Some of you may have even shot in high definition and then spent quite a bit of time trying to figure out how to get your footage into the editing system without sacrificing quality, through the use of an intermediate codec that necessitates additional encoding generations, such as Apple Intermediate Codec (AIC). Next month, I’ll discuss the quest for native HDV editing, in a format that doesn’t degrade the image before you even start editing. For now, let’s look at three formats that are vying for consumer and low-cost professional attention.
AVCHD: The Christmas 2006 season saw the advent of the AVCHD format. Jointly created by Panasonic and Sony, AVCHD is a new 1080i video format that is approximately 25% better than 1080-line HDV in terms of recording bit rate, at 18 megabits per second (Mbps) versus 1080-line HDV’s 25Mbps. Sony has been especially aggressive with the AVCHD format, rolling out both 60GB hard drive and miniDVD models. The cameras are the typical HandyCam size, and they get a bit hot if they have a hard drive in them (they use the same drive as the iPod Classic).
The video is relatively decent, although I’ve yet to see an AVCHD camera that matches the quality of a tape-based HDV camera. Word on the street is that Panasonic’s forthcoming shouldermounted AG-HMC70 camera, which looks like a throwback to the lower-end S-VHS cameras Panasonic used to make, has improved the quality of AVCHD capture, but I’ve not had a chance to test one yet.
AVCHD’s solid-state and nonlinear recording, whether by drive, disc, or flash memory, is sure to win the hearts of shooters who want instant nonlinear access to content. AVCHD is also now supported in Premiere Pro and Final Cut Pro and Final Cut Express, although the latter two use AIC, which has quality issues, in my opinion, and FCE doesn’t do well with flash memory-based file access. Since AVCHD uses H.264 as its primary video compression, it can also be transferred seamlessly to HD DVD or Blu-ray discs. The H.264 heritage also means that if transcoded down to a bitrate closer to 1Mbps, it can be streamed via Flash or QuickTime.
H.264: Speaking of H.264, there are several cameras out there now that capture full 1080i video on a disc or flash-based memory using an H.264 codec. One of the better ones is Hitachi’s DZ-BD7HA, which has the distinction of being the first camcorder to output video to the mini Blu-ray Disc format. Hitachi’s version is true H.264, which means it is incompatible with AVCHD's modified H.264 specification. The upside is that H.264 can be read natively by QuickTime and by most MPEG-based tools, such as MPEG Streamclip.
SANYO’s Xacti HD1000 camcorder is another example of an H.264 1080i camera. Looking somewhat like an old-school spot meter for still photography, it captures full 1920x1080 (1080i) video using a newer CMOS sensor. Given the capture medium, SD or SD High Capacity (SDHC) chips, the camera is also able to grab 4-megapixel stills at the same time it’s shooting video—a bit of a sleight of hand, as the camera is just tagging the appropriate video frame for later retrieval as a still.
HDV: This format has been around for a few years, and it was the first prosumer format to tout 1080i recording. But unlike AVCHD, which really does capture 1920x1080i, HDV captures 1440x1080i and then extrapolates it to 1920x1080. The big benefit of this tape-based format, though, is the ability to acquire HD video that can be in full-native mode on a variety of NLEs and transcoding tools. Final Cut Pro has a proprietary native HDV solution, while Adobe’s CS3 Premiere Pro and Canopus’ EDIUS both have native HDV capture and editing that conform to the HDV transport stream specs. That means that the HDV files captured in Premiere and EDIUS can be used on any HDV editing system with no modification other than changing the file extension; Final Cut’s can’t.
HDV also works quite nicely with H.264 transcoding tools, as its MPEG-2 transport stream can be quickly manipulated by an H.264 transcoder, such as Handbrake or Sorenson Squeeze, to create low-bit rate versions of the files (called transrating since the bit rate is changed but not the codec/format). Using MPEG Streamclip, a free tool, HDV can be demultiplexed into separate audio and video streams and then used by Adobe’s Flash Encoder 2, FlixPro, and other encoding tools. Canon makes a great little HDV camcorder that’s almost palm-sized, the HV10, and other cameras like Sony’s FX1 are good examples of HDV in use throughout the event videography space.
There you have it, a quick overview of three of the many HD acquisition formats. Next month I’ll spend some time talking about native HDV workflows from two of these companies: Adobe and Apple.
Tim Siglin, co-founder of Transitions, Inc., is a contributing editor to EventDV and Streaming Media. He has 18 years of film and video experience and heads a digital media business consultancy in Kingsport, Tenn.