How to Edit HDV

How to Edit HDV

Byline: Steve Mullen

Those shooting with JVC’s JY-HD10 are working on the cutting edge of technology. With a single-chip HD camcorder, they’re capturing material in HDV, a new format based on MPEG-2. Unfortunately, editing HDV means working on the bleeding edge of technology. Today’s editing solutions are inefficient and may be unreliable. That said, editing HDV is by no means impossible. What follows is a start-to-finish guide to editing HDV using tools that are currently available.

The root of the problem

If you have been creating DVDs, you already have a working knowledge of MPEG-2. What you may not know is that DVDs use MPEG-2-encoded video that has been encapsulated into a program stream. A program stream is generated from one (or more) audio plus one (or more) video elementary streams.

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 more types of soundtracks. Of course, it can also have multiple audio tracks as on a multilingual DVD. A DVD’s video elementary stream is encoded as MPEG-2. If the DVD offers multiple angles, each angle is a unique MPEG-2 stream.

A program stream generator takes elementary streams and weaves them together in a single stream. Once this stream is assembled, it can be burned to a DVD. To play back a DVD, software or hardware examines the data stream to find the audio and video streams. A header identifies every stream’s type.

The HDV format has two elementary streams. The total data bandwidth is 19Mbps for 720p and 25Mbps for 1080i. A camcorder’s 16-bit, 48kHz audio is encoded as MPEG-1, Layer 2. The stereo channels have a combined data rate of 384kbps. On disk, this type of stream should have an .mp2 file extension. Video is encoded, of course, using MPEG-2. More specifically, for both SD (480p) and HD (720p), JVC’s HD10 uses a closed, IBBP, six-frame GOP. The video data rate is 17.8Mbps using constant bit rate (CBR) encoding. On disk, it should have an .m2v file extension.

These two elementary streams are woven into a single stream. For HDV, however, the stream is a transport stream – not a program stream. Simply put, a transport stream carries additional information that enables its cargo of video and audio data to withstand corrupting transmission 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 cannot process a transport stream. This is the crux of the difficulty in playing, editing, and generating HDV. It’s likely that none of the MPEG-2 software on your computer can handle a transport stream. Thus, you’ll need additional software to work with HDV.

Capturing HDV

The JVC camcorders have a FireWire port that can transfer both DV25 and MPEG compressed data. To move DV25 via FireWire you need to flip the 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 data via FireWire. JVC bundles an i.LINK I/O Utility with the camcorders. It can be used to move source material to a computer file. (Non-copyright material from any D-VHS deck can also be captured to disk by the utility.) Each shot from the JY-HD10 is moved as a separate file, which can make the capture process tedious. Moreover, very short shots may be lost.

Material captured using this utility can be used by MPEG Edit Studio Pro 1.2 LE (bundled with JVC’s JY-HD10) or Vegas 4.0 ($489 download) or Vegas+DVD ($699 download) from Sonic Foundry. (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 can be output via the i.LINK I/O Utility. Thus an MPEG Edit Studio Pro’s timeline can be recorded back to an HDV camcorder or to any D-VHS deck.

When Aspect HD ($1,200) from CineForm (www.cineform.com) is used with Premiere, it provides a method of capturing to disk via IEEE 1394. (It can also capture non-copyrighted material from D-VHS.) During or after capture, Aspect HD transcodes MPEG-2 to very lightly compressed Wavelet video.

Mac users have to expend a bit of effort to obtain a suitable FireWire input/output utility. Apple has released a FireWire SDK for developers. Thankfully, in the latest releases of the FireWire SDK, Apple has included a utility that allows the transfer of MPEG-2 over FireWire. The application is called DVHScap and can be found in the 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).

Playing HDV

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, the shareware VLC Player from Videolan (www.videolan.org) will do the job. Of course, only a very high-performance computer is going to be able to play HD-resolution MPEG-2 video smoothly.

Importing HDV into an NLE

To edit HDV material, a transport stream must be “demuxed” into audio and video elementary streams. This can be accomplished using a separate utility – or the capability could be built into an NLE. NLEs that can accept a transport stream include MPEG Edit Studio Pro 1.2 LE and Vegas 4.0. While neither Adobe Premiere 6.5 nor Premiere Pro can import MPEG-2 transport streams, they can import Wavelet-compressed files from Aspect HD.

The OS X MoreMissingTools (http://homepage.mac.com/rnc) shareware utility can be used to demux a transport stream to MP2 audio and MPEG-2 video. And the 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 with Apple’s MPEG-2 decoder ($20). Therefore, MPEG-2 .m2v files output by MoreMissingTools cannot be played by Apple’s QuickTime Player nor imported into Final Cut Pro.

The HDVbridge plug-in in my 4HDV package (visit my website at www.mindspring.com/~d-v-c) upgrades MoreMissing Tools to generate audio and video files compatible with Final Cut Pro versions 3 and 4. Additionally, the 4HDV package ($100) includes an HD1/HD10 Shooting Guide (also available separately), an OS X HDV Production Guide, plus the HDVviaduct plug-in to enable ffmpegX (homepage.mac.com/major4) to encode HD MPEG-2 program streams. (Without HDVviaduct, ffmpegX is limited to SD resolution.)

The 4HDV bundle lets you edit with Final Cut Pro as usual. Playback from both the View and Canvas will be smooth. Moreover, effects will be realtime within the limits determined by FCP and your Mac’s architecture. Naturally, FCP version 4 will handle more streams in realtime than will version 3.

Editing HDV

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 both channels in a track. Simple transitions (dissolves and wipes) can be placed between video channels. Video inserts into a channel can also be performed. Simple titles can be placed in a video channel as well.

Unfortunately, no video or audio filters are available. JVC bundles an Audio Utility that converts Windows audio formats to MPEG-2 audio files so that background music and sound effects can be added to videos. Imported audio is inserted into an audio channel in a track. There is no utility to enable the import of graphics or NTSC video. A 2GHz Pentium 4 (3.06GHz recommended) with at least 256MB of RAM (512MB recommended) is required to run MPEG Edit Studio Pro 1.2 LE under XP. Edit Studio Pro generates MPEG-2 transport stream files that can be opened by the bundled i.LINK I/O Utility. Edit Studio also generates MPEG-2 program stream files for use by the bundled ImageMixer DVD. ImageMixer DVD creates anamorphic NTSC productions and burns them to DVDs.

The ideal HDV editing solution for PC users is CineForm’s Aspect HD with Premiere 6.5 or Premiere Pro. Aspect HD provides realtime editing on PCs with a 2GHz or faster Pentium 4 with at least 512MB of RAM. You can edit multiple HD video streams and add motion titles, color adjustments, dissolves, wipes, page peels, and picture-in-picture – all without rendering. Final output to both HD and SD resolutions is supported in a large range of formats: MPEG-2-TS, Windows Media 9, HUFF_YUV, uncompressed, DV, MPEG-2-DVD. CineForm claims a 3.2GHz Hyper-Threaded P4 with dual drives (in a RAID configuration) can playback up to six streams of HD video.

Presenting HDV

Once a production is complete, you have several options. In many situations, 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 a 1280×720 progressive display. Potential displays include CRT monitors, plasma panels, and LCD and DLP projectors. Many cards provide an all-digital DVI connection as well as an RGB output. With an RGB-to-analog component converter, even a rear-projection HDTV can be used. The Moonlight-Elecard MPEG Player can be used as the MPEG-2 player. (The Moonlight player accepts HD program streams, the only kind encoded by Vegas 4.0.)

Macs with a widescreen display can also be effective HDTVs. The 23in. 1920×1200, the 20in. 1680×1050, and the 20in. 1280×1024 Cinema Displays are all very effective HD display devices. Additionally, a 1440×900-resolution widescreen iMac is perfect for 720p HDV. Of course, Macs can also drive CRT monitors, plasma panels, and projectors – although unless the device accepts a DVI connection, you’ll need a DVI-to-RGB converter. Apple’s QuickTime Player – with the Apple MPEG-2 decoder – can play program streams.

Recording HDV

To record your HD production back to an HDV camcorder or a D-VHS deck, audio and video must be encapsulated as a transport stream – not a program stream. Audio must be encoded as MPEG-1, Layer 2 with a data rate of 384kbps. Video must be encoded as MPEG-2 at a data rate between 15Mbps and 25Mbps. (The specific maximum data rate is a function of the playback device.) If your NLE has this capability, as MPEG Edit Studio Pro 1.2 LE does, the timeline can be directly encoded to a transport stream. Likewise, Premiere with Aspect HD can generate the necessary transport stream. The MainConcept MPEG Encoder (www.mainactor.com) can be used to generate HD transport 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 into FCP. The Heuris MPEG Power Professional 2 DTV-HD plug-in ($4,785) can generate both program and transport streams. As an FCP plug-in, it enables you to encode directly from the timeline, thereby saving both time and disk space. While the encoder supports recording to D-VHS, at press time, Heuris had not announced support of recording to HDV camcorders.

Making NTSC productions

One other option exists for those working with HDV – the creation of NTSC material for either letterboxed or anamorphic DVDs or NTSC videotape. The conversion to letterbox or anamorphic video can be performed within most NLEs. MPEG Edit Studio Pro, however, generates only anamorphic widescreen encodings to pass to the ImageMixer DVD application bundled with the JY-HD10. See my review of JVC’s SR-VD400US on page 46 for an alternate way to generate NTSC programs.

Working with HDV

As you can see, there are only a few off-the-shelf solutions to editing HDV format material. That’s the peril of working on the bleeding edge. The available editing solutions can be inefficient and may be unreliable. Various solutions may offer different levels of image quality. Watch for reviews of HDV editing programs as they come to market.

While relatively few editing solutions are currently available, more will appear as the HDV rollout continues. We can expect Adobe, Apple, and Avid to provide HDV editing solutions that work as efficiently as their current DV products. Also, today’s solutions are typically more expensive than current DV solutions. We can expect prices to drop as MPEG-2 becomes more common as a format for acquisition and editing.

However, what will change the most over the next few years is our understanding of working in HD using the HDV format. Not only will we gain confidence in working with high-resolution images, we will also acquire – often through much struggle – a deeper knowledge of MPEG-2. Those of us who experienced the confusion engendered by the DV revolution should expect a repeat. Of course, we can also expect to reap the rewards that come from any technology revolution.

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