Earlier this month at IBC, Avid announced new versions of software that will enable editing HDV in its native format. Although a shipping HDV editing product from Avid was notably absent at NAB2005 while several other edit system manufacturers were loudly touting their native HDV editing capabilities, Avid executives repeatedly told me they were "waiting until we got it right."
Now with the release of software Version 2.2 for Avid Media Composer Adrenaline HD and Version 5.2 for Avid Xpress Pro systems, the edit system responsible for posting more than 90 percent of all edited primetime television programming, has entered the native HDV editing arena. We got one of the first looks at how they are doing it.
Avid demonstrated HDV editing at four booths during NAB2005 and has been giving previews of cutting native HDV at road shows and regional exhibitions all year. But the company wanted to work out all the bugs before releasing its final software to the public.
| Fig. 1 A screen shot from new versions of Avid Media Composer and Xpress Pro for HDV showing multicamera, multiformat editing.|
"While to most customers, HDV is a new format, to Avid editors, it needs to be treated with the real-time flexibility we have always handled other formats," said Tim Wilson, senior product marketing manager for Avid Technology. "One of the foundations of Avid-style editing is the ability to deal with both multiple formats and multiple resolutions in the same sequence, so the ability to handle SD and HD on the same timeline when incorporating HDV is critical."
The new software does not require HDV to be transcoded to the timeline's base resolution or into a proprietary intermediary format for editing. The resulting efficiency is staying native without disrupting the original I-, B-, P-frame MPEG-2 sequence.
"The monkey in the wrench is that HDV uses long-GOP [group of pictures] recording, which is fundamentally different from the notion of cutting on the open frame since its information is derived over a period of time and extracted from frames of lesser size," Wilson said. "So with these two very different approaches to media, it is not shocking that most other NLEs can't deal with both kinds of video at the same time. In addition, our software will be able to natively post both the Sony interlaced version of HDV and the 24p recording that JVC calls ProHD."
HOW IT WORKS
So let's look under the hood. First, transfer the transport stream of the recorded HDV into the Avid Xpress Pro or Media Composer Adrenaline HD system via FireWire, and then do a real-time inverse multiplex to separate out the audio and video. The elementary video stream is laid onto the hard drive and the sound is decompressed from the MPEG-1 (48 kHz, 16-bit) audio recording on the tape.
During editing, the I-B-P sequence of each cut is put onto the timeline and then, as Patrick McLean, senior product manager for Avid Xpress products explained, the magic begins.
"We bring it in under the general moniker of 'open timeline' so we can mix and match resolutions," he said. "The key to this is our new DNxHD mastering quality codec for HD, and it really compliments HDV during the editing process. If we tried rendering effects or adding titles using the HDV codec, the results would not look very good. But DNxHD can run at different data rates from 145 Mbps to 220 Mbps, the same as uncompressed standard-definition video. So by using DNxHD as the codec we can not only add graphics and effects to HDV cleanly, but also distribute mastering quality HD over a network designed for SD."
To ensure a frame-accurate edit from clip one to clip two, while clip one is playing, the new Avid software decodes the I-B-P sequence of clip two in the background. That way, when the cut point is reached, the system has all the information necessary to display clip two starting at the chosen frame, regardless of where that point lands in the I-B-P cadence.
"If you want to cut on a B-frame, for example, we essentially pre-roll clip two, decoding it from the last I-frame to baseband video," McLean said. "Once the editing process has been completed, we rebuild the whole sequence on the timeline in the format the user requests, and this will take some rendering upon output."
Although the new Avid software can combine different resolutions on the same timeline, different frame rates are still a challenge. You cannot put a native 24p clip on a 30i timeline.
Still, McLean assures us the system can edit the JVC 24p format in a 24 fps project, and Avid demonstrated that ability at the JVC booth at NAB2005. It also supports 1080i/60 and 1080i/50, 720p/60, 720p/29.97 (the first-generation of HDV from JVC) and 720p/23.976, the format for the new JVC GY-HD100U ProHD camcorder.
However, there is currently no widely available workflow to distribute HDV. You could record your edited program onto an HDV deck like the JVC BR-HD50U, but the most common approach is to output from a Media Composer Adrenaline HD running Version 2.2 software via HD/SDI to a standard HD format such as Sony HDCAM, or Panasonic D-5 or DVCPRO HD. McLean speculated that a third option on the horizon is the next-generation blue-laser optical media, the HD DVD and Blu-ray discs.
"Neither of those is fully formalized yet, but this should kick in early next year," he said. "HDV authoring on blue-laser discs may offer significant possibilities for distributing HDV-originated material in the not-so-distant future."
Out in Hollywood, David Benjamin is using Version 5.2 in his Avid Xpress Pro system to cut the indie feature "Team Extreme," directed by Jeff Burkett, about radical roller skaters and skateboarders. It's scheduled to be shown on the Fuel cable network and at next year's X-Dance Action Sports Film Festival that runs concurrently with the Sundance Film Festival in Park City, Utah.
Benjamin is cutting HDV on a 3.2 GHz single processor Hewlett-Packard platform, and said his system edits the HD recordings with the same speed he's accustomed to with standard DV.
"Avid has integrated the features very well into the expected Avid editing processes," he said. "We're using the same Sony HVR-Z1U that we shot with to load material into the edit system, and the software's deck control over FireWire has worked flawlessly.
You just have to remember to bypass the Mojo accelerator on the Xpress Pro when capturing, the same as you would have to when loading DVCPRO HD. However, during editing, Mojo downconverts my output to SD on the fly, so my director can simultaneously see the footage on a standard-definition monitor while I view the high-definition sequences on my computer screen."
So the long-awaited native HDV editing from Avid has arrived, and it is already in the hands of working editors. Expect more news on the HDV front between now and NAB2006.