14 DAY TRIAL // It's been less than a week since Netflix introduced the option to download its shows so you can watch them offline, and now another major update brings some improvements to this specific new feature.
Since the offline download feature is mostly meant for those who prefer to watch movies and TV shows on their smartphones/tablets while on the move, Netflix thought it would be great to improve the download speed or shrink the size of the files needed to be downloaded.
The latest update for Netflix is focused on delivering more efficient video encodes targeted towards low-bandwidth Internet connections. Basically, Netflix introduced two new types of mobile encodes: AVCHi-Mobile and VP9-Mobile.
These new encodes will only be available when watching or downloading movies on mobile devices. According to Netflix, the improvements in the new bitstreams fall into three categories: new video compression formats, more optimal encoder settings, and per-chunk bitrate optimization.
Thanks to the new changes combined, Netflix users should get better video quality for the same bitrate compared to the service's current streams (AVCMain).
But there's more, as Netflix has announced that the latest update also brings a new set of optimal encoder settings. These new settings will allow Netflix's engineers to further improve compression efficiency.
One of the new improved encoder settings refers to increased random access picture period, which is a parameter that trades off encoding efficiency with granularity of random access points.
Also, there are more consecutive B-frames or longer Alt-ref distance, which should allow the encoder to flexibly choose more B-frames in H.264/AVC or longer distance between Alt-ref frames. This is especially beneficial for slowly changing scenes.
Lastly, there's more exhaustive mode evaluation, which allows an encoder to evaluate more encoding options at the expense of compute time.
Netflix confirmed that it has started to re-encode its catalog last month, in order to generate the new mobile bitstreams, but it hasn't yet finished.
The good news is the new mobile encodes are already being used in the downloads feature, but in the not so distant future they will be used for mobile streaming as well.