deb-spice-html5/playback.js

"use strict";
/*
   Copyright (C) 2014 by Jeremy P. White <jwhite@codeweavers.com>

   This file is part of spice-html5.

   spice-html5 is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   spice-html5 is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with spice-html5.  If not, see <http://www.gnu.org/licenses/>.
*/

/*----------------------------------------------------------------------------
**  SpicePlaybackConn
**      Drive the Spice Playback channel (sound out)
**--------------------------------------------------------------------------*/
function SpicePlaybackConn()
{
    SpiceConn.apply(this, arguments);

    this.queue = new Array();
    this.append_okay = false;
    this.start_time = 0;
}

SpicePlaybackConn.prototype = Object.create(SpiceConn.prototype);
SpicePlaybackConn.prototype.process_channel_message = function(msg)
{
    if (!!!window.MediaSource)
    {
        this.log_err('MediaSource API is not available');
        return false;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_START)
    {
        var start = new SpiceMsgPlaybackStart(msg.data);

        PLAYBACK_DEBUG > 0 && console.log("PlaybackStart; frequency " + start.frequency);

        if (start.frequency != OPUS_FREQUENCY)
        {
            this.log_err('This player cannot handle frequency ' + start.frequency);
            return false;
        }

        if (start.channels != OPUS_CHANNELS)
        {
            this.log_err('This player cannot handle ' + start.channels + ' channels');
            return false;
        }

        if (start.format != SPICE_AUDIO_FMT_S16)
        {
            this.log_err('This player cannot format ' + start.format);
            return false;
        }

        if (! this.source_buffer)
        {
            this.media_source = new MediaSource();
            this.media_source.spiceconn = this;

            this.audio = document.createElement("audio");
            this.audio.spiceconn = this;
            this.audio.setAttribute('autoplay', true);
            this.audio.src = window.URL.createObjectURL(this.media_source);
            document.getElementById(this.parent.screen_id).appendChild(this.audio);

            this.media_source.addEventListener('sourceopen', handle_source_open, false);
            this.media_source.addEventListener('sourceended', handle_source_ended, false);
            this.media_source.addEventListener('sourceclosed', handle_source_closed, false);

            this.bytes_written = 0;

            return true;
        }
    }

    if (msg.type == SPICE_MSG_PLAYBACK_DATA)
    {
        var data = new SpiceMsgPlaybackData(msg.data);

        // If this packet has the same time as the last, just bump up by one.
        if (this.last_data_time && data.time <= this.last_data_time)
        {
            // FIXME - this is arguably wrong.  But delaying the transmission was worse,
            //          in initial testing.  Could use more research.
            PLAYBACK_DEBUG > 1 && console.log("Hacking time of " + data.time + " to " + this.last_data_time + 1);
            data.time = this.last_data_time + 1;
        }

        if (! this.source_buffer)
            return true;

        if (this.audio.readyState >= 3 && this.audio.buffered.length > 1 &&
            this.audio.currentTime == this.audio.buffered.end(0) &&
            this.audio.currentTime < this.audio.buffered.start(this.audio.buffered.length - 1))
        {
            console.log("Audio underrun: we appear to have fallen behind; advancing to " +
                this.audio.buffered.start(this.audio.buffered.length - 1));
            this.audio.currentTime = this.audio.buffered.start(this.audio.buffered.length - 1);
        }

        this.last_data_time = data.time;


        PLAYBACK_DEBUG > 1 && console.log("PlaybackData; time " + data.time + "; length " + data.data.byteLength);

        if (this.start_time == 0)
            this.start_playback(data);

        else if (data.time - this.cluster_time >= MAX_CLUSTER_TIME)
            this.new_cluster(data);

        else
            this.simple_block(data, false);

        if (this.audio.paused)
            this.audio.play();

        return true;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_MODE)
    {
        var mode = new SpiceMsgPlaybackMode(msg.data);
        if (mode.mode != SPICE_AUDIO_DATA_MODE_OPUS)
        {
            this.log_err('This player cannot handle mode ' + mode.mode);
            delete this.source_buffer;
        }
        return true;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_STOP)
    {
        return true;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_VOLUME)
    {
        this.known_unimplemented(msg.type, "Playback Volume");
        return true;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_MUTE)
    {
        this.known_unimplemented(msg.type, "Playback Mute");
        return true;
    }

    if (msg.type == SPICE_MSG_PLAYBACK_LATENCY)
    {
        this.known_unimplemented(msg.type, "Playback Latency");
        return true;
    }

    return false;
}

SpicePlaybackConn.prototype.start_playback = function(data)
{
    this.start_time = data.time;

    var h = new webm_Header();
    var te = new webm_AudioTrackEntry;
    var t = new webm_Tracks(te);

    var mb = new ArrayBuffer(h.buffer_size() + t.buffer_size())

    this.bytes_written = h.to_buffer(mb);
    this.bytes_written = t.to_buffer(mb, this.bytes_written);

    this.source_buffer.addEventListener('error', handle_sourcebuffer_error, false);
    this.source_buffer.addEventListener('updateend', handle_append_buffer_done, false);
    playback_append_buffer(this, mb);

    this.new_cluster(data);
}

SpicePlaybackConn.prototype.new_cluster = function(data)
{
    this.cluster_time = data.time;

    var c = new webm_Cluster(data.time - this.start_time);

    var mb = new ArrayBuffer(c.buffer_size());
    this.bytes_written += c.to_buffer(mb);

    if (this.append_okay)
        playback_append_buffer(this, mb);
    else
        this.queue.push(mb);

    this.simple_block(data, true);
}

SpicePlaybackConn.prototype.simple_block = function(data, keyframe)
{
    var sb = new webm_SimpleBlock(data.time - this.cluster_time, data.data, keyframe);
    var mb = new ArrayBuffer(sb.buffer_size());

    this.bytes_written += sb.to_buffer(mb);

    if (this.append_okay)
        playback_append_buffer(this, mb);
    else
        this.queue.push(mb);
}

function handle_source_open(e)
{
    var p = this.spiceconn;

    if (p.source_buffer)
        return;

    p.source_buffer = this.addSourceBuffer(SPICE_PLAYBACK_CODEC);
    if (! p.source_buffer)
    {
        p.log_err('Codec ' + SPICE_PLAYBACK_CODEC + ' not available.');
        return;
    }

    if (PLAYBACK_DEBUG > 0)
        playback_handle_event_debug.call(this, e);

    listen_for_audio_events(p);

    p.source_buffer.spiceconn = p;
    p.source_buffer.mode = "segments";

    // FIXME - Experimentation with segments and sequences was unsatisfying.
    //         Switching to sequence did not solve our gap problem,
    //         but the browsers didn't fully support the time seek capability
    //         we would expect to gain from 'segments'.
    //         Segments worked at the time of this patch, so segments it is for now.

}

function handle_source_ended(e)
{
    var p = this.spiceconn;
    p.log_err('Audio source unexpectedly ended.');
}

function handle_source_closed(e)
{
    var p = this.spiceconn;
    p.log_err('Audio source unexpectedly closed.');
}

function handle_append_buffer_done(e)
{
    var p = this.spiceconn;

    if (PLAYBACK_DEBUG > 1)
        playback_handle_event_debug.call(this, e);

    if (p.queue.length > 0)
    {
        var mb = p.queue.shift();
        playback_append_buffer(p, mb);
    }
    else
        p.append_okay = true;

}

function handle_sourcebuffer_error(e)
{
    var p = this.spiceconn;
    p.log_err('source_buffer error ' + e.message);
}

function playback_append_buffer(p, b)
{
    try
    {
        p.source_buffer.appendBuffer(b);
        p.append_okay = false;
    }
    catch (e)
    {
        p.log_err("Error invoking appendBuffer: " + e.message);
    }
}

function playback_handle_event_debug(e)
{
    var p = this.spiceconn;
    if (p.audio)
    {
        if (PLAYBACK_DEBUG > 0 || p.audio.buffered.len > 1)
            console.log(p.audio.currentTime + ": event " + e.type +
                dump_media_element(p.audio));
    }

    if (PLAYBACK_DEBUG > 1 && p.media_source)
        console.log("  media_source " + dump_media_source(p.media_source));

    if (PLAYBACK_DEBUG > 1 && p.source_buffer)
        console.log("  source_buffer " + dump_source_buffer(p.source_buffer));

    if (PLAYBACK_DEBUG > 0 || p.queue.length > 1)
        console.log('  queue len ' + p.queue.length + '; append_okay: ' + p.append_okay);
}

function playback_debug_listen_for_one_event(name)
{
    this.addEventListener(name, playback_handle_event_debug);
}

function listen_for_audio_events(spiceconn)
{
    var audio_0_events = [
        "abort", "error"
    ];

    var audio_1_events = [
        "loadstart", "suspend", "emptied", "stalled", "loadedmetadata", "loadeddata", "canplay",
        "canplaythrough", "playing", "waiting", "seeking", "seeked", "ended", "durationchange",
        "timeupdate", "play", "pause", "ratechange"
    ];

    var audio_2_events = [
        "progress",
        "resize",
        "volumechange"
    ];

    audio_0_events.forEach(playback_debug_listen_for_one_event, spiceconn.audio);
    if (PLAYBACK_DEBUG > 0)
        audio_1_events.forEach(playback_debug_listen_for_one_event, spiceconn.audio);
    if (PLAYBACK_DEBUG > 1)
        audio_2_events.forEach(playback_debug_listen_for_one_event, spiceconn.audio);
}