Apple Intermediate Codec
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The Apple Intermediate Codec abbreviated AIC (by users, Apple Engineers don't use the abbreviation) is a video codec designed by Apple Inc. to be an intermediate format in an HDV workflow. It features high performance and quality, being less processor intensive to work with than other editing formats. Unlike native MPEG-2 based HDV - and similar to the standard-definition DV codec - the Apple Intermediate Codec does not use temporal compression, enabling every frame to be decoded immediately without decoding other frames.[1] As a result of this, the Apple Intermediate Codec takes three to four times more space than HDV.
The Apple Intermediate Codec is available only on the Mac OS X platform and cannot be read on other platforms to date such as Windows or Linux. All Mac OS X software which makes use of the QuickTime codec libraries - primarily Final Cut Studio, Final Cut Express, and iMovie, but also freeware such as MPEG Streamclip - can use the Apple Intermediate codec.
The Apple Intermediate Codec was used because it was less processor intensive; as the compression scheme did not need the next frame to be displayed. It's still used in the iLife package, specificly iMovie, but it is rarely used in Final Cut Pro as of Version 6 since it now uses the ProRes codecs instead of the Apple Intermediate Codec, though some versions of Final Cut Pro (HD 4.5 through 5) and Final Cut Express use them regularly.
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[edit] About HDV
HDV (High Definiton Video) is a video format that allows you to record HD video in standard DV tape. Its compression scheme is called long-GOP MPEG2.
It uses MPEG2 compression to achieve a maximum data rate of 25mps, which is the same as normal DV video. This standard yields extremely High Def images in shorter space.
[edit] About the Apple Intermediate Codec
The Apple Intermediate Codec is an extremely precise high quality codec that was developed by apple as opposed to native MPEG2 HDV editing. Instead of directly using the HDV footage, video is captured and then transcoed to the Apple Intermediate Codec to optimize video for playback in real time.
Working with the Apple Intermediate Codec is less processor-intensive than working with native HDV. Unlike MPEG-2 HDV, the Apple Intermediate Codec does not use temporal compression, so every frame can be decoded and displayed immediately without first decoding other frames. The drawback of this codec is that it requires three to four times as much bandwidth and hard drive storage space as MPEG-2 HDV.
[edit] Color Recording Method
Both MPEG-2 HDV and Apple Intermediate Codec HDV record a 4:2:0 component (Y´CBCR) digital video signal. Each sample (pixel) has a resolution of 8 bit. This is not much of a concern for editors as HDV and AVCHD records in a 4:2:0 color space anyway. In fact you may actually lose data if you decide to use 4:2:2 codecs.
[edit] AVCHD Factor
AVCHD uses h.264 for video compression and AAC for audio. This is even more processor intensive than HDV. So you also need to convert to the Apple Intermediate Codec if you plan to edit in Final Cut Pro.
[edit] Format Details
| MPEG-2 HDV 720p30 | 2.5 MB/sec. (equivalent to 9 GB/hr.) |
|---|---|
| MPEG-2 HDV 1080i60/50 | 3.3 MB/sec. (equivalent to 12 GB/hr.) |
| Apple Intermediate Codec HDV 720p30 | approximately 7 MB/sec. (equivalent to approximately 25 GB/hr.) |
| Apple Intermediate Codec HDV 1080i50 | approximately 12 MB/sec. (equivalent to approximately 42 GB/hr.) |
| Apple Intermediate Codec HDV 1080i60 | approximately 14 MB/sec. (equivalent to approximately 49 GB/hr.) |
[edit] References
[edit] External links
- About HDV and the Apple Intermediate Codec
- Final Cut Pro 7 Professional Formats and Workflows: About the Apple Intermediate Codec
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