static const pcm_sample_description_t *caf_get_format(pcm_reader_t *reader)
{
    return &((caf_reader_t *)reader)->sample_format;
}
static const pcm_sample_description_t *caf_get_format(pcm_reader_t *reader)
{
    return &((caf_reader_t *)reader)->sample_format;
}