Video Encoding and Framerate Info for Netflix Streaming
In an interesting move, Netflix has opted to present their encoding strategy for Netflix Streaming on their Official Netflix Blog this month.
If you are like me, you will skip directly to the HD content section to see what they are offering.
They say that they are currently offering 400 streams in 720p quality. Frame rates are 24 fps for movies (which makes a lot of sense) and 30 fps for video sourced content, which would likely require deinterlacing prior to encoding.
They say that they want to save bandwidth at this stage – so it makes sense to stick with 720p 24 fps or 30 fps – which are roughly half the pixel rate of 1080p24 and 1080i respectively.
The encoder they are using is essentially the VC-1 codec that is also used for some Blu-ray Discs – though the bitrates of 2.6 to 3.8 Mbps is around 8 times less than a typical Blu-ray Disc encode. I would expect to see some artifacting at those bitrates, even with the reduced pixel rate.
Neflix says themselves that these encodes “won’t challenge well-executed Blu-ray encodes”.
That is not to say that they are settling – Netflix is aiming for better as Broadband rates improve.
On the audio side it is a little disappointing to see that they will not have 5.1 audio – however they appear to be pretty well locked into the Microsoft DRM model, so something will have to change in order for them to deliver multichannel – again they are working on it.
All in all it sounds like a good effort to at least deliver a performance superior to DVD, though it sounds like there needs to be quite an improvement in infrastructure, etc., to meet Blu-ray quality.
Still, for some titles, perhaps this will be seen as good enough by many…