audio计算

1 frame/sample/fs关系

frame = ch num * bit len / 8 bytes

sample = bit len / 8 bytes

timer = size(bytes)/sample/sample rate s

2 参考代码

pcm_native.c

snd_pcm_hw_params

runtime->sample_bits = bits;
bits *= runtime->channels;
runtime->frame_bits = bits;

include/soumd/pcm.h

/**
 * bytes_to_samples - Unit conversion of the size from bytes to samples
 * @runtime: PCM runtime instance
 * @size: size in bytes
 */
static inline ssize_t bytes_to_samples(struct snd_pcm_runtime *runtime, ssize_t size)
{
	return size * 8 / runtime->sample_bits;
}

/**
 * bytes_to_frames - Unit conversion of the size from bytes to frames
 * @runtime: PCM runtime instance
 * @size: size in bytes
 */
static inline snd_pcm_sframes_t bytes_to_frames(struct snd_pcm_runtime *runtime, ssize_t size)
{
	return size * 8 / runtime->frame_bits;
}

/**
 * samples_to_bytes - Unit conversion of the size from samples to bytes
 * @runtime: PCM runtime instance
 * @size: size in samples
 */
static inline ssize_t samples_to_bytes(struct snd_pcm_runtime *runtime, ssize_t size)
{
	return size * runtime->sample_bits / 8;
}

/**
 * frames_to_bytes - Unit conversion of the size from frames to bytes
 * @runtime: PCM runtime instance
 * @size: size in frames
 */
static inline ssize_t frames_to_bytes(struct snd_pcm_runtime *runtime, snd_pcm_sframes_t size)
{
	return size * runtime->frame_bits / 8;
}