Shooting for Streaming, Part 4

So, using the same camera settings, I zoomed out and shot again, playing Dickie V (which I found very freeing). Though the increased motion produced more visible interlacing artifacts, the deinterlaced image looks almost identical to the progressive image. In real-time playback trials, the interlaced video looked almost identical to the progressive source video. My conclusion? In a controlled, compression-friendly environment, with minimal detail, relatively low motion, and typical studio lighting, progressive source video won’t look substantially better than interlaced.

Sports
We’ve already seen that at a shutter speed of 1/2,000, progressive source video looks better than interlaced source video. This test is designed to determine how low you can go in terms of shutter speed and still see the difference. To determine this, I shot the same motions—golf and baseball swings—while adjusting the shutter speed from 1/2,000 to 1/30 and controlling exposure via a combination of aperture and ND filters. Gain was set to zero in all tests.

With a pitching wedge, the shaft started to get blurry at a shutter speed of 1/500, making the deinterlaced video tough to discern from the progressive video. What conclusions can we draw from this? Overall, if you’re shooting high-motion video, and don’t currently shoot at a shutter speed of 1/500 or higher, you may not see a significant difference between progressive and interlaced source, at least as it relates to motion-related deinterlacing artifacts.

This is significant, since at least some sports videographers recommend shooting at a shutter speed of 1/60, blurry still frames and all, to minimize jitter and maintain a smooth-looking image. Remember, your viewers will watch the entire video in real time, and won’t get to study an individual frame for blurriness.

Interestingly, however, in other areas of the frame, it seemed clear that the progressive frame retained much greater detail than the interlaced frame, particularly in areas of fine detail like branches in the background. This impression was confirmed on my final shoot, which I’ll affectionately call the horror show.

The Horror Show
The Horror Show was a series of three one-act plays performed by the Galax Theater Guild at a local gathering spot called String Bean. The stage was next to the plate glass window overlooking the street, and the plays started at 7:00 p.m. under full daylight, and ended at about 8:30 p.m., well after sunset. A thin rattan curtain covered the window, dulling the incoming light and muting street traffic and passersby, but provided tons of extraneous detail. I could have removed the curtain, but I was more concerned with traffic and backlighting.

All stage lighting was provided by overhead fluorescent lights of the normal office variety, and some of the lights directly overlooking the stage were out with no replacement bulbs in sight, exacerbating the backlighting. With shutter speed set at 1/60, and each camera’s aperture wide open, I still had to pump the gain up to 12dB to brighten the actors’ faces sufficiently.

To complete the picture, the head of the theater guild, who had asked me to shoot, breezed in about 30 seconds before show time, and it wasn’t until the shoot was over that I noticed he was wearing a black and white checkered coat. Between the curtain, coat, backlighting, and gain, I had no hope for the video, at least not without some significant filtering that would blur all detail. As it turned out, these circumstances tended to confirm that the progressive camcorder retained significantly more detail than the interlaced camcorder.

For example, in a scene that shows theater guild president Donn Bogert belting out an introductory number in the coat I should have ripped from his back before letting him onstage. As you can see, the detail is much better preserved on the right, in the progressive image.

The progressive camcorder also reproduced much better detail with the rattan curtain. This was unexpected at first, particularly because resolution tests that I had performed previously with the Canon XL H1, which shares the same optics as the XH A1, showed no difference in resolution when shooting in progressive vs. interlaced.