{
    pa_operation *o;

    pa_assert(s);
    pa_assert(PA_REFCNT_VALUE(s) >= 1);

    PA_CHECK_VALIDITY_RETURN_NULL(s->context, !pa_detect_fork(), PA_ERR_FORKED);
    PA_CHECK_VALIDITY_RETURN_NULL(s->context, s->state == PA_STREAM_READY, PA_ERR_BADSTATE);
    PA_CHECK_VALIDITY_RETURN_NULL(s->context, s->direction == PA_STREAM_PLAYBACK, PA_ERR_BADSTATE);
    PA_CHECK_VALIDITY_RETURN_NULL(s->context, s->buffer_attr.prebuf > 0, PA_ERR_BADSTATE);

    /* Ask for a timing update before we cork/uncork to get the best
     * accuracy for the transport latency suitable for the
     * check_smoother_status() call in the started callback */
    request_auto_timing_update(s, TRUE);

    if (!(o = stream_send_simple_command(s, PA_COMMAND_TRIGGER_PLAYBACK_STREAM, cb, userdata)))
        return NULL;

    /* This might cause the read index to start moving again, hence
     * let's request a timing update */
    request_auto_timing_update(s, TRUE);

    return o;
}