android - 如何从 Android 中的多个声音 block 创建单个声音文件

Question

我正在创建一个鼓应用程序，我必须在其中做两件事

播放各种声音

如果用户选择录制声音，我必须制作用户播放过的任何音乐的音频文件

该应用程序的工作原理是这样的 -
当用户点击按钮 A 时，我播放 SoundA。如果用户点击 B，我会播放 SoundB，同样...

因此，要播放而不是录制声音，我在想的是，当用户单击“开始录制”按钮时-
如果我保持用户单击按钮的时间戳，我可以通过混合我已经拥有的声音来重现质量更好的最终输出。

例如用户在 00:01 秒按下按钮 A，在 00:05 秒按下按钮 B，依此类推

我不确定的是 - 如何创建音频文件并在特定时间段插入这些声音，即声音 A 在 00:01 秒，声音 B 在 00:05 秒......依此类推。

对此的任何帮助都会有很大帮助。

先感谢您。

Answer 1

两部分答案:

解决方案一 :想到的一个想法是，与其尝试录制生成的音频，不如录制他们按下的按钮，并在他们播放文件时重新创建序列。

所以你的“录音”文件会是这样的:

A 0001(1 秒播放 A)

B 0005

A 0006(添加更多我的
自己)

C 0008

...

B 0194(使用纯秒而不是分钟/秒)

因此，当他们想要播放“录音”时，您可以设置一个计时器，等待适当的时间，然后播放适当的声音。因此，对于我上面的示例，您将:

等待一秒钟，播放声音 A

再等四秒钟，播放声音 B

再等一秒，再播放A音

等待两秒钟，播放声音 C

等

解决方案二 :如果您希望能够将录音导出到您的应用程序之外，这将更合适，因此需要一个真实的音频文件。

这假设您拥有原始格式的声音(此处可以使用 WAV，但必须先解码 MP3 或其他格式)。这还假设所有声音在样本/秒、立体声/单声道、8 位/16 位样本等方面都是一致的。然后当它们完成录制时，分配一个适当的数组(或两个，如果你做立体声)尺寸。因此，如果录制时间为 11 秒，并且您的声音是 44100 样本/秒的 16 位单声道，则您分配一个由 485100 个短片组成的数组(485100=11*44100)。如果它太大，那么您可能需要在较短的 fragment 中执行此操作(例如一次一秒)，并准备好让您的声音在 fragment 之间交叉。 16 位值是有符号的短裤，因此您应该能够将数组初始化为 0，并在适当的位置添加每个声音。请注意，8 位值是无符号的，带有偏移量，因此您必须在添加样本时调整偏移量。然后以某种格式写入文件(可能是 WAV，参见 http://www-mmsp.ece.mcgill.ca/documents/AudioFormats/WAVE/WAVE.html 了解 WAV 文件格式的说明)。如果您希望文件是 MP3 或其他压缩格式，几乎可以肯定有一些类(class)可以为您进行压缩，但在这方面我帮不了您太多。

编辑:创建 .WAV 文件的代码示例(在 C for Windows 中):

/* Create a .WAV file with a specified set of chirps */
#include<stdio.h>
#include<sys\stat.h>
#include<ctype.h>

/* length of one bit in 44100Hz units */
#define BIT_LEN 88.5

/* length of one half-cycle */
#define HALF_CYCLE (BIT_LEN/8)

/* samples per second */
#define SAMP_RATE 44100

/* seconds before chirps start */
#define LEAD_SILENCE 5

struct {
    unsigned long ID;           /* FILE ID "RIFF" */
    unsigned long Len;          /* file length (excluding 8-byte header) */
    unsigned long DataType;     /* Data type 'WAVE' (start of main file) */
} FileHeader;

struct {
    unsigned long ID;           /* chunk ID "DATA" */
    unsigned long Len;          /* chunk length */
} DataHeader;

struct {
    unsigned long ID;           /* chunk ID "FMT " */
    unsigned long Len;          /* chunk length */
    short FormatTag;            /* format (1 if uncompressed) */
    unsigned short Channels;        /* # of channels (mono, stereo, etc) */
    unsigned long SampPerSec;       /* # of samples per second */
    unsigned long AvgBytesPerSec;   /* # of bytes played per second */
    unsigned short BlockAlign;      /* Size of a 'frame' in bytes */
    unsigned short BitsPerSamp;     /* bits per sample */
} FormatHeader;

#define ID_RIFF 0x46464952  /* 'RIFF' (FFIR) */
#define ID_WAVE 0x45564157  /* 'WAVE' (EVAW) */
#define ID_DATA 0x61746164  /* 'data' (atad) */
#define ID_FMT  0x20746d66  /* 'fmt ' ( tmf)*/

/* count # of pos/negative parts done */
int pcount=0;
/* how many will fit on a normal line? */
#define PCOUNT_MAX 14

void disp_id( char * lbl, long ID )
{
   union {
      long l;
      char c[6];
   } u;

   u.l = ID;
   u.c[4] = 0;

   printf( lbl, u.c );
}

/* note where the samples begin */
unsigned long SampleStart;  /* where do samples begin? */

/* one-second chirp segment */

short NewChirp[SAMP_RATE],  /* 1-second block with chirp */
    Silence[SAMP_RATE];     /* 1-second silence */

/* insert a byte into the chirp */
/* location is specified in bit time units */
void insert_byte( int location, int value )
{
    int i, j;
    int data;   /* value to write to item */
    int dloc;   /* where we are within the byte */
    int cycle;

    printf("Inserting byte %d", value);

    /* insert bits in little-endian order */
    data = (value<<2) + 2;  /* add "10" to the number */

    /* round cycle low/high times to 11 samples low, 11 samples high */
    /* use BIT_LEN to put it in the proper place */
    for( i=0; i<10; i++ )
        if ( data & (1<<i) )
        {
            printf(" %d: ", i );

            /* have a 1-bit to insert, where should it be? */
            /* insert 4 cycles */
            for( cycle=0; cycle<4; cycle++ )
            {
                /* note: this may leave 0 samples between cycles or bits */
                dloc = (int)(location + i*BIT_LEN + cycle*(BIT_LEN/4) + 0.5);
                printf(" %d", dloc );

                /* insert 11 low samples */
                for( j=0; j<11; j++ )
                {
                    NewChirp[ dloc+j ] = -30000;
                }

                /* insert 11 high samples */
                for( j=11; j<22; j++ )
                {
                    NewChirp[ dloc+j ] =  30000;
                }
            }
        }

    printf("\n");
} /* insert_byte */

/* insert a chirp with the given value */
void insert_chirp( FILE *f, float speed, float incline )
{
   int i, i_speed, i_incline, i_chksum;

   /* convert values to integers */
   i_speed = (int)( speed*10 + 0.5 );
   i_incline = (int)( incline*10 + 0.5 );
   i_chksum = (i_speed + i_incline) & 0x0ff;

   /* set everything to 0 in advance */
   memset( NewChirp, 0, SAMP_RATE );

   /* start inserting chirp parts */
   insert_byte(  0, i_speed );
   insert_byte( (int)(10*BIT_LEN+0.5), i_incline );
   insert_byte( (int)(20*BIT_LEN+0.5), i_chksum );
   insert_byte( (int)(40*BIT_LEN+0.5), i_speed );
   insert_byte( (int)(50*BIT_LEN+0.5), i_incline );
   insert_byte( (int)(60*BIT_LEN+0.5), i_chksum );

   /* write the chirp */
   fwrite( NewChirp, 1, SAMP_RATE, f );
} /* insert_chirp */

/* maximum # of chirps per file we will permit */
#define CHIRP_MAX 50

int main(int argc, char *argv[])
{
    FILE *f;                    /* workout information file */
    FILE *audio;                /* output WAV file */

    /* hold information about the chirps */
    struct {
        int second_count;           /* where does this occur in seconds */
        float speed;                /* speed to use */
        float incline;              /* treadmill incline */
    } chirp_list[CHIRP_MAX+1];

    int chirp_count;                /* # of chirps in the current workout */
    int cur_chirp;              /* which chirp are we working on? */
    int cur_time;               /* current time we are writing */

    char wname[100];                /* workout name from the file */
    int len;
    char dbuf[100];             /* one chirp line from the file */

    /* for reading one chirp */
    int sec;
    int seqno;
    float speed, incline;
    int sec_length;             /* length of workout in seconds */

    printf("initializaing\n");
    /* build our 1 second of silence */
    memset( Silence, 0, SAMP_RATE );

    printf("opening input file %s\n", argv[1] );

    /* open the description file */
    fopen_s( &f, argv[1], "r" );

    if ( f == NULL )
    {
        printf("Unable to open file %s\n", argv[1] );
        return 1;
    }

    /* read one workout from the file */
    while( 1==1 )
    {
        printf("reading one line from the workout\n");
        /* at end of file? */
        if ( feof(f) )
        {
            return 0;
        }

        /* get the header line */
        fgets( wname, 90, f );

        /* did we now detect end of file? */
        if ( feof(f) )
        {
            return 0;
        }

        /* read the workout stages */
        chirp_count = 0;
        sec_length = 45;        /* account for lead and trail time */
        while( 1==1) {
            fgets( dbuf, 90, f );
            printf("read line %s", dbuf );

            /* did we now detect end of file? - Shouldn't happen, but check */
            if ( feof(f) || strlen(dbuf)<3 )
            {
                break;
            }

            if ( ! isdigit( dbuf[0] ) )
            {
                /* should have only numbers here */
                return 3;
            }

            /* extract the information */
            sscanf_s( dbuf, "%d %f %f %d", &seqno, &speed, &incline, &sec );
            printf("speed=%3.1f, incline=%3.1f, time=%d\n", speed, incline, sec );

            /* save it for later */
            chirp_list[chirp_count].second_count = sec;
            sec_length += sec;
            chirp_list[chirp_count].speed = speed;
            chirp_list[chirp_count].incline = incline;

            /* move to next chirp */
            chirp_count++;
        }

        /* replace ".txt" with ".wav" for the output filename */
        if ( strlen( argv[1] ) > 90 )
        {
            printf("Error: path/filename too long\n");
            exit(1);
        }
        strcpy( wname, argv[1] );
        strcpy( wname+strlen(wname)-3, "wav" );

        /* start creating our WAV file */       
        printf("Creating output file %s\n", wname );
        fopen_s( &audio, wname, "wb" );

        printf("Overall length: %d seconds\n", sec_length );

        /* create header */
        FileHeader.ID = ID_RIFF;
        FileHeader.DataType = ID_WAVE;

        /* create our format header */
        FormatHeader.ID = ID_FMT;
        FormatHeader.Len = 16;                      /* chunk length */
        FormatHeader.FormatTag = 1;                 /* format (1 if uncompressed) */
        FormatHeader.Channels = 1;                  /* # of channels */
        FormatHeader.SampPerSec = SAMP_RATE;        /* # of samples per second */
        FormatHeader.AvgBytesPerSec = SAMP_RATE*2;  /* # of bytes played per second */
        FormatHeader.BlockAlign = 1;                /* Size of a 'frame' in bytes */
        FormatHeader.BitsPerSamp = 16;              /* bits per sample */

        /* create our data header */
        DataHeader.ID = ID_DATA;
        DataHeader.Len = (sec_length+LEAD_SILENCE) * SAMP_RATE;

        /* update overall length, account for various headers except main RIFF part */
        /*      -- include 'WAVE' part of main header */
        FileHeader.Len = DataHeader.Len + 4 + 
                + sizeof(FormatHeader) + sizeof( DataHeader );

        /* write it to the file */
        fwrite( &FileHeader, sizeof(FileHeader), 1, audio );

        /* write it to the file */
        fwrite( &FormatHeader, sizeof(FormatHeader), 1, audio );

        /* write it to the file */
        fwrite( &DataHeader, sizeof(DataHeader), 1, audio );

        /* start with silence */
        printf("Writing lead-in\n" );
        for( cur_time = 0; cur_time < LEAD_SILENCE; cur_time++ )
        {
            fwrite( &Silence, 1, SAMP_RATE, audio );
        }

        /* now do the chirps */
        for( cur_chirp=0; cur_chirp < chirp_count; cur_chirp++ )
        {
            printf("Chirp #%d, time=%d, speed=%4.1f, incline=%4.1f\n",
                    cur_chirp+1, chirp_list[cur_chirp].second_count,
                    chirp_list[cur_chirp].speed, chirp_list[cur_chirp].incline );

            /* add the chirp */
            insert_chirp( audio, chirp_list[cur_chirp].speed,
                    chirp_list[cur_chirp].incline );

            /* add enough silence between this chirp and the next */
            for( cur_time = 1;
                cur_time < chirp_list[cur_chirp].second_count; cur_time++ )
            {
                /* add another second of silence */
                fwrite( &Silence, 1, SAMP_RATE, audio );
            }
        }

        /* add the stop chirp */
        printf("Stop chirp\n");
        insert_chirp( audio, 25.2, 25.2 );

        /* end with 30 seconds of silence */
        printf("Writing 30 seconds lead-out\n" );
        for( cur_time = 1; cur_time < 30; cur_time++ )
        {
            fwrite( &Silence, 1, SAMP_RATE, audio );
        }

        /* done with this workout */
        fclose( audio );
    } /* while reading workouts */
}