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MQC TERMINOLOGY

This page contains a brief explanation for each of the most common issues that are flagged during Manual QC of video assets submitted to Universal Music Group.

LUMA / CHROMA / SPATIAL

VIDEO LEVELS

Abrupt Chroma and/or Luma Shift

  • An abrupt change in colour or brightness.

CHROMA BLEED / MOIRE / DOT CRAWL

Chroma Bleed

  • When pigments in a color image move away from their intended position. A type of chroma shift where the color signals in a video image are misaligned.

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Chroma Noise 

 

  • Splotchy fluctuations of color tone between pixels.

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Moire

  • A rippled pattern appearing in images when lines are so close that the imaging system has difficulty differentiating them. Striped clothing + Venetian blinds are common sources of moiré. Can be colored or colorless.

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DIGITAL / ANALOG DROPOUTS / HITS

Video Dropouts (Hits)

  • A dropout is a small loss of data in an audio or video file on tape or disk.  Dropouts can arise from bad tape stock, dirt, the age of a tape or disk, among other things.

Dead Pixel

  • A loss of data at specific spot. Usually the result of an image recorded on a camera with a sensor defect (often present only in shots of a video that were recorded with such a camera). Could also be the result of an encoding error.

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MATTES

Letterbox

  • Black mattes (black bars) at the top and bottom of the frame – these are cropped by some partners.

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Pillarbox

  • Black mattes (black bars) on the left and right of the frame – these are cropped by some partners.

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Windowbox

  • An image presented inside a black box (black bars on all sides). This most often results when a widescreen image (1.85:1 or wider) is first letterboxed for presentation on a standard television screen (1.33:1) and then that image is pillar-boxed for presentation on a widescreen television (1.78:1).

Blanking

  • Blanking is a loss of video at the edge of a frame, presenting as a black band, either horizontal or vertical. 

Visible VBI Information

  • In an analog video signal, the vertical blanking interval (VBI), is the time between the end of the final line of a frame or field and the beginning of the first line of the next frame. The vertical blanking interval can be used for datacasting information such as timecode and closed captioning, since nothing sent during the VBI is displayed on the screen. This information becomes visible when an improper transfer from analog to digital video is performed.

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Matte Shifts

  • This is when a matte slightly changes sizes from shot-to-shot.  This is rarely intentional, and so should be reviewed.  Please note:  this is different than major matte changes, which would fall under "Mixed Aspect Ratios," and which are generally intended.

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VIDEO COMPRESSION ARTIFACTS

Aliasing

  • Aliasing (jagged edges) is a visual artifact caused by the limited spatial sampling of a resolved image. Often referred to as "jaggies," visual edges appear to shift sharply and not in a smooth gradient.

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Macroblocking / Banding / Posterization

  • Usually the result of bad compression, representing an image with far fewer tones than were in the original. Smooth gradations are replaced by bands of solid color with abrupt shifts between bands (posterization) or clearly defined blocks (macroblocking).

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PLAYBACK

FRAME SKIP

Frame Skip / Image Jump

  • When one or more frames are missing in the video.

DUPLICATE FRAMES

Duplicate Frames

  • A duplicate frame within the frame sequence that contains no different information than the adjacent frame.

TELECINE / CADENCE ISSUES

Cadence

  • Choppy motion caused by repeated frames in a sequence. For example, 2:1 cadence refers to 2 Frames Movement (Progressive) / 1 Frame No Movement (Duplicate Frame).

Mixed Cadences (Does NOT apply to creative slow motion effects)

  • Where the ratio of repeated frames in a sequence is inconsistent throughout the video. For example, the video contains a section that is 1:1 cadence in a video that is majority 3:1 cadence.

  • Mixed / Irregular Cadence is a result of multiple frame rate formats being utilized within one video program containing different transfer patterns. If mixed media is processed differently as part of the telecine process, in subsequent conversions, or as part of the creative process (slow motion, strobe, or other visual effects) it can result in an inconsistent cadence.

Combing / Interlacing Artifacts / Visible Scan Lines

  • If content is incorrectly handled during the post-production editing process, interlacing artifacts (horizontal lines) can become visible in a progressive file. Combing appears as ghosting and horizontal lines around objects in motion. A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube (CRT) display of a television set or computer monitor.

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Global 3:2 Pulldown on a 29.97 file

  • This often occurs when a file has been converted from a "film based" source 23.98 or 24 fps to "video based" 29.97 fps via a telecine process.

GHOSTING / BLENDED FRAMES

Ghosting / Blended Frames

  • Ghosting is when information from a set of adjacent frames has been combined and overlaid. Usually appears as a duplicate image.

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AUDIO

AUDIO LEVELS / PEAKS / DISTORTION

Overly Compressed Audio

  • Compression is used to reduce the size of a file, while also reducing the quality. Overly compressed audio can sound distorted and indicates that a lesser quality source has been used to produce the video. Original source quality audio should be used to ensure the listening experience isn’t compromised.

MONO / PHASE ISSUES

Dual Mono Audio

  • Dual Mono occurs when both the Left and Right channels are identical to one another. Dual Channel Mono Audio refers to the duplication of an audio track, causing stereophonic or intended surround elements to be absent.

    NOTE: It is acceptable for production audio in parts of a Behind the Scenes / Interview type video to be dual mono (as long as the entire file isn't dual mono, and as long as any underlying music in the video is in stereo).

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Inverse Phase (Global)

  • Occurs when the polarity of different channels in an audio mix are inadvertently opposite of each other. This causes the music to sound, thin, hollow, diffuse, and unnatural. True inverse phase issues between channels are easy to fix by flipping the polarity of a single channel.

Channel Imbalance

  • A track imbalance occurs when the two stereo channels have significantly different volumes. This may be the case for the entire video or it may be isolated to a specific section. This is different than instruments or sounds intentionally being placed in different channels to create a wide soundstage or directional effects.

MISCELLANEOUS

Slates / Bars / Tones

  • Bars & Tone are material traditionally placed at the head of a video program distributed for television broadcast or prepared for video duplication, including color bars, audio tone, and a countdown clock.

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  • A slate is a static screen containing descriptive information (such as title, producer, and running time) that appears at the head of a video program packaged for television broadcast.

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