src/libaudcore/vis-runner.cc

/*
 * vis_runner.c
 * Copyright 2009-2012 John Lindgren
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions, and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions, and the following disclaimer in the documentation
 *    provided with the distribution.
 *
 * This software is provided "as is" and without any warranty, express or
 * implied. In no event shall the authors be liable for any damages arising from
 * the use of this software.
 */

#include "internal.h"

#include <assert.h>
#include <stdint.h>
#include <string.h>

#include "hook.h"
#include "list.h"
#include "mainloop.h"
#include "output.h"
#include "threads.h"

#define INTERVAL 33 /* milliseconds */
#define FRAMES_PER_NODE 512

struct VisNode : public ListNode
{
    VisNode(int channels, int time)
        : channels(channels), time(time),
          data(new float[channels * FRAMES_PER_NODE])
    {
    }

    ~VisNode() { delete[] data; }

    const int channels;
    int time;
    float * data;
};

static aud::mutex mutex;
static bool enabled = false;
static bool playing = false, paused = false;
static VisNode * current_node = nullptr;
static int current_frames;
static List<VisNode> vis_list;
static List<VisNode> vis_pool;
static QueuedFunc queued_clear;

static void send_audio(void *)
{
    /* call before locking mutex to avoid deadlock */
    int outputted = output_get_raw_time();

    auto mh = mutex.take();

    if (!enabled || !playing || paused)
        return;

    VisNode * node = nullptr;
    VisNode * next;

    while ((next = vis_list.head()))
    {
        /* If we are considering a node, stop searching and use it if it is the
         * most recent (that is, the next one is in the future).  Otherwise,
         * consider the next node if it is not in the future by more than the
         * length of an interval. */
        if (next->time > outputted + (node ? 0 : INTERVAL))
            break;

        if (node)
            vis_pool.prepend(node);

        node = next;
        vis_list.remove(node);
    }

    if (!node)
        return;

    mh.unlock();
    vis_send_audio(node->data, node->channels);
    mh.lock();

    vis_pool.prepend(node);
}

static void flush(aud::mutex::holder &)
{
    delete current_node;
    current_node = nullptr;

    vis_list.clear();
    vis_pool.clear();

    if (enabled)
        queued_clear.queue(vis_send_clear);
}

void vis_runner_flush()
{
    auto mh = mutex.take();
    flush(mh);
}

static void start_stop(aud::mutex::holder & mh, bool new_playing,
                       bool new_paused)
{
    playing = new_playing;
    paused = new_paused;

    queued_clear.stop();

    if (!enabled || !playing)
        flush(mh);

    if (enabled && playing && !paused)
        timer_add(TimerRate::Hz30, send_audio);
    else
        timer_remove(TimerRate::Hz30, send_audio);
}

void vis_runner_start_stop(bool new_playing, bool new_paused)
{
    auto mh = mutex.take();
    start_stop(mh, new_playing, new_paused);
}

void vis_runner_pass_audio(int time, const Index<float> & data, int channels,
                           int rate)
{
    auto mh = mutex.take();

    if (!enabled || !playing)
        return;

    /* We can build a single node from multiple calls; we can also build
     * multiple nodes from the same call.  If current_node is present, it was
     * partly built in the last call and needs to be finished. */

    int at = 0;

    while (1)
    {
        if (current_node)
            assert(current_node->channels == channels);
        else
        {
            int node_time = time;

            /* There is no partly-built node, so start a new one.  Normally
             * there will be nodes in the queue already; if so, we want to copy
             * audio data from the signal starting at 30 milliseconds after the
             * beginning of the most recent node.  If there are no nodes in the
             * queue, we are at the beginning of the song or had an underrun,
             * and we want to copy the earliest audio data we have. */

            VisNode * tail = vis_list.tail();
            if (tail)
                node_time = tail->time + INTERVAL;

            at = channels * (int)((int64_t)(node_time - time) * rate / 1000);

            if (at < 0)
                at = 0;
            if (at >= data.len())
                break;

            current_node = vis_pool.head();

            if (current_node)
            {
                assert(current_node->channels == channels);
                vis_pool.remove(current_node);
                current_node->time = node_time;
            }
            else
                current_node = new VisNode(channels, node_time);

            current_frames = 0;
        }

        /* Copy as much data as we can, limited by how much we have and how much
         * space is left in the node.  If we cannot fill the node, we return and
         * wait for more data to be passed in the next call.  If we do fill the
         * node, we loop and start building a new one. */

        int copy = aud::min(data.len() - at,
                            channels * (FRAMES_PER_NODE - current_frames));
        memcpy(current_node->data + channels * current_frames, &data[at],
               sizeof(float) * copy);
        current_frames += copy / channels;

        if (current_frames < FRAMES_PER_NODE)
            break;

        vis_list.append(current_node);
        current_node = nullptr;
    }
}

void vis_runner_enable(bool enable)
{
    auto mh = mutex.take();
    enabled = enable;
    start_stop(mh, playing, paused);
}