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Adding support for FileSystemFileHandle writing
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Reading is already supported through the File interface with readahead
files. `mkfsfhfile` supports both the synchronous and asynchronous
interface, and uses the synchronous interface preferentially.
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@Yahweasel
Yahweasel committed Sep 25, 2024
1 parent 272ff78 commit 0d12712
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Showing 3 changed files with 239 additions and 2 deletions.
147 changes: 147 additions & 0 deletions demo/fsfh-demo.html
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@@ -0,0 +1,147 @@
<!doctype html>
<!--
* Copyright (C) 2019-2024 Yahweasel and contributors
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-->
<html>
<head>
<meta charset="utf-8" />
<title>LibAV.JS FileSystemFileHandle writer demo</title>
</head>
<body>
<script type="text/javascript">(async function() {
try {
const dce = document.createElement.bind(document);
const main = dce("div");
document.body.appendChild(main);

const variant = await new Promise(res => {
const label = dce("label");
label.innerHTML = "Variant:&nbsp;";
label.htmlFor = "variant";
main.appendChild(label);
const vbox = dce("input");
vbox.type = "text";
vbox.id = "variant";
vbox.value = "webm";
main.appendChild(vbox);
const ok = dce("button");
ok.innerHTML = "Load";
main.appendChild(ok);

vbox.focus();
vbox.select();

vbox.onkeypress = ev => {
if (ev.key === "Enter")
res(vbox.value);
};
ok.onclick = ev => {
res(vbox.value);
};
});
main.innerHTML = "Loading...";

// Load libav.js
LibAV = {base: "../dist"};
await new Promise(res => {
const scr = dce("script");
scr.src = `../dist/libav-${variant}.js?${Math.random()}`;
scr.onload = res;
scr.onerror = () => {
alert("Failed to load variant!");
};
document.body.appendChild(scr);
});
const libav = await LibAV.LibAV();

// Load the file
const file = await new Promise(res => {
main.innerHTML = "";
const label = dce("label");
label.innerHTML = "File:&nbsp;";
label.htmlFor = "load-file";
main.appendChild(label);
const picker = dce("input");
picker.type = "file";
picker.id = "load-file";
main.appendChild(picker);

picker.focus();

picker.onchange = () => {
if (picker.files.length > 0)
res(picker.files[0]);
};
});
main.innerHTML = "Loading...";

// Initial read
await libav.mkreadaheadfile("input", file);
const [fmt_ctx, streams] =
await libav.ff_init_demuxer_file("input");

// Create the writer
const fsfh = await showSaveFilePicker({
suggestedName: "out.mkv"
});
await libav.mkfsfhfile("out.mkv", fsfh);

// Get the codec parameters
const ostreams = streams.map(s => [
s.codecpar, s.time_base_num, s.time_base_den
]);

// And the muxer
const [oc, , pb] = await libav.ff_init_muxer({
filename: "out.mkv",
open: true,
codecpars: true
}, ostreams);
await libav.avformat_write_header(oc, 0);

const pkt = await libav.av_packet_alloc();

main.innerHTML = "Remuxing...";

// And read
while (true) {
// Read some packets
const [res, packets] = await libav.ff_read_frame_multi(fmt_ctx, pkt, {
limit: 1024 * 1024,
unify: true
});

// And write them out
if (packets[0])
await libav.ff_write_multi(oc, pkt, packets[0]);

if (res === libav.AVERROR_EOF)
break;
}

await libav.av_write_trailer(oc);
await libav.unlinkfsfhfile("out.mkv");

await libav.ff_free_muxer(oc, pb);
await libav.av_packet_free_js(pkt);
await libav.avformat_close_input_js(fmt_ctx);

main.innerHTML = "Done.";
} catch (ex) {
alert(ex + "");
}
})();
</script>
</body>
</html>
2 changes: 2 additions & 0 deletions funcs.json
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Expand Up @@ -140,6 +140,8 @@
"mkwriterdev",
"mkstreamwriterdev",
"mountwriterfs",
"mkfsfhfile",
"unlinkfsfhfile",
"mkworkerfsfile",
"unlinkworkerfsfile"
],
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92 changes: 90 additions & 2 deletions post.in.js
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Original file line number Diff line number Diff line change
Expand Up @@ -357,7 +357,7 @@ var preReadaheadOnBlockRead = null;
function readaheadOnBlockRead(name, position, length) {
if (!(name in readaheads)) {
if (preReadaheadOnBlockRead)
preReadaheadOnBlockRead(name, position, length);
return preReadaheadOnBlockRead(name, position, length);
return;
}

Expand Down Expand Up @@ -438,7 +438,7 @@ Module.unlinkreadaheadfile = function(name) {
* @param mode Unix permissions
*/
/// @types mkwriterdev@sync(name: string, mode?: number): @promise@void@
Module.mkwriterdev = function(loc, mode) {
var mkwriterdev = Module.mkwriterdev = function(loc, mode) {
FS.mkdev(loc, mode?mode:0x1FF, writerDev);
return 0;
};
Expand Down Expand Up @@ -498,6 +498,94 @@ Module.unlinkworkerfsfile = function(name) {
FS.rmdir("/" + name + ".d");
};

// FileSystemFileHandle devices
var fsfhs = {};

// Original onwrite
var preFSFHOnWrite = null;

// Passthru for FSFH writing.
function fsfhOnWrite(name, position, buffer) {
if (!(name in fsfhs)) {
if (preFSFHOnWrite)
return preFSFHOnWrite(name, position, buffer);
return;
}

var h = fsfhs[name];
buffer = buffer.slice(0);

if (h.syncHandle) {
h.syncHandle.write(buffer.buffer, {
at: position
});
return;
}

var p = h.promise.then(function() {
return h.handle.write({
type: "write",
position: position,
data: buffer
});
});

h.promise = p.catch(console.error);
return p;
}

/**
* Make a FileSystemFileHandle device. This writes via a FileSystemFileHandle,
* synchronously if possible. Note that this overrides onwrite, so if you want
* to support both kinds of files, make sure you set onwrite before calling
* this.
* @param name Filename to create.
* @param fsfh FileSystemFileHandle corresponding to this filename.
*/
/// @types mkfsfhfile(name: string, fsfh: FileSystemFileHandle): Promise<void>
Module.mkfsfhfile = function(name, fsfh) {
if (Module.onwrite !== fsfhOnWrite) {
preFSFHOnWrite = Module.onwrite;
Module.onwrite = fsfhOnWrite;
}

mkwriterdev(name);

var h = fsfhs[name] = {
promise: Promise.all([])
};
h.promise = h.promise.then(function() {
return fsfh.createSyncAccessHandle();
}).then(function(syncHandle) {
h.syncHandle = syncHandle;
}).catch(function() {
return fsfh.createWritable();
}).then(function(handle) {
h.handle = handle;
});
return h.promise;
};

/**
* Unlink a FileSystemFileHandle file. Also closes the file handle.
* @param name Filename to unlink.
*/
/// @types unlinkfsfhfile(name: string): Promise<void>
Module.unlinkfsfhfile = function(name) {
FS.unlink(name);
var h = fsfhs[name];
delete fsfhs[name];

if (h.syncHandle) {
h.syncHandle.close();
return Promise.all([]);
}

return h.promise.then(function() {
return h.handle.close();
});
}

/**
* Send some data to a reader device. To indicate EOF, send null. To indicate an
* error, send EOF and include an error code in the options.
Expand Down

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