Video Storage For Final Cut Pro

Submitted by Andrew Balis on April 7, 2008 - 1:41pm
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Video Bit Rates And Hard Drive Data Rates

All video formats have a specific bit rate, which is also often described as data rate. You can think of the bit rate as the "speed" of that particular format. The bit rate refers to how many bits are transferred or processed in a given period of time.

When working with video stored on hard drives, we can think of the bit rate as the speed with which a given format is read from, or written to a hard drive. Video storage needs to have data rates that exceed the specific rate of the video format in order to be able to reliably handle that format without problems. An example of a specific bit rate would be the DV format, which has a bit rate of 25 Megabits per second.

Megabits And Megabytes

One major area of confusion for users is that these speeds, both for video and storage, tends to be quoted using two different measurement standards.

  • Video formats' bit rates are usually listed in Megabits per second. These rates are often described with the following expressions: Mbps or Megabit/sec or Mbit/sec
  • Hard drives (storage for video) are usually given data rates in Megabytes per second. These rates are often described with the following expressions: MBps or Megabyte/sec or MByte/sec.

Converting Between These Two Different Standards

Here's a simple conversion:

1 Byte = 8 Bits

Therefore, to convert Megabits to Megabytes, use the following:

Divide Megabit/sec by 8 = The result is Megabyte/sec.
Example: DV is 25 Megabit/sec. Divide by 8 = DV is approx. 3 Megabyte/sec

To convert Megabytes to Megabits, use the following:

Multiply Megabyte/sec by 8 = The result is Megabit/sec

Storage Requirements For Specific Formats

If you know the bit rate of the video format, then you can pretty much figure out what kind of data rates you need for storage. Below we'll list some common formats and the data rates needed for them. These rates are just a base comparison for video, and do not include audio or any overhead for RT effects in the calculations. After the video charts, there is a chart for data rates of uncompressed audio.

Standard Definition Video



High Definition Video

Apple's ProRes 422

ProRes 422 is a new scalable codec designed for Final Cut 6 for SD and HD encoding at high quality. Next are some of its variations and bit rates.

Apple ProRes 422 HQ (high quality)

Apple ProRes 422

Audio

The chart below lists the bit rates for the most common audio format that we work with in video editing- uncompressed audio, 48 kHz sample rate, 16-bit. In a Mac, the most common file format is AIFF. In Windows, the most common format would be WAV, although WAV files are completely compatible with Final Cut (and your Mac). Most of the rates below are listed in Kilobytes per second (KByte/sec).

Overview Of Storage Options

As you can see from the previous charts, not all video formats are created equally. So our storage requirements will vary depending on the formats of video you'll be working with. The following is just a basic, broad look at your options. It is highly recommended that you run your own tests with a particular storage medium to be sure it will adequately handle the video format in question.

  • Single FireWire 400 drive: these drives are fine for DV, HDV and possibly DVCPRO HD 720p.
  • Single FireWire 800 drive: these drives are fine for DV, HDV and DVCPRO HD 720p.
  • FireWire 800 RAID: Depending on how many drives are striped together in the RAID, these systems can handle DV, HDV, DVCPRO HD 720 and 1080 formats, upwards to potentially being able to handle uncompressed SD 8-bit video and Apple's ProRes formats for HD. These RAIDs connect to the computer via a single FireWire 800 connection, allowing them to be used on G4, G5 and Mac Pro desktops, Powerbook and MacBook Pro laptops and iMacs.
  • SATA RAID: Similar to the FireWire 800 RAIDs, these systems may be capable of handling the above mentioned formats, 10-bit uncompressed SD, and possibly up to uncompressed HD. For uncompressed SD, you'll likely need at least 4 drives striped together and for uncompressed HD you'll likely need 8 or more drives striped together. These RAIDs connect to the computer via a SATA cable(s) to a SATA PCI card in a desktop Mac. Some smaller SATA RAIDS can even be connected to a MacBook Pro laptop.
  • Fibre Channel RAID: A RAID is connected to a Mac desktop computer via a fibre channel card. These RAIDS are capable of different configurations which can allow high transfer speeds and data backup protection. These RAIDS (depending on the configuration and amount of drives striped together) can handle data rates of 2K, uncompressed HD and all the other formats listed above.

For more information on RAIDs, visit our Knowledge Zone.