Rendering to video higher bit rate than source?

dalemccl wrote on 11/3/2011, 2:35 PM

My Sony XR-500V camcorder records video in 1920x1080 60i AVCHD at 16 Mbs (average). The bit rate seldom goes outside the 15-17 Mbs range. I render to 1920x1080 60i Blu-ray files for display on a large HDTV via a set top media player (Dune D1).

I use the Main Concept rendering template for 1920x1080 60i Blu-ray. The template's default bit rates are 30 Mbs max, 25 Mbs average, and 20 Mbs min. Is there any benefit (in terms of video quality) to rendering to a higher bit rate than the source material's 16 Mbs average?

Comments

malowz wrote on 11/3/2011, 3:41 PM

yes, but higher bitrate does not translate to higher quality. high bitrate means "better preservation of quality"

so, yes, higher bitrate will help maintain quality, and avoid more introduction of artefacts/smoothing/etc at each compression/recompression.

at higher bitrates, the difference is small. but any benefit is a benefit ;)

if you exporting for blu-ray/dvd, the ideal is to use the maximum bitrate allowed inside the specs and inside the available space of the media, there's no gain in burn a blu-ray with empty space.

Chienworks wrote on 11/3/2011, 4:31 PM

Yep, malowz is quite correct. Rendering to a higher bitrate won't make it better than the original, it will just make it less worse than rendering to a lower bitrate would.

dalemccl wrote on 11/3/2011, 8:59 PM

That's good to know. I knew higher bit rates couldn't improve the source material, but hadn't thought about the advantage of it being able to minimize decreases in quality. Makes sense. Thanks.

PeterDuke wrote on 11/4/2011, 1:04 AM

If you render virginal AVCHD to AVCHD in Vegas 9c, no recompression takes place, so you get 16 Mbps output with no quality loss. Rendering to a higher bit rate would probably give you a theoretical poorer quality because of the re-render.