Hitachi Ltd. will release two types of home camcorders that use Blu-ray discs as recording media for the first time in the industry.
One is DZ-BD70, which is equipped with a Blu-ray Disc/DVD device. And the other one, DZ-BD7H, is a hybrid model mounted with a 1.8-inch HDD, in addition to a Blu-ray Disc/DVD device.
"(In the past,) Hitachi brought about a revolution with hybrid-type camcorders of DVD and HDD," said Ikuo Yuki, a general manager of the Digital AV Products Division, Consumer Business Group of Hitachi. "We will raise a revolution with Blu-ray Disc."
The encoding method of high-definition images is MPEG-4 AVC/H.264 High Profile. The camcorders can record about an hour of 1920 × 1080 interlaced images on a 8-cm single-layer Blu-ray Disc medium (about 7.5GB).
DZ-BD7H can record four hours of images with the same quality in the 30GB HDD. It is not compatible with the AVCHD method.
The dimension of DZ-BD70 is 77 mm long, 87 mm wide and 165 mm high. The weight of the main body is 575 g and 650 g when in use. DZ-BD7H is 80 mm long, 87 mm wide and 165 mm high and weighs 630 g and 705 g when in use.
The expected street price is about 160,000 yen (USD 1,343) for DZ-BD70 and 190,000 yen (USD 1,594) for DZ-BD7H. They will be released Aug. 30, 2007.
In time with the release of those camcorders, Hitachi Maxell Ltd. will bring out 8-cm Blu-ray Disc media, BD-R and BD-RE, which are expected to be priced at about 2,500 yen (USD 21) and 3,500 yen (USD 29), respectively.
Optical head and CODEC LSI come with a twist
Hitachi developed four types of essential parts for a Blu-ray Disc camcorder. And the company apparently laid stress on the optical head and CODEC LSI.
The newly-developed optical head has two objective lenses, one for DVD and one for Blu-ray Disc. It is a successor to the two-lens optical head that the company developed for PC devices. The optical head was successfully downsized to be installed in a camcorder because the device to correct aberration of the blue-violet laser could be downsized.
Conventionally, the aberration was corrected by driving a convergent lens by a stepping motor.
"This time, although the details cannot be released, a drive element smaller than a stepping motor moves the lens," according to Hitachi.
A a result, the size of the correction unit became one fifth of the previous units.
The optical head is compatible with double speed Blu-ray Disc writing. The data transmission speed can be as high as 72 Mb per second. Because the speed of images' coded data is 16Mb per second at a maximum, it is possible to reduce power consumption by intermittent operation.
A technology to predict and switch frame/field was adopted to the CODEC LSI to enhance the fineness of the images.
To encode interlaced images in which a frame is displayed in two screens (two fields), conventionally, the prediction process was only conducted between fields. However, in the videos with few movements, this method might cause fuzzy images, which are specific to the interlacing method.
Hitachi managed to alleviate the fuzziness of images by predicting movements between framess in the areas with few movements. Specifically, the LSI first distinguishes between fast-moving blocks and slow-moving blocks by detecting vectors in each macro block comprising 16 pixel × 16 pixel.
In the fast-moving blocks, the encoding process is conducted between fields as is conventionally done. On the other hand, in the slow-moving blocks, the process is conducted between frames.