Reducing File Size when including Audio

[kimm25227567]

I need help! I am creating a standard 1280 by 720 Captivate course (currently Captivate 9) and I am publishing in both SWF and HTML5 as the course will be viewed on both mobile and desktop. I am about to capture audio this week.

What I am concerned with is the size of the file once I add audio. I have tested adding to certain slides and they are HUGE! I even reduced down to 64 KBPS. It is such an important course that I don't want to capture the audio and then have the file be too big to load onto the LMS. This is my first time including audio and I am recording directly onto each slide.

Does anyone have any recommendations on what I can do to reduce the file size beforehand or do you think it will not be a problem?  There are about 30 slides requiring audio.  This is a brand timeline and I have already made the course have a Part 1 and Part 2 so I cannot reduce the scope of the course anymore.

Any insight would be sooo helpful.

[Erik_Lord]

First, every 'current' browser will handle Captivate's HTML5 output just fine. The only reason you'd want to publish to SWF is if you need to support old browser versions. At least test it; if you output to just HTML and your users are not stuck on browser versions older than a year or two, it should work fine (excepting, of course, some things that don't work on HTML yet, like a few of the effects).

That alone will reduce your SCORM .zip file output significantly as, currently publishing to both SWF/HTML, your .zip has two versions of the lesson.

For audio itself:

Biggest size help, don't record in Stereo...or at least mix-down to Mono after recording. By reducing two tracks to one, you cut the file size in half.

Then it's just quality: 22kHz, 16bit should be fine (for .wav). I encourage recording to .wav and importing those, which are larger, but CP will convert those .wavs to .mp3 on publish. I think going .wav results in better end-quality...other disagree...

If you're more comfortable recording to .mp3, that's fine, and I think 64kbps is as low as you want to go...but still, ensure it's mono.

[kimm25227567]

Thank you soooo much Erik. How do I make sure that I am not recording in "Stereo". When I go to my settings, I don't even see that as an option. Is that just under the publish settings I make sure the box is checked to publish audio files as Mono and that will do the trick?

[Erik_Lord]

Ah, you're recording audio in Captivate. Nothing really wrong with that, but I prefer to use a 'real' audio recording program like Audacity (free) or Adobe Audition. Such programs give you a lot more control over recording, editing, and output.

So I'm not real sure about recording in CP but, yes, if the CP audio publish options include 'mono', definitely choose that option. As Lieve says, don't worry so much about the size in the CP source file - those audio files will compress down on publish (but do follow best-practices in general )

[Lilybiri]

Indeed audio files are much bigger in size than image files. Do never use stereo audio, 64 kbps is the lowest possible for acceptable quality. Keep audio as short as possible.

I never publish to both SWF and HTML anymore. If you still want the choice, publish separately to both, and let them choose in the LMS. Anyway soon SWF output will be over.  If you expect the course to be consumed on mobile phones the problem will be bigger.

Don't be confused by the fact that the audio files are in WAV-format in the Library. Those are RAW files, which are always very big. Once the course is published, audio files will be compressed to MP3 files which are a lot smaller in size (like RAW photo format and JPEG).

[kimm25227567]

Thanks Lilybiri! Good to know that they will be compressed when I publish. I will talk to our systems manager and see if I can just publish in HTML5!

[Lilybiri]

Never create a mp3 because it will be converted to a Wav-file by CP because that is needed to make editing possible. It has no sense to deflate a balloon twice, because on publishing a mp3 will be created again. Mp3 has not the same full quality as a wav, better to record to wav.

I recommend to use a dedicated audio app for recording, instead of doing it in CP. Audacity is free, I am using Audition because it is part of the CC.