14

More About Long-GOP Video

The term long refers to the fact that P- and B-frames are used between I-frame intervals. At the other end of the spectrum, the opposite of long-GOP MPEG is I-frame-only MPEG, in which only I-frames are used. Formats such as IMX use I-frame-only MPEG, which reduces temporal artifacts and improves editing performance. However, I-frame-only formats have a significantly higher data rate because each frame must store enough data to be completely self-contained. Therefore, although the decoding demands on your computer are decreased, there is a greater demand for scratch disk speed and capacity.

1080-line HDV media uses an open GOP structure, which means that B-frames in the MPEG stream can be reliant on frames in adjacent GOPs. 720-line HDV media uses a closed GOP structure, which means that each GOP is self-contained and does not rely on frames outside the GOP.

For example, suppose you record some typical “talking head” footage, such as an interview in which a seated person moves very little throughout the shot. Most of the person’s body stays still, so most of the visual information is stored in an I-frame; the subsequent P- and B-frames store only the changes from one frame to the next.

Because P- and B-frames depend on other frames to create a meaningful image, your computer spends more processing power decoding HDV frames for display than it does when displaying intraframe-only formats such as DV, uncompressed video, or the Apple Intermediate Codec.

Transcoding HDV to Other Apple Codecs

Instead of working with native MPEG-2 HDV video, you can transcode your HDV video to the Apple Intermediate Codec or Apple ProRes 422 codec during capture. For more information about these codecs, see “About the Apple Intermediate Codec” on page 10 and “About the Apple ProRes 422 Codec” on page 9.

Unlike MPEG-2 HDV, these Apple codecs do not use temporal compression, so every frame can be decoded and displayed immediately, without first decoding other frames.

You can also capture and edit native HDV but render your footage using the Apple ProRes 422 codec. For more information, see “Rendering HDV” on page 27.

Chapter 1 Working with HDV

Page 13 Page 15
Page 14
Image 14
Apple 6 manual More About Long-GOP Video, Transcoding HDV to Other Apple Codecs
Page 13 Page 15

6 specifications

The Apple iPhone 6, released in September 2014, marked a significant evolution in Apple's smartphone lineup. This model introduced a larger screen and a sleeker design, setting the stage for future devices in the iPhone series.

One of the most notable features of the iPhone 6 was its display. With a 4.7-inch Retina HD screen, the iPhone 6 offered a resolution of 1334 x 750 pixels, delivering vibrant colors and sharp images. This screen size was a departure from previous models, appealing to users who favored larger displays for better viewing experiences, whether for gaming, watching videos, or browsing the web.

The design of the iPhone 6 was another highlight. It featured a slim, curved aluminum body that not only made it more aesthetically pleasing but also improved its ergonomics. Weighing just 129 grams, the phone was light yet robust. The placement of volume buttons, the power button, and the headphone jack was thoughtfully designed to enhance usability.

Under the hood, the iPhone 6 was powered by the A8 chip, a 64-bit dual-core processor that offered impressive performance and energy efficiency. Coupled with the M8 motion coprocessor, the device could effectively handle demanding apps and services while optimizing battery life, providing users with a smooth experience throughout the day.

The camera capabilities of the iPhone 6 were also advanced for its time. It featured an 8-megapixel rear camera with optical image stabilization and a f/2.2 aperture, allowing for clearer low-light photography. The front-facing camera was improved as well, offering a 1.2-megapixel resolution and support for 720p HD video, making it great for selfies and video calls.

Connectivity options included LTE support, enabling faster download speeds, and Wi-Fi calling, which allowed users to make calls over Wi-Fi networks, enhancing communication in areas with poor cellular coverage. The iPhone 6 also introduced the Apple Pay feature, allowing users to make secure transactions using their devices.

In terms of software, the iPhone 6 originally came with iOS 8, which boasted new features such as HealthKit and HomeKit, further integrating technology into daily life. Regular software updates ensured that users could enjoy the latest features and security enhancements well into the device's lifecycle.

Overall, the iPhone 6 distinguished itself with a combination of innovative design, powerful performance, and a user-friendly experience, solidifying Apple's position in the smartphone market and paving the way for future iterations in the iPhone lineup.
Top Page Image Contents