Methods & Formats of Delivery

Goals: In this session, we will cover the various formats and methods of delivering audio and video content to students. We will discuss the correct format(s) for content delivery, and the differences in quality and performance of format and delivery options.

  1. Downloaded Delivery
  2. Streamed Delivery
  3. CD-ROM Delivery
  4. DVD Delivery
  5. QuickTime Format
  6. Real Media Format
  7. Windows Media Format
  8. Flash Video Format
  9. Recommendations

Download Delivery

Strengths

  1. Since files are downloaded to a user's computer, better quality video can be delivered to all users. The quality of downloaded media is not affected by connection speed. Conversely, the quality of streamed media is dependent on connection speed. When too much data is sent to the user the media does not play smoothly.
  2. Because the content is downloaded rather than streamed at a more or less constant data rate, the amount of the data devoted to high action sections of a video can be allowed to be higher while not changing the average data rate of the entire video.
  3. All users must download the entire clip to their computer and then play it. Alternate versions can be made for modem and LAN users to limit the time users wait for download. However, all users view the same quality media once downloaded. Users may have to wait longer for a higher quality video, but once received, they will appreciate the difference.
  4. Progressive download allows the user to view/listen to media as it is being downloaded. Users do not have to wait until the entire clip is downloaded to interact with the media. However, if the player can't keep up with the download, play may be choppy and users can get frustrated. In the end, they will have the file on their computer to play again and again.
  5. Since the file is downloaded to the users computer, the media can be reviewed at any time. A user can quickly move back and forth in the media without having to wait for any streaming server negotiation of the content.

Weaknesses

  1. Download time is the greatest problem, especially for users with 56k or slower modems. A 20-30 MB clip, for example, can take hours for a 56k modem user to download.
  2. Since files are downloaded to the user's computer, the user is free to distribute these files as they wish. There are some mechanisms to prevent this, but many can be circumvented by savvy users. This may cause copyright issues.

Streamed Delivery

Strengths

  1. Streamed media is delivered with little waiting time. While there is an initial buffering and synchronization time required, in most cases, delivery of content can begin in less than 30 seconds,.
  2. Multiple versions of content can be created and delivered based on connection speed.
  3. Streaming media prevents a user's hard drive from being filled with the remnants of past videos. Streaming sends the content to the computer and is deleted as soon as it is played.
  4. Streaming content can help control access to materials. Since content is not downloaded to a user's computer, the link can be removed to ensure that no one has access to it after a certain point.
  5. Copyrighted material can be controlled when content is streamed. Since content is never downloaded to a user's computer as a complete media file it is difficult to save the entire file and viewers are not able to use it in any other manner. Many streaming servers can be configured to restrict access by IP number and can require a password to view files.
  6. Since streamed files reside on a streaming server, web server space will not be consumed by video clips. Currently, the DoIT Streaming server does not restrict server space for instructional usage.

Weaknesses

  1. Since streamed content is delivered based on connection capacity, multiple versions for different connection speeds are recommended. If this doesn't occur, uses will experience dropped frames, and, in some situations, no audio.
  2. With the creation of multiple versions comes the problem of reduced quality for slower connection speeds. It is very difficult to delivery high action video to 56K modem users because the connection capacity does not allow that much content to be delivered.
  3. Streamed content has a built-in buffering and synchronization that occurs each time a media file is viewed. Each time a user moves to a different section of the video, or want to review a section, the server needs to rebuffer and synchronize to the computer.
  4. Streamed files reside on another server and creation of pointer or "reference files" are recommended. This means additional steps in the workflow.
  5. Streamed files are not downloaded to the user's computer, so an Internet connection is required each time a user wishes to review course materials. With downloaded materials, the user is only required to be connected once and is able to review materials at any time -- without being connected to the Internet.

CD-ROM Delivery

Strengths

  1. Writing media content to CD-ROM can ensure the user receives a high quality version of course materials.
  2. Full screen video can be delivered to users, instead of the smaller windowed video typically encountered on the Web.
  3. Viewing content does not require an Internet connection and is not dependent on connection speed.

Weaknesses

  1. Since content needs to be written to CD-ROM and delivered to students, it is difficult to provide updates or changes to content. Materials need to be prepared well in advanced or some alternative delivery mechanism needs to be created if additions or changes take place during a semester.
  2. Since content is housed on a CD-ROM, it is hard to embed media inside content. Users may need to find the files associated with each class and view them outside of the normal Web content.

DVD Delivery

Strengths

  1. DVD provides the opportunity to deliver the highest quality full screen video of all the available options.
  2. Using DVD Authoring software, an entire user interface can be created to present the course material.

Weaknesses

  1. Since content needs to be written to DVD-ROM and delivered to students, it is difficult to provide updates or changes to content. Materials need to be prepared well in advanced or some alternative delivery mechanism needs to be created if additions or changes take place during a semester.
  2. DVD media costs a little more than CDs when mastering, but that difference is shrinking constantly.

Quicktime Format

Strengths

  1. QuickTime has built-in progressive download capabilities, which makes delivery via download very nice.
  2. QuickTime supports the creation of reference files which will deliver different versions of a media clip based on connection speed.
  3. QuickTime will allow for the encoding of a user password to prevent unauthorized viewing of content.
  4. QuickTime supports multiple text track layers for captioning and multiple language support, if necessary.
  5. QuickTime supports the H.264 MPEG-4 format that is a standards-based format rather than proprietary codecs previously used by QuickTime or the other media formats
  6. The DoIT Streaming Server supports QuickTime formats.

Weaknesses

  1. The install base on PCs cannot be assumed, though Quicktime is installed with iTunes, which has greatly increased the installed base. While all Macs come with QuickTime installed, and the QuickTime installation base is very high, users will need to be provided links to download and install QuickTime.
  2. QuickTime has lower quality for streaming of content, particularly with lower connection speeds. If delivery of content is to those with 56K modems, either provide a downloadable version or use a different video format.

Real Media Format

Strengths

  1. Real format is consistently a top contender for quality.
  2. It offers support for Windows, Macintosh and Linux.
  3. The DoIT Streaming Server supports Real Media formats.

Weaknesses

  1. Real Media player has less than desirable support for backward compatibility. Users may be required to upgrade their player to view content.
  2. It can bedifficult for users to find the free Real Media Player on the Real Web site. Users often find themselves being asked to purchase a player or asked to enter a credit card number to subscribe to an online service. Be sure to click on the "Download Free RealPlayer" link.

Windows Media Format

Strengths

  1. Windows Media Player provides high quality delivery of video to all levels of users.
  2. The DoIT Streaming Server supports Windows Media formats.

Weaknesses

  1. Windows Media does not make it easy to deliver multiple versions of media content. Developers will need to create multiple links to different versions for users.
  2. Windows Media has a very low install base among Macintosh users. It is, of course, installed on all PCs today, but may not be installed on older PCs.

Flash Video

Strengths

  1. The Flash plugin has the highest installed base of any of the formats
  2. The Player can be customized through development in Flash
  3. Flash video supports progressive download

Weaknesses

  1. Flash Video does not make it easy to deliver multiple versions of media content. Developers will need to create multiple links to different versions for users.
  2. Flash video can be streamed when using a Flash Communication Server, but that is currently not available through the DoIT Streaming Server.

 

Recommendations

With all the information covered above, it can be difficult to figure out what is the right method and format to use. While there are usually not crystal clear lines of distinction in this matter, we do have some basic recommendations. If there are questions regarding any of the content or recommendations, please call us at 262-5667 and we will set up a consultation.

Question #1 -- What is the length of the video?

The length of a video will often determine how one should deliver content. If a clip is only several seconds long, downloading is probably best, since it will probably take as long to download the clip as it will to synchronize with the streaming server. If a clip is several minutes to an hour, streaming should be considered, as download would take a very long time. If content is greater than an hour, CD-ROM or DVD should be considered. If web delivery is required, it is recommended that the content be broken up into smaller and shorter pieces.

Question #2 -- How are students going to access this material?

The method by which students will access media content is an important consideration. There are several options for students to access content.

Campus Network

Campus InfoLabs and libraries provide high speed LAN connections through which students can access content. In this scenario, downloaded or streamed delivery can be chosen and the delivery speed is not an obstacle. A higher quality will be achievable through downloading content. However, if content is very long these public workstations may have limited disk space in which to hold the downloaded content.

Home Access - DSL & Cable Modems

A recent student computing survey showed that 48% of students have access to high speed Internet connections at home. Students using DSL or cable modems can have download speeds of 256kb to 1.5Mb available to them. These connection speeds are fast enough to receive better than average streamed content and download content in a reasonable period of time (from 1- 5 minutes for longer clips). If content is longer then a couple minutes, streaming is recommended, because not all formats allow for progressive download (a process by which a movie is delivered as it is being downloaded, instead of having to wait for the entire clip to download before it can be played).

Home Access - 56K Modems and slower

There are still a significant number of students using 56k modems or slower to connect to the Internet. Campus modem pool access is showing a decrease in usage each semester. However, if a high number of students in a course will be accessing content in this manner, delivery of media content can be difficult. If content is only several seconds long, download is probably the best method. Streamed content to this audience will usually be of a very low quality, particularly if it is full motion video. Consider narrative presentation technology for this audience. This solution can deliver lecture length content to students by streaming slides with a synchronized audio track. If content is longer than 1 or 2 minutes, delivery using a CD-ROM or DVD is probably needed. This will ensure that students receive a clean and crisp version of media content.

Learn@UW

Learn@UW warrants special attention as it relates to video and audio. Learn@UW provides the ability to restrict access to content to students only. There are some potential issues with regard to Learn@UW, however. If the clip is of a smaller size (under 2MB) download using Learn@UW may be fine for 56K modem users. It may be better to create a reference file which points to an file on the streaming server and place that inside Learn@UW. See the Video with Learn@UW lesson for further recommendation.

Question #3 -- What type of content is to be delivered?

There are different types of media content that can be delivered to students. Each has different challenges and recommendations.

Audio

Audio can be delivered very successfully to almost all students. A five minute audio clip with full stereo can be compressed to 3-5 MB and can be delivered via download or streaming. Streaming would be a better solution to 56K modem users, however, as a file of that size might take up to an hour to download.

Narrated Presentations

A narrative presentation consists of a slide show with a synchronized audio track. It is often a better way than delivering a full motion video of a presentation, particularly if the speaker isn't showing anything that is relevant to understand the content. A narrated presentation can be very successfully streamed to all kinds of users. Since it contains no video, file size is small. For an hour long presentation, however, this file could still be large enough to prevent it from being delivered via download. Streaming this type of content is recommended.

"Talking Head" Video

A talking head video usually consists of audio and video track of a presentation or lecture. There is usually little movement occurring. The lack of movement makes it possible to compress this type of content and deliver via streaming and still maintain an acceptable degree of quality. Most talking head videos are of a longer length and therefore, we recommend streaming in most cases.

Procedural Videos

Many faculty wish to deliver a video which captures the steps needed to complete a lab procedure or demonstrate a particular concept in an animated manner. These videos are usually shorter in length with moderate amounts of movement. Because clarity is very important in these clips, delivery via modem may be difficult. Some formats will provide acceptable quality and others will not. Our experience suggests that streaming using Windows Media Player provides the highest quality at this rate, with streaming with QuickTime provides the lowest quality when delivering to users with slow connections. Downloaded content using QuickTime can provide a very acceptable quality. CD-ROM would be another acceptable method of delivery.

Full Motion Video

There are times when a full motion video clip needs to be delivered to students. Again, 56K modem users are going to be the most difficult group to serve. Most full motion video clips are longer than 5 minutes and can be up to 10MB or more in size -- taking a modem users an hour or more to download. CD-ROM delivery is best for this group. As for the other groups, either download or streaming would work equally well.

Question #4 -- Does access need to be limited to protect content?

Faculty may be using material for which they don't own the copyright. They may also want to prevent non-students from accessing content. There are several solutions in place which will help accomplish these goals. First, streaming content never resides on a student computer. If the goal is to protect access to content, streaming is the best way to do so. QuickTime can also be used to prevent downloaded content from being saved. It can also be used to conceal the actual URL of the streamed media clip. Learn@UW can be used to restrict access to content to students only. This will help maintain fair use of copyrighted material. Web Servers can also be configured to restrict access to certain IP addresses or require a password. This would allow downloaded content from only being accessed by students. QuickTime also included the ability to embed a media key to view content. Students can be given the key via email. Those who don't have the key will not be able to content. DoIT is looking into providing IP restrictions on the Streaming Server, as well.