The lower resolutions all use identical audio settings to allow switching cleanly between them in an adaptive streaming scenario without any audible "pops". It acts both as the best local playback (non-web) version and as a long-term master for future transcoding (eg: YouTube uploads, burning to DVD/Blu-ray, re-encoding with future codecs etc).Īudio is encoded at 44.1 kHz in AAC format, mono at 64 kbps or stereo at 128 kbps, both of which are excellent quality, practically indistinguishable from the original master. The superbit version should be almost lossless, practically indistinguishable from the original master – a "transparent" encoding, as it's known. The bitrate chosen is 20 Mbps, which is a safe 80% of the maximum peak bitrate allowed for H.264 level 4.0. #KEEPING THE BITRATE THE SAME FOR FFMPEG COMMANDS 1080P#Nonetheless, we might as well take advantage of the user's link speed for improved quality from fewer compression artifacts, assuming the user's link is not fast enough to get up to the next higher resolution, which would be a significant step up in general sharpness and clarity.įinally, we also encode a "superbit", ultimate-quality version at full HD 1080p resolution using a very high bitrate similar to Blu-ray. The visual differences from the normal, "very good" quality version to the HQ version are generally quite small, such as less blur during rapid motion, less risk of banding in dark scenes, and less risk of crystallizing during difficult fades. It's unwise to push bitrates too low and risk delivering a blurry, unprofessional video, which other sites such as YouTube routinely do.įor most of the resolutions we also provide a higher quality (HQ) version encoded at a somewhat higher bitrate, for the benefit of users with sufficiently fast Internet links. If that means using a higher bitrate for a given resolution than some other web sites, then so be it – the 'net can take it, and bandwidth is less and less of a problem every day. Just like saving a still image for use on a web site, we put quality first and only compress as much as possible without introducing any noticeable degradation (hopefully). Simpler video embedding may also be used, of course, right down to a basic HTML5 tag pointing to a single version of the video, but the whole point of encoding at a variety of resolutions and bitrates is intended for an intelligent embedding mechanism to make sensible use of those many different versions, supplying high-quality HD video to those viewers with fast enough Internet links, while falling back gradually for viewers with increasingly slower links.įor each resolution, we use a bitrate which is the lowest sensible 64% cut (80% of 80%) of a common Internet link speed (see below) that still achieves "very good" visual quality, with no major visible compression artifacts. 1080p (1920x1080, 2.07 megapixels, "Full HD")Įncoding at such a wide range of resolutions is based on the assumption a web video embedding mechanism will be used that is capable of detecting the viewer's Internet connection speed and choosing the appropriate video file based on that link speed, along with the screen size and playback capabilities of the browser – thus supplying each different viewer with the best resolution and bitrate he/she can use.We provide video files at 7 different standard widescreen resolutions. #KEEPING THE BITRATE THE SAME FOR FFMPEG COMMANDS DOWNLOAD#With that in mind, you can download VideoEncoderSettings-202103.zip which has the article's settings in a form suitable for importing into HandBrake with x264, which we currently use, as well as Compressor with x264Encoder, which we used back in 2012 when this article was first written. UPDATE: While you're strongly encouraged to actually read this article and learn about the various settings and tradeoffs, many people just want to download the settings. UPDATE: If you're just getting into video encoding, this nice general overview of H.264 is probably a good place to start, before checking the more detailed links above. Video encoding is a game of tradeoffs, and these settings represent a balance which is very good, and difficult to improve upon.įamiliarity with basic video-encoding terms and technology is assumed when reading this document, and an understanding of the nitty-gritty details might also be helpful. This document describes in detail a set of resolutions, bitrates and settings used for high-quality H.264 video encoding, and the reasoning behind those choices.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |