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Support parsing 8bit uint and float format #24

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Support parsing 8bit uint and float format #24

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49 changes: 41 additions & 8 deletions wave/reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ type (
var (
// figure out which 'to int' function to use..
byteSizeToIntFunc = map[int]bytesToIntF{
8: bits8ToInt,
16: bits16ToInt,
24: bits24ToInt,
32: bits32ToInt,
Expand Down Expand Up @@ -79,23 +80,33 @@ func ReadWaveFromReader(reader io.Reader) (Wave, error) {
// for our wave format we expect double precision floats
func bitsToFloat(b []byte) float64 {
var bits uint64
var float float64
switch len(b) {
case 2:
bits = uint64(binary.LittleEndian.Uint16(b))
float = math.Float64frombits(bits) // float16??
case 4:
bits = uint64(binary.LittleEndian.Uint32(b))
float = float64(math.Float32frombits(uint32(bits)))
case 8:
bits = binary.LittleEndian.Uint64(b)
float = math.Float64frombits(bits)
default:
panic("Can't parse to float..")
}
float := math.Float64frombits(bits)
return float
}

func bits8ToInt(b []byte) int {
if len(b) != 1 {
panic("Expected size 1!")
}
return int(b[0]) - 128 // uint8 to int8
}

func bits16ToInt(b []byte) int {
if len(b) != 2 {
panic("Expected size 4!")
panic("Expected size 2!")
}
var payload int16
buf := bytes.NewReader(b)
Expand Down Expand Up @@ -141,7 +152,18 @@ func bits32ToInt(b []byte) int {
func readData(b []byte, wfmt WaveFmt) WaveData {
wd := WaveData{}

start := 36 + wfmt.ExtraParamSize
start := 20 + wfmt.Subchunk1Size

// skip additional subchunks such as "fact"
for {
subchunkID := b[start : start+4]
if string(subchunkID) == "data" {
break
}
subsize := bits32ToInt(b[start+4 : start+8])
start += 8 + subsize
}

subchunk2ID := b[start : start+4]
wd.Subchunk2ID = subchunk2ID

Expand All @@ -161,11 +183,22 @@ func parseRawData(wfmt WaveFmt, rawdata []byte) []Frame {

frames := []Frame{}
// read the chunks
for i := 0; i < len(rawdata); i += bytesSampleSize {
rawFrame := rawdata[i : i+bytesSampleSize]
unscaledFrame := byteSizeToIntFunc[wfmt.BitsPerSample](rawFrame)
scaled := scaleFrame(unscaledFrame, wfmt.BitsPerSample)
frames = append(frames, scaled)
switch wfmt.AudioFormat {
case 1: // int
fallthrough
default:
for i := 0; i < len(rawdata); i += bytesSampleSize {
rawFrame := rawdata[i : i+bytesSampleSize]
unscaledFrame := byteSizeToIntFunc[wfmt.BitsPerSample](rawFrame)
scaled := scaleFrame(unscaledFrame, wfmt.BitsPerSample)
frames = append(frames, scaled)
}
case 3: // float
for i := 0; i < len(rawdata); i += bytesSampleSize {
rawFrame := rawdata[i : i+bytesSampleSize]
unscaledFrame := byteSizeToFloatFunc[wfmt.BitsPerSample](rawFrame)
frames = append(frames, Frame(unscaledFrame))
}
}
return frames
}
Expand Down