Video Sequencer
From Quadrapedia
Contents |
Video Sequencer
What it does
In short, you can load a video clip and change how it plays back in real-time by using your mouse to set cue-points.
Getting started
Download VidSeq 0.1.0 - Released 7th March 2010
When you first load the program, you may need to adjust the panels so you can see all the controls. There are two boxes on the right hand side, the lower of which isn't being used at the moment (just in case you wondered!).
The first thing you will need to do is load a video clip, which can be done by opening the File menu and choosing Open.
In order to get the best results, your video clip should have been encoded with a codec that supports exporting every frame as a keyframe. Codecs such as DivX will, by default, insert keyframes at certain intervals, which is fine for normal playback but jumping to random frames will cause long delays while the codec calculates non-keyframes. We can recommend a MJPEG based codec such as PICvideo's M-JPEG codec.
Once the video clip as loaded, you should click the play button, which is to the left of the top row of controls and looks like '>'.
Your video clip should now start playing.
Cue Points
The light blue bars that you see overlayed on the video are the cuepoints. The playhead (the white line) moves from left to right (the horizontal time axis) and the green line shows the position within the video clip (the vertical position axis).
We've tried to make setting cuepoints as quick as possible but it can take a little while to get comfortable with the mouse controls.
Each cuepoint has a beginning and an end value. These are set by using the left and right mouse buttons respectively. You should first try holding down both buttons and dragging the mouse across the video clip. You should see the bars changing height as your mouse cursor passes over the lines between the cuepoints.
If you just use the left mouse button only the beginning values will be changed, and using only the right mouse button will affect the ending values.
You can also use the middle mouse button to control the heights of the cue points and it has the effect of setting both the beginning and end cuepoint values to the same value, effectively pausing the video for the duration of that cue point.
If you hold down the shift key while setting cuepoints, they will snap to frames in the video clip, which can be very useful when used in conjunction with keyframes.
There is a 'Set Y' control that will turn editing of the cuepoint values on and off allowing you to adjust other cuepoint options without changing their values.
Selecting the "Loop" feature, the first and last cuepoint will share their beginning and end values respectively.
Cue Point Length
By default there are 32 cue points but you can alter this by changing the 'Length' control. Setting this to smaller values and then changing the beginning values of cuepoints with the left or middle mouse buttons will change the length of the cuepoints.
Beats
By default the video clip is played back at its original framerate. We provide a very simple feature to sync the video clip to music. By repeatedly clicking on the BEAT button you can set the tempo of the playback. You can set the tempo with as little as five clicks though continuing will give you a more accurate match. The current tempo will be displayed in the box to the right of the BEAT button.
Once you've set the tempo, wait for at least two seconds, and then you can press the BEAT button once to sync the start of the clip.
You can clear the current tempo by clicking on the "Clear Beat" button.
By default the video clip is timed to be spread over 8 beats (2 bars of 4/4). You can change this by setting a different value in the "Beat Count" box.
Saving and loading
Once you have a sequence that you'd like to save you have the option of saving it just for the current video clip or in a global file. In the top-right panel, either right click on GLOBAL -> Sequence or MEDIA -> Sequence. A menu should pop-up saying "Save Sequence...", which, when selected, will prompt you for a name that will then be added to this panel.
Sequences in the GLOBAL file are always available, MEDIA sequences are loaded when you load the same video clip.
To replace your current sequence with a saved one, just double-click on its name.
To delete a sequence, right click on its name and select "Delete Sequence..."
To overwrite a saved sequence, just enter the same name as an existing sequence. Interpolation
By default the cuepoints use straight lines (linear interpolation) between their beginning and ending values. There are several other interpolation methods available that will give smoother results. Select a method from the "Interpolation" drop-down and then set the cuepoints with the left/middle/right mouse buttons.
Keyframes
If you want to loop only certain parts of a clip, it can be useful to set markers at specific frames within the video clip to act as a visual guide when editing cuepoints.
To set keyframes the video must be paused (turn off the '>' play button) which will enable the frame slider above the other controls.
Move the slider to the frame you want to mark as a keyframe and then right click on the MEDIA -> Keyframe label in the top-right panel. The number of the keyframe will be added and a horizontal marker will appear on the video allowing you to quickly move cuepoints to that location (remember to use shift to snap to the video frames).
Streaming
This program uses the same video streaming technology as used in our FreeFrame plugins. You can stream the video output from this program into other VJ software. We'll explain more about this as the software develops.
Feedback
We hope you will like this small program. If you have any problems or suggestions then please let us know.
