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Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

关于period_size的概念,之前有提过了,表示DMA一次传输的数据量:
http://blog.csdn/kris_fei/article/details/72780656

用户空间对period_size的设置:
struct pcm_config pcm_config_in = {
    .channels = 2,
    .rate = 44100,
    .period_size = 128,
    .period_count = 4,
    .format = PCM_FORMAT_S16_LE,
};
传到Kernel:
struct pcm *pcm_open(unsigned int card, unsigned int device,
                     unsigned int flags, struct pcm_config *config)
{
......
    //作为最小值
    param_set_min(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);
......
    //
    ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, ¶ms)
......
}

dma

本文标签: 规则periodsizeAudio