Originally Posted by bdraw
After some more research, it appears Amazon is using WMApro to deliver 5.1, which means the player is transcoding to AC3. It appears there are different streams depending on if the file is being downloaded vs streamed. Evidently the streaming doesn't do 5.1, but the download does.http://unbox.typepad.com/amazon_unbo...video_qua.html
Perhaps the reason Netflix doesn't do 5.1 is because the MS codec used for streaming can't contain WMAPro, while the downloadable files can.
The blog entry at that link is 2.5 years old; at that time, Unbox only supported downloads for PC, TiVo and PMPs, with no HD content and no streaming to embedded players, which they've since added. (That blog seems to have been abandoned--there hasn't been a new post there since January).
On pages for available Amazon VOD items (likethis
one for an HD episode of Heroes
), there's a section labelled "Video Format Details". For each viewing option (Online Viewing, PC Download, TiVo Box, Portable Device, Connected Device) it gives the audio and video format; if you roll the cursor over one of the sections a little pop-up appears giving the file size, bit rate, AR and number of audio channels. They claim to have 5.1 sound in the PC and TiVo download files and for streams to embedded devices. I don't have one of the embedded streaming players, but I can attest that there is 5.1 sound on TiVo downloads. I suppose that it's possible, but I have a hard time believing that TiVo can handle WMA Pro transcoding--I don't think that it can do it in hardware--and I doubt that the embedded devices can do it either. (Back in the time of that blog entry that you cited, they were packaging TiVo downloads in "Best Quality" recording format. The HD files available now have to be encoded in VC-1 or AVC--5 Mbps HD-res MPEG2 would be an unwatchable mess).
They're apparently using Adobe Flash video for streaming delivery to PC and Mac, with Flash DRM. The Flash wrappers can handle H.264 and AAC--I wonder if the hardware embedded streaming players can handle Flash Video?