ {
|
|
r := int64(0)
|
|
for j := 0; j < len(coeffs); j++ {
|
|
c := coeffs[j]
|
|
s := samples[i-j-1]
|
|
r += c * s
|
|
}
|
|
samples[i] = samples[i] + (r >> shift)
|
|
}
|
|
return samples
|
|
}
|
|
|
|
var samples []int64 //nolint:makezero
|
|
switch subframeType {
|
|
case SubframeConstant:
|
|
samples = make([]int64, blockSize)
|
|
// <n> Unencoded constant value of the subblock, n = frame's bits-per-sample.
|
|
v := d.FieldS("value", subframeSampleSize)
|
|
for i := 0; i < blockSize; i++ {
|
|
samples[i] = v
|
|
}
|
|
case SubframeVerbatim:
|
|
samples = make([]int64, blockSize)
|
|
// <n*i> Unencoded subblock; n = frame's bits-per-sample, i = frame's blocksize.
|
|
// TODO: refactor into some kind of FieldBitBufLenFn?
|
|
d.FieldBitBufRange("samples", d.Pos(), int64(blockSize*subframeSampleSize))
|
|
for i := 0; i < blockSize; i++ {
|
|
samples[i] = d.S(subframeSampleSize)
|
|
}
|
|
case SubframeFixed:
|
|
// <n> Unencoded warm-up samples (n = frame's bits-per-sample * predictor order).
|
|
warmupSamples := decodeWarmupSamples(lpcOrder, subframeSampleSize)
|
|
// Encoded residual
|
|
residuals := decodeResiduals()
|
|
// http://www.hpl.hp.com/techreports/1999/HPL-1999-144.pdf
|
|
fixedCoeffs := [][]int64{
|
|
{},
|
|
{1},
|
|
{2, -1},
|
|
{3, -3, 1},
|
|
{4, -6, 4, -1},
|
|
}
|
|
coeffs := fixedCoeffs[lpcOrder]
|
|
samples = make([]int64, 0, blockSize)
|
|
samples = append(samples, warmupSamples...)
|
|
samples = append(samples, residuals...)
|
|
samples = decodeLPC(lpcOrder, samples, coeffs, 0)
|
|
case SubframeLPC:
|
|
// <n> Unencoded warm-up samples (n = frame's bits-per-sample * lpc order).
|
|
warmupSamples := decodeWarmupSamples(lpcOrder, subframeSampleSize)
|
|
// <4> (Quantized linear predictor coefficients' precision in bits)-1 (1111 = invalid).
|
|
precision := int(d.FieldUFn("precision", func() (uint64, decode.DisplayFormat, string) {
|
|
return d.U4() + 1, decode.NumberDecimal, ""
|
|
}))
|
|
// <5> Quantized linear predictor coefficient shift needed in bits (NOTE: this number is signed two's-complement).
|
|
shift := d.FieldS5("shift")
|
|
if shift < 0 {
|
|
d.Invalid(fmt.Sprintf("negative LPC shift %d", shift))
|
|
}
|
|
// <n> Unencoded predictor coefficients (n = qlp coeff precision * lpc order) (NOTE: the coefficients are signed two's-complement).
|
|
var coeffs []int64
|
|
d.FieldArrayFn("coefficients", func(d *decode.D) {
|
|
for i := 0; i < lpcOrder; i++ {
|
|
coeffs = append(coeffs, d.FieldS("value", precision))
|
|
}
|
|
})
|
|
// Encoded residual
|
|
residuals := decodeResiduals()
|
|
samples = make([]int64, 0, blockSize)
|
|
samples = append(samples, warmupSamples...)
|
|
samples = append(samples, residuals...)
|
|
samples = decodeLPC(lpcOrder, samples, coeffs, shift)
|
|
}
|
|
|
|
if wastedBitsK != 0 {
|
|
for i := 0; i < len(samples); i++ {
|
|
samples[i] <<= wastedBitsK
|
|
}
|
|
}
|
|
|
|
channelSamples = append(channelSamples, samples)
|
|
})
|
|
}
|
|
})
|
|
|
|
// <?> Zero-padding to byte alignment.
|
|
d.FieldValidateUFn("byte_align", 0, func() uint64 { return d.U(d.ByteAlignBits()) })
|
|
// <16> CRC-16 (polynomial = x^16 + x^15 + x^2 + x^0, initialized with 0) of everything before the crc, back to and including the frame header sync code
|
|
footerCRC := &crc.CRC{Bits: 16, Table: crc.ANSI16Table}
|
|
decode.MustCopy(d, footerCRC, d.BitBufRange(frameStart, d.Pos()-frameStart))
|
|
d.FieldChecksumLen("footer_crc", 16, footerCRC.Sum(nil), decode.BigEndian)
|
|
|
|
streamSamples := len(channelSamples[0])
|
|
for j := 0; j < len(channelSamples); j++ {
|
|
if streamSamples > len(channelSamples[j]) {
|
|
d.Invalid(fmt.Sprintf("different amount of samples in channels %d >= %d", streamSamples, len(channelSamples[j])))
|
|
}
|
|
}
|
|
|
|
// Transform mid/side channels into left, right
|
|
// mid = (left + right)/2
|
|
// side = left - right
|
|
switch channelAssignment {
|
|
case ChannelLeftSide:
|
|
for i := 0; i < len(channelSamples[0]); i++ {
|
|
channelSamples[1][i] = channelSamples[0][i] - channelSamples[1][i]
|
|
}
|
|
case ChannelSideRight:
|
|
for i := 0; i < len(channelSamples[0]); i++ {
|
|
channelSamples[0][i] = channelSamples[1][i] + channelSamples[0][i]
|
|
}
|
|
case ChannelMidSide:
|
|
for i := 0; i < len(channelSamples[0]); i++ {
|
|
m := channelSamples[0][i]
|
|
s := channelSamples[1][i]
|
|
m = m<<1 | s&1
|
|
channelSamples[0][i] = (m + s) >> 1
|
|
channelSamples[1][i] = (m - s) >> 1
|
|
}
|
|
default:
|
|
// no side channel
|
|
}
|
|
|
|
bytesPerSample := sampleSize / 8
|
|
p := 0
|
|
le := binary.LittleEndian
|
|
|
|
interleavedSamplesBuf := ffi.SamplesBuf
|
|
interleavedSamplesBufLen := len(channelSamples) * streamSamples * bytesPerSample
|
|
// TODO: decode read buffer?
|
|
// reuse buffer if possible
|
|
if interleavedSamplesBuf == nil || len(interleavedSamplesBuf) < interleavedSamplesBufLen {
|
|
interleavedSamplesBuf = make([]byte, interleavedSamplesBufLen)
|
|
}
|
|
|
|
// TODO: speedup by using more cache friendly memory layout for samples
|
|
for i := 0; i < streamSamples; i++ {
|
|
for j := 0; j < len(channelSamples); j++ {
|
|
|
|
s := channelSamples[j][i]
|
|
switch sampleSize {
|
|
case 8:
|
|
interleavedSamplesBuf[p] = byte(s)
|
|
case 16:
|
|
le.PutUint16(interleavedSamplesBuf[p:], uint16(s))
|
|
case 24:
|
|
interleavedSamplesBuf[p] = byte(s)
|
|
le.PutUint16(interleavedSamplesBuf[p+1:], uint16(s>>8))
|
|
case 32:
|
|
le.PutUint32(interleavedSamplesBuf[p:], uint32(s))
|
|
}
|
|
p += bytesPerSample
|
|
}
|
|
}
|
|
|
|
return format.FlacFrameOut{
|
|
SamplesBuf: interleavedSamplesBuf,
|
|
Samples: uint64(streamSamples),
|
|
Channels: int(channels),
|
|
BitsPerSample: sampleSize,
|
|
}
|
|
}
|