mirror of https://bitbucket.org/ausocean/av.git
adpcmgo: added ported encode and decode functions
This commit is contained in:
parent
6beefc536b
commit
33d62672c6
cmd/adpcmgo
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@ -0,0 +1,70 @@
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package main
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import (
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"flag"
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"fmt"
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"io/ioutil"
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"os"
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"github.com/bovarysme/adpcm"
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"github.com/go-audio/audio"
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"github.com/go-audio/wav"
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)
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func main() {
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var inPath string
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var nChannels int
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var rate int
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var bps int
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flag.StringVar(&inPath, "path", "out.adpcm", "file path of input data")
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flag.IntVar(&nChannels, "channels", 1, "number of channels in adpcm data")
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flag.IntVar(&rate, "rate", 8000, "number of channels in adpcm data")
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flag.IntVar(&bps, "bps", 16, "number of channels in adpcm data")
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flag.Parse()
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//read adpcm
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comp, err := ioutil.ReadFile(inPath)
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if err != nil {
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panic(err)
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}
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fmt.Println("Read ADPCM from " + inPath + ". First 8 bytes: ")
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for i := 0; i < len(comp) && i < 16; i++ {
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fmt.Print(comp[i], ", ")
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}
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fmt.Println()
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//decode adpcm
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var decoded []int
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deco := adpcm.NewDecoder(nChannels)
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deco.Decode(comp, &decoded)
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//encode wav and save to file
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finalWavPath := "decoded.wav"
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of, err := os.Create(finalWavPath)
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if err != nil {
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panic(err)
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}
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defer of.Close()
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sampleBytes := bps / 8
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// normal uncompressed WAV format
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wavformat := 1
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enc := wav.NewEncoder(of, rate, bps, nChannels, wavformat)
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format := &audio.Format{
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NumChannels: nChannels,
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SampleRate: rate,
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}
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intBuf := &audio.IntBuffer{Data: decoded, Format: format, SourceBitDepth: sampleBytes * 8}
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if err := enc.Write(intBuf); err != nil {
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panic(err)
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}
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if err := enc.Close(); err != nil {
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panic(err)
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}
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fmt.Printf("Saved audio to %s\n", finalWavPath)
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}
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package main
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import (
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"fmt"
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"bitbucket.org/ausocean/av/cmd/adpcmgo"
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)
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func main() {
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var input byte = 4
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sample := adpcmgo.DecodeSample(input)
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fmt.Println(sample)
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input = 5
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sample = adpcmgo.DecodeSample(input)
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fmt.Println(sample)
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input = 6
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sample = adpcmgo.DecodeSample(input)
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fmt.Println(sample)
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input = 16
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sample = adpcmgo.DecodeSample(input)
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fmt.Println(sample)
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input = 235
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sample = adpcmgo.DecodeSample(input)
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fmt.Println(sample)
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}
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@ -0,0 +1,31 @@
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package main
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import (
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"fmt"
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"io/ioutil"
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"github.com/bovarysme/adpcm"
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)
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// WIP
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func main() {
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//read pcm
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pcm, err := ioutil.ReadFile(inPath)
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if err != nil {
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panic(err)
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}
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//encode adpcm
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var comp []byte
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adpcm.Encode(pcm, &comp)
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// save adpcm to file
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adpcmPath := "out.adpcm"
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err = ioutil.WriteFile(adpcmPath, comp, 0644)
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if err != nil {
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panic(err)
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}
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fmt.Println("Saved ADPCM to " + adpcmPath + ". First 8 bytes: ")
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for i := 0; i < len(comp) && i < 16; i++ {
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fmt.Print(comp[i], ", ")
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}
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fmt.Println()
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}
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@ -67,6 +67,11 @@ func main() {
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if err != nil {
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panic(err)
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}
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fmt.Println("Saved ADPCM to " + adpcmPath + ". First 8 bytes: ")
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for i := 0; i < len(comp) && i < 16; i++ {
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fmt.Print(comp[i], ", ")
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}
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fmt.Println()
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//decode adpcm
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var decoded []int
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deco := adpcm.NewDecoder(nchannels)
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@ -0,0 +1,30 @@
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package main
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import (
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"fmt"
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"bitbucket.org/ausocean/av/cmd/adpcmgo"
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)
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func main() {
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input := -370
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nibble := adpcmgo.EncodeSample(input)
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fmt.Println(nibble)
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input = 8
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nibble = adpcmgo.EncodeSample(input)
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fmt.Println(nibble)
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input = 1
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nibble = adpcmgo.EncodeSample(input)
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fmt.Println(nibble)
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input = 31793
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nibble = adpcmgo.EncodeSample(input)
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fmt.Println(nibble)
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input = -7386
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nibble = adpcmgo.EncodeSample(input)
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fmt.Println(nibble)
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}
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@ -0,0 +1,137 @@
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package adpcmgo
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import (
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"fmt"
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"math"
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)
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// table of index changes
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var indexTable = []int{
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-1, -1, -1, -1, 2, 4, 6, 8,
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-1, -1, -1, -1, 2, 4, 6, 8,
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}
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// quantize step size table
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var stepTable = []int{
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7, 8, 9, 10, 11, 12, 13, 14,
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16, 17, 19, 21, 23, 25, 28, 31,
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34, 37, 41, 45, 50, 55, 60, 66,
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73, 80, 88, 97, 107, 118, 130, 143,
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157, 173, 190, 209, 230, 253, 279, 307,
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337, 371, 408, 449, 494, 544, 598, 658,
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724, 796, 876, 963, 1060, 1166, 1282, 1411,
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1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
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3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
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7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
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15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
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32767,
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}
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var (
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encPred = 0
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encIndex = 0
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encStep = 7
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decPred = 0
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decIndex = 0
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decStep = 7
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)
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// EncodeSample takes a single 16 bit PCM sample and
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// returns a byte of which the last 4 bits are an encoded ADPCM nibble
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func EncodeSample(sample int) byte {
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// find difference from predicted sample
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delta := sample - encPred
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// set sign bit and find absolute value of difference
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var newSample byte
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if delta < 0 {
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newSample = 8
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delta = -delta
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}
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step := stepTable[encIndex]
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diff := step >> 3
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var mask byte = 4
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// quantize delta down to four bits
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for i := 0; i < 3; i++ {
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if delta > step {
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newSample |= mask
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delta -= step
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diff += step
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}
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mask >>= 1
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step >>= 1
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}
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// adjust predicted sample based on calculated difference
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if newSample&8 != 0 {
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encPred -= diff
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} else {
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encPred += diff
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}
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// check for underflow and overflow
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fmt.Print("max, min: ", math.MaxInt16)
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fmt.Println(math.MinInt16)
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if encPred < math.MinInt16 {
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encPred = math.MinInt16
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} else if encPred > math.MaxInt16 {
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encPred = math.MaxInt16
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}
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encIndex += indexTable[newSample&7]
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// check for underflow and overflow
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if encIndex < 0 {
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encIndex = 0
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} else if encIndex > len(stepTable)-1 {
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encIndex = len(stepTable) - 1
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}
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return newSample
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}
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// DecodeSample takes a byte, the last 4 bits of which contain a single
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// 4 bit ADPCM value/sample, and returns a 16 bit decoded PCM sample
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func DecodeSample(nibble byte) int {
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diff := 0
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if nibble&4 != 0 {
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diff += decStep
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}
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if nibble&2 != 0 {
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diff += decStep >> 1
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}
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if nibble&1 != 0 {
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diff += decStep >> 2
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}
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diff += decStep >> 3
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if nibble&8 != 0 {
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diff = -diff
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}
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decPred += diff
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if decPred > math.MaxInt16 {
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decPred = math.MaxInt16
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} else if decPred < math.MinInt16 {
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decPred = math.MinInt16
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}
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decIndex += indexTable[nibble]
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if decIndex < 0 {
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decIndex = 0
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} else if decIndex > len(stepTable)-1 {
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decIndex = len(stepTable) - 1
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}
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decStep = stepTable[decIndex]
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return decPred
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}
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