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frame: Update TODO comments.

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This commit is contained in:
mewmew 2014-07-31 03:05:39 +02:00
parent 58d1de7242
commit 5057601481
3 changed files with 48 additions and 90 deletions
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4
frame/frame.go
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@ -57,9 +57,7 @@ func NewFrame(r io.Reader) (frame *Frame, err error) {
}
// Padding.
/// ### [ TODO ] ###
/// - verify paddings
/// ### [/ TODO ] ###
// TODO(u): Verify paddings.
// ignore bits up to byte boundery.
br = bit.NewReader(hr)

42
frame/header.go
View file

@ -22,7 +22,7 @@ type Header struct {
HasVariableSampleCount bool
// Sample count is the number of samples in any of a block's subblocks.
SampleCount uint16
// Sample rate.
// Sample rate. Get from StreamInfo metadata block if set to 0.
SampleRate uint32
// Channel order specifies the order in which channels are stored in the
// frame.
@ -68,23 +68,25 @@ const (
ChannelMidSide // mid/side stereo: mid (average), side (difference)
)
// channelCount maps from a channel assignment to its number of channels.
var channelCount = map[ChannelOrder]int{
ChannelMono: 1,
ChannelLR: 2,
ChannelLRC: 3,
ChannelLRLsRs: 4,
ChannelLRCLsRs: 5,
ChannelLRCLfeLsRs: 6,
Channel7: 7,
Channel8: 8,
ChannelLSide: 2,
ChannelSideR: 2,
ChannelMidSide: 2,
}
// ChannelCount returns the number of channels used by the provided channel
// order.
func (order ChannelOrder) ChannelCount() int {
var m = map[ChannelOrder]int{
ChannelMono: 1,
ChannelLR: 2,
ChannelLRC: 3,
ChannelLRLsRs: 4,
ChannelLRCLsRs: 5,
ChannelLRCLfeLsRs: 6,
Channel7: 7,
Channel8: 8,
ChannelLSide: 2,
ChannelSideR: 2,
ChannelMidSide: 2,
}
return m[order]
return channelCount[order]
}
// NewHeader parses and returns a new frame header.
@ -224,10 +226,8 @@ func NewHeader(r io.Reader) (hdr *Header, err error) {
switch n {
case 0:
// 000: get from STREAMINFO metadata block.
/// ### [ todo ] ###
/// - Should we try to read StreamInfo from here? We won't always have
/// access to it.
/// ### [/ todo ] ###
// TODO(u): Should we try to read StreamInfo from here? We won't always
// have access to it.
log.Println(fmt.Errorf("not yet implemented; sample size spec: %d", n))
case 1:
// 001: 8 bits per sample.
@ -344,9 +344,7 @@ func NewHeader(r io.Reader) (hdr *Header, err error) {
switch n {
case 0:
// 0000: get from STREAMINFO metadata block.
/// ### [ todo ] ###
/// - add flag to get from StreamInfo?
/// ### [/ todo ] ###
// TODO(u): Add flag to get from StreamInfo?
log.Println(fmt.Errorf("not yet implemented; sample rate: %d", n))
case 1:
//0001: 88.2kHz.

92
frame/subframe.go
View file

@ -55,7 +55,7 @@ func (h *Header) NewSubFrame(br *bit.Reader) (subframe *SubFrame, err error) {
case PredVerbatim:
subframe.Samples, err = h.DecodeVerbatim(br)
default:
return nil, fmt.Errorf("Header.NewSubFrame: unknown subframe prediction method: %d", sh.PredMethod)
return nil, fmt.Errorf("frame.Header.NewSubFrame: unknown subframe prediction method: %d", sh.PredMethod)
}
if err != nil {
return nil, err
@ -112,7 +112,7 @@ func (h *Header) NewSubHeader(br *bit.Reader) (sh *SubHeader, err error) {
// Padding.
// field 0: padding (1 bit)
if fields[0] != 0 {
return nil, errors.New("Header.NewSubHeader: invalid padding; must be 0")
return nil, errors.New("frame.Header.NewSubHeader: invalid padding; must be 0")
}
// Subframe prediction method.
@ -136,18 +136,18 @@ func (h *Header) NewSubHeader(br *bit.Reader) (sh *SubHeader, err error) {
case n < 8:
// 00001x: reserved
// 0001xx: reserved
return nil, fmt.Errorf("Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
return nil, fmt.Errorf("frame.Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
case n < 16:
// 001xxx: if(xxx <= 4) SUBFRAME_FIXED, xxx=order ; else reserved
const predOrderMask = 0x07
sh.PredOrder = int8(n) & predOrderMask
if sh.PredOrder > 4 {
return nil, fmt.Errorf("Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
return nil, fmt.Errorf("frame.Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
}
sh.PredMethod = PredFixed
case n < 32:
// 01xxxx: reserved
return nil, fmt.Errorf("Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
return nil, fmt.Errorf("frame.Header.NewSubHeader: invalid subframe prediction method; reserved bit pattern: %06b", n)
case n < 64:
// 1xxxxx: SUBFRAME_LPC, xxxxx=order-1
const predOrderMask = 0x1F
@ -155,7 +155,7 @@ func (h *Header) NewSubHeader(br *bit.Reader) (sh *SubHeader, err error) {
sh.PredMethod = PredLPC
default:
// should be unreachable.
panic(fmt.Errorf("Header.NewSubHeader: unhandled subframe prediction method; bit pattern: %06b", n))
panic(fmt.Errorf("frame.Header.NewSubHeader: unhandled subframe prediction method; bit pattern: %06b", n))
}
// Wasted bits-per-sample, 1+k bits.
@ -166,9 +166,7 @@ func (h *Header) NewSubHeader(br *bit.Reader) (sh *SubHeader, err error) {
if hasWastedBits != 0 {
// k wasted bits-per-sample in source subblock, k-1 follows, unary coded;
// e.g. k=3 => 001 follows, k=7 => 0000001 follows.
/// ### [ todo ] ###
/// - verify.
/// ### [/ todo ] ###
// TODO(u): Verify that the unary decoding is correct.
n, err := bitutil.DecodeUnary(br)
if err != nil {
return nil, err
@ -203,9 +201,8 @@ func (h *Header) DecodeConstant(br *bit.Reader) (samples []Sample, err error) {
}
// DecodeFixed decodes and returns a slice of samples.
/// ### [ todo ] ###
/// - add more details.
/// ### [/ todo ] ###
//
// TODO(u): Add more detailed documentation.
//
// ref: http://flac.sourceforge.net/format.html#subframe_fixed
func (h *Header) DecodeFixed(br *bit.Reader, predOrder int) (samples []Sample, err error) {
@ -227,16 +224,13 @@ func (h *Header) DecodeFixed(br *bit.Reader, predOrder int) (samples []Sample, e
return nil, err
}
_ = residuals
/// ### [ todo ] ###
/// - not yet implemented.
/// ### [/ todo ] ###
// TODO(u): not yet implemented.
return nil, errors.New("not yet implemented; Fixed encoding")
}
// DecodeLPC decodes and returns a slice of samples.
/// ### [ todo ] ###
/// - add more details.
/// ### [/ todo ] ###
//
// TODO(u): Add more detailed documentation.
//
// ref: http://flac.sourceforge.net/format.html#subframe_lpc
func (h *Header) DecodeLPC(br *bit.Reader, lpcOrder int) (samples []Sample, err error) {
@ -260,7 +254,7 @@ func (h *Header) DecodeLPC(br *bit.Reader, lpcOrder int) (samples []Sample, err
}
if n == 0x0F {
// 1111: invalid.
return nil, errors.New("Header.DecodeLPC: invalid quantized lpc precision; reserved bit pattern: 1111")
return nil, errors.New("frame.Header.DecodeLPC: invalid quantized lpc precision; reserved bit pattern: 1111")
}
qlpcPrec := int(n) + 1
@ -269,10 +263,8 @@ func (h *Header) DecodeLPC(br *bit.Reader, lpcOrder int) (samples []Sample, err
if err != nil {
return nil, err
}
/// ### [ todo ] ###
/// - NOTE: this number is signed two's-complement.
/// - special case for negative numbers required?
/// ### [/ todo ] ###
// TODO(u): Check; special case for negative numbers required? This number is
// signed two's-complement.
_ = qlpcShift
// Unencoded predictor coefficients.
@ -283,7 +275,7 @@ func (h *Header) DecodeLPC(br *bit.Reader, lpcOrder int) (samples []Sample, err
return nil, err
}
dbg.Println("pc:", pc)
pcs[i] = int(pc) /// ### todo ### is int the right type for pc?
pcs[i] = int(pc) // TODO(u): Check; is int the right type for pc?
}
residuals, err := h.DecodeResidual(br, lpcOrder)
@ -291,9 +283,7 @@ func (h *Header) DecodeLPC(br *bit.Reader, lpcOrder int) (samples []Sample, err
return nil, err
}
_ = residuals
/// ### [ todo ] ###
/// - not yet implemented.
/// ### [/ todo ] ###
// TODO(u): not yet implemented.
return nil, errors.New("not yet implemented; LPC encoding")
}
@ -318,9 +308,8 @@ func (h *Header) DecodeVerbatim(br *bit.Reader) (samples []Sample, err error) {
}
// DecodeResidual decodes and returns a slice of residuals.
/// ### [ todo ] ###
/// - add more details.
/// ### [/ todo ] ###
//
// TODO(u): Add more detailed documentation.
//
// ref: http://flac.sourceforge.net/format.html#residual
func (h *Header) DecodeResidual(br *bit.Reader, predOrder int) (residuals []int, err error) {
@ -340,7 +329,7 @@ func (h *Header) DecodeResidual(br *bit.Reader, predOrder int) (residuals []int,
return h.DecodeRice2(br, predOrder)
}
// 1x: reserved
return nil, fmt.Errorf("Header.DecodeResidual: invalid residual coding method; reserved bit pattern: %02b", method)
return nil, fmt.Errorf("frame.Header.DecodeResidual: invalid residual coding method; reserved bit pattern: %02b", method)
}
// DecodeRice decodes and returns a slice of residuals. The residual coding
@ -381,10 +370,9 @@ func (h *Header) DecodeRice(br *bit.Reader, predOrder int) (residuals []int, err
// 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
/// ### [ CONTINUE ] ###
/// - create a comment which maps blocksize to SampleCount? and so on.
/// - verify the above blue comment.
/// ### [/ CONTINUE ] ###
// TODO(u): Continue here;
// - verify the above comment.
// - create a comment which maps blocksize to SampleCount? and so on.
sampleCount := partSampleCount
if partOrder == 0 || partNum == 0 {
sampleCount -= predOrder
@ -393,10 +381,8 @@ func (h *Header) DecodeRice(br *bit.Reader, predOrder int) (residuals []int, err
dbg.Println("sampleCount:", sampleCount)
}
/// ### [ todo ] ###
/// - not yet implemented.
/// ### [/ todo ] ###
return nil, errors.New("Header.DecodeRice: not yet implemented; rice coding method 0")
// TODO(u): not yet implemented.
return nil, errors.New("frame.Header.DecodeRice: not yet implemented; rice coding method 0")
}
// DecodeRice2 decodes and returns a slice of residuals. The residual coding
@ -404,30 +390,6 @@ func (h *Header) DecodeRice(br *bit.Reader, predOrder int) (residuals []int, err
//
// ref: http://flac.sourceforge.net/format.html#partitioned_rice2
func (h *Header) DecodeRice2(br *bit.Reader, predOrder int) (residuals []int, err error) {
/// ### [ todo ] ###
/// - not yet implemented.
/// ### [/ todo ] ###
return nil, errors.New("Header.DecodeRice: not yet implemented; rice coding method 1")
// TODO(u): not yet implemented.
return nil, errors.New("frame.Header.DecodeRice: not yet implemented; rice coding method 1")
}
/**
type SubFrameLpc struct {
Precision uint8
ShiftNeeded uint8
PredictorCoefficients []byte
}
type Rice struct {
Partitions []RicePartition
}
type Rice2 struct {
Partitions []Rice2Partition
}
type RicePartition struct {
EncodingParameter uint16
}
type Rice2Partition struct{}
*/