Combining video-only mp4s and mp3 audio, then publishing to HTML5

Oct 08, 2015

We have a client that gives us instructional videos in MP4 format. However, the audio in his files are very quiet. I would like to figure out a solution to making his audio louder without resorting to a professional video editor.

On way I could do this is to split the MP4 file in a video-only MP4 file, and exporting the MP3 audio from the original MP4. (VLC media player can do this.) I can then use Audacity to boost the audio, and edit it if need be. I can then add them both back to a Storyline slide timeline.  

I have done this, and not noticed any if all sync issues. The program material is not terribly sync-needy. However, this only seems to work with a Flash-based publishing build. The audio doesn't play in the HTML5 build.

I know that Storyline, when it publishes, obfuscates file names for things like MP4, MP3, SWF, JPGs etc. I thought that perhaps the HTML5 side wants to see .OGG files; so I exported versions of the MP3 audio files, found the obfuscated audio file MP3 names, and copied these names to the OGG files, then placed them in the story_content sub-folder of my build alongside the original MP3 audio files. This did not work.

So I guess I have a couple of questions:

1) Can HTML5 handle simultaneous MP4 and MP3 playback as separate files, or do they have to be all one file?

2) If HTML5 can handle it, is this a limitation of Storyline?

3) If this is not a limitation of Storyline, was I on the right track with the extra audio file inclusion idea listed above?

Thanks for any illumination on this matter. If we have to get a video editor to just boost the audio portions of the videos, we will do it but I'd rather not.

10 Replies
Patryce Smith

Hello Leslie, 

I am stilling having the issue described by Mark. I have two separate files, one video and one audio. Initially when set to autoplay on the timeline, both played, as long as the audio did not begin at 0 sec. However now that I have added custom buttons to pause and play the audio, I cannot adjust where it begins on the timeline and it will not play. Any ideas?

Thank you.


Dave Cox

I've found that it is really best to have your audio and video in the same file for them to play correctly. I use Premier Pro when I need to combine audio and video back together. PP does a great job, but a Creative license can be pricey. There are other video editor solutions that will work just fine. BB Flashback is an example, that only runs around $100 or so, and sometimes cheaper if you can catch a sale. There are also other free editors that can work as well. You just need to do some searches. Just be careful with the free ones to be sure that you get an official package, not one repackaged with malware. 

Leslie McKerchie

Hello Patryce - Looks like Dave has popped in to assist you here, but I'm not sure that I'm following your question. If you do not have the audio set to auto-play, then you would need a trigger to play it, correct? Do you have triggers on the buttons you mentioned or did you want to trigger the audio to play 'when the timeline reaches x'?

Patryce Smith

Dave - thank you for your suggestion. However, if I combine the audio with the video I would not be able to pause and play the audio separately. The audio does not need to be in sync with the video. 

Leslie - I have a ,mp4 video playing and an audio track playing as well. The timeline of the slide is paused when the slide begins, and the learner will click a button to begin the video. The button actually just plays the timeline. At that point I expect both audio and video to play. The video  plays but the audio file does not. To address this I added a trigger that said "play media" when clicked. However the audio does not play. 

A little background - in a previous version:

  • Initially, before pausing the timeline, the audio and video played in html5 IF the audio did not begin at timestamp 0.  Triggers were then created to pause and play the the media. Creation of the trigger to play the media, changes how the audio acts and even appears on the timeline. In the first image, no triggers exist to play the media. In the second image, a trigger was created that said "play the media" on click. 
  • Audio file with Play trigger

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