Golang: Read buffered input as signed 16bit ints

问题

I am trying to read a buffered stream of signed 16 bit integers (wav format), but the bufio.Read method only accepts an array of bytes. My question is a 2-parter:

Can I preformat the byte stream into a buffered int16 array?

If I can't, whats the best way of post-processing the byte array into int16 array? My initial thought is to use tmp arrays and keep pushing/processing them, but I was curious if there was a more idiomatic way of doing this?

package main

import (
     "bufio"
     "io"
     "log"
     "os/exec"
)

func main() {

    app := "someapp"

    cmd := exec.Command(app)
    stdout, err := cmd.StdoutPipe()
    r := bufio.NewReader(stdout)
    if err != nil {
        log.Fatal(err)
    }
    if err := cmd.Start(); err != nil {
        log.Fatal(err)
    }

    //"someapp" outputs signed 16bit integers (little endian))
    buf := make([]byte, 0, 4*1024)

    for {
        n, err := r.Read(buf[:cap(buf)])    //r.Read only accepts type []byte
        buf = buf[:n]
        if n == 0 {
            if err == nil {
                continue
            }
            if err == io.EOF {
                break
            }
            log.Fatal(err)
        }

        log.Printf("%x\n", buf)
        //process buf here

        if err != nil && err != io.EOF {
            log.Fatal(err)
        }
    }
}

回答1:

When working with IO, you always work with []bytes, there's no way to substitute that with []int16, or pre-format that as int16s, it's always a stream of bytes.

You can look at the encoding/binary package to decode this stream.

// to get the first uint16 as i
i := binary.LittleEndian.Uint16(buf[:2])

You can then iterate through the buf as needed.

You can also use binary.Read to read directly from the io.Reader.

var i uint16
for {
    err := binary.Read(r, binary.LittleEndian, &i)
    if err != nil {
        log.Println(err)
        break
    }
    fmt.Println(i)
}

It may worth noting the simplicity of what needs to be done. Each uint16 is created via:

func (littleEndian) Uint16(b []byte) uint16 {
    return uint16(b[0]) | uint16(b[1])<<8
}

回答2:

You can use encoding/binary.Read to fill an []int16 directly from your reader, although technically the answer to your first question is still no (check the source of binary.Read, it reads the data to a []byte first).

来源：https://stackoverflow.com/questions/28949063/golang-read-buffered-input-as-signed-16bit-ints

标签

buffer

wav