A lot more information has come to light regarding how video works on the iPhone 3GS so I thought I would spend a little time summarizing things.
I. In-camera editing is destructive
This unfortunate “feature” looks as though it will be remedied with the OS 3.1 update, which has been reported to have the option of saving a copy before trimming.
II. The iPhone recompresses videos uploaded to YouTube or for email
Full quality iPhone 3GS video is 640 x 480 encoded with H.264 video and AAC audio; according to Robert Mohns, the data rate averages 3700 kbit/sec (this varies with program content). By my math that averages to 27 MB per minute. CamcorderInfo estimates an average of 25 MB/minute.
When emailing, the video is scaled down to 480 x 360 and recompressed at 800 kbit/s, resulting in a file size that is around 5-6 MB/minute.
III. Battery life
From CamcorderInfo.com:
We ran the battery test on the iPhone 3G S with the phone in Airplane mode, which disengages all wireless and cell-phone network connection activity. In this mode, the phone recorded video for 2 hours, 33 minutes, and 9 seconds before the battery died. This is a very good battery life and it is better than most ultra-compact camcorders are capable of. In our test, we also noticed the phone stopped recording video after roughly 1 hour and 15 minutes of straight recording. This must be due to the phone having a maximum clip length restriction of some sort.
This gives people some good tips on increasing battery life if you’re trying to record an event with a less than ideal battery situation, but what I find confusing is the file size limit, which appears to be around the 2 GB mark. Earlier in the review, however, CamcorderInfo says the clip limit is 10 minutes, however, this is disputed in one of the comments, so I don’t think it is accurate. Again, I suspect that the file size limit is 2 GB.
IV. The 3GS camera chip is capable of 720P HD
The RapidRepair teardown reported that the camera chipset (SoC S5PC100 from Samsung and thus confirm an ARM Cortex A8 running at 600 MHz (operates at up to 833MHz though)). Still resolution is 2048 x 1536 (3 megapixel). This HD feature is not enabled – it is uncelar whether from battery drain concerns, inconsistent framerate, or increased storage demands. It will be interesting to see if any 3rd party apps are able to take advantage of this possible feature, although I’m not holding my breath for Apple to make hacking into the camera very easy.
V. The lens:
The lens is the 35mm equivalent of a 37 mm lens, giving a 49 degree view angle, compared to the Flip Ultra HD’s 42 degree angle. Aperture is f2.8
VI. Autofocus
Autofocus is locked once recording begins. I would like to see this be updated in 3.1 or a future update.
Links of Interest
Robert Mohns iPhone 3GS review on Macintouch
Camcorder Info iPhone 3GS review
Chris Pirillo iPhone 3GS video upload test – link
Review from the Hawaii Blog. Includes a comparison of full-size and emailed videos.
iPhone Savior article with “Save a Copy” screenshot – link