ClassXInteractive Lecture Streaming

 
 

ClassX Equipment

ClassX is an experimental interactive lecture streaming system developed in the Electrical Engineering Department at Stanford University.

Unlike conventional lecture capturing systems, which require costly equipment and intensive human operation to record and publish content, ClassX requires very simple consumer-grade equipment and minimal human operation. No fixed installations for camera or microphone are necessary.

In order to help you estimate the costs for a recording set, and to help you decide whether ClassX is for you, we have put together an equipment-shopping guide.

ClassX is not paid by or affiliated with any of the given brands or websites: shopping tips on this website only reflect our experiences with equipment. ClassX was established as an open-source project that is offered for free to the public (http://sourceforge.net/projects/classx/).
Equipment marked with an asterisk (*) was previously used in ClassX recordings.

The ClassX–team uses consumer-grade equipment to film talks and lectures at Stanford University. A complete standard set costs about 1000 USD. This one-time investment allows you to record as many lectures, talks and events as you like, publish them through ClassX, and share them with the world.

List of recommendations for recording equipment:

Camcorder, able to record full HD videos

In order for the interactive pan and zoom features, lecturer tracking and automatic slide synchronization to work, the camcorder must be able to record full High-Definition videos (resolution of 1920x1080 pixels).

Since lecture halls and talk venues are often insufficiently lit, we suggest paying attention to an increased low light sensitivity of the camera.

The slide synchronization feature of ClassX will only work flawlessly if the recorded slides offer enough contrast to be machine-readable. The camcorder’s color settings should be able to reflect this and record vivid colors that make human protagonists look natural at the same time.

Since we are aiming to film a wide-shot angle of the scene, zoom features of a camcorder were not relevant for the selection. The camcorder will be mounted on a tripod, so the image stabilization features can also be neglected.

Camcorders capable of recording full HD start as low as 150 USD, but might have a low performance. We have tested models around 500 USD.

(*) Canon VIXIA HF M40 Full HD Camcorder with HD CMOS Pro and 16GB Internal Flash Memory

Panasonic HDC-TM90K 3D Compatible Camcorder with 16GB Internal Flash Memory

Canon VIXIA HF G10 Full HD Camcorder with HD CMOS Pro and 32GB Internal Flash Memory

Back to top

Additional memory card, if necessary

If the camcorder has only 16GB or less memory built in, we highly recommend to purchase additional memory cards that are compatible with your camera model. Please check the manual or instructions.

Most Laptops and PCs have a card reader built-in, if not, you can purchase a USB-device for about 10 USD.

Please be aware that MXP and FXP modes record in 1920 x 1080 and often require a Class 4 or higher or SDXC card. Check your camcorder manual for details.

Back to top

Camcorder power chord

Since most recordings will be about 90 minutes long (a standard lecture), we highly recommend to plug the camcorder in using the power chord, and not rely on batteries or rechargeables. Running out of power during a recording is an irreversible problem. Once the camcorder shuts down, it will stop recording and might not have saved anything of the session.

Back to top

Tripod including top mount

The higher you can mount the camcorder, the better the video results usually are. To avoid talk attendees walking through your recorded scene, or filming the audience, you might have to put the tripod on an additional podium.

The ClassX-team records sessions with camcorders mounted on 72-inch tripods that we put as far back into the room as possible. Be aware that you might have to make attendees aware of the camera, so they avoid disturbing the scene.

Zeikos ZE-TR101A 72-Inch Photo / Video Tripod

(*) Ravelli APGL3 Professional Three Axis Head Camera Video Photo Tripod

Ravelli APGL4 New Professional Tripod

Back to top

Microphone

In order to record the lecturer, the built-in camcorder microphone is not sufficient in most cases, since it will incorporate ambient noises in the video. To ensure you will hear the speaker, we are using wireless microphones during our recordings. Lecturers can move freely with the small devices, and do not have to focus their talk in one direction only. By placing a microphone on your subject, speech is captured more clearly, with much less background noise.

Wireless microphone sets come in two pieces: a transmitter (the microphone that is worn by the speaker), and a receiver (which is plugged into the camcorder). The transmitter and receiver are set to one channel so that the audio signal is being transferred between the two. Our standard set Shure PG14/PG185 Wireless Lavalier System, which we use in most cases, will allow you to record one channel, so one speaker only. Be aware that if you are planning to record a panel or audience discussion or talks of several speakers that do not allow the passing of the wireless microphone between the speakers, you should plan on purchasing a combo wireless system.

The Shure PG1288/PG185 Vocal/Lavalier Combo Wireless System works with two channels that can be received simultaneously. It comes with a wireless body pack for a speaker, and a handheld microphone that could be used for audience questions, or might make the sharing of a microphone easier.

If you plan on buying a Canon camcorder, you might want to look into the WM-V1 Wireless Microphone, which is specific to Canon camcorders. Consisting of receiver and microphone units, the WM-V1 wireless microphone improves the quality of the sound you record with your compatible camcorder. Additionally, when earphones are connected at both ends, conversations can be held between the camcorder operator and the subject. We have not tested this yet though, and cannot give any review.

(*) Shure PG14/PG185 Wireless Lavalier System

(*) Shure PG1288/PG185 Vocal/Lavalier Combo Wireless System

Canon-specific microphone

Back to top

Microphone batteries

One of the crucial factors of a video recording is the sound. As described above, all recommended systems use a wireless transmitter and a receiver that is plugged into the camcorder (connected to the power supply). The wireless transmitters work with batteries, which will be empty after about four to five 90-minute lectures.

Since the wireless microphones will not warn you before the power runs out, and the batteries might die during the recording, we highly recommend buying rechargeable batteries with a charger, which you can easily replace after every recording session. It is a money-saver, as well as a great contribution to saving our environment, while ensuring that your videos always have sound.

The Shure lavalier systems use 9V batteries for all microphones.

(*) Tenergy TN141 2 Bay 9V Smart Charger with 4 pcs Centura Low Self-discharge 9V NiMH Rechargeable Batteries

Back to top

Audio cable

Camcorder and microphone receiver will be connected by a standard audio cable, which is included in the Shure Lavalier systems.

Back to top

Headphones

Any headphones can be connected to the camcorder to check the audio before you start recording. Connect all parts as described in our instruction video and the Publisher 101, then connect the headphones to the camcorder, switch on the wireless microphone transmitter and test the setup. Sometimes cables might be lose or plugged into the wrong jack, this procedure will help you to make sure to find any errors in the setup.

Back to top

 

Copyright © 2012 ClassX - All Rights Reserved

Stanford University