.. Copyright (c) 2008-2016 OpenShot Studios, LLC
 (http://www.openshotstudios.com). This file is part of
 OpenShot Video Editor (http://www.openshot.org), an open-source project
 dedicated to delivering high quality video editing and animation solutions
 to the world.

.. OpenShot Video Editor is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

.. OpenShot Video Editor is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

.. You should have received a copy of the GNU General Public License
 along with OpenShot Library.  If not, see <http://www.gnu.org/licenses/>.

.. _glossary_ref:

Glossary
========

There is much technical terminology in today's fast-moving media-centric world.  
If you find yourself wondering what a video production term or an acronym 
means, you are certainly not alone. Like most industries, video production has
a language all its own. Here is a list of terms commonly found in video
editing. Becoming familiar with these terms only makes your job easier.

.. image:: images/ui-example.jpg

Definitions
-----------

These definitions are a work-in-progress. Please let us know if you need a term defined by
contacting support@openshot.org.

:ref:`letter_A_ref`
:ref:`letter_B_ref`
:ref:`letter_C_ref`
:ref:`letter_D_ref`
:ref:`letter_E_ref`
:ref:`letter_F_ref`
:ref:`letter_G_ref`
:ref:`letter_H_ref`
:ref:`letter_I_ref`
:ref:`letter_J_ref`
:ref:`letter_K_ref`
:ref:`letter_L_ref`
:ref:`letter_M_ref`
:ref:`letter_N_ref`
:ref:`letter_O_ref`
:ref:`letter_P_ref`
-Q-
:ref:`letter_R_ref`
:ref:`letter_S_ref`
:ref:`letter_T_ref`
-U-
:ref:`letter_V_ref`
:ref:`letter_W_ref`
-X-
-Y-
:ref:`letter_Z_ref`

.. _letter_A_ref:

-A-
~~~
A-Roll:
   The Principal video that is usually someone speaking. 
Aliasing:
   The undesirable jagged or stair-stepped appearance of angled lines in an image, graphic, or text. 
Alpha:
   Alpha blending is a convex combination of two colors allowing for transparency effects in computer graphics.  The value of alpha in the color code ranges from 0.0 to 1.0, where 0.0 represents a fully transparent color, and 1.0 represents a fully opaque color.
Alpha Channel:
   An alpha channel is a channel in an image or movie clip that controls the opacity region.
Ambient Noise:
   Ambient noise is background noise specific to the shooting location.
Animation:
   The technique of making inanimate objects or drawings appear to move in motion pictures or computer graphics.
Anti-Aliasing:
   Anti-aliasing is a process for smoothing jagged lines in an image.  Anti-aliasing can also mean a method of filtering out erroneous frequencies in an audio signal.
Artifact:
   An artifact is undesired data in an image because of digital processing.
Aspect Ratio:
   The ratio of width to height in a flat surface or 2-dimensional abstract construction, such as an image, video, character, or pixel.  The standard ratios for NTSC SD videos are 4:3 (or 1.33:1) and HD 16:9 (or 1.77:1).  The most common aspect ratios for motion pictures are 1.85:1 and 2.35:1.
ATSC:
   ATSC is a digital broadcast standard that replaced the older analog NTSC standard.  The standard covers both standard and high-definition formats.
Audio Sample Rate:
   The number of samples taken per second to reproduce audio digitally.  The higher the sample rate, the higher the quality of the digital audio.  A rate of 44,100 samples per second produces CD-quality audio and captures the range of human hearing.

.. _letter_B_ref:

-B-
~~~
B-roll: 
   B-roll is supplemental footage that provides supporting details and greater flexibility when editing video.  Common examples include the footage used to cut away from an interview or news report to help tell the story.
Bit:
   The elementary unit for digital storage.  A BIT can be either a 1 (one) or a 0 (zero).
Bit Depth:
   In digital graphics and video, bit depth indicates the number of colors an image can display.  A high-contrast (no gray tones) black and white image is 1bit, meaning it can be off or on, black or white.  As bit depth increases, more colors become available.  24-bit color allows for displays of millions of colors.  Similarly, in digital audio, bit depth indicates the number of bits per sample.  The higher the number, the better the sound quality.
Bitrate:
   The frequency at which bits (binary digits) pass a given physical or metaphorical point, measured in bps (bits per second).  For every second in the video, the Bit Rate, or Data Rate, is the amount of data used each second.  The bitrate, in Kilobits per second, can be variable or constant.
Blue Screen:
   A blue screen is a blue background that the subject stands in front of that the computer later replaces with another background in post-production.  See also blue screen compositing and green screen.
Blue Screen Compositing:
   The process of making all blue elements in an image transparent and placing a different background underneath.   

.. _letter_C_ref:

-C-
~~~
Capture:
   The process of transferring source video from a camcorder or tape deck to a computer.  If the source video is analog, the capture process converts the video to digital.
Channel:
   A channel is one of several grayscale components used to make up a color image.  Red, green, and blue channels make up RGB images, with an optional alpha channel for transparency.
Chromakey:
   Chromakey is a method of creating transparency in a video source by selecting a specific "key color" to create an alpha matte.  It is frequently used on news programs to display weather graphics behind talent and for visual effects compositing.
Clip:
   A digitized or captured portion of video, audio, or both.  Clips are media files added to the Timeline, usually part of a more extensive recording.
Codec:
   Codec is a video compression technology used to compress data in a video file.  Codec stands for "Compression Decompression." An example of a popular codec is H.264.
Color Correction:
   The process of altering the color of a video, especially one shot under less than ideal conditions, such as low light.
Compositing:
   Construction of a composite image by combining multiple images and other elements.
Coverage:
   Coverage is the process of shooting additional footage and camera angles to cover the action in the scene.  Coverage is so that the editor has a more excellent range of choices when the film reaches the post-production stage.
Compression:
   The process of reducing data, such as in an audio or video file, into a form that requires less space.
Crop Factor:
   Crop factor is a number (typically from 1.3-2.0) that represents the ratio of a sensor's imaging area to that of a full-frame sensor.  Try multiplying the focal length of your lens by your camera sensor's crop factor.  It gives you the focal length for the lens/sensor combination.
Crawl:
   Crawl is a text effect where the text moves right-to-left (in the English-speaking world).
Cross-fade:
   A cross-fade is a simultaneous fade-in of one audio or video source as another fades out so that they overlap temporarily.  Also called a dissolve.
Cut:
   A cut is an instantaneous change from one shot to another.
Cut-in (Insert Shot): 
   It is a type of shot that most often shows the objects the subject is in contact with or manipulating.  Cut-in shots are correspondingly helpful to b-roll because they stray from the subject for a short time.
Cutting on Action:
   Cutting on action is a technique used to create a more interesting scene. The concept is simple… when you cut in the middle of an action, it will appear less jarring and more visual interesting. 

.. _letter_D_ref:

-D-
~~~
Data Rate:
   The amount of data moved over time (for example, 10 MB per second).  Often used to describe a hard drive's ability to retrieve and deliver information.
Denominator:
   The number or expression below the line in a fraction (such as 2 in ½).
Digital Video:
   Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data.  In contrast, analog video represents moving visual images with analog signals.  Digital video comprises a series of digital images displayed in rapid succession.
Digitize:
   To convert analog video or audio to digital form.
Dissolve:
   Dissolve is an image transition effect where one picture gradually disappears as another appears.  Also called a cross-fade.

.. _letter_E_ref:

-E-
~~~
Editing:
   Editing is the process or result of selectively sequencing video and audio clips into a new video file.  Typically involves reviewing raw footage and transferring desired segments from source footage into a new predetermined sequence.
Effect:
   Synthetic sounds and animations created in the digital domain applied to a clip to change a specific parameter of video or audio.  Examples: the color of a visual element or the reverb on an audio track.
Encode:
   To merge the individual video signals (for example, red, green, and blue) into a combined signal, or to convert a video file to a different format using a codec.
Export:
   Export refers to the process of assembling your edited video project into a single file that then plays back on its own, shared, or uploaded.

.. _letter_F_ref:

-F-
~~~
Fade:
   A fade is the gradual diminishing or heightening of visual or audio intensity.  Usage: fade-out, fade to black, fade-in, or fade up from black.
Fade-in:
   1.(n.) a shot that begins in total darkness and gradually lightens to full brightness.  2. (v.) To gradually bring sound from inaudibility to the required volume.
Fade-out:
   1.(n.) a shot that begins in full brightness and gradually dims to total darkness.  2. (v.) To gradually bring sound from the required volume to inaudibility.
Filter:
   A video filter is a software component that performs some operation on a multimedia stream.  Multiple filters used in a chain, known as a filter graph, are the process in which each filter receives input from its upstream filter.  The filter graph processes the input and outputs the processed video to its downstream filter.
Final Cut:
   The final video production, assembled from high-quality clips, and ready for export to the selected delivery media.
Finishing: 
   The stage that brings together all assets of a piece.  Your output from this stage is your master/sub-master.
Footage: 
   Derived from having feet of film, this is almost synonymous with video clips.
Frame:
   In filmmaking, video production, animation, and related fields, a frame is one of the many still images which compose the complete moving picture.
Frames Per Second (fps):
   The number of frames played every second.  At 15 fps and lower, the human eye can detect individual frames, causing the video to appear jerky.
Frame Rate:
   Frame rate (expressed in frames per second or FPS) is the frequency (rate expressed in Hz) at which consecutive images called frames appear on display.  The term applies equally to film and video cameras, computer graphics, and motion capture systems.  Common Frame Rate Examples: 24, 25, 29.97, 30, 50, 60.
Frequency:
   The number of audio cycles per second, expressed in hertz (Hz).  Frequency determines the pitch of a sound.

.. _letter_G_ref:

-G-
~~~
Gamma:
   A measurement of the intensity of mid-tones in an image.  Adjusting the gamma adjusts the level of the mid-tones while leaving the blacks and whites untouched. 
GPU:
   Graphics processing unit.  A microprocessor with built-in capabilities for handling 3D graphics more efficiently than a CPU (central processing unit).
Gravity:
   Gravity in OpenShot is a property of each clip that sets the clip's initial position on the screen.
Green screen
   A green background that the subject stands in front of that is another background in post-production.
Green Screen Compositing
   The process of making all green elements in an image transparent and placing a different background underneath, so it appears that the subject is in a different location.

.. _letter_H_ref:

-H-
~~~
High Definition (HD):
   A general term for a video signal with a significantly higher resolution than standard definition.
HDMI:
   High Definition Multimedia Interface.  Interface for transmitting high definition digital audio and video data.
HDR:
   HDR (high dynamic range) is the compositing of two images, one that correctly exposes the highlights, and another that properly exposes the dark areas.  When composited together, you get a properly exposed image.
HDTV:
   High Definition TV.  A broadcast format that allows for a higher resolution signal than the traditional formats, NTSC, PAL, and SECAM.
HDV:
   High Definition Video.  The format used to record HDTV-quality data with video camcorders.
Headroom:
   The space between the top of a character's head and the top of the frame.
Hiss:
   Noise caused by imperfections in the recording medium.
Hue:
   The shade of a color.  This is the general color category into which the color falls.  For example, pink, crimson, and plum are different colors, but they all fall under the hue of red.  White, black, and gray tones are not hues.

.. _letter_I_ref:

-I-
~~~
Image Stabilizer:
   Also referred to as an electronic image stabilizer.  A technique used to remove the movement caused by camera shake.
Importing:
   Importing is the process of transferring videos from your camera onto your computer or into a piece of editing software.
Interframe Compression:
   A compression scheme, such as MPEG that reduces the amount of video information by storing only the differences between a frame and those preceding it.
Interpolation:
   Used in animation to calculate the motion in between two user-generated keyframes so that the editor does not need to animate each frame manually.  This speeds up the process and makes the resulting animation smoother.
Intertitles:
   Titles that appear on their own between footage.  Commonly seen in silent movies to substitute dialogue, also used as chapter headings.

.. _letter_J_ref:

-J-
~~~
J-Cut:
   An edit in which the audio starts before the video, giving the video a dramatic introduction.  Also known as an audio lead.
Jog
   To move forward or backward through video by playing it one field or frame at a time.
Jump Cut:
   A jump cut is an unnatural, abrupt switch between shots identical in the subject but slightly different in screen location, so the subject appears to jump from one screen location to another.

.. _letter_K_ref:

-K-
~~~
Key:
   A method for creating transparency, such as a bluescreen key or a chroma key.
Keyframe:
   A keyframe is a frame that contains a record of specific settings (e.g., scale, rotation, brightness).  Start and endpoints for animated effects.  By setting multiple keyframes, you can adjust these parameters as the video plays to animate certain aspects.

.. _letter_L_ref:

-L-
~~~
L-Cut:
   An L-cut is an edit in which the video ends before the audio.  L-cuts act as a subtle transition from one scene to the next.
Letterbox:
   A technique used to preserve the original aspect ratio of a motion picture when played on a TV.  Letterboxing adds black bars to the top and bottom of the screen.
Linear Editing:
   A form of video editing which lays out cuts sequentially, one by one, to produce the final scene. This contrasts with non-linear editing which allows cutting in any order.
Log:
   A record of start and end timecode, reel numbers, scene descriptions, and other information for a specified clip.
Lossless:
   A compression scheme that results in no loss of data from decompressing the file.  Lossless files are generally quite large (but still smaller than uncompressed versions) and sometimes require considerable processing power to decode the data.
Lossy:
   Lossy compression is a compression scheme that degrades quality.  Lossy algorithms compress digital data by eliminating the data least sensitive to the human eye and offer the highest compression rates available.

.. _letter_M_ref:

-M-
~~~
Mark In:
   Placing a marker at the beginning of where you want your clip to start.
Mark Out:
   Placing a marker at the beginning of where you want your clip to end.
Match Action:
   Match action (or match cut) is a technique where an editor will cut from one visually similar scene to another.
Memory Bank: 
   A Memory Bank is a video that documents specific periods or events in someone's life.  It can be set to music, make use of natural sound, record vacations, or just capture moments in everyday life.
Marker:
   An object used to mark a location.  Clip markers signify essential points within a clip.  Timeline markers indicate scenes, locations for titles, or other significant points within an entire movie.  Use clip markers and timeline markers for positioning and trimming clips.
Mask:
   The transparent area of an image, typically defined by a graphic shape or a bluescreen background.  Also called a matte.
Matte:
   Matte is an image mask used in visual effects to control applying an effect to certain parts of the image.
Montage:
   A montage is a self-contained sequence of shots assembled in juxtaposition to each other to communicate an idea or mood.  The implied relationship between seemingly unrelated material creates a new message.
Motion Artifact:
   Visual interference caused by the difference between the frame rate of the camera and the motion of the object.  The most common display of this is when filming a computer or television screen.  The screen flickers or a line scans down it, which is the difference in frame rates and a lack of synchronization between the camera and television.

.. _letter_N_ref:

-N-
~~~
Noise:
   Undesired data in a video or audio signal.  See also artifact.
Non-linear Editing:
   An editing system that performs edits at any time, in any order.  Access is random, which means that the system can jump to specific pieces of data without having to look through the whole footage to find it.
Numerator:
   The number or expression above the line in a fraction (such as 1 in ½).
NTSC:
   NTSC is an abbreviation for National Television Standards Committee.  NTSC is the group that initially developed the black & white and subsequently color television system.  The United States, Japan, and many other countries use NTSC.  Five-hundred twenty-five interlaced lines make up NTSC that display at a rate of 29.97 frames per second.  ATSC Has now superseded by NTSC.

.. _letter_O_ref:

-O-
~~~
Offline Editing:
   Editing a rough cut using low-quality clips, and then producing the final cut with high-quality clips, usually on a more sophisticated editing system than that used for developing the rough.
Online Editing:
   Doing all editing (including the rough cut) on the same clips that produce the final cut.
Opacity:
   An inverse measure of the level of transparency in an image, which is of importance when compositing.  An image's alpha channel stores its opacity information.

.. _letter_P_ref:

-P-
~~~
PAL:
   PAL is an abbreviation for Phase Alternate Line.  This is the video format standard used in many European countries.  Six-hundred twenty-five lines make up a PAL picture that displays at a rate of 25 frames per second.
Pan:
   A horizontal movement of the camera on a fixed axis.
Pan and Scan:
   A method of converting widescreen images to a 4:3 aspect ratio.  Cropping the video so that it fills the entire screen and panning it into position shows the essential parts of the scene.
Picture in Picture (PIP):
   An effect of superimposing a small window of footage over a larger window and the two play at the same time.
Pixel:
   One of the tiny dots that make up the representation of an image in a computer's memory.  The smallest unit of a digital image.
Pixel Aspect Ratio:
   Aspect ratio is the ratio between the width and height of your video; the Pixel Aspect Ratio is the ratio between the width and height of the pixels.  A standard Pixel Aspect Ratio is 1:1.
Pixelation:
   The display of large, blocky pixels in an image caused by over-enlarging it.
Playhead:
   When editing audio or video in a current computer, the Playhead is a graphic line in the Timeline that represents the current accessed position, or frame, of the material.
Post-production (Post):
   Post-production (post) is any video production activity following the initial recording.  Typically, post involves editing, the addition of background music, voice-over, sound effects, titles, and various visual effects resulting in completed production.
Poster Frame:
   A single frame of a clip, selected as a thumbnail to indicate the clip's contents.
Project:
   A project is all the files, transitions, effects, and animations that you make or use within OpenShot.

.. _letter_R_ref:

-R-
~~~
Raw Footage:
   Raw footage is pre-edited footage, usually direct from the camera.
Real-time:
   Real-time occurs immediately, without delay for rendering.  If a transition occurs in real-time, there is no waiting, the computer creates the effect or transition on-the-fly, showing it the results immediately.
Rendering:
   The process by which the video editing software and hardware convert the raw video, effects, transitions, and filters into a new continuous video file.
Render Time:
   The render time is the time it takes an editing computer to composite source elements and commands into a single video file.  Rendering allows the sequence, including titles and transition effects, to play in full motion.
Resolution:
   Resolution refers to the actual number of horizontal and vertical pixels your video contains.  Common resolution Examples: (SD) 640×480, (HD) 854x480, (HD) 1280×720, (FHD) 1920×1080, (QHD) 2560x1440, (UHD) 3840x2160, and (FUHD) 7680x4320.  Often the numbers that appear vertically refer to the resolution.  The examples listed would appear as SD, 480p, 720p, 1080p, 1440p, 4K and 8K, respectively.
RGB:
   Monitors, cameras, and digital projectors use the primary colors of light (Red, Green, and Blue) to make images.
RGBA:
   A file containing an RGB image plus an alpha channel for transparency information.
Roll:
   Roll is a text effect commonly seen in end credits, where text typically moves from the bottom to the top of the screen.
Rough cut:
   A rough cut is a preliminary edit of footage in the approximate sequence, length, and content of a finished program.

.. _letter_S_ref:

-S-
~~~
Sample Rate:
   In digital audio, the number of samples per second.  The higher the number, the better the sound quality.
Scene:
   Action that occurs in one location at one time.
Scrub:
   Scrubbing is an act of moving the cursor or playhead across the Timeline manually.  Once specific to audio tracks, the term now also refers to video tracks.
Shot:
   A recording of a single take.
Slow-motion:
   A shot in which action takes place at a slower than average speed.  The camera achieves slow-motion by speeding up the frame rate during recording and then playing back the frames at a slower speed.
Snap:
   Snapping quickly positions an object in alignment with grid lines, guidelines, or another object.  Snapping causes the object to automatically jump to an exact position when the user drags it to the proximity of the desired location.
Splice:
   The process of physically attaching two pieces of film using tape or cement.
Split cut (L-cut or J-cut):
   An edit in which the audio starts before or after the picture cut.  Used for easing the transition from one scene or shot to another.
Splitscreen:
   A unique effect that displays two or more scenes simultaneously on different parts of the screen.
Sound Effects:
   Sound effects are contrived audio, usually prerecorded, incorporated with a video soundtrack to resemble a real occurrence.  Blowing on a microphone, for example, might simulate wind to accompany hurricane images.
Soundtrack:
   The soundtrack is the audio portion of a video recording, often multifaceted with natural sound, voiceovers, background music, or other sounds.
Stabilization:
   Image stabilization is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure.
Standard Definition (SD):
   Television broadcasting standard with a lower resolution than high definition.
Step:
   The act of moving forward or backward through video one frame at a time.
Still Frame:
   A single frame of video is repeated, so it appears to have no motion.
Straight Cut:
   The most common edit, consecutive clips placed one after another in the Timeline window.  Straight cuts are preferable to transitions when the scenes are similar, and you do not want edits to be noticeable.
Superimposing:
   Combining images, where one or more layers involve transparency.
Sync (Synchronization):
   Synchronization refers to the relative timing of audio (sound) and video (image) parts during creation, post-production (mixing), transmission, reception, and play-back processing.
SECAM:
   Systeme Electronique Couleur Avec Memoire, a TV format used mainly in Eastern Europe, Russia, and Africa. 

.. _letter_T_ref:

-T-
~~~
Tilt:
   Tilting is a cinematographic technique in which the camera stays in a fixed position but rotates up/down in a vertical plane.
Timecode:
   The timecode is the discrete address given to each frame of the video (for example, 1:20:24:09).  Timecode makes frame-accurate editing possible and allows editors to identify scenes precisely in a log.
Time-lapse: 
   It is a technique for capturing each frame in a video at a much slower rate than usual.  When played back at regular speed, time appears to go by faster.  An editing program achieves this by fast-forwarding or increasing the speed of your video.
Timeline:
   The Timeline is an editing interface that lays out a video project in a linear fashion consisting of clips laid horizontally across the screen.
Timeline Editing:
   Timeline editing is a computer-based method of editing, in which bars proportional to the length of a clip, represent video and audio clips on a computer screen.
Titling:
   Titling is the process or result of incorporating on-screen text as credits, captions, or any other alphanumeric communication.
Track:
   A separate audio or video layer on a timeline.
Transcode: 
   Converting a digital file to another digital file format.  This usually involves audio and video compression.
Transparency:
   Percentage of the opacity of a video clip or element.
Transition:
   A method of juxtaposing two scenes.  Transitions can take many forms, including cuts, dissolves, and wipes.
Trim:
   Removing frames from the beginning, middle, or end of a clip.

.. _letter_V_ref:

-V-
~~~
Video Format:
   The video format is a standard that determines the way a video signal records on videotape.  Standards include DV, 8-mm, Beta, and VHS.
Voiceover:
   A term used to describe off-camera narration that is not part of a scene (non-diegetic).
VTR:
   A Videotape recorder also referred to as a 'deck'.  Decks duplicate videotapes and inputting and outputting from a computer.

.. _letter_W_ref:

-W-
~~~
Widescreen:
   A format in which the width-to-height ratio of the frame is greater than 4:3 so that it is significantly wider than it is tall.
Wipe:
   A wipe is a transition from one shot to another.  The edge of the transition moves across the original image as a line or a pattern, revealing the new shot.

.. _letter_Z_ref:

-Z-
~~~
Zoom:
   A shot where the image grows more substantial or smaller by adjusting the focal length of the lens instead of physically moving the camera.

