Live lecture streaming and capture by smartphones

Smart-phones only with standard wired hands-free has recently been applied as capturing devices to capture lectures with UNINETT IoUs experimental Live Streaming service, with reasonable success.

Many cloud services support live streaming and recording from smart-phones (e.g., Youtube, UStream, facebook,…) however they typically handle a single stream per channel.

Live streaming a lecture with a single mobile phone as capture device has its challenges with respect to placement.

  1. A medium distance from the lecturing scene gives the best video quality. Less zooming means better quality as zoom on smart-phones is digital, i.e. the resolution is lowered and the image is cropped.
  2. A long distance is preferable to be non-invasive. Placing a camera “up in the face” of a lecturer will often make him feel uncomfortable. Capturing both the blackboard and a projection screen is usually also easier from a longer distance.
  3. A very short distance is required if the built in microphone or a standard wired hands-free set is to be used for audio capture.

Pin 3 may potentially be amended by applying a bluetooth hands-free device. We did not have a suitable bluetooth device, however we had multiple phones (with cracked displays) laying around. Investing in a new wireless device seemed unnecessary as we already had several.

Our solution was to install MIV Dev team’s “RTP Camera” app on two Android phones. We configured both to push their streams to the same server. We manually “merged” the SDPs output by the phones such that audio was received from our phone with wired hands-free connected to it, and video from the phone mounted on our camera stand. Ref. the images below.

The phone capturing and streaming audio was place in the speaker’s pocket. The ear plugs of wired hands-free was stuffed inside the speaker’s collar leaving the hands-free mic outside on the chest.

To be as none-invasive as possible we placed the video capture rig at the upper row of the lecture theater. Hence we chose to trade off video quality some what.

The resulting live stream and recording had a quality “good enough” ¬†according to the students following the course where capturing was tested. Audio quality was very good, however the video quality has room for improvement. Wireless streaming of high quality video using RTP has its challenges with respect to packet loss.

A commercial alternative to our setup seems to been getting close to production. is about to offer and app for multi-phone live streaming to facebook and Youtube.

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