Update readmes

Readme.md

@@ -21,7 +21,8 @@ browsers, check out the [Blob size limits][].
 ## Compatibility
 
 Because this code relies on browser support for encoding a Canvas as a WebP image (using `toDataURL()`), it is presently
-only supported in Google Chrome. It will throw an exception on other browsers.
+only supported in Google Chrome, or a similar environment like Electron. It will throw an exception on other browsers or
+on vanilla Node.
 
 ## Usage (Chrome)
 
@@ -33,7 +34,7 @@ project.
 Include the script in your header:
 
 ```html
-<script type="text/javascript" src="webm-writer-0.1.0.js"></script>
+<script type="text/javascript" src="webm-writer-0.3.0.js"></script>
 ```
 
 First construct the writer, passing in any options you want to customize:
@@ -47,6 +48,10 @@ var videoWriter = new WebMWriter({
     // You must supply one of:
     frameDuration: null, // Duration of frames in milliseconds
     frameRate: null,     // Number of frames per second
+
+    transparent: false,      // True if an alpha channel should be included in the video
+    alphaQuality: undefined, // Allows you to set the quality level of the alpha channel separately.
+                             // If not specified this defaults to the same value as `quality`.
 });
 ```
 
@@ -87,6 +92,15 @@ videoWriter.complete().then(function(webMBlob) {
 The video encoder can use Node.js file APIs to write the video to disk when running under Electron. There is an example
 in `test/electron`. Run `npm install` in that directory to fetch required libraries, then `npm start` to launch Electron.
 
+## Transparent WebM support
+
+Transparent WebM files are supported, check out the example in test/transparent. However, because I'm re-using Chrome's 
+WebP encoder to create the alpha channel, and the alpha channel is taken from the Y channel of a YUV-encoded WebP frame, 
+and Y values are clamped by Chrome to be in the range 22-240 instead of the full 0-255 range, the encoded video can 
+neither be fully opaque or fully transparent :(.
+
+Sorry, I wasn't able to find a workaround to get that to work.  
+
 ## License
 
 This project is licensed under the WTFPLv2 https://en.wikipedia.org/wiki/WTFPL

src/Readme.md

@@ -12,6 +12,9 @@ When not streaming to disk, it can instead buffer the video in memory as a serie
 returned to the calling code as one composite Blob. This Blob can be displayed in a <video> element, transmitted 
 to a server, or used for some other purpose. Note that Chrome has a [Blob size limit][] of 500MB.
 
+Because this library relies on Chrome's WebP encoder to do the hard work for it, it can only run in a Chrome environment 
+(e.g. Chrome, Chromium, Electron), it can't run on vanilla Node.
+
 [Whammy]: https://github.com/antimatter15/whammy
 [Blob size limit]: https://github.com/eligrey/FileSaver.js/
 
@@ -30,12 +33,17 @@ var
     WebMWriter = require('webm-writer'),
 
     videoWriter = new WebMWriter({
-        quality: 0.95,    // WebM image quality from 0.0 (worst) to 1.0 (best)
-        fd: null,         // Node.js file descriptor to write to instead of buffering to memory (optional)
+        quality: 0.95,    // WebM image quality from 0.0 (worst) to 0.99999 (best), 1.00 (VP8L lossless) is not supported
+        fileWriter: null, // FileWriter in order to stream to a file instead of buffering to memory (optional)
+        fd: null,         // Node.js file handle to write to instead of buffering to memory (optional)
 
         // You must supply one of:
         frameDuration: null, // Duration of frames in milliseconds
         frameRate: null,     // Number of frames per second
+
+        transparent: false,      // True if an alpha channel should be included in the video
+        alphaQuality: undefined, // Allows you to set the quality level of the alpha channel separately.
+                                 // If not specified this defaults to the same value as `quality`.
     });
 ```
 
@@ -65,3 +73,12 @@ videoWriter.complete().then(function(webMBlob) {
 There's an example which saves the video to an open file descriptor instead of to a Blob on this page:
 
 https://github.com/thenickdude/webm-writer-js/tree/master/test/electron
+
+## Transparent WebM support
+
+Transparent WebM files are supported, check out the example in https://github.com/thenickdude/webm-writer-js/tree/master/test/transparent. However, because I'm re-using Chrome's 
+WebP encoder to create the alpha channel, and the alpha channel is taken from the Y channel of a YUV-encoded WebP frame, 
+and Y values are clamped by Chrome to be in the range 22-240 instead of the full 0-255 range, the encoded video can 
+neither be fully opaque or fully transparent :(.
+
+Sorry, I wasn't able to find a workaround to get that to work.