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A friend of mine, Baptiste Coudurier, is the person at Hulu who manages the transcoding of all their videos. He told me they also transcode a video to multiple
by mrb 14y ago
A friend of mine, Baptiste Coudurier, is the person at Hulu who manages the transcoding of all their videos. He told me they also transcode a video to multiple versions to accommodate different streaming devices and bandwidth characteristics.
I think it only makes sense to lazily-transcode videos on demand (and cache them) when you have millions of videos (eg. Youtube). Netflix and Hulu have much smaller catalogs, so they can afford to transcode ahead of time, and it simplifies their processes.
- morsch 14y agoI wonder if there's some lengthy preprocessing step that's common to transcoding regardless of the target resolution/quality. That way you could precompute and store the intermediary format and finish of the encoding to an arbitrary format as required.
- keeperofdakeys 14y agoFor two-pass encoding, the video is first scanned to assess complexity, so a second encode pass can work out which frames require a higher bitrate to get the same quality. However this is not used that often, in favour of a quantiser approach, which uses a number to indicate target quality. The encoder then changes the bitrate depending on the frames complexity and the target quality/quantiser. The quantiser approach is much more common because it's easier to specify an output quality that is independent of resolution. As for the actual encoding, nearly all the computation is very specific to the output resolution/quality. Luckily encoding multiple videos can be spread over many machines, and encoders can take advantage of multiple cores.