How to Edit HDV
From capture to final output, the format of the JVC JY-HD10 posessome unique postproduction problems. Here are solutions.
Those shooting with JVC's JY-HD10 are working on the cutting edge oftechnology. With a single-chip HD camcorder, they're capturing materialin HDV, a new format based on MPEG-2. Unfortunately, editing HDV meansworking on the bleeding edge of technology. Today's editing solutionsare inefficient and may be unreliable. That said, editing HDV is by nomeans impossible. What follows is a start-to-finish guide to editingHDV using tools that are currently available.
If you have been creating DVDs, you already have a working knowledgeof MPEG-2. What you may not know is that DVDs use MPEG-2-encoded videothat has been encapsulated into a program stream. A program stream isgenerated from one (or more) audio plus one (or more) video elementarystreams.
An audio elementary stream for a DVD can be 16-bit, 48kHz PCM; AC-3(Dolby Digital); or DTS Surround Sound. A DVD can have one or moretypes of soundtracks. Of course, it can also have multiple audio tracksas on a multilingual DVD. A DVD's video elementary stream is encoded asMPEG-2. If the DVD offers multiple angles, each angle is a uniqueMPEG-2 stream.
A program stream generator takes elementary streams and weaves themtogether in a single stream. Once this stream is assembled, it can beburned to a DVD. To play back a DVD, software or hardware examines thedata stream to find the audio and video streams. A header identifiesevery stream's type.
The JY-HD10 camcorder opens up low-cost HD production like nothingbefore, but the camcorder’s HDV acquisition format presents someunique problems for post-production.
The HDV format has two elementary streams. The total data bandwidthis 19Mbps for 720p and 25Mbps for 1080i. A camcorder's 16-bit, 48kHzaudio is encoded as MPEG-1, Layer 2. The stereo channels have acombined data rate of 384kbps. On disk, this type of stream should havean .mp2 file extension. Video is encoded, of course, using MPEG-2. Morespecifically, for both SD (480p) and HD (720p), JVC's HD10 uses aclosed, IBBP, six-frame GOP. The video data rate is 17.8Mbps usingconstant bit rate (CBR) encoding. On disk, it should have an .m2v fileextension.
These two elementary streams are woven into a single stream. ForHDV, however, the stream is a transport stream — not a programstream. Simply put, a transport stream carries additional informationthat enables its cargo of video and audio data to withstand corruptingtransmission conditions. On disk, this type of stream should have a.m2t file extension, but typically will have an .mpg extension.
The software and hardware that process a program stream cannotprocess a transport stream. This is the crux of the difficulty inplaying, editing, and generating HDV. It's likely that none of theMPEG-2 software on your computer can handle a transport stream. Thus,you'll need additional software to work with HDV.
The JVC camcorders have a FireWire port that can transfer both DV25and MPEG compressed data. To move DV25 via FireWire you need to flipthe camcorder's side-panel switch to DV. To move MPEG via FireWire,flip the side-panel switch to MPEG-2.
On the PC, there are several ways to input and output MPEG-2 datavia FireWire. JVC bundles an i.LINK I/O Utility with thecamcorders. It can be used to move source material to a computer file.(Non-copyright material from any D-VHS deck can also be captured todisk by the utility.) Each shot from the JY-HD10 is moved as a separatefile, which can make the capture process tedious. Moreover, very shortshots may be lost.
Material captured using this utility can be used by MPEG EditStudio Pro 1.2 LE (bundled with JVC's JY-HD10) or Vegas 4.0($489 download) or Vegas+DVD ($699 download) from SonicFoundry. (Sony Pictures Digital now owns Vegas, but find info at www.sonicfoundry.com/products/vegasfamily.asp.)Once edited, an MPEG-2 transport stream file from Edit Studio Pro canbe output via the i.LINK I/O Utility. Thus an MPEG Edit Studio Pro'stimeline can be recorded back to an HDV camcorder or to any D-VHSdeck.
When Aspect HD ($1,200) from CineForm (www.cineform.com) isused with Premiere, it provides a method of capturing to disk via IEEE1394. (It can also capture non-copyrighted material from D-VHS.) Duringor after capture, Aspect HD transcodes MPEG-2 to very lightlycompressed Wavelet video.
Mac users have to expend a bit of effort to obtain a suitableFireWire input/output utility. Apple has released a FireWire SDKfor developers. Thankfully, in the latest releases of the FireWire SDK,Apple has included a utility that allows the transfer of MPEG-2 overFireWire. The application is called DVHScap and can be found inthe Application folder in the SDK package. You will need to search for“FireWire SDK” at the developers' page at the Apple website(www.apple.com).
For the PC, the shareware Moonlight-Elecard MPEG Player 2.1(www.elecard.com)will play back HDV transport stream material. For users of OS X, theshareware VLC Player from Videolan (www.videolan.org)will do the job. Of course, only a very high-performance computer isgoing to be able to play HD-resolution MPEG-2 video smoothly.
To edit HDV material, a transport stream must be“demuxed” into audio and video elementary streams. This canbe accomplished using a separate utility — or the capabilitycould be built into an NLE. NLEs that can accept a transport streaminclude MPEG Edit Studio Pro 1.2 LE and Vegas 4.0. While neitherAdobe Premiere 6.5 nor Premiere Pro can import MPEG-2transport streams, they can import Wavelet-compressed files from AspectHD.
The OS X MoreMissingTools (http://homepage.mac.com/rnc) shareware utility canbe used to demux a transport stream to MP2 audio and MPEG-2 video. Andthe m=Madplaywrap (www.underbit.com/products/mad) shareware utility,also for OS X, can be used to convert MP2 audio to an AIFF file.Unfortunately, there is an obstacle to using MoreMissingTools.
The JVC MPEG-2 video elementary stream file is incompatible withApple's MPEG-2 decoder ($20). Therefore, MPEG-2 .m2v files output byMoreMissingTools cannot be played by Apple's QuickTime Playernor imported into Final Cut Pro.
The HDVbridge plug-in in my 4HDV package (visit mywebsite at www.mindspring.com/~d-v-c) upgrades MoreMissingTools to generate audio and video files compatible with Final Cut Proversions 3 and 4. Additionally, the 4HDV package ($100) includes anHD1/HD10 Shooting Guide (also available separately), an OS XHDV Production Guide, plus the HDVviaduct plug-in to enableffmpegX (homepage.mac.com/major4) to encode HD MPEG-2program streams. (Without HDVviaduct, ffmpegX is limited to SDresolution.)
The 4HDV bundle lets you edit with Final Cut Pro as usual. Playbackfrom both the View and Canvas will be smooth. Moreover, effects will berealtime within the limits determined by FCP and your Mac'sarchitecture. Naturally, FCP version 4 will handle more streams inrealtime than will version 3.
MPEG Edit Studio Pro 1.2 LE, for the PC, supports two A/V tracks.Each track has a video and channel. Imported HDV clips fill bothchannels in a track. Simple transitions (dissolves and wipes) can beplaced between video channels. Video inserts into a channel can also beperformed. Simple titles can be placed in a video channel as well.
Unfortunately, no video or audio filters are available. JVC bundlesan Audio Utility that converts Windows audio formats to MPEG-2audio files so that background music and sound effects can be added tovideos. Imported audio is inserted into an audio channel in a track.There is no utility to enable the import of graphics or NTSC video. A2GHz Pentium 4 (3.06GHz recommended) with at least 256MB of RAM (512MBrecommended) is required to run MPEG Edit Studio Pro 1.2 LE under XP.Edit Studio Pro generates MPEG-2 transport stream files that can beopened by the bundled i.LINK I/O Utility. Edit Studio also generatesMPEG-2 program stream files for use by the bundled ImageMixerDVD. ImageMixer DVD creates anamorphic NTSC productions and burnsthem to DVDs.
The ideal HDV editing solution for PC users is CineForm's Aspect HDwith Premiere 6.5 or Premiere Pro. Aspect HD provides realtime editingon PCs with a 2GHz or faster Pentium 4 with at least 512MB of RAM. Youcan edit multiple HD video streams and add motion titles, coloradjustments, dissolves, wipes, page peels, and picture-in-picture— all without rendering. Final output to both HD and SDresolutions is supported in a large range of formats: MPEG-2-TS,Windows Media 9, HUFF_YUV, uncompressed, DV, MPEG-2-DVD. CineFormclaims a 3.2GHz Hyper-Threaded P4 with dual drives (in a RAIDconfiguration) can playback up to six streams of HD video.
Once a production is complete, you have several options. In manysituations, a computer can be an ideal HD playback system. An SXGA(1280×1024) graphics card with PowerStrip software (www.entechtaiwan.com/ps.htm) can support a1280×720 progressive display. Potential displays include CRTmonitors, plasma panels, and LCD and DLP projectors. Many cards providean all-digital DVI connection as well as an RGB output. With anRGB-to-analog component converter, even a rear-projection HDTV can beused. The Moonlight-Elecard MPEG Player can be used as the MPEG-2player. (The Moonlight player accepts HD program streams, the only kindencoded by Vegas 4.0.)
When Cineform Aspect HD is used with Adobe Premiere, it provides amethod of capturing HDV to disk via IEEE 1394.
Macs with a widescreen display can also be effective HDTVs. The23in. 1920×1200, the 20in. 1680×1050, and the 20in.1280×1024 Cinema Displays are all very effective HD displaydevices. Additionally, a 1440×900-resolution widescreen iMac isperfect for 720p HDV. Of course, Macs can also drive CRT monitors,plasma panels, and projectors — although unless the deviceaccepts a DVI connection, you'll need a DVI-to-RGB converter. Apple'sQuickTime Player — with the Apple MPEG-2 decoder — can playprogram streams.
To record your HD production back to an HDV camcorder or a D-VHSdeck, audio and video must be encapsulated as a transport stream— not a program stream. Audio must be encoded as MPEG-1, Layer 2with a data rate of 384kbps. Video must be encoded as MPEG-2 at a datarate between 15Mbps and 25Mbps. (The specific maximum data rate is afunction of the playback device.) If your NLE has thiscapability, as MPEG Edit Studio Pro 1.2 LE does, the timeline can bedirectly encoded to a transport stream. Likewise, Premiere with AspectHD can generate the necessary transport stream. The MainConcept MPEGEncoder (www.mainactor.com) can be used to generate HDtransport streams from the output of Vegas 4.0.
Apple's Compressor, included with Final Cut Pro 4,unfortunately cannot support an image size of 1280×720.Heuris, however, offers an HD MPEG-2 encoder that plugs intoFCP. The Heuris MPEG Power Professional 2 DTV-HD plug-in($4,785) can generate both program and transport streams. As an FCPplug-in, it enables you to encode directly from the timeline, therebysaving both time and disk space. While the encoder supports recordingto D-VHS, at press time, Heuris had not announced support of recordingto HDV camcorders.
One other option exists for those working with HDV — thecreation of NTSC material for either letterboxed or anamorphic DVDs orNTSC videotape. The conversion to letterbox or anamorphic video can beperformed within most NLEs. MPEG Edit Studio Pro, however, generatesonly anamorphic widescreen encodings to pass to the ImageMixer DVDapplication bundled with the JY-HD10. See my review of JVC's SR-VD400USon page 46 for an alternate way to generate NTSC programs.
As you can see, there are only a few off-the-shelf solutions toediting HDV format material. That's the peril of working on thebleeding edge. The available editing solutions can be inefficient andmay be unreliable. Various solutions may offer different levels ofimage quality. Watch for reviews of HDV editing programs as they cometo market.
While relatively few editing solutions are currently available, morewill appear as the HDV rollout continues. We can expect Adobe, Apple,and Avid to provide HDV editing solutions that work as efficiently astheir current DV products. Also, today's solutions are typically moreexpensive than current DV solutions. We can expect prices to drop asMPEG-2 becomes more common as a format for acquisition and editing.
However, what will change the most over the next few years is ourunderstanding of working in HD using the HDV format. Not only will wegain confidence in working with high-resolution images, we will alsoacquire — often through much struggle — a deeper knowledgeof MPEG-2. Those of us who experienced the confusion engendered by theDV revolution should expect a repeat. Of course, we can also expect toreap the rewards that come from any technology revolution.
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