THL Toolbox > Audio-Video > Audio-Video Help For End Users
Audio-Video Help For End Users
Contributor(s): David Germano.
Media players
The delivery of audio-video over the Web continues to be beset by significant problems. Web browsers themselves don't have built-in support for playing audio-video and hence require "plug-ins" to provide that function. Fortunately, these plug-ins are available for free, and the most common are QuickTime 7 or greater, RealPlayer and Windows Media Player.
THL practice: Quicktime is the recommended free Web browser plugin for THL to play audio and video (download from Apple at: www.apple.com/quicktime/download/). It is required for THL's streaming audio-video content (see below). The "progressive download" or "fast start" versions of audio-video now being made in THL are all MPEG-4, or MP3, which can be played in any standard media player. However, older versions in THL are at times available only in formats that require the use of QuickTime as the media player.
Bandwidth issues
The major problem is that audio-video files are simply too large to deliver easily over the Web given the continuing limits of bandwidth. In simple terms, "bandwidth" simply refers to how wide the pipe is through which information is sent to users via the Web. A simple modem conneciton has a very narrow pipe, while cabel modem, DSL and other "high" bandwidth connections have a much wider pipe. The wider the pipe, the higher the bandwidth, and hence the faster information arrives to your local computer from the Web. When the information sent over the Web is too large for the width of your Web connection, you either get excessively slow downloads or it may simply not work. Because audio-video files have a great amount of information, they are thus far more difficult to deliver over the Web than text files, and hence require high bandwidth. For this reason, the "raw" audio-video content is never delivered as such over the Web, but rather first the file is "compressed" in various formats. "Compression" in simple terms involves making the file smaller by eliminating detail _ the resultant file is much easier to deliver through a narrow Web pipe-connection, but the audio-visual quality suffers since detail has been eliminated. Thus one is balancing quality with deliverability. These different compression schemes are what is referred to with labels like MPEG-4, MPEG-1, MP-3 and so forth.
THL practice: The typical user only has to be concerned with two issues as pertains to compression. Firstly, is the compressed format supported by the media player they have installed in their computer. On this front, if you simply get the free QuickTime plug-in, you will be fine for all THL content. Secondly, you have to make sure that you are accessing the right compression for your bandwidth. We typically make three levels of compression that are labeled to indicate the general type of Web connection they are suited for:
- 56k modem (low): the smallest and hence fastest form, but also the worst quality; suited for slow Web connections
- cable modem (medium): intermediate quality and size; suited for reasonably fast Web connections
- fast ethernet (high): the highest quality, but also the largest files and hence slowest to access; suited for fast Web connections
Of course these labels are relative. For a short audio-video title, even a 56k modem connection might be sufficient to view just 1 minute; for a long audio-video title, even a user with a very fast connection may prefer to use the inferior compressions in order to not have to wait excessively. In practice, users must simply try out the different formats and come to determine their own preferences.
Finally, we use MPEG-4, the emergent global standard, for all three levels of compression. We also create MP-3 audio files. Thus each title _ at least from June, 2003 - comes in four versions: low, medium and high quality MPEG-4 versions of the video, and a MP-3 audio-only version.
Streaming vs. progressive download
Another crucial issue surrounding use of audio-video content is streaming vs. progressive downloads (also known as "fast start". "Streaming" means that the audio-video is is delivered over the Web in small packets as you play it, rather than downloaded onto your computer from the Web before playing. Thus you can specify you want to listen to the middle of a file by dragging the playbar to that point, and the player will communicate only that small segment surrounding the middle to you as you watch it, skipping over all the earlier parts of the audio-video. The benefits of this are obvious _ one can listen to various parts of a long title without waiting for the download of earlier parts one has no interest in. However, streaming technology is greatly hampered by bandwidth still _ if the quality of the streaming video is too high for the bandwidth of your Web connection, then you will only see stuttering video frames, frozen video, or even worse. Thus if a streaming video is playing back erratically, most likely the culprit is that the quality of the streaming is too high for your Web connection, and its choking the pipe such that much of the streaming material is lost in transmission. The only solution is to try a lower quality streaming if available. Streaming thus is often relied upon when one is not as concerned with the quality, but wants to make the experience of using the media as immediate as possible.
The other way to deliver audio-video content is to simply have it downloaded from on to the user's computer, and then played as local content. The advantage of such a delivery system is that once downloaded, the computer — assuming it is an up to date computer — can play very high quality audio-video. In addition, the files can played subsequently while off-line, and the process need not be repeated. The downside is that of course the download can be extremely slow, and if one is interested in a later part of the audio-video, one must wait until the download gets to that segment. Thus Apple introduced "fast start" or "progressive download" formats, which essentially allow one to start viewing the content as soon as any portion is downloaded without having to wait for the entire media file to be downloaded. This doesn't solve the problem of not being able to see the middle or later portions of a title from the start, but it does allow one to watch the initial portions of a title while the rest is downloading in the background. Fast start downloads thus are often used when one is concerned to get the highest quality playback.
THL practice: as of June 2003, THL's practice is to create both streaming and fast-start versions of all three levels — low quality, medium quality and high quality. While this takes additional staff time to create and additional storage space on the server, it provides optimal flexibility on the user end. Associated content: cataloging records/metadata, subtitles, transcripts and annotations
One of the most exciting developments in the use of audio-video is the emergence of new tools that allow for creating associated textual data in the form of cataloging records, subtitles, transcripts, annotations and the like. For the present purposes we can divide these into three classes:
- Cataloging: cataloging databases keep track of "metadata" about the audio-video titles, namely "data about the data" in the form of catalog records which detail the actors, location of the recording, thematic information and so forth
- Transcripts: a variety of programs allow one to transcribe speech in the audio-video, or create independent narrative "voice-overs", which can then be delivered as real-time subtitles or as transcripts synchronized with the playback of the audio-video
- Annotations: annotation features allow one to make annotations on specific segments of the audio-video; in contrast to "transcripts", our use of "annotations" signifies more extensive notations on the content rather than textual content to be viewed in real time as the audio-video plays
Catalog databases are powerful amplifications of audio-visual materials, since they allow users to search on diverse criteria to find titles corresponding to their interests. Thus a user can find a title corresponding to a specific place, topic or time. In addition, such databases can offer "collections" views, which allow users to browse through presentations of collections of affiliated titles _ such as "the festivals of Nepal", or "monastic life in Tibet" and so forth. Ultimately, such archives can be used to integrate the media titles with other archives, such that a map or gazetteer of places could request all media content with place=Lhasa, and have that media content automatically delivered it to simply on the basis of the titles being cataloged with recording location.
Just as powerful is the ability to associate audio-video with textual resources, such that one can view a written translation of an interview with a Nepali politician which highlites the relevant section as the video plays, or view the translation of a Tibetan scholar's lecture on a text while also viewing the text itself on which s/he is commenting. Such programs are opening up audio-video materials to the same analytical and creative uses we are accustomed to applying to texts, and are especially valuable when working in an international context where language barriers greatly impede the use of audio-video content.
THL practice: THL has created its own on-line audio-video system for management of workflow on audio-video, as well as creating a permanent cataloging record of each audio-video title in THL. It not only allows searching on multiple criteria, but also has an attractive collections view that allows one to browse through the various collections of affiliated audio-video titles. The audio-video database also provides direct links from cataloging records to the actual files, allowing users to specify which type of compression they want (high, medium, low or or audio-only), and whether they want to view annotated transcripts (when available). The same interface allows one to view the materials on-line, or download the materials for subsequent use on their own computer while off-line.mode=content">permanent cataloging record of each audio-video title in THL. It not only allows searching on multiple criteria, but also has an attractive collections view that allows one to browse through the various collections of affiliated audio-video titles. The audio-video database also provides direct links from cataloging records to the actual files, allowing users to specify which type of compression they want (high, medium, low or or audio-only), and whether they want to view annotated transcripts (when available). The same interface allows one to view the materials on-line, or download the materials for subsequent use on their own computer while off-line.
One of THL's major technological initiatives has been to create a suite of software that allows for the creation of rich, annotated and timecoded transcriptions of audio-video titles using multiple languages and scripts, as well as their playback for users. QuillDriver is the software used for creating such transcripts, while Savant is the procedures for delivering that content over the Web or off-line. Please see QuillDriver and Savant respectively for details.
Troubleshooting
Conflict between media players
Question: I get a broken looking interface where the media player should be.
Answer: It is quite common in Windows for media players like RealPlayer and Quicktime to struggle with each other over control over audio-video playback. This can create problems when one media player takes over control of your playback, and forces you to use it to playback a specific compressed format of audio-video file which in fact requires another media player. Thus if you try to play a video but you get a broken looking interface and no coherent playback, the first culprit to look for is the wrong media player trying to take control. Unfortunately, since different sites you use may suggest you different media players, this can be quite frustrating. THL suggests you stick with QuickTime as your default media player if you will be using THL audio-video collections routinely.
The issue at stake is video players and file associations. The Windows operating system keeps track of what video player you prefer to use for a specific type of video format. Unfortunately, RealPlayer and QuickTime—two of the most common video players—sometimes try to wrest control of these associations without the user's permission. For example, at times RealPlayer can switch the user's choice of QuickTime as the default video player, and will inform the user with an alert, "The application listed below has repeatedly attempted to change your choice of RealPlayer as your default media player. RealPlayer has been re-established as the default player for the media types listed below?h. If the media file type in question is an .mpg, .mp3, or .mp4, then both QuickTime and RealPlayer should work fine. However the .mov files that we use are specific to QuickTime and cannot be played by RealPlayer. If Windows File Associations force RealPlayer to display them, it will not work and you will see a confusing and broken interface for playing videos in our Media Database.
The solution is to open up the media players, and unchoose such preferenes for one, and re-choose such preferences for the other. From the Windows Start Menu open RealPlayer. Click on "Tools" in the menu of RealPlayer, and choose Preferences. Within RealPlayer click Media Types. Then scroll through the list and uncheck any file types that you would like to be handled with QuickTime. It is essential that .mov file types NOT be handled by RealPlayer. Then click OK. Now set QuickTime as your default player for QuickTime files. This can be done in one of two ways. The first is to open the QuickTime player and click Edit -> Preferences -> QuickTime Preferences. Then select File Type Associations from the drop-down menu. Make sure that middle box, Macintosh File Types is checked. The second way to set QuickTime as your default player is to use Windows directly. To open Windows Explorer in XP, click on Start -> Program Files -> Accessories, . On the menu, then choose "Tools", and then from Tools choose "Folder Options". Click the tab, "File Types". Find the file formats in question (.mov), and change the default application back to QuickTime. It may be necessary for you to quit your browser application, such as Internet Explorer, and then reopen it before the changed file associations will go into operation. Unfortunately any time you upgrade RealPlayer it will generally repeat this switch, making you go through the entire process again. In summation, the .mov files are the only files that require QuickTime. .mpg, .mp3, and .mp4 files can be viewed with any standards-compatible browser plug-in for those file types.
Stuttering playback
Question: Why does the fast start video stutter on playback?
Answer: Fast start videos allow playback to begin while they are still being downloaded. On some computers with low power or bandwidth simultaneously playing the video while downloading might create problems, such as a stutter. In such cases, it is best to wait until download is finished because the computer is able to focus on one disk-intensive task at a time. If this does not solve the problem, see the question below for troubleshooting QuickTime Issues.
Broken QuickTime logo
Question: Why is there a broken QuickTime logo in my video window?
Answer: This has to do with a change in plug-in support in Internet Explorer 5.5 and 6.0 . To restore compatibility, Apple has provided an ActiveX control in QuickTime 5.0.5 and later. You can download latest version of QuickTime. Once you have the new ActiveX control installed, you are unaffected by this issue. See this article for more details.
Troubleshooting QuickTime in Windows
Question: Where can I find more information on Troubleshooting QuickTime for the Windows platform.
Answer: Try this page at apple.com or this discussion group.
Streaming doesn't play
Question: Why do the streaming media not play at all?
Answer: If streaming media stall out in the "configuring" phase and won't play, one possible reason is that your firewall is blocking it. If you disable the firewall, the streaming should play fine. However, there is no simple way to explain where your firewall settings might be - check with your computer vendor or other technical support staff you to which you may have access.
Streaming stutters and freezes
Question: Why does the streaming media stutter and freeze?
Answer: Most likely you have chosen a higher quality media (and hence larger file size) than your internet connection's bandwith can handle. By choosing a lower quality media, you should be able to get a smootly streaming version. In cases of extremely poor internet connections, it may be that you can only play back audio.
