Brightcove Player Sample: Download Transcript

Product(s)
Video Cloud
Brightcove Player
Role(s)
Player Developer
Topic(s)
Captions
Type
Support Doc

In this topic, you will learn how to use the captions WebVTT file and convert it into a downloadable transcript.

Player example

The video in the CodePen below uses the following WebVTT file to define captions:

WEBVTT

00:00.000 --> 00:05.000 align:middle line:90%
The waves rhythmically pound against the rocks.

00:05.000 --> 00:10.000 align:middle line:84%
Here in the quaint village of Yachats on the central Oregon coast.

00:10.000 --> 00:15.000 align:middle line:84%
Come visit and enjoy the surf and sand.

00:15.000 --> 00:19.000 align:middle line:84%
Remember, it never rains on the Oregon coast!

The sample supplies a Download Transcript button in the controlbar which downloads a text file with the WebVTT formatting stripped from the file. In essence, it permits the user to download a transcript of the captions based on a modified version of the WebVTT file.

See the Pen Download Transcript by Brightcove Learning Services (@rcrooks1969) on CodePen.

View the source code.

Using the CodePen

Here are some tips to effectively use the above CodePen:

  • Toggle the actual display of the player by clicking the Result button.
  • Click the HTML/CSS/JS buttons to display ONE of the code types.
  • Later in this document the logic, flow and styling used in the application will be discussed in the Player/HTML configuration, Application flow and Application styling sections. The best way to follow along with the information in those sections is to:
    1. Click the EDIT ON CODEPEN button in the CodePen and have the code available in one browser/browser tab.
    2. In CodePen, adjust what code you want displayed. You can change the width of different code sections within CodePen.
    3. View the Player/HTML configuration, Application flow and/or Application styling sections in another browser/browser tab. You will now be able to follow the code explanations and at the same time view the code.

Development sequence

Here is the recommended development sequence:

  1. Use the In-Page embed player implementation to test the functionality of your player, plugin and CSS (if CSS is needed)
  2. Put the plugin's JavaScript and CSS into separate files for local testing
  3. Deploy the plugin code and CSS to your server once you have worked out any errors
  4. Use Studio to add the plugin and CSS to your player
  5. Replace the In-Page embed player implementation if you determine that the iframe implementation is a better fit (detailed in next section)

For details about these steps, review the Step-by-Step: Plugin Development guide.

iframe or In-Page embed

When developing enhancements for the Brightcove player you will need to decide if the code is a best fit for the iframe or In-Page embed implementation. The best practice recommendation is to build a plugin for use with an iframe implementation. The advantages of using the iframe player are:

  • No collisions with existing JavaScript and/or CSS
  • Automatically responsive
  • The iframe eases use in social media apps (or whenever the video will need to "travel" into other apps)

Although integrating the In-Page embed player can be more complex, there are times when you will plan your code around that implementation. To generalize, this approach is best when the containing page needs to communicate to the player. Specifically, here are some examples:

  • Code in the containing page needs to listen for and act on player events
  • The player uses styles from the containing page
  • The iframe will cause app logic to fail, like a redirect from the containing page

Even if your final implementation does not use the iframe code, you can still use the In-Page embed code with a plugin for your JavaScript and a separate file for your CSS. This encapsulates your logic so that you can easily use it in multiple players.

API/Plugin resources used

API Methods API Events API Properties
on() loadstart player.mediainfo
player.controlBar.customControlSpacer.el()    

Player/HTML configuration

This section details any special configuration needed during player creation. In addition, other HTML elements that must be added to the page, beyond the in-page embed player implementation code, are described.

Player configuration

No special configuration is required for the Brightcove Player you create for this sample.

Other HTML

No other HTML elements are added to the page.

Application flow

The basic logic behind this application is:

  • Build a regular expression to remove the WebVTT formatting from the file.
  • Wait for the loadstart event and retrieve the URL to the captions WebVTT file.
  • Build a button and place it in the controlbar.
  • On button click, download the remote WebVTT file using an XMLHttpRequest() object.
  • Use the download JavaScript library to have the browser download the file.

Define the regular expression

Find the code which is labeled:

// ### Define the regular expression ###

You need to create a regular expression to remove any unwanted formatting from the WebVTT file. In this case, the regex removes lines that start with the standard way to define times in a WEBVTT file. If you are not a regex expert, you might find https://txt2re.com/ of help.

Retrieve URL and get file

Find the code which is labeled:

// ### Retrieve the URL for the text track, which is in this case a WebVTT caption file ###

You must wait for the loadstart event to access the mediainfo property, which contains the text track information. Note that if the page is served from a secure (https) page, you must alter the URL to the file to also use a secure connection. Once you have the correct URL, you then call the getFile() method that actually returns the file. Finally, you use the JavaScript replace() method in conjunction with the regular expression to reformat the text.

Build a button and place it in the controlbar

Find the code which is labeled:

// ### Create button and place in player ###

An HTML button element is built and placed in the controlbar. Note that the click event listener is also dynamically added. In this case, the button is place in the spacer region of the controlbar. For further details on the spacer, see the Customizing Player Appearance document.

Get the file based on URL provided

Find the code which is labeled:

// ### Function that gets the actual file based on URL ###

This function uses AJAX, via an XMLHttpRequest object, to retrieve the file. Asynchronous behavior dictates the use of a callback function.

Download the modified file to the user computer

Find the code which is labeled:

// ### download function used for graceful browser download ###

As mentioned earlier in this document, the default browsers' behaviors as most likely NOT what you wish to happen, that is a new tab or window being opened to display the file. This JavaScript tool forces a file download of the text file.

Application styling

The CSS sets the buttons colors and position in the controlbar.

Plugin code

Normally when converting the JavaScript into a Brightcove Player plugin nominal changes are needed. One required change is to replace the standard use of the ready() method with the code that defines a plugin.

Here is the very commonly used start to JavaScript code that will work with the player:

videojs.getPlayer('myPlayerID').ready(function() {
var myPlayer = this;
});

You will change the first line to use the standard syntax to start a Brightcove Player plugin:

videojs.registerPlugin('pluginName', function(options) {
var myPlayer = this;
...
});

As mentioned earlier, you can see the plugin's JavaScript code in this document's corresponding GitHub repo: download-transcript.js.

Using the plugin with a player

Once you have the plugin's CSS and JavaScript files stored in an Internet accessible location, you can use the plugin with a player. In Studio's PLAYERS module you can choose a player, then in the PLUGINS section add the URLs to the CSS and JavaScript files, and also add the Name and Options, if options are needed.