3 Replies Latest reply on Nov 14, 2006 7:07 PM by spritc

    Filesize Calculation

      I know this can be a broad question, but is there any way of predicting how big movies will be if you know certain criteria? I am trying to estimate how much server space I will need for my presentations. I am really hoping for some kind of Mb per minute formula, even if it is just based on experience, instead of mathematics.

      Here's the criteria:

      The resolution will probably be 800x600;
      They will contain a voiceover, (I'm open for suggestions for the quality);
      Delivered in Flash format;
      Will contain quizzes;
      Will include 3D graphics.

      Can an estimate be reasonably assumed? 1Mb per minute of animation? 2Mb/min? 5Mb/min?

      I am also open to any suggestions to keep filesizes down. I'm actually kinda surprised that there isn't a detailed document that specifically details all the options one can take to reduce filesize. Maybe there is such a comprehensive document. If so, please let me know.

      I would gratefully receive any information regarding this matter. I especially look forward to constructive advise from people who are experienced at producing highly optimized animations for use on the internet.

      Many thanks in advance.


        • 1. Re: Filesize Calculation
          Captiv8r Adobe Community Professional & MVP
          Hi spritc

          Perhaps the article linked below will be of interest and value to you.

          Click here to read the article

          Cheers... Rick
          • 2. Filesize Calculation
            spritc Level 1
            Hi Rick

            Thanks so much for your reply!

            This article was indeed helpful, as it contains a lot of general tips, and is well written. So it was of good use to me, however I am still looking for more specific answers. Excuse the long post, but I hope it provokes some thought into providing more detailed information for all levels of users, and ensures they get off to a good start when they make their projects.

            Please let me start by giving the example of the sound files. Are there accurate figures or formulas available to really pinpoint the areas we should consider to minimize our files? I did a couple of short tests on a single slide movie, and imported MP3's into it, Specifically to see what effect the Audio Settings had on the size of the resultant movie. Here's what I found:

            TEST 1

            Testing Criteria: File Length

            Original MP3: File size: 673.8 kB
            File Length: 43.0 seconds
            Bit Rate: 128kbps
            Sample Rate: 44.100kHz

            Highest: 877Kb 20.395Kbps 100%

            High: 718Kb 16.698Kbps 82%

            Medium: 553Kb 12.860Kbps 63%


            Original MP3: File size: 12.82Mb
            File Length: 820.2 seconds
            Bit Rate: 128kbps
            Sample Rate: 44.100kHz

            Highest: 12.4Mb 15.48Kbps 100%

            High: 9.3Mb 11.611Kbps 75%

            Medium: 6.25Mb 7.803Kbps 50%

            Conclusion: The longer the file, the better the reduction?

            TEST 2

            Testing Criteria: Bit Rate

            Original MP3: File size: 7.3Mb
            File Length: 235.5 seconds
            Bit Rate: 256kbps
            Sample Rate: 44.100kHz

            Highest: 3.72Mb 16.18Kbps 100%

            High: 2.82Mb 12.26Kbps 76%

            Medium: 1.95Mb 8.48Kbps 52%


            Original MP3: File size: 7.3Mb
            File Length: 479.5 seconds
            Bit Rate: 128kbps
            Sample Rate: 44.100kHz

            Highest: 7.39Mb 15.78Kbps 100%

            High: 5.55Mb 11.85Kbps 75%

            Medium: 3.77Mb 8.05Kbps 51%

            Conclusion: Bit Rate has no effect on reduction?

            These conclusion are by no means correct, but you see my point, there must be a more mathematically correct method of evaluating file size.

            Please take these other points as mentioned in David's article:

            1. Minimize file size by reducing the recording area in Captivate:

            Sure, but what is the relationship between recording area and file size? I know there's a relationship between total number of pixels x bytes per pixel, but there must be more to it than that.

            2. Reduce the amount of background noise;
            3. Reduce the color gradients in your recording area:

            How much does this really affect the final size? Is it closer to .05% reduction or 50% reduction? I can see how this may be appropriate for simple slideshows, but what if the animations are graphically intensive, do the color gradients really matter then? Is this point outdated with the increasing complexity of animations?

            4. When recording in "Full Motion" format, Captivate converts the recording from AVI format to static screen shots. This increases the overall file size more than a traditional recording:

            Again, in producing a thoroughly enthralling animation, with 3D graphics and voiceovers, etc, full motion is a necessity. If the Full Motion Recording options (which is only briefly mentioned in the demonstration) are altered, is there a proven relationship between all the settings (Smoother Movie/Video Quality/Video Color Mode) and the final size of that recording?

            5. Remove any extra slides that do not add any value to the presentation:

            Sounds like a sensible idea. Is there anywhere where we can see the size of an actual slide?

            6. If you insert large images, expect your Captivate file size to grow more than if you insert small images:

            Like point 1, what's the magic formula? Even a ballpark figure would help. David mentions SWF files and the file size should increase only by about the same amount as the inserted SWF file. That's good stuff - a tangible amount.

            7. On the Start and End tab:

            Okay, but I'm definitely going to need those. Again is there anywhere where we can find out how big they are?

            8. Advanced movie compression: Select this option to compress slide data shared between slides, thereby reducing overall file size:

            Sweet, consider it done. How much did it just save me?

            9. Compress compiled SWF file: Do not deselect this option.

            I won't. In fact I am not sure why it's even an option!

            10. Include Breeze metadata: This option, which is selected by default, increases the size of the project. If you are not going to use the project with Macromedia Breeze, deselect the option to decrease the size of the finished project file (SWF). However, if there is the possibility that the output file (SWF) may be used in Breeze, it is best to select this option.

            Bit of a crap shoot at this stage. If I knew just how much I was saving in the file size, I would be better informed to know whether to include it or not.

            11. 508 compliance: Publishing 508-compliant output increases your file size. If audience analysis concludes that are no learners with disabilities that need to access your content—or if you are not otherwise required to comply with Section 508 government regulations—you can safely turn off 508 support.

            C'mon sevens! Again if only I knew the real impact on my filesize, I would know whether to just leave it checked, just in case it will one day be needed.

            12. Frames per second: The default setting is 30 Flash frames per second (fps) and this is appropriate in most cases. Note: Decreasing the number of frames per second does not significantly decrease the size of your Captivate project and therefore is not recommended. For example, decreasing the fps rate by half does not halve the file size. Also, reducing the fame rate of Captivate is not the same as reducing the frame rate of an AVI. Lowering the frame rate of an AVI removes static images from the file, which reduces its size. Removing a single frame from a Captivate project where no change takes place does not reduce the file size.

            Mine defaults to 10 fps, is that bad? Now I'm confused! So what is the best frame rate, and just how much does it reduce the file size when changed?

            13. Movie background color: Depending upon the type of slide and how you took screen shots, the background color might not appear on all slides. Double-click the color box to open the color picker, and select a new color. Remember that using a bright background color will increase the file size.

            Does this ~really~ matter if I have 3D Virtual models and constant audio? Or is it like worrying about if the temperature in Antarctica is -70 below or -71?

            14. JPEG image quality: Adjust this setting depending upon the images used in your movie. Lowering your image quality to as low as 50% (from the default 75%) is often not noticeable to the naked eye. Higher percentage values allow for very high quality images. Of course, this also increases file size.

            Okay, but numbers would be good again.

            15. Play tap audio for recorded typing when movie is generated: This option plays tapping sounds in the final movie whenever keys are pressed during recording. Including this option adds a small audio file to your project and does increase the file size, but only by a small amount.

            No sure how much they'll hear the taps with me talking over them the whole way through it, but I can turn them off. I think a lot of people finding them slightly annoying anyway, but how much did I just gain with that happy move?

            16. Including a playback control bar increases the file size by a small amount. If your users do not need a playback control—as is often the case with simulations and quizzes—select None from the menu.

            Well they are going to need to play these things back somehow, but I may have that created separately. What's the average size of a playback control bar anyway? And how does You Tube get away with all this stuff?

            I am not trying to be cynical, I'm really not, but I am surprised that this has been raised and addressed by Macromedia/Adobe already. I would assume that as users develop more engaging and interactive content, these will become more important. Is there any hope or support for someone like myself, who wants to know every shortcut there is in order to deliver the best possible animations? Is this something that should be brought up with David directly.

            As always, any help from any of the experts here, would be gratefully received!

            Thanks and I look forward to your replies.

            • 3. Re: Filesize Calculation
              spritc Level 1
              I'm surprised no one has responded to this. Besides the fact that it took me bloody ages to write, I thought it would concern more than a few users. Maybe there's just not enough people using it yet?

              Is it worth directing David's attention to it, so that he may respond?