Thanks Kirloy, Best Regards, Mike Tsinberg http://keydigital.com On Jul 25, 2014, at 8:06 PM, "Kilroy Hughes" <Kilroy.Hughes@xxxxxxxxxxxxx<mailto:Kilroy.Hughes@xxxxxxxxxxxxx>> wrote: Saw this on an infrequent visit, and it doesn’t look like you got any responses. My answer: Depends on the workflow. · For last mile encoding, most of the files and streams we get are already 4:2:0 8-bit, so we have to avoid any re-quantization, colorspace conversion, etc. to avoid visible banding (usually Internet adaptive streaming or download). We don’t use interlaced source because of poor quality and poor compression (spatial/temporal cross products). · Upstream in house production and editing is hopefully 4:4:4 10-bit. · For interchange, that is usually mezzanine compressed, such as ProRes or Cineform (VC-5). · Contribution formats are unpredictable. Might be a project format (e.g. ProRes), or a delivery format used for broadcast, DVD, BD, etc. I’m only considering files and streams, because I consider tape dead; even for archive (start the ten year conversion now so you can finish before all the spare parts are gone). Plus, it is really hard to ship tapes to the cloud. I’m anticipating live ingest and last mile moving to 10+-bit 4:2:2 for 4K and HDR. 8-bit looks like shit at 4K, and HDR gamut and dynamic range make it more obvious. The HEVC codec treats 10 and 12 bit as a first class citizen, and I expect the infrastructure to support 10+ bit from the start. AVC was designed and implemented at 8-bit, so higher precision usually isn’t supported at some point in a workflow. It’s possible that HEVC will be both a mezzanine and delivery codec just by turning the bitrate knob. The video production and delivery model needs to be entirely overhauled for HEVC/UHD generation. Capture should be at the limits of human perception … including spatial and temporal sampling, color space, dynamic range, gamma, precision, etc. It’s useful to store the capture conditions and render intent to help intermediate and endpoint rendering in reduced range, gamut, gamma, resolution, etc. (“color correction”). Today each device must approximate the producer’s render intent with different screen aspect ratio, display technology, refresh rate, brightness, dynamic range, viewing condition (e.g. dark home theater or iPad in the sunlight), etc. This has been true for REC 709 content that was color graded for a studio monitor in a studio, but is now officially broken with HDR content that isn’t squashed to fit on existing interfaces and devices. No matter how old you are, It is now officially impossible to frame and color-correct video like it was all going to be displayed on a 27” CRT in a living room. Only the display device knows it display capabilities and viewing environment. Frame rate sampling and display refresh, spatial sampling (“resolution”) and scaling/cropping/padding/framing were converted to a device function, not studio function, with the rise of internet video. Adaptive streaming makes spatial subsampling and bitrate device controlled. Now control of endpoint precision, color volume scaling, etc. need to be transferred to devices. Kilroy Hughes | Senior Digital Media Architect |Windows Azure Media Services | Microsoft Corporation <image001.png><http://www.windowsazure.com/media> From: opendtv-bounce@xxxxxxxxxxxxx<mailto:opendtv-bounce@xxxxxxxxxxxxx> [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of Mike Tsinberg Sent: Thursday, June 12, 2014 8:58 AM To: opendtv@xxxxxxxxxxxxx<mailto:opendtv@xxxxxxxxxxxxx> Subject: [opendtv] Common encoding formats I would appreciate experienced opinion about HD encoding practices: Is 8 bit a most common encoding grayscale resolution for streaming and broadcasting or 10 bit is used as well? Also what about color subsampling? Is 4:2:0 most common or 4:2:2 is used as well? Best Regards, Mike Tsinberg http://keydigital.com<http://keydigital.com/>