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| Convert
Screen Capture Video to Flash Video with Flix |
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| Note: This
tutorial was written using Flix Pro 3.1 as the
encoder. However, the basic principles can also
be applied to Flix SE 3.1, and other versions
of Flix with MX video output - though not all
of the features referenced in this tutorial will
be available in all those versions. Please note,
that Flix versions 3.1 and up have features specifically
designed to improve screen capture conversions. |
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| Contents |
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| Introduction |
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Many
Flix users
have written and requested information on using
Flix to encode screen capture video into Flash.
Screen capture video is widely used for tutorials, presentations, distance learning,
computer based training, and other applications. With the introduction of Flash
MX video, it is now possible to put high quality, high resolution video of screen
captures into the Flash format. This can be a great way to create low bandwidth
video that can be used for both web deployment and offline distribution of your
video. Also, since Flash is a great format for creating interactive presentations,
having your screen captures in Flash, can be very useful in integrating the video
into larger Flash presentations and websites.
The first step is to get a video of the screen capture that you want. There are
many programs available that do this. (Since Flix does not do screen capture,
this tutorial assumes that you already have your screen capture video in a format
that Flix can convert.)
The process of converting screen captures with Flix is fairly simple. I will
go through the Flix program tab by tab and outline the settings you need to make. |
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| Flix
Pro File Tab |
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Select
a file
Open Flix and browse to the source file you want to convert. Once you have selected
your source file, the output file name will automatically fill in. You can either
use this name or create a new one.
Determine what bandwidth you want to set.
You can encode your video into almost any bandwidth. As a general rule we advise
people to create video for both a low bandwidth (e.g., 56k dial up) and a high
bandwidth (e.g., 300k dsl or cable) connection. That way your end user has the
option to select which one they would like to view, and if they are unable to
view the larger file they can view the modem video.
56k video
Creating a 56k video will ensure that virtually everyone on the Internet will
be able to view your video. Flix can usually convert screen captures into a 56k
viewable stream. But there are certain instances in which it will not be able
to reduce the file size enough to achieve that bitrate without sacrificing quality
more than you may be happy with. This is because screen captures usually have
much larger dimensions than the recommended 56k video size. In that case the
options are to reduce the video size (image dimensions), reduce the video framerate,
and/or reduce audio bitrate. If none of those options works for you, then you
can keep the larger size and apply a preloader to your video. (This is for web
streaming purposes only. Preloaders will not work on Flix videos played locally
from a hard drive or CD.) The purpose of using preloaders is to ensure smooth
playback of larger videos for users on slower connections. In this way, users
on slower speed connections (e.g., dial up modems) can view larger, higher quality
video files without the video stopping and starting. Flix Pro and Flix SE include
a feature to automatically add a preloader to your output.
Presets
Next, you can select a preset, or you can fill in all the values manually. You
can also create your own screen capture preset and save it. I have included the
format of two possible screen capture presets that you can cut and paste into
your presets file (you can find the link to that below).
Make sure to select one of the MX presets or the MX video output option. (The
Flash 3-6 video is not usually able to encode screen captures because the quality
is not high enough.) If your video has audio you should select that option as
well.
Options
If you want any of the other features of the File tab, such as the html code
to play your video in a webpage, or a projector file for offline distribution
of your files, you can select it here. |
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| Flix
Pro SWF Tab |
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In
this tab you can set various SWF properties.
You do not need to set anything in this tab if
you do not want any of the features. (Note: In
earlier versions of Flix - pre 3.1 - the SWF
framerate was in the SWF tab, but it has been
moved to the Video tab.)
In the SWF tab you can set your video to loop, you can embed variables in your
video or you can add a preloader, and there are several other useful features.
(The preloaders can be very useful if you are preparing large videos for users
on 56k connections.) For the purposes of this tutorial we won't need to add any
features in the SWF tab. |
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| Flix
Pro Audio Tab |
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If
your video has audio you will need to set your
Output audio options. For 56k video you will
probably need to use a sampling rate of 11 kHz
and a bitrate of 8 kbps. You can also use a bitrate
of 16 kbps, which will yield better audio quality,
but it will take away 8 kbps of data that can
be applied to the image portion of your video.
When the total allotted bits are only 40kbps,
as they are with 56k video, you can see that
8 kbps represents 20% - which is quite a lot.
The only way to tell for sure is to experiment.
For 300k video I recommend audio settings of 22 kHz and 40 kbps. This will yield
good quality audio. This setting is also the minimum recommended setting required
for stereo audio if that is what you want to use. |
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| Flix
Pro Video Tab |
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This
is the most important tab in Flix for encoding
screen captures. You may find that you need to
play with these settings a bit before you get
the results you want.
Image Dimensions
First, you should select the "Use source dimensions" option in the "Output
video dimensions" area. This will automatically set your output video to
be the same size as your source. Usually, this is the size people want when creating
screen capture video. However, you can also reduce the size to whatever dimensions
you want. Be aware, that when you reduce the size, the shrinking of the image
may make it difficult to read some of the text and other small details in your
video. If you choose to reduce the output video size, you may want to select "Maintain
source aspect ratios" in order to ensure that your output has the same aspect
ratio as the source. The aspect ratio is the ratio of the width to the height
of your video. Changing the output aspect ratio can result in distortions so
you probably want to avoid doing that. If you absolutely have to do that to get
your video to fit into a specific sized area, then try it out and see how it
looks.
Framerate
Next, you can set your framerate options. Depending on what is happening in your
screen capture, you can usually set a video framerate of 1 or 2. That will typically
result in a good quality output. Since screen captures are not like real life
action, the low framerate is usually not a problem. If you screen capture dimensions
are large, than using a very low framerate, such as 1 or 2, is the only way you
will get the video into a 56k viewable file. You can then set your SWF framerate
to whatever value you want, as long as it is a multiple of the video framerate.
As a general rule, I make the SWF framerate the same as the video framerate for
screen captures, but you don't have to. If you need to bring the video into a
larger Flash project, you will want to make the framerate the same as your larger
Flash movie. Otherwise, your larger Flash movie will play back at the speed of
your video (if your video has audio), or your video may play back at the speed
of your larger Flash movie (if your video does not have audio and the larger
Flash movie does).
Maximum Bitrate
The maximum bitrate is set by the bitrate you want to encode for. For 56k video
we recommend a maximum bitrate of 40kbps, and for 300k video we recommend a maximum
bitrate of 280kbps. This is based on the idea that listed connection speeds (such
as 56k) represent optimal connection speeds and not actual connection speeds.
As mentioned above, you may find that it is difficult to get your screen capture
to fit into a 56k viewable file (usually because of the large image dimensions
of screen captures - which are much larger than the recommended 56k image sizes).
One issue to keep in mind with regard to the maximum bitrate, is that Flix uses
the maximum bitrate to determine how large to make the keyframes (for an explanation
of keyframes, see below). Since keyframes are the higher quality frames used
to create the frames in between the keyframes (the "interframes"),
you can sometimes end up with a smaller total file size by setting a higher maximum
bitrate. When you set a higher maximum bitrate, Flix will make the keyframes
larger, which can result in smaller interframes, resulting in a smaller overall
file size. However, you should be aware that if the keyframes are too large,
it may result in stopping and starting for users connecting on a 56k modem. This
issue can be dealt with by using a preloader.
Average Image Quality
For Average image quality you can set any number. We generally advise using something
in the range of 75-80. When you are using variable bitrate encoding, Flix will
change your quality settings as required to achieve the maximum bitrate. In this
field you can also use the "video filters" button to open the Edit,
Crop, Filters window where you can apply various image filters to further improve
the appearance of your video. You may find that the "Noise reduce" option
will reduce the amount of pixelation of your output. But you will need to experiment
to find the best options. In general, if your source video is clean, you will
not need to use any of these filters.
MX Options
The MX video options are very important. For MX video you will always get the
best quality by using 2-pass VBR encoding with a maximum bitrate. This is because
VBR (variable bitrate) encoding is based on the target bitrate you set.
Compressed video frames are defined as "interframes" or "intraframes".
Interframe means many frames are described based on their difference from the
preceding frame. Intraframe means each frame is compressed separately, independent
of surrounding frames. Flix's MX video is an interframe codec, but it also uses
intraframes. The intraframes are the "keyframes", or reference frames,
that are used to generate the interframes.
With regard to the keyframing options, for screen captures, I recommend using
a setting of "100" and the "Max" option. The "Max" option
applies natural keyframing to your output. This means that Flix inserts a keyframe
whenever there is a large change in the image (such as a cut or a scene change),
but will go no farther than the Max keyframe value before inserting a new keyframe.
Keyframes are important, because they are the higher quality frames that are
used to create the other frames in your video. But keyframes use up a lot more
file size than the interframes, so if you have more than you need, you will be
wasting file size, and will usually not be able to achieve a 56k output file
size.
If you feel that you need to use the fixed keyframing option, you can. The fixed
keyframe will insert a keyframe at the interval you specify. This could be every
single frame if you select a fixed keyframe interval of "1". This may
work for 300k output, but it won't for the 56k output - and it is not necessary.
However, there are certain situations when you may want to have complete control
over the keyframing and that is why the fixed keyframing option is there. |
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| Additional
Flix Pro options |
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Edit
and Crop
If your video is longer than you want, you can use Flix Pro's editing feature
to reduce the file size. If your source video is long and you want to test your
settings before encoding the whole file, you can also use the editing feature
to select a smaller portion of your video for testing. In order to get a good
idea how your output will look, you should use at least 30 seconds - 1 minute
of video for testing.
If your video has unwanted elements in the frame, you can crop them out with
Flix's crop feature.
Players
Flix Pro can also automatically output your video in a player. This can be very
useful as it will allow viewers to stop, start, rewind and apply other controls
to the video while they are watching it. (Flix SE also has the option to automatically
output your video with basic play controls.)
You may want to output the video by itself and apply a player later. Flix Pro
will allow you to do that in the "Existing SWF" tab of the Players
window. By having the video by itself (without a player skin) you can use it
for other applications later. |
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| Flix
Screen Capture Presets |
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This
file (2K download) is a text file with
Flix presets for creating screen captures.
Just cut and paste them into your Flix presets
file and they will appear when you close and
reopen Flix.
To edit the presets, select View>Options>Edit. The presets file will open
in a text editor. Cut and paste the sample presets into your existing presets
file. Make sure you use the exact same format that is used in the EncodingPresets
file as even a small typo can cause the presets not to be read by Flix. (Prior
to editing, you may want to save a copy of the original presets as a backup.)
Once you are finished making your changes, save the file and quit the text editor.
Then click "Reload Presets" and "OK" and the presets should
be updated. If you need to adjust these presets, just change them and follow
this same process again. |
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| Conclusion |
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| So
that's it. The main changes you need to make
to your normal Flix output settings are to your
video framerate and video size. And as with all
video encoding, you will find that experimentation
is the key to getting the results you want. |
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| ©2010
Wildform, Inc | Policies | Contact
Us | Newsletter
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provides a 100% satisfaction guarantee on all our Flash software.
If you are not completely satisfied with our Flash multimedia software
for any reason you may request a refund within 15 days
of purchase.
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