The SNES audio chip emulation is happening in your browser, in JavaScript. How cool is that?
71 |Sometimes a browser refresh improves performance
72 | 73 |
87 |
88 |
89 |
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/js/js-snes-player.js:
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1 | /* js-snes-player - a HTML SNES SPC file player
2 | (c) 2012 James Hall
3 | */
4 |
5 |
6 | bufferSize = 16384*2;
7 |
8 | var jsSNESPlayer = function() {
9 |
10 |
11 | function error(str) {
12 |
13 | if (str != '(null)') {
14 | alert(str);
15 | }
16 | }
17 |
18 | var proxy;
19 | var proxy;
20 | var first
21 |
22 | var play = function(SongData) {
23 | //run();
24 | //console.log(window);
25 |
26 | console.log('Make new SPC instance...');
27 | var snes_spc = _spc_new();
28 |
29 | console.log('Load filter...');
30 | var filter = _spc_filter_new();
31 | if (!snes_spc || !filter) {
32 | alert('Failed to load');
33 | } else {
34 | // Load SPC file into memory
35 | // @TODO: Actually load the file in
36 |
37 |
38 | var spc = allocate(SongData, 'i8', ALLOC_STACK);
39 |
40 | console.log('Load SPC data into pointer...');
41 |
42 | var spc_size = SongData.length;
43 |
44 | console.log('SPC size is ' + spc_size);
45 |
46 | console.log('Loading SPC');
47 | var load = _spc_load_spc(snes_spc, spc, spc_size);
48 | console.log('SPC file loaded');
49 |
50 | _spc_set_tempo(snes_spc, 320);
51 | _spc_set_output();
52 | _spc_clear_echo(snes_spc);
53 | _spc_filter_clear(filter);
54 |
55 | console.log('Creating audio sink...');
56 | buf = allocate(new Uint8Array(1e6), 'i8', ALLOC_STACK);
57 | myaudioprocess= function(buffer, channelCount){
58 | var retval = _spc_play(snes_spc, bufferSize/2 , buf);
59 | _spc_filter_run(filter, buf, bufferSize);
60 |
61 | for (i = 0; i < bufferSize; i =i+2) {
62 |
63 | // Take a mono stream
64 | if ((i - 1) % 2 == 0) {
65 | buffer[i/2] = HEAP8[i + buf] / 120;
66 |
67 | } else {
68 | buffer[i/2] = HEAP8[i + buf - 1] / 120;
69 |
70 | }
71 | }
72 | };
73 |
74 | }
75 |
76 | context = new AudioContext();
77 |
78 |
79 | audioNode = context.createScriptProcessor(bufferSize/2, 0, 1);
80 |
81 | audioNode.onaudioprocess = function(audioProcessingEvent) {
82 |
83 | // The output buffer contains the samples that will be modified and played
84 | outputBuffer = audioProcessingEvent.outputBuffer;
85 | for (var channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
86 | outData = outputBuffer.getChannelData(channel);
87 |
88 |
89 | myaudioprocess(outData,1);
90 | }}
91 |
92 | audioNode.connect(context.destination);
93 | }
94 |
95 |
96 | return {
97 | init: function() {
98 | $.get('songs/index.json', function(response) {
99 | response = $.parseJSON(response);
100 | $.each(response, function() {
101 | $('.song-selector').append('');
102 | });
103 | });
104 |
105 | $(document).ready(function() {
106 | $('.js-snes-start').click(function() {
107 | console.log('Start playing');
108 |
109 | var song = $('.song-selector').val();
110 | if (song == null) {
111 | alert('You need to select a song first silly!');
112 | } else {
113 | $.get('songs/' + song + '.json', function(response) {
114 | SongData=response;
115 | response = $.parseJSON(response);
116 | play(response);
117 | });
118 | }
119 |
120 | });
121 |
122 | $('.js-snes-stop').click(function() {
123 | console.log(proxy);
124 | proxy.parentSink.kill();
125 |
126 | })
127 | });
128 |
129 | }
130 | }
131 |
132 | }();
133 |
134 | //setTimeout(function() {
135 | jsSNESPlayer.init();
136 | //}, 2000);
137 |
138 |
139 |
140 |
141 |
142 |
143 |
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/notes:
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1 | These are my notes (Liam Wilson). I gave MrRio's js-snes-player a go, but it failed to work in both Firefox 31 and Chrome 36.0.1985.143.[3~
2 |
3 | Error messages:
4 |
5 | Firefox: Error: No audio sink available. sink.js:412
6 | Chrome: Uncaught [object Object] sink.js:35
7 |
8 | Seems to be using a project called sink.js to play back audio. sink.js seems to be broken in both FF and Chrome.
9 |
10 | I'll concentrate on Firefox for now. Strangely it fails in different places in FF and Chrome.
11 |
12 | Looking at the code:
13 |
14 | Emscripten generated code in snes_spc-0.9.0/snes_spc.js . This looks like old Emscripten code (pre-asm.js ). From the comments at the top:
15 |
16 | // Note: Some Emscripten settings will significantly limit the speed of the generated code.
17 | // Note: Some Emscripten settings may limit the speed of the generated code.
18 | // TODO: " u s e s t r i c t ";
19 |
20 | Last commit by MrRio is Aug 2012. This explains it (that's about 6 months before asm.js was available). Will need to regenerate the code at some point. Shouldn't affect fixing the audio bug.
21 |
22 | Web Audio was also a mess in 2012 (and still is in 2014 really). This probably explains why sink.js just fails.
23 |
24 | Looks like last commit to sink.js was https://github.com/jussi-kalliokoski/sink.js/commits/master in October 2012. Maybe abandoned.
25 |
26 | Anyway, back to the audio bug...
27 |
28 | Next it loads js/js-snes-player.js
29 |
30 | Module pattern. jsSNESPlayer created then init function called. init sets up a bunch of stuff (I assume it's twitter bootstrap bumpf). In the end, when you click the play button play gets called on line 111.
31 |
32 | From debugger, play defined on js-snes-player.js:22 .
33 |
34 | Had a look through play function. It fails when it tries to initialize the Sink. sink.js is totally broken. 2 years old, overly complicated and unmaintained. I'll need a new way to play back the audio.
35 |
36 | The business end of the play function is on line 67:
37 |
38 | proxy.on('audioprocess', function(buffer, channelCount){
39 |
40 | var retval = _spc_play(snes_spc, bufferSize / 2, buf);
41 | _spc_filter_run(filter, buf, bufferSize);
42 |
43 | for (i = 0; i < bufferSize; i ++) {
44 |
45 | // Take a mono stream
46 | if ((i - 1) % 2 == 0) {
47 | buffer[i] = HEAP8[i + buf] / 120;
48 |
49 | } else {
50 | buffer[i] = HEAP8[i + buf - 1] / 120;
51 |
52 | }
53 | }
54 | console.log('Send audio to buffer... Memory points from HEAP ' + i + ' to ' + (i + buf));
55 | }, 2, null, 12000);
56 |
57 |
58 | This is the audio callback. The buffer "buffer" is the output buffer for the Web Audio API. bufferSize is the number of samples to generate. buf is an offset in to the Emscripten heap. It is where the audio data is calculated and stored by the Emscripten code.
59 |
60 | Plan of attack: disable sink.js and turn the audio generation in to a normal function
61 |
62 | That worked. I took https://developer.mozilla.org/en-US/docs/Web/API/ScriptProcessorNode example code and increased the buffer size. I also had to tweak things slightly as the original code interlieves stereo channels. I had to generate tiwce as much audio data and then extract one channel for playback.
63 |
64 |
65 | Rebuilt with new Emscripten. Sprinkled a bunch of EMSCRIPTEN_KEEPALIVE over the relevant functions in spc.cpp and compiled using emcc -O1. It seems that O2 doesn't work atm. Probably my fault, I'll have a look at this some point. Anyway, O1 seems to be enough to enable asm.js which gives a nice performance boost (10x in my unscientific benchmark)
66 |
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/snes_spc-0.9.0/.DS_Store:
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https://raw.githubusercontent.com/MrRio/js-snes-player/9aa14e281218cbcd57b59375babb5fb33d461c69/snes_spc-0.9.0/.DS_Store
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/snes_spc-0.9.0/changes.txt:
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1 | snes_spc Change Log
2 | -------------------
3 |
4 | snes_spc 0.9.0
5 | --------------
6 | - Improved documentation
7 |
8 | - SPC: Added spc_skip() function for quickly seeking in an SPC music
9 | file. Runs 3-4x faster than normal playback using the fast DSP (or about
10 | 43-60X real-time on my 400 MHz Mac).
11 |
12 | - SPC: Added spc_set_tempo() to change tempo of SPC music playback.
13 |
14 | - SPC: Sample generation is now corrected to generate exactly one pair
15 | of samples every 32 clocks without exception. Before it could generate a
16 | few samples more or less depending on how far ahead or behind DSP was at
17 | the moment.
18 |
19 | - SPC: Changed spc_reset() and spc_soft_reset() to also reset output
20 | buffer (see spc.h).
21 |
22 | - SPC: Fixed minor timer counting bug.
23 |
24 | - SPC: Stack pointer wrap-around is now emulated (and without any
25 | noticeable performance hit).
26 |
27 | - SPC: Runs about 5% faster due to various optimizations.
28 |
29 | - SPC: Found way to make fast DSP register accesses cycle-accurate in
30 | most cases, without reducing performance. Allows fast DSP to pass most
31 | of my validation tests.
32 |
33 | - DSP: Added surround disable support to fast DSP again.
34 |
35 | - DSP: Improved voice un-muting to take effect immediately on fast DSP.
36 |
37 | - DSP: Noise shift register now starts at 0x4000 instead of 0x4001 as it
38 | incorrectly did before.
39 |
40 | - Converted library to C++ code internally. A C interface is still
41 | included in spc.h and dsp.h. Note that these are different than the
42 | previous interface, so your code will require minor changes:
43 |
44 | Old SPC code New SPC code
45 | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
46 | #include "spc/spc.h" #include "snes_spc/spc.h"
47 |
48 | snes_spc_t* spc; SNES_SPC* spc;
49 | spc = malloc( sizeof (snes_spc_t) ); spc = spc_new();
50 | spc_init( spc );
51 |
52 | spc_end_frame( time ); spc_end_frame( spc, time );
53 | /* etc. */
54 |
55 | /* done using SPC */ spc_delete( spc );
56 |
57 |
58 | Old DSP code New DSP code
59 | - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
60 | #include "spc/spc_dsp.h" #include "snes_spc/dsp.h"
61 |
62 | spc_dsp_init( ram ); SPC_DSP* dsp;
63 | dsp = spc_dsp_new();
64 | spc_dsp_init( dsp, ram );
65 |
66 | spc_dsp_run( count ); spc_dsp_run( dsp, count );
67 | /* etc. */
68 |
69 | /* done using DSP */ spc_dsp_delete( dsp );
70 |
71 |
72 | snes_spc 0.8.0
73 | --------------
74 | - Added several demos
75 |
76 | - Added high-pass/low-pass filter to better match SNES sound
77 |
78 | - Added save state functionality for SPC and accurate DSP (but not fast
79 | DSP)
80 |
81 | - Added emulation of reset switch on NES (soft reset)
82 |
83 | - Made source more compatible with pre-C99 compilers by eliminating
84 | mid-block declarations
85 |
86 | - SPC: Many S-SMP accuracy improvements, mostly in memory access times
87 |
88 | - SPC: S-SMP speed improvements
89 |
90 | - SPC: Added SPC load/save functions and KON checking to help trim
91 | silence from beginning
92 |
93 | - SPC: Changed spc_init() to have you allocate most of the memory used
94 | by the library so you have more control over it
95 |
96 | - DSP: New highly accurate DSP and faster version derived from same code
97 |
98 | - DSP: Changed prefix from dsp_ to spc_dsp_. Your DSP code will require
99 | changes.
100 |
101 | - DSP: Removed surround disable and gain. Gain can now be done with the
102 | dsp_filter module, and surround disable will probably only be
103 | implemented in the fast DSP at some point.
104 |
105 | - DSP: Changed interface to work in clocks rather than samples,
106 | necessary for the new accurate DSP. Sample output is now done with
107 | separate functions. Your DSP code will require changes.
108 |
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/snes_spc-0.9.0/demo/benchmark.c:
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1 | /* Measures performance of SPC emulator. Takes about 4 seconds.
2 | NOTE: This assumes that the program is getting all processor time; you might need to
3 | arrange for this or else the performance will be reported lower than it really is.
4 |
5 | Usage: benchmark [test.spc]
6 | */
7 |
8 | #include "snes_spc/spc.h"
9 |
10 | #include "demo_util.h" /* error(), load_file() */
11 | #include