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PC VIDEO ARTICLES

HD on the Desktop: HDV and AVCHD (1/08)
Consumer Software for HD Playback & Editing

by Douglas Dixon

HD Video Formats
Dealing with HDV
Dealing with AVCHD
Playing HD Video
Editing HD Video
New Software for New Formats

High-definition video is here -- not just for broadcast television and professional videographers, but now in under-$1000 consumer camcorders, and supported by sub-$100 consumer video software that can run on your desktop.

However, while today's computers have grown to be able to handle the demands of standard-definition video, the advent of HD, like the beginnings of DV, places heavy demands on a standard computer. First, HD video is big -- some four times bigger than standard definition -- so it takes more storage and bandwidth just to move clips around. And HD uses new formats like HDV and AVCHD, which require more processing power to display (much less edit) the frames.

As a result, we're back to the beginnings in some ways -- consumer software applications are past ten generations in their development, but again have to play catch-up with the new formats, new demands, and new hardware developments like multi-core processors.

As a result, some applications, like CyberLink PowerDVD, are very sensitive to your system configuration, refusing to even to try to play back HD clips if they cannot validate your system and video hardware. Others, like Pinnacle Studio, are willing to try anyway, even on an older or lower-power system. After warning that performance might suffer, it still tries to play and even edit HD clips, albeit with some stuttering when the system runs out of horsepower.

So let's look at the two new HD formats for playback and editing -- HDV and AVCHD -- and see some of the issues in working with them on the newest generation of consumer video software.

HD Video Formats

The big question with bringing high-def video to consumer computers and camcorders is how to store the HD frames -- what compression format to use, and how aggressively to compress so that it is feasible to store and process all that data with desktop and handheld equipment. We can't just use the same old processing for this much higher resolution -- this is a major step up in resolution -- from MPEG-2 on DVD and DV on tape at 720 x 480, to HD at what's called 720p (1280 x 720) and full 1080i (1920 x 1080).

Instead, we need new compression approaches to still be able to fit a reasonable amount of HD video on a consumer devices and storage media -- tape cassettes, DVD discs and mini-DVDs on camcorders, small hard disks on camcorders, or even multi-gigabyte solid-state memory cards. The developers of the new high-def disc formats, Blu-ray Disc and HD DVD, were faced with a similar problem -- even with higher-capacity optical discs (15 to 50 GB double-sided) they needed to fit several hours of a high-def movie, plus sound tracks, plus special features.

The result of these needs was convergence on several options for storing high-def video: HD MPEG-2, WMV HD, and MPEG-4 AVC / H.264.

- The most direct option is to scale up MPEG-2 to high-def, since it's well supported from desktop DVD to digital television broadcast equipment. However, this requires significantly more storage with the increased resolution, and newer compression approaches like WMV and H.264 promise the same quality for roughly have the size.

- Microsoft Windows Media Video (WMV) is designed to scale from tiny handheld screens, to Internet streaming, to full-screen TV, to widescreen HD, and so is an especially good option for delivering HD for desktop playback.

- The enhanced MPEG-4, called both AVC (Advanced Video Codec) and H.264, is similarly improved and scalable, and is often used for mobile phones and handheld video devices like the Apple iPod.

All three of these HD video formats were adopted as options for both of the competing high-def disc formats. And they were also used as the basis of new industry formats for HD video in consumer products, using specific variants of MPEG-2 HD (called HDV) and MPEG-4 H.264 (AVCHD) adapted for use in consumer devices, especially small handheld camcorders.

Dealing with HDV

The HDV format was developed by Canon, Sharp, Sony, and JVC in 2003 to fit HD video into the capacity of standard DV media (DV or Mini DV cassette tape), allowing DV-like camcorders to shoot in high-def, and then deliver it to a computer with the same workflow as DV, over USB or FireWire / IEEE 1394 interfaces (www.hdv-info.org).

This required several adaptations to squeeze the HD video to fit into the same tape that is used to store an hour of standard-def DV video. To start, DV is a relatively lightly compressed format, in which each frame is compressed independently, which makes it very convenient for editing. MPEG-2 compresses harder using inter-frame compression, in which frames are compressed in relation to each other, storing only the differences between adjacent frames. This provides better compression (i.e., from DV on tape at 25 Mbps data rate to MPEG-2 on DVD at 9 to 6 Mbps), but is more difficult to edit since each frame can only be decompressed and processed in relation to the group of frames adjacent to it.

The next step for HDV is to compress more aggressively, using a longer group of pictures (GOP) of adjacent frames --- which means even more work when editing. And the final trick with HDV for the higher HD resolution is to not store the full 1080i resolution (1920 x 1080), but instead give up some horizontal resolution and use 1440 x 1080.

The HDV video format, then, supports MPEG-2 compressed video, at two widescreen 16:9 resolutions:

- 720p (1280 x 720, progressive), at 19 Mbps (less than DV!)
- 1080i (1440 x 1080, interlaced), at 25 Mbps (same as DV)

at both NTSC and PAL television rates (30 and 25 frames per second):

- 720p at 60p, 30p, 50p, 25p
- 1080i at 60i, 50i

For audio, HDV supports MPEG-1 Audio Layer II compression at 48 kHz sample rate, with 16-bit samples, stereo (2-channel) at 384 kbps data rate.

The result is a nice compromise, fitting HD video into the existing DV workflow -- with the same tape capacity, and the same data rates -- although requiring significantly more processing, not only for decompressing the larger frames, but for dealing with the larger groups of adjacent frames that need to be processed together.

Another issue for playback and editing on computers is that the HDV file format is optimized for capture on consumer devices, and uses the MPEG-2-TS (Transport Stream) format designed for transmission, and not for data file storage and processing. Unfortunately, not all video software can deal directly with this format, since they expect the common MPEG computer file formats: program streams (typically .MPG, with mixed video and audio) and elementary streams (typically .M2V, with just the video data, plus separate audio .WAV files). Instead, there's now video in transport stream files with names like .M2T, .MTS, and even .M2TS.

A further confusion is that consumer HD camcorders are no longer just tape-based -- the data may be stored on mini-DVD or hard disk or memory cards. As a result, video editing software that was designed to "capture" video (importing it over USB or FireWire from a video camera), now also needs to be able to handle opening the files directly, i.e., after they have been copied directly to hard disk.

Dealing with AVCHD

As HDV was originally designed to fit high-def video on DV tapes, AVCHD was designed by Sony and Panasonic to fit HD on mini (8cm) DVD media (www.avchd-info.org).

Since the format was developed later,in 2006, instead of using MPEG-2 compression, AVCHD uses MPEG-4 H.264, also called AVC. As a newer and more advanced format, AVC can provide similar video quality for less storage and bandwidth.

Like HDV, AVCHD supports multiple video resolutions:

- HD at 1920/1440 x 1080 and 1280 x 720 -- 16:9
- SD at 720 x 480/576 (NTSC/PAL) -- 4:3 or 16:9

And it supports multiple frame rates, for NTSC, PAL, and film:

- 1080/60i, 50i, 24p
- 720/60p, 50p, 24p

For audio, AVCHD supports two formats, including multi-channel surround sound:

- Dolby Digital (AC-3), 64 - 640 kbps, 1-5.1 channels
- Linear PCM, 1.5 Mbps (2 channels), 1-7.1 channels

Since AVC is one of the formats used for Blu-ray high-def discs, AVCHD could be designed so that discs recorded on a consumer DVD camcorder could be played directly on a Blue-ray set-top player. The result, however is a messy folder structure similar to what you also find on today's digital still cameras that shoot both still photos and video clips.

For example, the Panasonic HDC-SD1 and -SD5 tapeless AVCHD camcorders with Leica lenses and 3 CCD sensors record HD video direct to SD / SDHC memory cards (www.panasonic.com). Since there's not tape or disc drive mechanism, they can be designed to about the size and shape of a soda can: a big lens plus some associated electronics.

The older SD1 records at 1440 x 1080 video with Dolby AC3 5.1 sound, and the new SD5 records at full HD 1920 x 1080 with stereo audio -- at a size of only 2.6 x 2.6 x 5.3 inches and 3/4 pounds.

Find the Panasonic HDC-DX1 DVD camcorder

and Panasonic HDC-SD1 memory card camcorder on Amazon.com

The Panasonic AVCHD camcorders use the following file structure:

DCIM\                             Photos
    100CDPFP\
    IMGAnnnn.JPG         JPEG photos, i.e. 1920 x 1080
MISC\
    AUTPRINT.MRK
PRIVATE\
    AVCHD\                     Video
        AVCHDTN\
            THUMB.TID
            THUMB.TDT
        BDMV\                     Video clips
            INDEX.BDM
            MOVIEOBJ.BDM
            CLIPINF\
                nnnnn.CPI
            PLAYLIST\
                nnnnn.MPL
            STREAM\
                nnnnn.MTS     Video clips (MPEG Transport Stream), 1440/1920 x 1080

In this disc-based format, each video segment that you shoot is stored as a separate .MTS file, numbered consecutively in the same way a digital camera stores each photo. The camera than can easily display a thumbnail index of all the clips for you to review and play back.

However, since the AVCHD format is newer than HDV, the latest versions of consumer video player and video editing software are just starting to support it. Some can import the individual video files, and some can import the entire disc folder structure (i.e., under the AVCHD directory) like a DVD, allowing you to quickly choose the clips that you ant to use in your project.

Unfortunately, there are two "flavors" of AVCHD, from Panasonic and Sony, so, for example, Sony Vegas Movie Studio only supported the Sony version. This is representative of a more general problem with all these video formats -- there is so much variety possible even within one specific format that it's not uncommon to find cases of apparently similar files where one will play fine while the other has problems. Expect to always need to check and test new files from different camcorders or different software tools to make sure they work as needed.

Playing HD Video

The first step with HD video is just to play it back and view it on a computer. Both the consumer DVD player applications for Windows -- CyberLink PowerDVD and InterVideo WinDVD -- can play a wide variety of video and audio formats, including versions of MPEG-2 and MPEG-4, and Windows Media Video, including WMV HD. But not all of today's software can handle the MPEG formats embedded in a transport stream file, or some of the HD variants.

Some of these applications recognize the .M2T / .MTS MPEG transport stream file types by default, or can open them if you explicitly import them. As a work-around, some can import the files if they are renamed to .MPG.

Most of today's software can handle HDV, since it's been out for a while, and the latest versions have been adding support for AVCHD, also as an outgrowth of their expansion to cover MPEG-4 formats and high-definition discs.

Today's software also is optimized for playback on multi-core CPUs, so on my quad-core 2.66 GHZ MHz test system, I saw playback using around 25% of the CPU, and spread across all four core processors.

Since the Microsoft Windows Media Player is built on top of the Windows media architecture, it can take advantage of new codec components (encode/decode modules) that are installed with new player and editing software, and also play these new formats (www.microsoft.com/windows/windowsmedia).

Meanwhile, Apple's QuickTime Player has been leading in the playback of the new MPEG-4 formats, especially for clips from mobile phones and portable devices (free, www.apple.com/quicktime). However, in my testing with Windows version 7.2 it did not play sample HDV and AVCHD transport stream files.

CyberLink PowerDVD Ultra (version 7.2) did a great job of playing my sample HDV and AVCHD files ($99, www.gocyberlink.com). It provided full controls during playback -- with responsive single step forward and back, dragging the slider to scan forward and reverse, or clicking to jump to a new point.

PowerDVD did not recognize M2V AVCHD files, but would open them when they were renamed to MPG. It also could open the AVCHD folders as a disc, playing though the numbered collection of .MTS clip files like a DVD (or actually Blu-ray) disc, with each clip as a new title.

InterVideo (now Corel) WinDVD 8 could play HDV .H2T files after renaming them to .MPG, but was slow in jumping within the file ($59, www.intervideo.com). It also could play individual AVCHD files, but not open the full folder structure. Unfortunately, WinDVD did not display the slider control to seek back and forward in the file, so you could play and pause, but not single step or skip around.

Editing HD Video

Similarly, the latest versions of consumer editing applications typically support working with HDV, and are starting to support AVCHD. Most can import directly from popular camcorders, and some can open files that have been copied to a hard disk.

Apple iMovie '08 supports standard and high definition video, including DV, HDV, MPEG-2, MPEG-4, and now AVCHD ($79, www.apple.com/imovie). However, Apple currently lists only a few AVCHD camcorders as tested and supported: the Sony HDR-SR1 and SR7 (hard disk) and Panasonic HDC-SD1 (memory). AVCHD DVD camcorders are not supported. AVCHD support also requires an Intel-based Mac.

(iMovie '08 Camcorder Support - http://docs.info.apple.com/article.html?artnum=306171)

Pinnacle Studio 11 Plus version provides an end-to-end HD video editing workflow, including native HDV and AVCHD editing ($99, www.pinnaclesys.com). It is designed to import from HDV camcorders, but could not process the .M2T files directly. It did the best job of working with AVCHD videos on my system -- opening, playing, editing, and exporting with good response.

Studio could browse quickly though the AVCHD folder structure, view thumbnails of the clip files, and then click to preview the clips. The interface was very responsive, dragging the slider to scan though the clip, playing fast forward and reverse modes at 2, 4, and 10X speeds, and even resizing the application window while playing video. It also has a handy full-screen playback mode.

Ulead (now Corel) VideoStudio 11 Plus version supports HD formats including AVCHD and MPEG-2 HD ($129 www.ulead.com/vs). It opened and edited HDV video clips, including .M2T, with a nice Info window to show clip properties. While it did not open individual AVCHD files, it could import clips from a folder, displaying an Import DVD dialog listing the clips, and to preview and select the ones to import into your project.

However, VideoStudio was sluggish when dealing with AVCHD files -- taking seconds to switch between the editing steps, or to display a new frame when you drag the slider to a new position (it could not scan though the video).

Sony Vegas Movie Studio+DVD 8 Platinum Edition supports HD video, including HDV capture and editing ($119, www.sonycreativesoftware.com). It also supports AVCHD import and edit, but only from Sony camcorders, so it refused to import my Panasonic files. Sony says support for Panasonic AVCHD is in the works.

CyberLink PowerDirector 6 supports high-definition video editing, with the HDV format for capture, editing, and export back to tape if desired ($89, www.gocyberlink.com). AVCHD support should be coming in the next release.

Nero Vision 4 supports HDV and AVCHD editing (part of the Nero 7 Ultra Edition Enhanced suite, $79, www.nero.com/nero7). It processed HDV files after renaming to .MPG, and played and scanned though AVCHD files.

New Software for New Formats

The bottom line is that you can use $100 consumer software to work with HD formats -- but make sure you have the new versions, and check for the latest updates. The developers are still working to catch up to the new formats (like AVCHD), and to new ways of accessing formats (as with HDV in .M2T files).

I've explained how these applications worked for me when I tested the versions available at the time. However, the software that works best for you will depend on your specific HD camcorders, and sources for HD video files. So check the websites for new releases and updates, and for trial versions that you can download to experiment with how they work with your clips and perform on your system.