c - libao : Playing blocks of audio as sequenze stutters

Question

嘿嘿，

所以我正在尝试用 libao 播放 pcm 音频。我的目标是让播放可以暂停和取消。

出于某种原因，alsa 驱动程序的输出断断续续，播放速度非常非常快。就像您正在擦洗输出一样。如果我只是播放整个缓冲区，它就可以正常工作。

这是播放循环:

uint_32 next_read = 8192;

while (1) {
    ao_play(device, (char *) buffer, next_read);
    buffer += next_read;

    if (cancel_playback) {
        printf("Cancel\n");
        break;
    }
}

这是准备缓冲区的代码。我正在将整个流加载到内存中:

ao_device *device;
ao_sample_format format;
SF_INFO sfinfo;

int default_driver;

short *buffer;
uint_32 buf_size;

signal(SIGINT, on_cancel_playback);


SNDFILE *file = sf_open("test.wav", SFM_READ, &sfinfo);


printf("Samples: %d\n", sfinfo.frames);
printf("Sample rate: %d\n", sfinfo.samplerate);
printf("Channels: %d\n", sfinfo.channels);

ao_initialize();

default_driver = ao_default_driver_id();

switch (sfinfo.format & SF_FORMAT_SUBMASK) {
    case SF_FORMAT_PCM_16:
        format.bits = 16;
        break;
    case SF_FORMAT_PCM_24:
        format.bits = 24;
        break;
    case SF_FORMAT_PCM_32:
        format.bits = 32;
        break;
    case SF_FORMAT_PCM_S8:
        format.bits = 8;
        break;
    case SF_FORMAT_PCM_U8:
        format.bits = 8;
        break;
    default:
        format.bits = 16;
        break;
}

format.channels = sfinfo.channels;
format.rate = sfinfo.samplerate;
format.byte_format = AO_FMT_NATIVE;
format.matrix = 0;

device = ao_open_live(default_driver, &format, NULL);

if (device == NULL) {
    fprintf(stderr, "Error opening device.\n");
    return 1;
}


buf_size = (uint_32) (format.channels * sfinfo.frames * sizeof(short));
buffer = calloc(buf_size, sizeof(char));

printf("buffer-size: %d\n", buf_size);

printf("Loading file into buffer...\n");
sf_readf_short(file, buffer, buf_size);
printf("Closing file...\n");
sf_close(file);
printf("Playback...\n");

Answer 1

找到我自己的答案:D

short *buffer; 

->

char *buffer;

问题是我想跳过这一行中的 next_read 个字节:

buffer += next_read;

但是类型很短 * 所以我跳过了 2 个字节而不是一个。 :/