Compression technology is a critical element to the file workflow of high-definition video production, and the workflow should be a key factor in deciding which camera you purchase. But each manufacturer uses its own implementation of compression and it is often difficult for layman users to understand what is best for their personal application.

On the professional side, Panasonic promotes AVC-Intra, while Ikegami and Sony employ the MPEG-2 Long GoP format. JVC records directly to an Apple Quicktime format using a 35Mbps MPEG 2 codec. Canon uses a proprietary H.264 codec that is contained in an Apple Quicktime MOV wrapper. The RED One camera uses Redcode RAW, a variable bit rate wavelet codec that allows raw sensor data at resolutions of up to 4096 x 2304.

Fortunately, with the latest versions of the commonly used nonlinear editing systems, most of these formats are natively supported. For most users, it’s simply a matter of plug and play. However, camcorder manufacturers go to great lengths to explain the reasons for their proprietary choices.

For pro applications, Sony and Panasonic—the two main camcorder brands—went in different directions on their choice of codecs. However, video technology moves quickly. Hardware and software is constantly being upgraded to accommodate weaknesses. Last month’s problem has often been solved before you even know it exists.

Sony selected the video compression scheme of MPEG-2 Long GoP—at up to 50 Mbps with full 4:2:2 high definition signals—for what it considers the most mature and balanced video compression scheme available at this time.

Panasonic chose AVC-Intra. Though incompatible with Sony’s format, it is fully compliant with the H.264/MPEG-4 AVC standard and follows the SMPTE RP 2027-2007 recommended practice. AVC-Intra is available in a number of Panasonic’s high-definition P2 card-equipped broadcast cameras.

Both Sony and Panasonic’s compression schemes provide production quality HD video at bit rates more normally associated with electronic news gathering applications, permitting full resolution, 10 bit field capture of high-quality imagery in one piece camera-recorders.

AVC-Intra defines 10-bit intra-frame only compression, which is easy for editing and preserves maximum video quality. Panasonic said it outperforms the older HDV (MPEG-2-based) and DVCPRO HD (DV-based) formats, allowing the codec to maintain better quality at 2x less storage. There are two classes: AVC-Intra 50 at 50 Mbps and AVC-Intra 100 at 100 Mbps.

In a white paper comparing the formats released last December, Sony noted that its MPEG HD files are half the size of comparable AVC-Intra files. It contends that with Apple’s Final Cut Pro (not the latest version released this summer), that AVC-Intra took two times real-time to complete an import while it MPEG HD format was imported 1.5 times faster than real-time.

On average, Sony said, MPEG HD was 36 percent faster than AVC-Intra for file import times on Final Cut Pro. On Avid’s Media Composer, Sony gave MPEG HD a 57 percent import speed advantage.

Sony cited MPEG’s ability to efficiently create high quality clips at a lower bit rate translating into smaller file sizes. AVC-Intra, it said, only makes the file size larger and the file import/export speed slower while penalizing the system with double the data rate. This, Sony claimed, requires more processing in Panasonic cameras and makes the editing more difficult.

Panasonic counter argues that AVC-Intra allows higher quality video using lower bit rates. AVC-Intra 50 is the same quality as DVCPRO HD at half the bit rate (50 Megabits) or substantially higher quality with the full AVC-Intra 100 Megabits (close to HDD5 master quality), Panasonic noted.

Another major advantage of AVC-Intra is 10-bit compression at 4:2:2 recorded with no subsampling. If the production is working with a green screen or in grading suites, a much enhanced picture quality is achieved even after several digital processes.

Panasonic also cited the advantage of working in AVC-Intra when it comes to re-purposing content. The H.264 basis of the codec means it translates very easily into other mediums such as IPTV, video gaming and the web, which also uses H.264 compression codecs.

RED’s Redcode RAW comes with two variants, one with a maximum data rate of 28 MB/s (224 megabits) and one with a maximum data rate of 36 MB/s (288 megabits). Compared with the uncompressed data captured by the camera’s sensor, these bit rates represent compression ratios of about 12:1 and 9:1, respectively.

Because Redcode RAW is a wavelet codec, similar to CineForm RAW and JPEG2000, the blocking artifacts associated with other digital video compression algorithms are absent. Redcode RAW is a mathematically lossy codec, meaning that decompression does not fully restore the original image data captured by the camera.

RED, however, claims the codec is “visually lossless,” meaning that the information loss is not visible to the naked eye when images are viewed. Recording raw data allows white balance, gamma and other image processing parameters like sharpening to be set during postproduction.

Adjusting these settings directly on camera does not impact the raw data that is actually recorded. Such adjustments only influence live monitoring outputs, but are attached to the recorded data as metadata.

Editing the very high-resolution 4K files directly is too hardware demanding for most current computers. However, Redcode RAW files contain several lower resolution versions of the video. That means a 4K file can easily supply 2K, 1K, or even 0.5K footage directly, without decoding the full 4K resolution data followed by scaling.

In Final Cut Pro, the user may import QuickTime reference files that have pointers to the parts of the 4K file that contain the lower resolution version. This way work is done with speedy low-resolution video without need for a separate low-resolution copy.

This summer, Apple upgraded its Final Pro Studio, giving it wider file support for camcorders from Sony, Panasonic, JVC and Canon. Now there is native support for AVC-Intra, Sony XDCAM EX, DVCPRO HD from P2 cards, AVCHD and RED’s Redcode RAW. Sony’s free XDCAM Transfer software can be used to ingest XDCAM, 18-, 25-, and 35-Mbps XDCAM HD, and XDCAM HD 422 media into the Final Cut Pro applications.

Avid’s Media Composer also provides full native support including metadata integration and card/disc support for Panasonic’s P2, Sony’s XDCAM-HD/EX formats and RED’s Redcode RAW.

While the manufacturers choose their codecs for a variety of reasons, the good news for the end user is the differences are quickly vanishing. Most codecs are now invisible in daily use, though it’s still important to understand why the manufacturer chose a certain codec before you buy.