Sony HDR-CX7 Camcorder Reviewby David KenderPublished on Sep 10, 2007 10:00 AM
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Compression (7.0)
The Sony HDR-CX7 is among the second generation of Sony camcorders to use the AVCHD compression format. AVCHD is still very new and there are a lot of reasons not to buy into it yet. The biggest reason is lack of support. There are only a handful of editing programs that can edit footage natively (meaning that it does not have to convert it first). Secondly, the codec is so tightly wound that it requires an immense amount of processing power to do anything with the footage, either editing or converting.
Those post-production headaches alone should steer many people clear of AVCHD. But there’s more. Because the codec is new, manufacturers are still early in the stages of figuring out the best way to implement it in camcorders. While the codec is spec’d out for a max 24 Mbps bit rate, most camcorders are only operating at a fraction of that speed. For various reasons, that’s the speed limit right now, but it will eventually get better. The Sony HDR-CX7 records at a maximum 15 Mbps, the same speed as the Sony’s HDR-SR5 and SR7, both AVCHD camcorders recording to hard drive. The HDR-UX series (UX5 and UX7) record to DVD, which records at a slower 12 Mbps. Canon’s HG10 is a hard drive model that records up to 15 Mbps. The Panasonic HDC-SD1 only records at a max 13 Mbps, which may factor into the motion delay we saw in its video.
We should stop and say, however, that bit rate can be a numbers race, just like zoom levels or megapixels or whatever else. A lot goes into compression other than bit rate. As far as we can see, the video from the HDR-CX7 looks pretty good. We can only assume future models will look better as the codec matures.
There are four quality settings in AVCHD: HD XP (15 Mbps), HD HQ (9 Mbps), HD SP (7 Mbps), and HD LP (5 Mbps). The camcorder can also record in standard definition, which is a feature that, while less exciting, certainly increases its flexibility. SD video is captured in good old MPEG2 in three quality settings: SD HQ (9 Mbps), SD SP (6 Mbps), and SD LP (3 Mbps).
Media (7.0)
The Sony HDR-CX7 records video and stills to a tiny MemoryStick Duo or PRO Duo card. Cards capacities range up to 8 GB, though the CX7 will only support cards up to 4 GB (go figure that one). No card ships with the camcorder, which means you’ll have to factor that into the total cost. The online Sony store has been running special bundle packages, so you may be able to snag yourself a deal.
A 4GB card will hold about 30 minutes of video in the highest quality (XP), 55 minutes in HQ, 65 minutes in SP, and 85 minutes in LP. In standard definition, a 4GB card holds 55 minutes in HQ, 80 minutes in SP, and 160 minutes in LP.
Editing (4.0)
Editing AVCHD footage is still painful. The most powerful platform right now is Sony Vegas 8, as more powerful NLEs still lack AVCHD support. HDR-CX7 owners will be pleased to know that Vegas 8 will only work with Sony-brand AVCHD camcorders. Canon and Panasonic owners, you’re out of luck. Corel also has an AVCHD-compatible editing platform, Ulead Video Studio 11, though it’s strictly beginner-level software. Mac users can now use iMovie ’08, though the editing features on that platform have been curtailed compared with ’06. Even software that does work with AVCHD natively tends to be sluggish due to the processor-intensive work of decoding.
In short, editing AVCHD is a time-consuming, frustrating business, and not at all recommended for hobbyist editors.
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