JVC's camcorders offer the ability to switch between two file structures.
The ability of video camcorders to switch between different formats became common with the release of DVC-based units that could switch from DV to either DVCAM (Sony) or DVCPRO (Panasonic). More recently, camcorders have evolved to support multiple codecs, e.g., DVC-based formats (DVCPRO, DVCPRO50 and DVCPROHD) and an H.264/AVC-based codec AVC-Intra.
Along the way, camcorders also acquired the ability to shoot at multiple frame sizes and frame rates. This flexibility, although obviously offering great value, has a downside. Producers, seemingly unaware of the many shooting options provided by today's camcorders, often fail to define the recording parameters required for the post-production workflow they plan to employ. Thus, post houses now routinely receive media shot with incorrect parameters. Moreover, different shooters, working on the same project, often set up their cameras differently. The greater the flexibility engineered into a camcorder, the greater the risk of these errors.
The next step in flexibility
At NAB2009, JVC introduced two additions to its ProHD series — the GY-HM100 and GY-HM700. With these camcorders, JVC has taken advantage of the general industry move to file-based recording by adding a recording option — the ability to switch between two file structures.
The company has licensed from Sony the right to encode, using a JVC-developed MPEG-2 encoder, a bit stream compatible with XDCAM EX. Additionally, it has licensed both an XDCAM EX-compatible MPEG-4 (MP4) file structure, as well as the QuickTime (MOV) file structure. Therefore, both camcorders are able to record the multiple shooting options displayed in Table 1 to either MOV or MP4 files. (The 19Mb/s data rate is a JVC HD1 HDV-compatible format, while the 25Mb/s data rate is a Sony HD2-compatible format.)
Both camcorders write data to SDHC media. Data can be accessed from SDHC via a USB 2.0 connection when the cards are in the camcorder, or it can be read from cards inserted into a reader.
The GY-HM700 supports an additional media type when an optional JVC KA-MR100G memory recorder is installed. The KA-MR100G provides a slot for an S×S (Sony/SanDisk) card. Recordings, which can be made only at 35Mb/s and 25Mb/s, are treated in post as Sony XDCAM EX.
The camcorders' ability to write MOV files initially led to the impression that this file type was only for use with Final Cut Pro. And, conversely, MP4 files were to be written only when a Windows-based NLE was to be used. Working with the HM100, I learned this was incorrect.
Editing MOV files
As expected, MOV files can be natively edited by Final Cut Pro (v6.0.4 or later) without any need to transcode to another format. Although MOV files can be edited directly from SDHC media, in most cases, media files will be dragged to a hard disk prior to editing. When FCP is installed, its MPEG-2 codec supports the reading of MOV files by other OS X applications, including Cinema Tools, Final Cut Express and iMovie 09 — plus the import, with transcoding to DN×HD, by Avid's Media Composer.
Macs, without FCP installed, require the addition of an XDCAM EX decoder, either the free Perian XDCAM component or XD Decode from Calibrated Software. Once installed, MOV files can be read by Adobe applications. The XP and Vista version of XD Decode enable MOV files to be used by Windows applications, including the QuickTime player and Vegas Pro 8 and 9.
Editing MP4 files
Avid Media Composer V3.5 and V4.0, using Avid Media Access (AMA), can natively edit MP4 files. Native editing of MP4 files is also possible with Premiere Pro CS4, Grass Valley EDIUS 5.0 and Vegas Pro 9.
For OS X users who need to edit MP4 files, Calibrated Software markets its MP4-EX Import component, which enables MP4 files to be read by FCP. The component rewraps MP4 so it can be decoded by the FCP MPEG-2 codec. (Without this FCP codec installed, Calibrated Software's XD Decode component must be purchased.)
The free Sony XDCAM EX browser, available for OS X and Windows, can transcode XDCAM EX to DV, as well as rewrap MP4 files to MXF clips that can be imported by versions of Media Composer without AMA. With the appropriate encoders purchased from Main Concept, the Sony browser can also transcode XDCAM EX clips to H.264/AVC (PSP and iPod), Windows Media, XDCAM HD and XDCAM HD422.
The vast number of shooting and recording options provided by the GY-HM100 and GY-HM700 make it absolutely necessary that producers develop and document a precise workflow for camera operators. This requirement will become more critical as camcorders increasingly offer multiple shooting and recording options.
Steve Mullen is owner of Digital Video Consulting.
|Frame ||Frame size |
|1280 × 720 ||1440 × 1080 ||1920 × 1080 |
|23.98p ||35Mb/s || ||35Mb/s |
|19Mb/s || || |
|25p/29.97p ||35Mb/s || ||35Mb/s |
|19Mb/s || || |
|50/59.94p ||35Mb/s || || |
|19Mb/s || || |
|50i/59.94i || ||35Mb/s only as MOV ||35Mb/s |
| ||25Mb/s || |