5.2 Basic editing

Here we show you aspects of a muvee style that is likely to cross-cut all the styles that you might develop. It is therefore worth working through the concepts in this tutorial so you can tweak the editing behaviour of your style to match your audio-visual effects. All the action in this tutorial happens in the style’s "data.scm" file so that’s the file to direct your attention to.

5.2.1 STAGE 1 : Starting from the S10000_BlankTemplate

Style: S10000_BasicEditing_Stage1

1. Make sure muvee Reveal isn’t running.

2. Start by copying the Blank template style. If you’re unsure how to do this, refer to Getting Started. The rest of the tutorial assumes that your style has the id S10000_MyBasicEditingStyle. Do change the name of the style to something like “My basic style” and its description to, say, “A masterpiece in the works.” just so you can distinguish it from the original.

3. Launch muvee Reveal and your new style will show up in Reveal’s styles panel, ready for action.

This style, although very minimal, already gives you a lot. For example, you can use pictures, video and music with it, your pictures get an automatic Ken-Burns effect based on face detection and your video is automatically summarized to the duration you give, or to the music duration, depending on your setting. Of course, you can use highlights and exclusions on your video to control the content. Your style responds to pretty much everything that the muvee Reveal interface allows you to specify (... except captions, which we’ll defer).

Now select your new style and make some muvees. Try different media, personalization settings, etc. You may notice that captions don’t work yet. We’ll come to that later in this tutorial. If you’re a new-comer to muvee Reveal and automatic editing, you might find the tutorials at the muvee Maniacs forum useful.

You now have the beginnings of your style.

5.2.2 STAGE 2 : Playing around with editing pace

Style: S10000_BasicEditing_Stage2

If you played around with the “Stage1” style, you’ll have noticed that your style edits at the same pace no matter what piece of music you give it. “Pace” refers to the overall rate of happenings in the muvee. A faster paced muvee will have more pictures shown per minute than a slower paced one, at the very least. We’ll add some user level control of the editing pace in this stage and follow it up with music driven pace control in the next one.

Add a style parameter named "PACE" and directly specify the segment-durations using PACE -

IMPORTANT: Changing style-parameters needs muvee Reveal to be relaunched to take effect.

; muSE v2

(style-parameters

; Specify a PACE slider with a default of 2.0,

; a minimum value of 0.5 and a maximum of 8.0.

(continuous-slider PACE 2.0 0.5 8.0))

(segment-durations PACE)

Now when you open the “Style settings” panel, you should see a PACE slider that you can twiddle to make your style edit faster (to the left) or slower (to the right). Notice that even though you make the muvee go faster or slower, the transition points (a.k.a. “cut points”) are synchronized to the music events.

5.2.3 STAGE 3 : Better PACE control

Style: S10000_BasicEditing_Stage3

This kind of issue arises very often when you are designing sliders for user control and is therefore worth paying some attention to. You always want to make your sliders correspond to the user’s intuition as much as you can - by making it control one independent aspect of the production, making it always increase something when you move it from left to right and by making it increase proportionately.

IMPORTANT: Changing style-parameters needs muvee Reveal to be relaunched to take effect.

The expression (/ 2.0 (pow 2.0 PACE)) is the Scheme code equivalent of the mathematical form 2.0 / (2.0 PACE) which becomes 0.5 when PACE is -2.0 (the left extreme point) and becomes 8.0 when PACE is 2.0 (the right extreme point).

We now have a PACE slider that goes from “4x slower” to “4x faster” more evenly than it did before.

5.2.4 STAGE 4 : Making the editing pattern respond to music

Style: S10000_BasicEditing_Stage4

Controlling the pace of your edits using a slider is fine and fun, but if you tried your style with many types of music with some dynamics, you soon begin to want to be able to move the PACE slider depending on the music - for example, you might want to edit faster during the more energetic portions of a music and slower during the softer portions.

Though you cannot control the PACE slider during muvee playback, you can encode the music dependence into your style using the concept called segment duration transfer curve. During music analysis, muvee Reveal computes a loudness function that varies in the range 0.0 to 1.0 over the course of the music. Obviously, during the louder sections of the music, the loudness value is closer to 1.0 and during the softer sections, it is closer to 0.0.

The segment durations scale up and down based on the value of loudness as specified by the segment-duration-tc. Here is what you can add to Stage 3 to get music-dependent editing pace.

(segment-duration-tc ; loudness scaling-factor

0.0   6.0

0.5   1.0

1.0   1/4)

The first column gives the music loudness and the second column gives the scaling factor to be applied to each segment duration when the loudness of the music during the segment is that value. The value of 6.0, for example, says that the editing pace when the loudness value is near 0.0 should be 6x slower than the pace specified by the segment-durations expression. The value of 1/4 for loudness of 1.0 means the cutting pace will be 4x faster than normal pace for loud portions of the music.

You only specify certain “knee” points in the transfer curve and scaling factors for other loudness values will be determined by proportional interpolation.

See "data.scm" for all the style code up to this point. You now have a style whose pace you can control and which responds to the dynamics of the music.

5.2.5 STAGE 5 : Adding transitions

Style: S10000_BasicEditing_Stage5

In our style so far, each segment changes to the next one abruptly. Such a transition is known in editing parlance as a cut. Cuts are effective when the music is energetic and the editing pace is fairly high. However, you can enhance the emotive appeal of the slower parts of your music by using soft transitions when loudness goes low.

Once you add the above expression to the Stage 4 style, you’ll get cross fades *everywhere* instead of cuts.

Basic transition specification

See "data.scm" for all the style code up to this point.

5.2.6 STAGE 6 : Making transition durations respond to music

Style: S10000_BasicEditing_Stage6

Now we have transitions adding to the character of the style. Play around with it and try different kinds of music. In this stage, we’re going to introduce a subtlety that is often used by human editors, but something that most viewers are seldom aware of - that it is generally nicer to have longer transitions when the music is soft and shorter transitions when the music is energetic.

Like what we did with segment durations in Stage 2 above, we want to tie the transition durations to the music loudness. .. and just like what we did with segment-durations, we have a corresponding transition duration transfer curve to help us specify the relationship.

(transition-duration-tc ; loudness scale-factor

0.0    3.0

0.5    1.0

1.0    0.25)

The first column specifies the loudness value and the second column specifies a corresponding factor that multiplies with the preferred transition duration indicated by the preferred-transition-duration expression.

See "data.scm" for all the style code up to this point.

5.2.7 STAGE 7 : Adding a MUSIC RESPONSE control

Style: S10000_BasicEditing_Stage7

We have a fairly complete basic style now and more importantly we’re aware of all the basic aspects of style authoring that have to do with its editing behaviour. We’ll top it off by wanting just a bit more - to be able to dictate the extent to which we want our style to respond to music. This is a good exercise in parameter design and we’ll leave the details for you to work out as an exercise.

IMPORTANT: Changing style-parameters needs muvee Reveal to be relaunched to take effect.

Ok.. here is the full code for stage 7 - "data.scm".

5.2.8 STAGE 8 : Some polish

Style: S10000_BasicEditing_Stage8

In this stage, we’re going to add a bit of polish to the style.

Title -> Body and Body -> credits transitions

In Stage 6, we added transitions, but if you noticed, the muvee begins abruptly after the title ends and at the end of the muvee, it abruptly jumps to the credits section. That’s not very smooth since the main muvee itself uses cross-fades to soften things up. So now we use the same cross-fade transition for the title->body and body->credits jumps as well.

Add the following two lines to the end of your "data.scm" file -

(muvee-title-body-transition muvee-transition 0.5)

(muvee-body-credits-transition muvee-transition 0.5)

Since we’ve already defined muvee-transition, we can re-use that for the title->body and body->credits transitions. Of course, you can use different transitions for these if you want to.

Try it out. Looks better?

Captions

If you’d added captions for your pictures or video, you might have noticed that they didn’t turn up when you viewed your muvees. This is because each style has to explicitly describe how captions are to be presented and we haven’t done that yet for our new style.

You can easily specify a “standard treatment” for captions by defining muvee-segment-effect to muvee-std-segment-captions.

(define muvee-segment-effect muvee-std-segment-captions)

muvee-std-segment-captions scans all the captions that need to be presented during its application period and shows them as indicated in muvee Reveal’s captions UI. Since it is a normal effect, it is possible to combine this with other effects to create more sophisticated captions like those in muvee Reveal’s Reflections style. We’ll defer that to another tutorial.

Strings

When you open your style’s settings panel, you see ugly looking names for your parameters and their ranges - PACE, PACE_MIN, PACE_MAX, etc. Lets clean that up by writing down some nice labels for our precious user-level controls, since we put in so much effort into getting them behave nicely.

The key file here is "strings.txt", which you can edit by right clicking on your style in the muveeStyleBrowser and selecting Edit strings.txt.

Your current strings.txt file probably contains the following two lines -

STYLEDESC       en-US   A masterpiece in the works.

STYLENAME       en-US   My basic style

You can add similar strings for each parameter that your style exposes. muvee Reveal’s UI will look up these strings and use them instead of showing PACE, PACEMIN etc.

So edit your "strings.txt" and add the following lines -

PACE    en-US   Pace

PACE_MIN        en-US   Slow

PACE_MAX        en-US   Fast

MUSIC_RESPONSE  en-US   Music response

MUSIC_RESPONSE_MIN      en-US   Inverse

MUSIC_RESPONSE_MAX      en-US   Normal

WARNING: Do not copy-paste the above lines into your strings.txt. Copy from the original file "strings.txt" instead to get the correct formatting.

Here is a link to the "strings.txt" file.

Localization

Ideally, you’ll want your strings to be localized in all the languages that you want your style to work on, but we’ll stop with English for the moment. You can take a look at the "strings.txt" files in muvee Reveal’s bundled styles for examples of how to add UTF-8 encoded strings in other languages. Its not very different from what we did here, you just need to know the language codes.

5.2.9 Now what?

You now have a style that shows interesting music response characteristics and does some simple transitions. You now also know how to get there in an incremental fashion. You can go ahead and add more complexity to your style to make it more interesting and our documentation and discussion group are there to help you get to where you want to go.

5.2.10 Appendix

5.2.10.1 Mathematical expressions in Scheme

In Scheme, operators always come first in (....) expressions. It is easy to get used to it if you read these expressions operationally - for example, (/ (+ a b) (- a b)) can be read as “divide the sum of a and b by the difference of a and b”.

IMPORTANT: You *must* leave a space surrounding the mathematical operators. You cannot write (math a*b+c), for instance. You must write (math a * b + c). This is because a*b+c is a valid Scheme symbol.