追加功能会覆盖切片中的现有数据

Question

我写了一个小应用程序,它记录声卡中的数据,并将数据存储在一个数组中,以便以后处理.

每当有新数据可用时,portaudio就会执行回调record.在回调中,我将数据附加到数组RecData.data.

golang builtin函数append按预期将另一个元素添加到切片中,但无论出于何种原因,还会使用完全相同的数据覆盖数组中的所有现有元素.

我一直试图将问题隔离两天以上,但没有成功.

这是代码的精简版本,它可以工作并显示问题:

package main

import (
    "fmt"
    "time"
//    "reflect"

    "github.com/gordonklaus/portaudio"
)

type RecData struct{
    data [][][]float32
}

func main() {

    var inputChs int = 1
    var outputChs int = 0
    var samplingRate float64 = 48000
    var framesPerBuffer int = 3 //for test purpose that low. Would normally be 1024 or 2048

    rec := RecData{make([][][]float32, 0, 1000)}

    portaudio.Initialize()

    stream, err := portaudio.OpenDefaultStream(inputChs, outputChs, samplingRate, framesPerBuffer, rec.record)
    if err != nil {
        fmt.Println(err)
    }

    defer stream.Close()
    stream.Start()
    for {
        time.Sleep(time.Millisecond * 10)
    }
}

// callback which gets called when new data is in the buffer
func (re *RecData)record(in [][]float32) {
    fmt.Println("Received sound sample: ")
    fmt.Println(in)
    re.data = append(re.data, in)
    fmt.Println("Content of RecData.data after adding received sound sample:")
    fmt.Println(re.data, "\n")
    time.Sleep(time.Millisecond * 500) //limit temporarily the amount of data read
    // iterate over all recorded data and compare them
    /*
    for i, d := range re.data{
        if reflect.DeepEqual(d, in){
                fmt.Printf("Data at index %d is the same as the recorded one, but should not be!\n", i )
        }
    }*/
}

2.更新

这是应用程序输出:

Received sound sample:
[[0.71575254 1.0734825 0.7444282]]
Content of RecData.data after adding received sound sample:
[[[0.71575254 1.0734825 0.7444282]]]

Received sound sample:
[[0.7555193 0.768355 0.6575008]]
Content of RecData.data after adding received sound sample:
[[[0.7555193 0.768355 0.6575008]] [[0.7555193 0.768355 0.6575008]]]

Received sound sample:
[[0.7247052 0.68471473 0.6843796]]
Content of RecData.data after adding received sound sample:
[[[0.7247052 0.68471473 0.6843796]] [[0.7247052 0.68471473 0.6843796]] [[0.7247052 0.68471473 0.6843796]]]

Received sound sample:
[[0.6996536 0.66283375 0.67252487]]
Content of RecData.data after adding received sound sample:
[[[0.6996536 0.66283375 0.67252487]] [[0.6996536 0.66283375 0.67252487]] [[0.6996536 0.66283375 0.67252487]] [[0.6996536 0.66283375 0.67252487]]]


.... etc ....

正如我们所看到的,随着时间的推移,切片的大小正在增长,但是不仅仅是附加数据,数组中的数据也会被覆盖.

这不应该发生.portaudio在回调a中[][]float32提供从声卡记录的音频样本.正如你所看到的,它们总是不同的.

如上所述,上面的代码是我的应用程序的精简版本.通常我会记录5秒,然后对样本执行快速傅立叶变换(FFT)以计算频谱.我把这部分留下了,因为它对这个特殊的问题没有影响.

我非常感谢任何帮助.也许有人可以指出我做错了什么.

谢谢!

Answer 1

传递给回调的缓冲区由portaudio包重用,因此您将相同的切片结构附加到data切片.每次portaudio分配的缓冲区都会覆盖数据,您会在data切片的每个元素中看到结果.

您需要分配新切片并复制数据:

func (re *RecData) record(in [][]float32) {
    buf := make([][]float32, len(in))
    for i, v := range in {
        buf[i] = append([]float32(nil), v...)
    }
    re.data = append(re.data, buf)

示例:https: //play.golang.org/p/cF57lQIZFU