Jun 18 2018 11:19 PM
Jun 18 2018 11:19 PM
I am looking for information on the transcoding process and compression ratios of Microsoft Stream. I understand that when I upload a video that video will undergo a transcoding process that will convert into upto 3 different compressions (1080, 720, Lower) or the like. AND further to that the video that a viewer watches is dependent upon their bandwidth, high internet speeds (bandwidth) will allow the video to be watched at full res and data rate. If bandwidth is lower then a lower data rate or resolution version of the video will be played. AND that if the bandwidth increases then after each segment of video (`2-10 seconds) the quality of the video played will also increase. My question is what is the compression ratios of microsoft stream and what is the transcoding process? How can I convince my employer that this platform will play our videos better then say Vimeo????
Jun 19 2018 02:12 AM
Hi Brendan, this is the most detailed information I have seen on this topic, though it's not that recent I doubt much has changed since:
On choosing the number of renditions or qualities that a video is encoded into:
"For example, if the input video is at full 1080p HD resolution (1920x1080 pixels), then we would decide to use 6 steps, starting from 1920x1080, down to 320x180. If instead the input video is of standard definition resolution (eg. 640x480 pixels), then we would pick just 3 steps, from 640x480 down to 240x180. Naturally, we would never exceed the resolution of the input video."
On selecting a bitrate and what goes into determining this:
"the next stage is to determine the bitrate for each rendition. Naturally, higher the quality of the rendition, the more bits it requires - but not all videos are created equal. Different types of videos require different bitrates to achieve 'high quality' - so we needed to be smart about choosing the bitrate. Here too, our experience with Office365 Video came in handy. We've observed, for example, that marketing videos are delivered at high bitrates, since they were most often produced by professional agencies. We also receive a ton of PowerPoint presentations which are captured at full 1080p HD resolution, but at very low bitrates - the screen has mostly static text content."
This goes on to say:
"We used all this information to come up with a simple yet elegant function that measures the characteristics of the input video, and comes up with a recommended bitrate for that rendition. In our tests, this function is holding up well - the marketing videos end up getting encoded at close to 6 Mbps at 1080p, whereas a PowerPoint presentation would use just around 500 kbps."
This page has more general details on what happens - Upload process overview.
Jun 19 2018 03:17 PM
Jun 19 2018 04:21 PM
Not sure you'll find what you're looking for. The only comparison I have seen is related to Office 365 Video, the more established video service that's being replaced by Stream later in the year.
You can get a deep dive into the mechanics of Microsoft Stream in the presentation here - Learn how Microsoft Stream was built using Azure and you could always check out Azure Media Services accordingly, which provides some of these related services that are mentioned.
Since every video is different, which you will know better than me, how it might be rendered and under what conditions it is played could vary, personally, I'd test Stream with sample content and do an analysis, as part of an evaluation.
You can always sign up for a dev tenant - https://developer.microsoft.com/en-us/office/dev-program to help with this. Also, you'll want to be aware of some of the current limitations like no public (anonymous) access to videos, API access etc., if you don't know about these already.
Jun 27 2018 08:14 AM
Hi Brendan, hope that helped a bit even if it wasn't exactly the outcome you were looking for.
I think it would be useful if the official documentation did go more in-depth on the sorts of technical details you mentioned.