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Improving Quality of Meeting Recordings

  • Article

By Tolga Kilicli, Product Owner, Microsoft

We released the Lync 2013 client for Windows almost a year ago, which included some changes to how calls and meetings are recorded. Those changes included introducing MP4 as the recording format to make recordings more broadly accessible across different devices and applications. As a side benefit, MP4 recordings are processed much faster on Windows 8 thanks to support for hardware acceleration.

We also discovered and received feedback on some problems with the recording feature in Lync 2013, principally:

  • Meeting recording files got larger – too large to be uploaded or easily shared, which is important to people who use Lync recordings for training or knowledge sharing.
  • Meeting recording quality got worse, much worse in some cases.
  • These issues are interrelated – higher quality recordings usually result in larger files, all else being equal. We made some changes in a subsequent update to Lync 2013 for Windows (the CU2 update), which fixed the size but made quality even worse.

So we took a harder look at the different parameters for meeting recordings – what we could change, and why. We looked more closely at the nature of what is being recorded, in terms of screen refresh and motion and text and graphics resolution.

Analysis and user testing

Based on our analysis and useful customer feedback, we calculated a new set of recording resolutions, frame rates, and bitrate ranges. We aimed to increase the resolution of recordings yet also provide smart tradeoffs with recording size, so we landed on 3 different resolutions options: 480p (854x480 pixels), 720p (1280x720) and 1080p (1920x1080). We also increased the frame rate from 10 to 15 frames per second – not quite movie quality, but sufficient to capture PowerPoint animations and document scrolling. That improved frame rate plus the resolution options were designed to produce sufficiently high-quality recordings and yet allow users to pick their preferred balance between recording resolution and file size.

But how would that work in the real world? Before shipping an update to Lync client recording, we tested these options and few others by taking a set of real meetings and creating recording using a range of settings. We also varied the maximum bitrate of the recording, which impacts both quality and file size. Then we came up with perceptual measures of video quality, such as readability of text, animation smoothness, and image clarity.

We talked to a small group of users, had them watch different versions of the same recorded meeting (with different options), and asked them to rate each video for each perceptual measure. The results are shown below:

 

These results led us to a few conclusions:

  1. The 15 fps frame rate is necessary for sufficient quality, regardless of resolution.
  2. Lower bitrate (kbps) for lower resolutions does not cause a significant decrease in quality.
  3. Increasing bitrate without changing resolution improves quality up to a point but beyond that point quality does not significantly change.

We then finalized the options that are now available in the latest update of the Lync 2013 client for Windows:

 Resolution   Bitrate, Frame Rate  Estimated file size for 1-hour meeting (observed on Windows 8*)
 480p (854 x 480)   500kbps, 15fps   150MB
 720p (1280 x 720)   1250kbps, 15fps   250MB
 1080p (1920 x 1080)   2500kbps, 15fps   400MB

 

 

 

 

Which option to choose?

We worked on the 720p resolution to provide a good quality in a size that would fit in SharePoint 2013's default max file size limit for uploading to lists. Even though file size is dependent on the content in the video, in our tests for regular meetings we have seen 1-hour, 720p recordings to be less than 250MB on Windows 8 PCs. Also if you are using SkyDrive Pro, you can share your videos by just putting them in the local synchronized folder and sharing them with your colleagues. SkyDrive Pro also offers 25GB storage and 2GB upload limit with SharePoint Online. 

For a meeting that did not have much content shared, or if file size is more important for you compared to readability of text or fine details on the content shared, you might want to consider the 480p resolution.

On the other hand, if you intend to view or present the recording on a large screen (wall display, TV), and you have multiple things being shared in addition to videos of participants (e.g. screen sharing), then the 1080p option will work much better. And the 720p option sits in the middle as the default choice and gives decent quality, decent file size, and decent resolution for most users.

To change the option used for your recordings, go to the Lync Options dialog (Tools > Options) and find the Recording tab:

 

Recording Manager follows these settings and when you "Publish" a meeting to an MP4 file the output will be in your selected resolution:

 

This also gives you an option to change the resolution in the options dialog and "Publish" your meeting again in the resolution.

We look forward to hearing your feedback on these updates and improvements to the recording feature.

*Codecs shipped in Windows 8 provides more granular control over encoder parameters. File size might be different and higher on Windows 7 as a result.

Comments

  • Anonymous
    January 01, 2003
    We were using Lync to record video interviews that we can "ship" to our representatives, but found out afterwards that majority (>80% of the video feed) was not captured. Any idea on what caused the problem and how I can avoid it? we are scheduling a retake for these interviews and would hate for it to happen again.XY MesinaPhilippinesxymesina@gmail.com+639266602542

  • Anonymous
    January 01, 2003
    Thanks

  • Anonymous
    January 01, 2003
    Oh, I also have the Skype for Business Tech Preview, so I might see what I can do with that.

  • Anonymous
    January 01, 2003
    Thanks for the great article Tolga, particularly the explinations behind the decisions.

    However it would appear that a number of us (vocal minority?) are still experiencing video quality issues with the Lync 2013 recordings.

    In particular, I've been experimenting with corporate branded PowerPoints and I'm finding three main issues:
    1. Colour matching is way off.
    2. Significant colour banding.
    3. Obvious ghosting of text and hard edges (colour bleed?)


    It's like watching very early DivX encoded movies with very low bit rates.

    I've tried both 720p and 1080p and both end up with bit rates that rarely hit a quarter of the rates you state above. This is somewhat understandable, since the PowerPoint is fairly simple with no complex animations or page transitions, but I would expect H264 to do a much better job, but it's like your implimentation is trying trying way to hard to reduce bitrates.

    At the end of the day, the quality of the resulting video isn't really something I want to be showing to Clients.

    What are our options going forwards?

    FYI Happened to test on Lync 2013 client v 15.0.4615.1000 - May 2014 update.
    I also have available 15.0.4693.1000 - which I think is the Feb or March 2015 update.

    Thanks
    Craig

  • Anonymous
    December 02, 2013
    Would there be any benefit from converting the .MP4 to a FLV format?  I am not sure if this would actually reduce the file size significantly enough to justify a loss in fidelity, but it would be great to reduce the file size.  Even better would be to stream them. Great article either way.

  • Anonymous
    December 03, 2013
    The comment has been removed

  • Anonymous
    December 10, 2013
    Thank you for a detailed article. With the recording features introduces the latest year with increased sound quality and now better video quality things is getting very good. For record of lectures and meetings with video and screen sharing things are now good enough. Still there is a problem with video quality when not sharing any content. At our point, i looks like the quality has decreased since Lync 2010. This is a problem while we at our University we are also using Lync to record for instance:  

  • Record how students perform in the nursing lab.
  • Instruction videos on how to measure blood procure.
  • Screencast for teacher while filming whiteboard or his notebook.
  • ++ We very much would like the video to be at least 24 frames pr. second and the video should match the 720p and 1080p option. It is a bit misleading with the quality option while the video is still 15 frames pr. second and a bit blury in full screen. We would very much like another option were also the video recording is 720p HD while creating these videos. Another challenge is when the teacher record lectures. When the recording is started and even more when the recording is paused it should be more visible. The teachers often forget to start an paused recording while there is no "blinking pause lamp" or other visible signs expect an small icon. The pause sign should in some way be more visible like in Camtasia relay. There is an big difference recording an meeting in front of your own computer at the desk and preforming in front of an crouwd. Things should be as easy and visible as possible for recording lectures, seminars and other happenings when the speaker is also the "director". Thank you for a great job in the last year with the recording feature in Lync 2013.  We have now stopped using other screen recording software and use Lync big time to record lectures and meeting. We also use it in auditoriums where it is removes less flexible and more expensive AV systems. With the small adjustments I describe here, it would be close to perfect also in these scenarios. Regards Kay Morten Myrbekk Mobile: +47 922 08 613 email: kay.m.myrbekk@hint.no Our UC blog (translated) translate.google.no/translate
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  • Anonymous
    April 16, 2014
    Why not give us the option to control the framerate? 15 is useless when video is an issue.
  • Anonymous
    May 07, 2014
    At least Lync 2010 had a raw files directory where we could pull individual video, audio and screen content into an editor and edit and fine tune the compression to suit our needs. We would LOVE this to be available once more - especially if the raw video files were higher frame rate. Until that's available, the Lync 2013 recording feature is a step backwards from Lync 2010. We're using other screen capture tools for now. We get more flexibility and higher quality.
  • Anonymous
    May 30, 2014
    My Linc 2013 does NOT have the "Recording" option. It has all the others listed. What do I do about this?
  • Anonymous
    July 17, 2014
    In Lync 2010 the meeting were much smaller, our meetings are really just Audio and a PPT. But we need to put the recordings up on SharePoint so our other offices can watch it.. Problem is they are all have low bandwidth.
    Is there anyway to just record the audio, then I can post the PPT.
    thx
  • Anonymous
    May 22, 2015
    HiTolga ,
    Thanks for this nice article. We figured out that standup meetings are great but needed improvement (they took a lot of time, de-focussed our colleagues and interrupted their workflows). Because of this we developed a SaaS tool to "automate" the daily standup meetings - with just a single email. If you like to take a look: www.30secondsmail.com.
    Best,
    Ajie
  • Anonymous
    May 22, 2015
    HiTolga ,
    Thanks for this nice article. We figured out that standup meetings are great but needed improvement (they took a lot of time, de-focussed our colleagues and interrupted their workflows). Because of this we developed a SaaS tool to "automate" the daily standup meetings - with just a single email. If you like to take a look: www.30secondsmail.com.
    Best,
    Ajie