Originally Posted by Brian Conrad
Originally Posted by michaeltscott
I believe that older systems get a completely different set of encodes, non-adaptive-bit-rate VC-1 w/WMA sound instead of the adaptive bit rate AVC encode sets with separated sound (DD+ for 5.1, but I'm not sure how they encode the 64- and 192 Kbps stereo; MP3, maybe? I'd think that stereo PCM would be horrible at either bit rate).
What Netflix does is rather a "black box". There are some articles out there including an announcement a while back from one encoder firm boasting that Netflix had begun using their encoder. Not much technical data given but mostly a marketing blurb on their blog. And I highly doubt when they changed encoders they re-encode older films.
I don't know which blog entry you're talking about, but the ancient "Encoding for streaming
" blog entry was hardly "marketing"--I'd judge it to be too technical for most people to follow. Devices which were around back then were getting VC-1 with stereo WMA sound, and I believe that they still maintain their entire library in all of the old formats which were created and discarded along the way (perhaps they can get rid of a set when nothing is asking for it). In a recruiting slide show
they've stated that they generate 120 "downloadables" for every title to accomodate all of the different kinds of devices that they stream to. If they move to a new format they just regenerate the entire library in that format--it's just CPU time; the storage to contain the new encodes on the commercial CDNs is the expensive part.
All of the modern players use a set of AVC video encodes set up for adaptive bit-rate streaming (ABS) with constituent encodes at 235-, 375-, 560-, 750-, 1050- and 1750 Kbps for standard def; if the title is available in HD there will be 720p encodes at 2350- and 3000 Kbps and most HD titles will have a 1080p encode at 3850 Kbps. If your ISP is set up for Open Connect CDN access then there will also be 4300- and 5800 Kbps "Super HD" encodes for those titles with 1080p video (again, most of the HD). I have no idea why they continue to produce the 235- and 375 Kbps SD encodes. IMHO if you can't handle at least 560 Kbps you should give it up. I have seen titles which only have 560-, 1050- and 1750 Kbps SD encodes, but some of the very latest titles still have the ultra-crappy ones, so I suppose that Netflix must see significant usage of them.
The high 720p and the 1080p ABS video encodes used to be 3600- and 4800 Kbps, respectively; Netflix started using an H.264 encoder from a company called eyeIO which promises to deliver the same or better quality at lower bit rates and replaced those encodes with 3000- and 3850 Kbps ones. Just google "eyeIO" for info; the company basically came into existence because Netflix bought the tech when they demonstrated it to them.
Sound in the ABS encode sets is separated, so you can get either 64- (PC only) or 192 Kbps stereo or 384 Kbps DD+ 5.1 (E-AC-3) for some titles. This feature also allows for multiple languages; in the US most titles only have English soundtracks, but in other regions there's a selection. In the Nordic regions, for instance, you can get your soundtrack in any of 5 languages and if 5.1 sound is available it's usually available in multiple languages. I've heard that the use of regular Dolby Digital (AC-3) requires that the sound be in the files with the video and that they generate a set of encodes like that for Apple TV.