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Work with non-square pixels (D1, DV) in After Effects (4.0-6.5)

What's covered

Choosing a DV or D1 composition preset

Interpreting the pixel aspect ratio of imported files

Creating graphics for DV or D1 output

Viewing your work

Understanding DV and D1 formats

Editing DV or D1 source footage accurately in Adobe After Effects can be challenging because DV and D1 footage consists of non-square pixels while computer monitors use square pixels to display images; this difference often causes DV and D1 footage to appear stretched on computer monitors. Because of the discrepancy between square and non-square pixels, graphics created with square pixels may not scale correctly in non-square compositions. By using the correct composition preset, preparing graphics with the appropriate frame size, and interpreting the pixel aspect ratio of imported files correctly, you can accurately edit, view, and export non-square pixel source footage. For more information, see "About D1, DV, and various pixel aspect ratio footage," "Setting pixel aspect ratio," and "Using square-pixel footage for output to D1 or DV NTSC" in After Effects Help.

Choosing a DV or D1 composition preset

When you use DV or D1 pixel source footage in After Effects for DV or D1 output, choose a DV or D1 preset in the Composition Settings dialog box. When you choose a preset that has a non-square pixel aspect ratio (for example, NTSC DV, 720x480), After Effects automatically sets the Pixel Aspect Ratio value to D1/DV.

Interpreting the pixel aspect ratio of imported files

You can combine footage that has different pixel aspect ratios with After Effects and generate output that appears correct, as long as After Effects can interpret each imported file's pixel aspect ratio correctly. Some file formats, such as QuickTime movies (.mov) and Video For Windows (.avi), can include information in the file that lets After Effects identify the file's pixel aspect ratio, but most other formats do not save this information. The Photoshop CS (.psd) file format always saves the pixel aspect ratio information to the file, which ensures After Effects interprets the pixel aspect ratio correctly.

Except for Photoshop CS (.psd) files and other file formats that include information on the pixel aspect ratio, After Effects interprets imported files that have a frame size of 720x486 or 720x480 as non-square, whether the files have square or non-square pixels. Therefore, you must reinterpret the pixel aspect ratio for square pixel files of that size if the file format doesn't provide that information.

To check the pixel aspect ratio interpretation for a file:

1. Select the file in the Project window.

2. In the thumbnail view at the top of the Project window, After Effects displays one of the following to the right of the frame size value:

-- Nothing, if the file is interpreted to have square pixels

-- A pixel aspect ratio displays, if the file is interpreted to have non-square pixels.

For example, After Effects displays the following information and the pixel aspect ratio "D1/DV NTSC" appears to the right of the frame size (720x480):

[Filename.mov]

720x480, D1/DV NTSC

D 0:00:05:02, 29.97 fps

Millions of Colors

<Compressor>

48.100KHz / 16 bit / Stereo

To reinterpret the pixel aspect ratio of a still graphic that is 720x486 or 720x480 and contains square pixels:

1. Select the file in the Project window, and then choose File > Interpret Footage > Main.

2. Choose Square Pixels from the Pixel Aspect Ratio pop-up menu, and then click OK.

Note: Although After Effects automatically separates fields for video footage during import to prevent unwanted flickering, you may need to manually separate fields for imported DV or D1 files if you use a codec or format that After Effects doesn't recognize. For instructions, see document 319908 , "Working with Interlaced Video and Fields in After Effects."

Creating graphics for DV or D1 output

Because many graphics applications create files that consist of square pixels, most graphics imported into a D1 or DV project have a square pixel aspect ratio. Photoshop CS supports non-square pixels and has video presets you can choose from when you create a new document. Photoshop CS also lets you preview your work in different pixel aspect ratios. (See "Saving images for use in video" in Photoshop CS Help.)

If you create a square pixel graphic with the same dimensions as the DV or D1 composition, you must crop the sides or stretch the image to make the graphic fit in the D1 or DV frame. Stretching the file may cause the image to appear pixelated. To avoid cropping or stretching square pixel graphics, use an image size that's proportionate to the DV or D1 composition when you create square pixel graphics files (see instructions that follow this paragraph). If the square pixel graphic doesn't need to fit perfectly in the composition's frame, use the file as it is; After Effects interprets it correctly as square.

To create square pixel graphics that are proportionate to a DV or D1 (non-square pixel) composition:

1. In a graphics application, create files using one of the following frame sizes:

-- 720x534, for DV NTSC

-- 720x540, for D1 NTSC

-- 768x576, for DV or D1 PAL

Photoshop CS provides these settings as a file preset you can choose in the New (file) dialog box.

2. Import the graphic into After Effects.

3. Drag the graphic to the composition, and apply the Stretch to Fit command by pressing Ctrl+Alt+F (Windows) or Command+Option+F (Mac OS).

4. (PAL compositions only) With the graphic layer selected, choose Layer > Transform > Scale, and choose Current Aspect Ratio (xy) from the Preserve pop-up menu. (In After Effects 4.x, press Command+Shift+S [Windows] or Control+Shift+S [Mac OS], select Preserve Frame Aspect Ratio in the Scale dialog, and then click OK.)

This table lists the video presets available in Photoshop CS and the associated pixel aspect ratio for each preset.
Photoshop CS preset file sizes for video
Pixel aspect ratio
NTSC DV 720x480 (with guides)
D1/DV NTSC ( .9)
NTSC DV Widescreen, 720x480 (with guides)
D1/DV NTSC Widescreen (1.2)
NTSC D1 720 x 486 (with guides)
D1/DV NTSC (0.9)
NTSC D1 Square Pix, 720 x 540 (with guides)
Square
PAL D1/DV, 720 x 576 (with guides)
D1/DV PAL (1.066)
PAL D1/DV Square Pix, 768 x 576 (with guides)
Square
PAL D1/DV Widescreen, 720 x 576 (with guides)
D1/DV PAL Widescreen (1.42)
HDTV, 1280 x 720 (with guides)
Square
HDTV, 1920 x 1080 (with guides)
Square

Viewing your work

Because computer monitors display square pixels, the horizontal pixel spacing on a monitor is wider than that of DV and D1 formats, and DV or D1 format images appear distorted or horizontally stretched. To display DV or D1 source footage in correct proportion and prevent it from appearing distorted, use one of the following methods when you check your work.

Display projects on a DV video monitor

After Effects 6.x , 5.x, and 4.x include a Video Preview feature that allows you to preview compositions on a DV video monitor or camera using your firewire output or a plug-in from your capture card manufacturer. For more information, see document 326110 , "Previewing Video on Output Devices in After Effects 4.0 and Later."

Use Pixel Aspect Correction

In After Effects 5.x and later, view your work by using theToggle Pixel Aspect Ratio Correction button (6.x) or the Pixel Aspect Correction option (5.x). These features are best for previewing only and may cause performance in After Effects to slow significantly. If you edit layers while this option is on, layer placement isn't precise and image quality can be reduced.

View all pixels for precision editing

Work in a square pixel composition. This technique is primarily used to create motion graphics using square pixel source footage when exact positioning is necessary. When After Effects renders the composition, frames appear stretched on-screen, but the final output is correctly proportioned on a DV video monitor.

To work in a square pixel composition in After Effects:

1. Create a new composition with the following settings:

-- For DV NTSC output:

a. Deselect Lock Aspect Ratio.

b. Type 720 in the Width text box and 534 in the Height text box.

c. Choose Square Pixels from the Pixel Aspect Ratio pop-up menu.

d. Type 29.97 in the Frame Rate text box, and then click OK.

-- For D1 NTSC output, choose NTSC D1 Square Pix, 720x540 from the Preset pop-up menu (After Effects 5.x) or the Frame Size pop-up menu (After Effects 4.x).

-- For DV or D1 PAL output, choose PAL D1/DV Square Pix, 768x576 from the Preset pop-up menu (After Effects 5.x) or the Frame Size pop-up menu (After Effects 4.x).

Note: If you use a field order to render that's different from the field order of your original source footage, your source footage may be blurry in the final output. To prevent blurry output, move the layer that uses video as its source footage up one pixel by clicking the Up arrow once after placing the layer in the composition.

2. Create square source footage, and import it in After Effects. (See "Creating graphics for DV or D1 output" in this document.)

3. Add DV or D1 source footage to the composition, and apply the Stretch To Fit command by pressing Ctrl+Alt+F (Windows) or Command+Option+F (Mac OS).

4. When you're ready to render the composition, create a new composition, and choose one of the following settings from the Preset pop-up menu (After Effects 5.x) or the Frame Size pop-up menu (After Effects 4.x) in the Composition Settings dialog box:

-- For DV NTSC, choose NTSC DV 720x480.

-- For D1 NTSC, choose D1 720x486.

-- For DV and D1 PAL, choose PAL D1/DV, 720x576.

5. Drag the composition you created in step 1 into this final composition.

6. Select the nested composition in either the Composition window or the Timeline, and then apply the Shrink To Fit command by pressing Ctrl+Alt+F (Windows) or Command+Option+F (Mac OS).

7. With the nested composition still selected, click Collapse Transformations in the Switches panel of the Timeline.

8. Add the DV or D1 composition you created in step 4 to the Render Queue, and render it.

Create a viewing composition

Create a second, square-pixel, viewing composition in After Effects. The viewing composition does not, however, show all the pixels in the DV or D1 composition. If you then edit the DV or D1 composition, any changes also affect the square-pixel composition, making rendering slow and more memory-intensive. When you render, be sure that you render the DV or D1 composition, not the viewing composition.

To create a viewing composition:

1. Create a new composition, choose Square Pixel from the Pixel Aspect Ratio pop-up menu, and select one of the following frame sizes:

-- 640x480, for DV NTSC

-- 648x486, for D1 NTSC

-- 768x576, for DV or D1 PAL

2. Drag the DV or D1 composition to the center of the composition you created in step 1. After Effects automatically resizes the DV or D1 composition to fit the viewing composition.

Understanding DV and D1 formats

DV (also called IEEE 1394) is a digital video standard that has a 4:3 frame aspect ratio, a .9:1 pixel aspect ratio, and a screen resolution of either 720x480 (NTSC) or 720x576 (PAL). D1 (also called CCIR-601 or ITU-R 601 ) is another video format with a non-square pixel aspect ratio. D1 has a screen resolution of either 720x486 (NTSC) or 720x576 (PAL), and a .9:1 pixel aspect ratio. Because DV and D1 are international standards, you can use them with video formats for both NTSC (the broadcast standard in the United States and Japan) and PAL (the broadcast standard in Europe).

DV and D1 are composed of rectangular (that is, non-square) pixels, instead of the square pixels for most Mac OS and Windows systems. Some video components that use non-square pixels include most DV capture cards; Media 100 and Avid editing systems; and Digital Disk Recorders (DDR), which store uncompressed D1 frames.


Related Documents

Document 322300
Last edited - 03/13/2005

 

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