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POJavascript: Send Array of ints through node.js binary websockets
 

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  1. POJavascript: Send Array of ints through node.js binary websockets
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    <p>I have the following case. I capture a webcam frame via a canvas with <code>context.getImageData().data</code>. That gives me a nice Array (or UInt8ClampedArray says Bidelman) of ints like <code>[r, g, b, a, r, g, b, a, r, g, b, a, etc.]</code> when I <code>console.log()</code> them. Now I want to send this to a node.js server via binaryjs and of course the data get's scrambled like hell: <a href="https://gist.github.com/thgie/6550638" rel="nofollow">https://gist.github.com/thgie/6550638</a></p> <p>How can I convert the Array to something binary first or how do I get the binary back to a readable array?</p> <p><strong>Code examples</strong></p> <p>Client:</p> <pre><code>client.send(ctx.getImageData(0, 0, CANVAS_WIDTH, CANVAS_HEIGHT).data, {'id': 'bin', 'frame': frame}); </code></pre> <p>Server:</p> <pre><code>client.on('stream', function(stream, meta){ var bufs = []; stream.on('data', function(data){ bufs.push(data); }); stream.on('end', function(){ var buf = Buffer.concat(bufs); fs.writeFile(__dirname + "/tmp/"+meta.frame+".dat", buf, "binary", function(err) { if(err) { console.log(err); } else { console.log("The file was saved!"); } }); }); } </code></pre> <p>It will look like this:</p> <pre><code>H&gt;DÿNDJÿL@FÿPCJÿR@KÿQ?IÿLDPÿKCOÿMCKÿLAIÿL@DÿL@DÿLBGÿKAFÿIAHÿLDLÿLAIÿLAIÿO@IÿO@IÿIAJÿJBKÿMCIÿNDJÿQEIÿQEIÿPGHÿOFGÿMIHÿMIHÿPDFÿNCEÿIBDÿLEHÿPDFÿPDFÿMHLÿLGKÿMHLÿNIMÿOGLÿNFKÿOEMÿPFNÿRFSÿPERÿPERÿPERÿRGOÿSHPÿSGMÿSGMÿRJRÿQIPÿQJNÿRKPÿRKPÿQJNÿSGMÿSGMÿOHJÿSLOÿQJLÿRKMÿSIJÿTKKÿQLPÿPJNÿSLQÿRKPÿSLQÿUMRÿSKSÿUMTÿVMWÿSKUÿUJUÿRGQÿUMTÿUMTÿSKUÿVMWÿSMTÿSMTÿQNVÿQNVÿSMVÿTNWÿZMVÿXKTÿUJUÿVKVÿTOSÿTOSÿWQUÿWQUÿYTVÿYTVÿXRVÿUPTÿYSZÿYSZÿXRVÿZUYÿWPRÿYRTÿWRQÿXSRÿVOOÿWPPÿXRVÿXRVÿZOYÿ[P[ÿZO[ÿ\Q^ÿZT_ÿZT_ÿZV`ÿZV`ÿ]T^ÿ]T^ÿ^TZÿ`V[ÿ[VXÿ[VXÿ]UZÿ^V[ÿZV`ÿ[Waÿ_Xdÿ_Xdÿ]X`ÿ]X`ÿaZ_ÿaZ_ÿ_Y]ÿ`[_ÿ`Y] </code></pre>
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    1. COIf you are using binaryjs then it does it for you. Make sure you use binaryjs on server and client sides to communicate, and it will handle compressing and decompressing for you.
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      1. USmoka
    2. COThen I do something wrong with the buffer. Because doesn't matter how I convert it, I just get scrambled traces.
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      1. USthgie
    3. COThe `buf` argument you're passing to `fs.writeFile` is an actual Buffer, right? Something is stringifying your data, apparently.
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      1. USrobertklep
 

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