August 5, 2010

Audio-Video Sync in Captivate published movie

Audio makes your elearning content more engaging and useful to learners. You can add audio to your Adobe Captivate project either by recording yours or somebody else’s voice directly or by inserting a previously recorded audio file (.AVI, .WAV). When you add audio to a slide, it appears as a separate ‘element’ in the timeline. You can synchronize the audio with the slide by adjusting its timeline.

When you publish the project, Adobe Captivate embeds the audio within the output file. The embedded audio can be a single file or multiple files based on the timing and type of audio. Adobe Flash Player that plays the Adobe Captivate movie also plays the audio along with the movie.

Sometimes, you may notice a lag in the audio timing and that it is not synchronized perfectly with the movie. The audio that must ideally end with a slide spills over to the next slide. In this article, let’s examine why such issues occur and how they can be solved.

Why does this issue occur? Before understanding the reason for this issue, let’s first understand how Adobe Captivate publishes audio.

Whenever an audio starts and ends at the same time as that of the slides, Adobe Captivate ‘stitches’ up the audio objects on the contiguous slides into a single file when the project is published.

Suppose the audio on slide 1 runs till the end of the slide as shown below:

Audio spreads till end of slide

Audio spreads till end of slide

The audio on the next slide, slide 2 starts right from the beginning of the slide as shown below:

Audio begins at start of slide

Audio begins at start of slide

In such a case, the audio files on both the slides are ‘stitched’ and published as a single audio file. Similarly, if all the slides contain audio that start at the same time as that of the slides and spread till the end of slide, Adobe Captivate creates a single audio file in the published output.

Note: If the audio on the contiguous slides are of different types (mono and stereo), Adobe Captivate generates separate audio files for each of the types even if the audio starts and ends at the same time as that of the slides.

Adobe Captivate is designed to do so to logically stitch up users’ narrations that are done during or post-recording of a screen or application. A single audio file helps to keep the continuity in the narration intact.

Adobe Flash Player plays the Captivate published audio and stops only when the specified duration elapses or when you intervene and stop it. Therefore, with a single audio file in an Adobe Captivate movie, the audio and video run parallelly at their own pace resulting in synchronization issues.

Is there a workaround? Yes, a very easy one. Tweak the audio timing in such a way that Adobe Captivate generates and embeds multiple audio files in the output. To do so, extend the duration of the slide a little more than that of the audio. For example, if the current slide and audio duration is 4 seconds, extend the slide duration by another 0.3 seconds, and retain the audio duration at 4 seconds.

The following illustration shows the difference between the audio and the slide duration:

Slide time longer than audio

Slide time longer than audio

Now, Adobe Flash player can control the beginning of each audio file at the specified time in the movie.

Posted by Mukul Vinay Lele5:21 PM
  • http://millercreativemedia.com Scott Miller

    Nice work around…however, will this make your closed captioning blink on and off from slide to slide?

  • vilu

    It’s truly flabbergasting that inventors and sole-pushers of Acrobat technology don’t have a utility on their info pages to allow the reader to download a pdf copy. What do you expect us to do … memorize the info? Yes, I’ve Acrobat installed on my machine but when I download (print) the page in pdf it is almost never properly formatted. And what about those who don’t have Acrobat? Hope this outcry will have some effect.

  • Mukul

    Hi Scott,
    As the gap introduced between audio files is in mili-secs (0.1sec), Closed Captioning should not appear to be blinking to human eye.

  • http://magdadiaz.com magda diaz

    I have tried this “fix” but it doesn’t work on the first slide. Any ideas why not?

  • Anand

    This works as intended. Thank you for the detailed explanation.

  • Aimee

    I found that sometimes extending the end time alone is not always enough. Sometimes this works but sometimes it does not, especially with audio files I’ve edited directly in CP. What I’ve had to resort to doing is puting a transparent highlight box which extends longer than the audio in order to avoid the audio being truncated at the end. This works but it’s very annoying and time consuming.

    • http://blogs.adobe.com/captivate/ Allen Partridge

      Aimee – good tip. Have you updated to the patch? Can you send an email to wish-captivate@macromedia.com – i’m sure the engineers would like to see samples of this if they could. It will help them sort it out to avoid the truncation – figure out why the issue is intermittent.

    • Estela Mulloy

      Thank you!!!

      It worked!! Hallelujah!

  • http://www.lsmarketing.co.yuk Laura

    Aimee
    THANK YOU so much – I have spend the last 3 days trying to resolve this issue – the Bug fix team at Adobe didn’t even mention there was a patch – not that it worked.
    However your transparent highlight box workaround has done the trick
    I will get my first good nights sleep in days now I know my publication due to go live in 2 days will actually work.

  • Estela Mulloy

    I didn’t just give it 3 seconds after the audio was over- I gave it 30 seconds, and the final part of my audio is still cutting off…

    My deadline is in an hour, and cannot fix this yet. I am very disatisfied with your product.

  • Mark

    None of the workarounds listed here worked for me. I installed the updates, tried extending my slide duration a bit past the audio clip duration all to no avail.

    What finally did work was to go in and add some silence at the end of each audio clip.
    Audio>Edit>Slide and click on the add silence icon.

    I couldn’t find a specific amount of silence to add that worked consitently – sometimes a half a second was good enough, sometimes I needed a second and a half. Oh, and when you chose the “insert silence” command make sure you have the playhead positioned at the end of the clip and choose “playhead position” from the drop down menu. choosing “at audio end” does not work because the additional silence doesn’t get saved.

    Honestly Adobe, It’s astounding to me that these bugs made it out of beta testing. I expect more from you.

  • http://www.accuray.com Bill Main

    I appreciate the “work-around”, it does help somewhat. However, this synchronization issue is more complex and is also related to the computer processor type used to play the pdf files. Since resolving this issue is important to me, I have taken the time to research it a bit.

    The sync delay between audio and video tracks is most severe if there are fast changing images, that are captured as separate screens and not a full motion video. I have two PCs with Captivate 5, a relatively slow laptop (Dell E4300 Core-duo 2.4 GHz with a 1200×1600 external monitor) and a screaming fast desktop (Dell 7500 Xenon 64-bit dual processor 2.67 GHz with same monitor). I created a Captivate 5 test where I quickly (2 image/sec) page through a stack of 51 images calling each image number as it appears on the screen. I saved and then published this as a pdf and copied the pdf file to both of my computers.

    On the laptop the audio tracks the video correctly for about 27 images, by the 51st image, the video track has fallen behind by 16 images (8 sec). Strangely, on the desktop PC I see the opposite problem. The audio lags the video by the end of the 51 images by about 4 images (2 sec).

    I implemented your workaround by adding 0.1 sec to each of the 51 slides. Thus, there are fifty-one 0.1 sec gaps in the audio track.

    On the laptop this causes three breaks of several seconds in the audio track where Adobe Reader X lets the video “catch-up”. And the audio and video end roughly together. Thus, much of the content is still out of sync.

    On the desktop, Adobe Reader X cuts out several sections of the audio so I never hear the numbers for several of the slides The audio and video tracks finish roughly together.

    You might think that this test is unrealistic, however in the medical field it is not uncommon for someone performing an e-learning software simulation to rapidly click through a stack of CT slices while commenting on the changing features. I appreciate your careful attention to resolving this issue.

    Would it help you if I posted my pdf files, or even captured the resulting movies and uploaded them to You Tube so your engineers could see how serious this issue is?

    Thanks!

    • http://blogs.adobe.com/captivate/ Allen Partridge

      Bill, thanks for the details. I’m sending them to wish-captivate and will cc you. I’m sure it would help to get more detail / samples etc. You’ll be able to share via wish-captivate as well.

  • http://www.accuray.com Bill Main

    Allen
    I uploaded the cptx source files I used to do the above tests. One has the workaround applied the other doesn’t. Both fail to get reasonable a/v sync. I welcome anyone to repeat my test on their system.

    http://ftp.accuray.com

    login adobe
    password Today789!

  • http://www.accuray.com Bill Main

    Also Allen

    Your web software added the http:// to my ftp address in my previous post. Thus the link wont work. , It should have added ftp://

  • Jestersmith

    This program is severly limited in features and usability. I can’t believe my company is using it. Very frustrating.

    • Vish

      Hello Jestersmith, I’d like to know the Usability issues and Feature limitations you are talking about. Can you please help me here? Let me know your email ID and I’ll email you.

      Thanks,
      Vish
      viswanat@adobe.com

  • paul

    I have had the same problem and tried increasing the timeline for increasing the slide timinag and also by adding a silence at the end of the narration; both without success. Then in a moment of inspiration (or desperation) I increased the timeline by sliding the click box slider and lo and behold it worked! Haleluja

  • Janet

    I’m jumping onto an old thread, but I am having this same audio truncation issue with Captivate 5.5. I have extra time on my slides following audio. Not all of my slides are having this issue, and there’s nothing special about the ones that are. Any suggestions?

  • Mario

    Like Mark, below, I’ve had these same issues and have somewhat, very unscientifically, been able to semi-remedy them with this silence insertion technique. If I had known that Captivate had this problem, I never would have purchased it. As Mark mentioned, there is no rhyme or reason as to how much silence you need to add to the end of the slide. I don’t necessarily add silence like he does, I copy and paste “silence” from my audio. It’s not true lack of sound but rather times when I’m not narrating.

    By the way, don’t waste your time calling their support. You’ll get “Mike” in India. Mike no doubt is looking up similar bugs and then tries to implement solutions with you over the phone that do not work. Nothing against “Mike”, he’s trying his best, but I’d love to be able to speak with someone that speaks English as a FIRST language and has a better working knowledge of the product.

    Extremely frustrated.

  • Megarita

    I see I am a little late discovering this problem. I have version 5.0.something. Has it been resolved in Captivate updates?

  • Saurabh Gupta

    Hi Mukul, Thanks a million my friend! I was always wondering why resuming from a bookmark repeated audio from earlier slides whereas the on-screen animation synchronized perfectly, whereas some of them didn’t. Now that I know the secret, I went back to those files and found that the slides that had audio stream touching the end of timeline had this issue; others didn’t. This is exactly the solution that I was looking for.

    Regards,

    Saurabh Gupta

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