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Not quite sure how to word this but, does BitTorrent natively support distributing videos encoded with MPEG4's Scalable Video Coding (SVC) in the different possibleversions?


Or rather, is it possible to distribute a video file encoded with SVC in different resolutions inside the same torrent? Or link swarms that represent different resolution versions of the same SVC-encoded movie file? I'm not sure on the terminology...


If so, can someone please point me in the right direction as to how I can do this myself - it sounds sweet.

If this isn't yet possible, to whom do I send the cheque to make this happen?  :P



For those who don't know, Scalable Video Coding allows several different quality/bitrate/resolution/framerate versions of a video to be represented inside of the same bit stream. There is a baseline video layer, to which several improvement layers can be optionally added to bring up the quality while still limited by some criteria (e.g. bandwidth)




I'm imaging that instead of having separately encoded files, torrents and hence swarms for each version of a video (e.g. 480p, 720p & 1080p) there would be a single source file, a single torrent and a single swarm. Each person would pick what version they want when they open the torrent. Then of course only download and then seed the pieces needed for their version. Availability of the baseline video stream would be super-high since you could get those pieces of the torrent from anyone with any version of the video. Availability of higher res versions would drop off in proportion with how many people wanted them.


e.g. instead of 3 different swarms of 75, 150 and 75 seeders for the 480p, 720p and 1080p versions, there would be a single swarm with availability of 300 for the 480p, 225 for the 720p and 75 for the 1080p version. When a downloader wants the 1080p version, seeders with the higher-res versions could concentrate on distributing the pieces unique to their version while those with lower-res versions filled in the rest. 


In my head this all sounds pretty amazing and would seem like it would increase speed and availability for everyone while reducing waste and duplication - an almost unmitigated win except for a more complicated encode/decode. But I can't find much on this anywhere.


The closest I can find is a reference about 2 years ago to a prototype system called WuKong built on BitTorrent, WMV and SVC - but I don't feel like spending the money to buy the article! At least not right now. 


So, can anyone shed some light on this topic for me? Is it possible? How? If not, past discussions? ETA?

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Found a little more on the subject here (14 page PDF) from a research team in Germany. This was published back in October 2009 and focuses more on p2p streaming rather than downloading.


One of the guys who wrote it went on to publish his Ph.D Thesis on the subject in 2012 with the title:

Quality Adaptation In Peer-to-Peer Video Streaming: Supporting Heterogeneity and Enhancing Performance using Scalable Video Coding
The thesis is 160 pages long - so I think I'll read the full thing it later! But skimming the conclusion it mentions benefits such as more granular varying of quality compared to resources (of peers, bandwidth, processing etc.) and it seems they have already done a lot of work in customizing the BitTorrent protocol to be aware of SVC-encoded content.
I guess this must still be more 'out there' than I had hoped it was given it's the subject of a Ph.D paper just 2 years ago. I hope someone is able to come up with a solution that is deployable en-mass to whoever wants it soon: It'd be amazing. 
Weren't the BitTorrent team experimenting with streaming a few years ago? Now might be a good time to revisit it. Please? :D
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