Video #1 - Duq



Video.doc rev 11/17/13

JMA501

Objectives/New Terms:

• Nonlinear Editing (NLE)

• What are NTSC, and ATSC

• What is Persistence of vision

• State Frame Rates for video and film

• Compare interlaced and progressive displays

• What is the impact of improper White Balancing

• What are the two aspect ratios used for video?

• How do you interpret the SMPTE time code?

• What do pan and dolly mean?

• Premiere Fundamentals

Shooting Guidelines

• Recall rule of thirds from Photoshop…same with shooting video

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• Headroom

o Leave some space above the subject’s head.

• Have subject looking into the frame

• If there is motion, generally make it go left to right when possible

• Fill the frame…zoom in on your subject

• Use a tripod…studies

• White Balance before you shoot.

o Tell the camera what is white in the scene

o Light has color, different light sources have differing colors, light color measured in degrees Kelvin.

o Outside light is a different color (temperature) than regular indoor light

o If you tell camera what white looks like indoors, then you go outside and don’t white balance, everything is blue!!

Red light said to be warm colors, blue light said to be cool

o Be sure you white balance…best way: Turn camera off, hold pure white card/paper in front of the lens, turn camera on., or zoom in at something white

• You’re telling camera, “this is white, so adjust yourself to make sure when you see this color, mix the RGB so it produces white.”

Most advanced digital cameras provide the feature to manually set the white balance, or may have presets like flash, outdoors, cloudy etc.

Time Code (SMPTE)

Society of Motion Picture and Television Engineers.

Specifies a point on the timeline

Two formats: drop and non-drop codes

HH:MM:SS:FF

01:10:10:24

Read as :One hour, 10 minutes, 10 seconds, 24th frame

Called non-drop-frame time code:

• uses : as separator

There is also drop frame

01;10;10;24 (Premiere uses this)

Notice the use of semicolons, which are the preferred separator. It’s called drop frame time code...drops a frame periodically

Has to do with fact that the rate is actually 29.97 fps…use drop frame option

Pan, Dolly and zoom

Pan…move camera horizontally or vertically...use a tripod! Do it slowly

Dolly…to move in physically (dolly in) or to move away (dolly out)

• Zoom… Change focal length to make it appear subject closer or farther away

Dolly vs Zoom

In a dolly-in, more and more of the background disappears "behind" the person in the scene. In a zoom, while the central image gets bigger, what is just beside it in the long view is still there in the short view.

Suppose a person whose head was 6" wide was standing in front of an 8" wide tree and at a distance, so that we see an inch of the tree showing on either side of the head.

On a dolly-in, as the nose loomed larger and larger, the view of the tree on either side would vanish because the cheeks were blocking the view.

On a zoom, at some point the face would pretty much fill the frame, but the tree would still be visible on either side, also bigger.

US Video Standards

• First standards Established by the NTSC (National Television Standards Committee…,there are other standards (such as for HD) but for this class: NTSC

Frames, Frame Rates, Frame Sizes

• Conceptually, motion is captured and displayed as a sequence of still pictures at a constant frequency, 24 (theaters) or 30 per second (home).

• Each “picture” is called a frame.

Note: Titanic’s most recent version (3D) has over 270,000 frames …each was analyzed and modified for 3D

• How fast the pictures are captured or played back is called the frame rate, which is measured in frames per second (fps).

• We see a frame of video, then another frame etc.

o Like old flip books you might have created!

o Our eyes are fooled …(called persistence of vision)

…The ability of the eye to retain the impression of an image for a short time after the image has disappeared

• As long as the frame rate is 24-30 times per second, we don’t see any flickering...called Critical Flicker Frequency

Frame Rates

• Movies use 24 frames/second (fps)

• Video (including Blu-Ray) shows 30 fps

• We perceive it as motion, again, called persistence of vision

Frame Sizes

|TV Frame size |Pixels/Line |Lines |

|Standard Definition |720 |480 |

|HD |1920 |720 |

|Full HD |1920 |1080 |

|Ultra HD |4096 |2304 |

Note 1: FHD: There are 2,073,600 pixels (1920 * 1080) or 2M pixels. Most of us want phone cameras of 10 M…not needed

Note 2: Sample 4K Camera (as of November, 2013)

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How are frames created: Scanning Methods

Interlaced versus progressive Scanning

Interlaced Scanning…

• A picture displayed on a TV or monitor (no tuner) TV is made up of horizontal lines, They are traced a line at a time

• NTSC frame is 525, but only 480 are actually picture.

• With Standard Definition TV (SDTV) and some HDTVs, the image is created by an electronic gun that “paints” every other scan line one line at a time, starting with even lines (a.k.a the lower field…2,4,6,…), top to bottom…gun goes back to the top and “paints’ then the odd lines. This is called interlaced scanning (HD 1080i, SDTV,…)

• Results in two fields…odd/even a.k.a upper/lower per frame

Watch for 1080i TV s, and also 720i..Genrally don’t buy…cheap but quality suffers, especially with motion artifacts.

Progressive Scanning…Go for it

• Entire frame done at once, not odd then even lines…all lines are “painted” one after another.

Used with DVDs, HDTV

File Formats: When video has been captured to a computer: Compression

• AVI (Audio Video Interleaved) most common. It is a “wrapper”, you can put anything inside it. It’s like a box, the box can hold anything. When you capture video from a camera, this is the format

• MPEG-2: (Moving Pictures Experts Group) It supports HDTV and DVD Video We will have to change video format from AVI to MPEG-2...final format for DVDs…called transcoding (switch from one video format to another)

• FLV Flash Video---used on Web…not on IPad , IPhone, Androids

• MOV – Apple Quicktime format

• MP4 - a file format (a container, like zip, avi) that can store anything…like an avi file; images, subtitle etc. Can be streamed, can be played in almost every browser. We will see these later

How Compression works

• Mpeg Video can be compressed spatially and temporally.

• Spatial compression removes small differences in color in areas of the picture that are next to each other within a frame:. Instead of saving 1,000 consecutive pixels that are the same color, save the number 1,000 and then the pixel value…very much the way jpeg compresses

• Temporal Compression takes advantage of the fact that neighboring frames are very similar: is called Temporal redundancy.

• MPEG compression exploits temporal redundancy to reduce video file size by looking for differences from one frame to the next

How does this temporal compression work?

• A video frame image is read in as a reference frame, an “I” or k frame

• Read the next video frame image

• Compare the image content between this current frame (target frame) with the reference frame one block of pixels at a time

• Save only the difference

i.e.

• Exploits the repetitious nature of image content over time in video

• Save more information for selected frames, i.e. less compressed.

Streaming Video versus progressive downloads

Both allow the video to be played as soon as it has sufficient frames. Streaming video requires a streaming server (audio on the web streams) that analyzes the viewer’s connection information and adjusts the speed accordingly.

When the incoming stream sends the stream too slowly, you will see a “buffering…” message. The stream is not saved to your computer.

Progressive download does not require a server. The movie begins playing as soon as soon as there are a sufficient number of frames. The movie may be stored, often in the browser’s cache.

Without knowing who your video will be served to, progressive download will always be a safer option because no matter what connection they have, they will be able to view your video. For live streaming, a streaming server has to be used.

Aspect Ratios

Frame width divided by height. Common ratios:

• 4:3

• 16:9 a.k.a. wide-screen

Let’s use Premiere to see how some of these terms can be applied

Getting Started

• Create folder:

o InClass>Premiere>Project1

We will download the assets into the Project1 folder

Premiere

Premiere is a Non-Linear Editing (NLE) program video editing application

• Can go directly to a particular (SMTPE) location…don’t need to linearly navigate to the spot

• The videos we make are built around a timeline…show this asset ( a picture, a video clip,…) for x seconds, then this clip for y seconds, etc, then add music to play for z seconds while a certain image is showing etc.

Download some assets

• Right-click the Video Assets link (project1.zip) on our Web site, and save, then unzip, the file into your InClass>Premiere>Project1 folder. Contains two music clips, several jpg pictures, and a small avi file.

Premiere Basics

• Start Premiere Pro CS6

• Choose New Project

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A New Project window opens

• For Location, browse to your InClass>Premiere>Project1 folder

• Enter a project Name, such as: CatsMovie

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• Click OK

• Another window opens… a collection of presets, or templates

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• Choose DV-NTSC>Standard 48kHz (see above)

DV is a codec: Compressor/Decompressor,

• Sequence Name: Default is OK It’s the name of our timeline

Notes:

• NTSC…defaults to Standard Definition

• Audio: 48,000 samples/second …= sample rate, and 16 bit sample size

• Frame Rate: 30 fps (29.97)

• Frame Size: 720 x 480

• Note: Firewire – a connection cable for some older camcorders

• Click OK

Today, we mainly save video to SD cards (Secure Data)…of course you then need a SD card reader.

• Choose Editing CS5.5 workspace:

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Will see the default workspace: Looks intimidating, three main windows a.k.a. monitors: Project, Source and Program , plus a small toolbox

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Project Window

Where you store all your imported assets

• Try it: File>Import> pic1.avi ( small 6-second movie clip of one of my cats)

• You will see this in your project panel:, if you choose icon view

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• Click List view to show asset names, not icons

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• Click the pic1.avi movie clip in the Project Window

• Click Info tab:

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• Notice the frame size: 720 x 480

• Frame rate essentially 24 fps (source was a tape-based camera, that defaulted to 24 fps)

• Captured sound was 32 KHz…32,000 samples per second.

• (When we start a new project, choose 48KHz)

Import the remaining assets (including two mp3’s..Cold Play and Cat Scratch Fever.), but not the pproj nor Premiere assets

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Timeline Idea

• Drag the pic1.avi video clip to the timeline, the Video 1 track

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• Choose + and – to zoom

There was also an audio track (See Audio 1?) on the tape, but it was actually silent…I didn’t capture the sound, but space was allocated for it on the tape

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• Here is Coco bed…

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What is the size of the picture?

What is the frame size we are using?

Will become a problem…

• Drag it to the timeline after the pic1 video

• Next, Rocco Tree Calendar

• Drag Cat Scratch Fever (an mp3 file)

to the beginning of audio 2 track…

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• The audio from the pic1.avi movie clip hogs the Audio 1 track

• Also, notice how long the Ted Nugent song plays

Let’s fix those problems:

Goal: Delete the (silent) part of the video clip and trim the end portion of the audio clip using the razor blade and Selection tools

o Select (white arrow) the pic1.avi audio 1 track…notice it also selects the video

o Need to unlink the audio from the video:

▪ Clip>Unlink

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• Now, select and then delete the pic1.avi audio track

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Leaves empty area;

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Now, to trim the Cat Scratch track (delete excess music), find the Razor Tool:

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• Position the razor blade tool where you want the music to end (say 24 second mark) and click

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o Select right portion using selection tool

o Delete the selection

I then moved the Audio 2 track to the Audio 1 track

Volume Indicator:

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• If you don’t see the yellow line, click the Collapse-Expand Track dropdown:

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Playing the current video

• To play: Space bar or Enter key, or press Play in Program window

• Plays in Program window

o Space Bar again to stop

• Also, can use the gold play head above the timeline

• Audio (music) plays after movie clip and the still picture end

• Later will see how to fade

A Bit more about the interface

Note the two main windows…

• Left one for editing video and audio clips ( a.k.a.Source window)

• Right one shows playback movie (a.k.a.Program)

Safe Areas

• Move the playhead so it’s over one of the cat images, select it

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• Right-click the Program window, choose Safe-Margins

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• The safe outer rectangle area (inside the outer rectangle) is where the significant action takes place. This is what will show when we create the actual movie

• The safe title area (inside rectangle) is where you should place text titles

Finally, the jpeg images you added to the timeline are a lot bigger than 720 x 480

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Can see the actual size if you click it in Project window and click Info tab (1280 x 1002 pixels)

• Resize by selecting the clip on the timeline, right clicking, and choosing Scale to Frame Size

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Result:

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File>Save as> Cats Movie2.prproj

Close and Exit

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