Read *.wav file in golang - php

Question

I've used file_get_contents for reading a WAV file in PHP and I want to use package github.com/mjibson/go-dsp/wav for same task in Go. But there is not any simple example about this package. I am new to Go and do not understand it. Is there anyone guiding me or suggest another way?
Code in PHP:
$wsdl = 'http://myApi.asmx?WSDL';
$client = new SoapClient($wsdl));
$data = file_get_contents(public_path() . "/forTest/record.wav");
$param = array(
'userName' => '***',
'password' => '***',
'file' => $data);
$res = $client->UploadMessage($param);

Answer 1

It looks like you do not need to use this package github.com/mjibson/go-dsp/wav. file_get_contents function is the preferred way to read the contents of a file into a string.
In Go, you can do something like this:
package main
import (
"fmt"
"io/ioutil"
)
func public_path() string {
return "/public/path/"
}
func main() {
dat, err := ioutil.ReadFile(public_path() + "/forTest/record.wav")
if err != nil {
fmt.Println(err)
}
fmt.Print(string(dat))
}
https://play.golang.org/p/l9R0940iK50

Answer 2

I think you just need to read the file, it really does not matter whether it is .wav or some other file. You can use go's builtin package io/ioutil.
Following is what you should do in go to read a disk file:
package main
import (
"fmt"
"io/ioutil"
"log"
)
func main() {
// Reading .wav file from disk.
fileData, err := ioutil.ReadFile("DISK_RELATIVE_PATH_PREFIX" + "/forTest/record.wav")
// ioutil.ReadFile returns two results,
// first one is data (slice of byte i.e. []byte) and the other one is error.
// If error is having nil value, you got successfully read the file,
// otherwise you need to handle the error.
if err != nil {
// Handle error here.
log.Fatal(err)
} else {
// Do whatever needed with the 'fileData' such as just print the data,
// or send it over the network.
fmt.Print(fileData)
}
}
Hope this helps.

Answer 3

Given a WAV file this returns its payload as a floating point audio curve along with essential audio file details like bit-depth, sample-rate and num-channels.
Had you simply read in the binary audio file using one of the underlying IO primitives in order to obtain the audio curve you would have to battle with your own bit shifting to pluck multi-byte ints as well as handling big or little endianness.
You still must be aware of how to handle multi-channel interleaving of audio samples from each channel which is not an issue for mono audio.
package main
import (
"fmt"
"os"
"github.com/youpy/go-wav"
"math"
)
func read_wav_file(input_file string, number_of_samples uint32) ([]float64, uint16, uint32, uint16) {
if number_of_samples == 0 {
number_of_samples = math.MaxInt32
}
blockAlign := 2
file, err := os.Open(input_file)
if err != nil {
panic(err)
}
reader := wav.NewReader(file)
wavformat, err_rd := reader.Format()
if err_rd != nil {
panic(err_rd)
}
if wavformat.AudioFormat != wav.AudioFormatPCM {
panic("Audio format is invalid ")
}
if int(wavformat.BlockAlign) != blockAlign {
fmt.Println("Block align is invalid ", wavformat.BlockAlign)
}
samples, err := reader.ReadSamples(number_of_samples) // must supply num samples w/o defaults to 2048
// // just supply a HUGE number then actual num is returned
wav_samples := make([]float64, 0)
for _, curr_sample := range samples {
wav_samples = append(wav_samples, reader.FloatValue(curr_sample, 0))
}
return wav_samples, wavformat.BitsPerSample, wavformat.SampleRate, wavformat.NumChannels
}
func main() {
input_audio := "/blah/genome_synth_evolved.wav"
audio_samples, bits_per_sample, input_audio_sample_rate, num_channels := read_wav_file( input_audio, 0)
fmt.Println("num samples ", len(audio_samples)/int(num_channels))
fmt.Println("bit depth ", bits_per_sample)
fmt.Println("sample rate ", input_audio_sample_rate)
fmt.Println("num channels", num_channels)
}