如何使用 libsndfile 打开加载到内存中的声音文件?
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【中文标题】如何使用 libsndfile 打开加载到内存中的声音文件?【英文标题】:How can I open a sound file loaded in memory with libsndfile? 【发布时间】:2020-11-10 13:08:44 【问题描述】:为了理解这一点,我想讲述以下场景: 我设计了一个游戏并完成了它。我用 AES 加密了音频数据。然后我将在游戏打开时解密这些加密文件。这些文件在内存中以字节编码。 例如,我想为 OpenAL 创建缓冲区。
注意:这里没有加密功能。因为我的例子会很复杂很困难。
这是我想用 CGo 和 Go 做什么的简单草图:
package main
// #cgo windows CFLAGS: -DGO_WINDOWS -I.
// #cgo windows LDFLAGS: -L. -lsndfile-1
/*
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <math.h>
#include <string.h>
#include <errno.h>
#include "sndfile.h"
typedef struct
sf_count_t offset, length ;
unsigned char data [16 * 1024] ;
VIO_DATA;
static sf_count_t
vfget_filelen(void *user_data)
VIO_DATA *vf = (VIO_DATA *) user_data;
return vf->length;
static sf_count_t
vfseek(sf_count_t offset, int whence, void *user_data)
VIO_DATA *vf = (VIO_DATA *) user_data ;
switch (whence)
case SEEK_SET :
vf->offset = offset ;
break ;
case SEEK_CUR :
vf->offset = vf->offset + offset ;
break ;
case SEEK_END :
vf->offset = vf->length + offset ;
break ;
default :
break ;
;
return vf->offset;
static sf_count_t
vfread (void *ptr, sf_count_t count, void *user_data)
VIO_DATA *vf = (VIO_DATA *) user_data ;
if (vf->offset + count > vf->length)
count = vf->length - vf->offset ;
memcpy (ptr, vf->data + vf->offset, count) ;
vf->offset += count ;
return count ;
static sf_count_t
vfwrite (const void *ptr, sf_count_t count, void *user_data)
VIO_DATA *vf = (VIO_DATA *) user_data ;
if(vf->offset >= sizeof(vf->data))
return 0;
if (vf->offset + count > sizeof(vf->data))
count = sizeof (vf->data) - vf->offset;
memcpy(vf->data + vf->offset, ptr, (size_t) count);
vf->offset += count;
if(vf->offset > vf->length)
vf->length = vf->offset ;
return count;
static sf_count_t
vftell(void *user_data)
VIO_DATA *vf = (VIO_DATA *) user_data ;
return vf->offset;
void voidTest(void *data)
printf("value in c: %s \n", (char*)data);
static VIO_DATA vio_data ;
// static short fdata [256];
SF_VIRTUAL_IO vio ;
SNDFILE * file ;
SF_INFO sfinfo ;
vio.get_filelen = vfget_filelen;
vio.seek = vfseek ;
vio.read = vfread;
vio.write = vfwrite;
vio.tell = vftell;
vio_data.offset = 0;
vio_data.length = 0;
memset (&sfinfo, 0, sizeof (sfinfo));
sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
if((file = sf_open_virtual (&vio, SFM_READ, &sfinfo, &vio_data)) == NULL)
printf("Sndfile error: %s\n", sf_strerror(file));
exit(1);
// return;
// !As an example I want to know the number of channels etc.
printf("Channel: %i\n", sfinfo.channels);
sf_close(file);
*/
import "C"
import (
"io/ioutil"
"fmt"
"unsafe"
)
func main()
byt, err := ioutil.ReadFile("birds22.wav")
if err != nil
fmt.Println(err)
return
var v unsafe.Pointer
v = (unsafe.Pointer)(&byt[0])
C.voidTest(v)
// fmt.Println("byte:", string(byt))
fmt.Println("No crash: test successfuly")
项目文件夹:
main.go birds22.wav libsndfile-1.dll sndfile.h我的构建命令:go build .
我不是经验丰富的 C 开发人员。这就是我与 CGo 合作的原因。但我会尝试使 C 代码适应 CGO,这说明了如何做到这一点。
我使用的来源和我尝试调整的代码: libsndfile virtualio test gosndfile virtualio test
【问题讨论】:
"我用 AES 加密了音频数据。" ——但是为什么? 我不希望未经许可使用我的音频数据。这些声音是我买来并精心设计的。此外,其他游戏公司也会加密他们的数据。 除非您有一些非常可靠的 DRM,否则简单地加密数据是浪费时间。如果你有可靠的 DRM,你就不会在 SO 上问这个级别的问题。 :// 我不这么认为。我知道很多项目都是这样工作的。如果我认为这些步骤还不够,我可以创建不同的文件格式。但我会再次谈到同样的话题。最终我必须用 libsndfile 处理这些文件。 嗯,这是你的项目。所以做你想做的。但我不会浪费我的时间。 【参考方案1】:这里有一个解决方案。如果要使用它,必须将 libsndfile 和 openal '库放在正确的位置。 使用 Go 15.2 64 位测试。 我是 Windows 用户。 从虚拟源读取文件,打印信息(通道、帧、可搜索等)并使用 OpenAL 播放。 还有 GitHub 上的问题。阅读可能会有所帮助。 #16
主要代码:
package main
// #cgo CFLAGS: -Wall -O3 -Iinclude
// #cgo LDFLAGS: -O3 -L. -llibsndfile-1 -lopenal32
/*
#include "extras.h"
#include "sndfile.h"
#include "stdlib.h"
#include "AL/al.h"
#include "AL/alc.h"
#include "AL/alext.h"
*/
import "C"
import (
"fmt"
"unsafe"
"io/ioutil"
"bytes"
"time"
"os"
"./oal"
)
type MyData struct
MyBytes *bytes.Reader
Count int64
func main()
fullFileByte, err := ioutil.ReadFile(os.Args[1]); errHandler(err)
reader := bytes.NewReader(fullFileByte)
// file info (Channels, frames, seekable etc...)
var myInfo Info
data := &MyDataMyBytes: reader, Count: 0
getLen := func() int64
l := data.MyBytes.Len()
println("Lenght:", l)
return int64(l)
vRead := func(o []byte) int64
//println("Read:", data.Count)
i, _ := data.MyBytes.Read(o) // ; errHandler(err)
data.Count += int64(i)
return int64(i)
seek := func(offset int64, whence int) int64
println("Seek:", data.Count)
goWhence := whence
data.Count, _ = data.MyBytes.Seek(offset, goWhence) // ; errHandler(err)
return data.Count
tell := func() int64
println("Tell: ", data.Count)
return data.Count
globVB.GetFileLen = getLen
globVB.Read = vRead
globVB.Seek = seek
globVB.Tell = tell
f := OpenVirtual(ModeRead, &myInfo)
fmt.Println("Channel:", myInfo.Channels, "\nFrames:", myInfo.Frames, "\nFormat:", myInfo.Format, "\nSections:", myInfo.Sections, "\nSample Rate:", myInfo.Samplerate, "\nSeekable:", myInfo.Seekable)
s := Source
s.Create(uint32(C.CreateVirtualBuffer(f.SFile, *myInfo.fromGoToCInfo())))
s.Play()
for
time.Sleep(500 * time.Millisecond)
func OpenVirtual(mode FMode, info* Info) File // File
We're tricking the libsndfile. It's actually unnecessary code.
var vb *C.VirtualCallbacks
var file File
// Go → C
cInfo := info.fromGoToCInfo()
cVirtualIO := C.NewVirtualIO()
file.SFile = C.sf_open_virtual(cVirtualIO, C.int(mode), cInfo, (unsafe.Pointer)(vb))
if file.SFile == nil
panic(C.GoString(C.sf_strerror(file.SFile)))
*info = fromCToGo(cInfo)
return file
type File struct
SFile* C.SNDFILE
type Info struct
Frames int64
Samplerate int
Channels int
Format int
Sections int
Seekable int
func (s Info) fromGoToCInfo() *C.SF_INFO
val := new(C.SF_INFO)
val.frames = C.sf_count_t(s.Frames)
val.samplerate = C.int(s.Samplerate)
val.channels = C.int(s.Channels)
val.format = C.int(s.Format)
val.sections = C.int(s.Sections)
val.seekable = C.int(s.Seekable)
return val
type SFile C.SNDFILE
func fromCToGo(info* C.SF_INFO) Info
val := Info
val.Frames = int64(info.frames)
val.Samplerate = int(info.samplerate)
val.Channels = int(info.channels)
val.Format = int(info.format)
val.Sections = int(info.sections)
val.Seekable = int(info.seekable)
return val
// File modes: read, write and readwrite
type FMode int
const (
ModeRead FMode = C.SFM_READ
ModeWrite FMode = C.SFM_WRITE
ModeReadWrite FMode = C.SFM_RDWR
)
func errHandler(e error)
if e != nil
panic(e)
func init()
device, err := oal.OpenDevice("")
errHandler(err)
ctx, err := oal.CreateContext(device, nil)
errHandler(err)
oal.MakeContextCurrent(ctx)
type TGetFileLen func() int64
type TVioseek func(offset int64, whence int) int64
type TVioRead func(o []byte) int64
type TVioWrite func( ptr unsafe.Pointer, count int64, user_data unsafe.Pointer)
type TVioTell func() int64
type SVirtualIO struct
GetFileLen TGetFileLen
Seek TVioSeek
Read TVioRead
Write TVioWrite
Tell TVioTell
// Data interface
var globVB SVirtualIO
//export goVirtualRead
func goVirtualRead(buffPtr unsafe.Pointer, count int64, data unsafe.Pointer) int64
byteBuff := (*[1 << 31]byte) (buffPtr)[0:count]
return globVB.Read(byteBuff)
//export goGetLen
func goGetLen(userData unsafe.Pointer) int64
return globVB.GetFileLen()
//export goVirtualSeek
func goVirtualSeek(offset int64, whence int, userData unsafe.Pointer) int64
return globVB.Seek(offset, whence)
//export goVirtualTell
func goVirtualTell(userData unsafe.Pointer) int64
return globVB.Tell()
type Source struct
Source C.ALuint
Buffer C.ALuint
func (s Source) Delete()
C.alDeleteSources(1, &s.Source)
C.alDeleteBuffers(1, &s.Buffer)
func (s* Source) Create(b uint32)
var source C.ALuint
var buffer C.ALuint = C.ALuint(b)
source = 0
C.alGenSources(1, &source)
C.alSourcei(source, C.AL_BUFFER, C.ALint(buffer))
s.Source = source
s.Buffer = buffer
func (s Source) Play()
C.alSourcePlay(s.Source)
extras.c:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "extras.h"
#include "_cgo_export.h"
#include "sndfile.h"
#include "AL/al.h"
#include "AL/alc.h"
sf_count_t
virtualRead(void *ptr, sf_count_t count, void *userData)
return goVirtualRead(ptr, count, userData);
sf_count_t
virtualGetFileLen(void *udata)
return goGetLen(udata);
sf_count_t
virtualSeek(sf_count_t offset, int whence, void *user_data)
return goVirtualSeek(offset, whence, user_data);
sf_count_t
virtualTell(void *userData)
return goVirtualTell(userData);
SF_VIRTUAL_IO*
NewVirtualIO()
static SF_VIRTUAL_IO sndVirtualIO;
sndVirtualIO.read = virtualRead;
sndVirtualIO.get_filelen = virtualGetFileLen;
sndVirtualIO.seek = virtualSeek;
sndVirtualIO.tell = virtualTell;
// sndVirtualIO.write= virtualWrite;
return &sndVirtualIO;
ALuint
CreateVirtualBuffer(SNDFILE *file, SF_INFO info)
ALenum err, format;
ALuint buffer;
SNDFILE *sndfile;
SF_INFO sfinfo;
sfinfo = info;
short *membuf;
sf_count_t num_frames;
ALsizei num_bytes;
sndfile = file;
if(!sndfile)
return 0;
if(sfinfo.channels == 1)
format = AL_FORMAT_MONO16;
else if(sfinfo.channels == 2)
format = AL_FORMAT_STEREO16;
else
sf_close(sndfile);
return 0;
membuf = malloc((size_t)(sfinfo.frames * sfinfo.channels) * sizeof(short));
num_frames = sf_readf_short(sndfile, membuf, sfinfo.frames);
if(num_frames < 1)
free(membuf);
sf_close(sndfile);
return 0;
num_bytes = (ALsizei)(num_frames * sfinfo.channels) * (ALsizei)sizeof(short);
buffer = 0;
alGenBuffers(1, &buffer);
alBufferData(buffer, format, membuf, num_bytes, sfinfo.samplerate);
free(membuf);
sf_close(sndfile);
err = alGetError();
if(err != AL_NO_ERROR)
if(buffer && alIsBuffer(buffer))
alDeleteBuffers(1, &buffer);
return 0;
return buffer;
extras.h(头文件):
#ifndef EXTRAS_H
#define EXTRAS_H
#include "sndfile.h"
#include "AL/al.h"
#include "AL/alc.h"
// **redundant code. Because NULL is not accepted. :)
typedef sf_count_t (*goreadfunc)(void* sf_count_t, void*);
struct VirtualCallbacks
goreadfunc vRead;
sf_vio_get_filelen vGetFileLen;
sf_vio_seek vSeek;
sf_vio_write vWrite;
;
typedef struct VirtualCallbacks VirtualCallbacks;
sf_count_t goVirtualRead(void *ptr, sf_count_t count, void *user_data);
SF_VIRTUAL_IO*
NewVirtualIO(void);
ALuint
CreateVirtualBuffer(SNDFILE *file, SF_INFO info);
#endif
【讨论】:
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