Last changed 2 Nov 2005 ............... Length about 1400 words (15,000 bytes).
(Document started on 18 Mar 2004.) This is a WWW document maintained by Steve Draper, installed at http://www.psy.gla.ac.uk/~steve/ilig/videotech.html. You may copy it. How to refer to it.

Web site logical path: [www.psy.gla.ac.uk] [~steve] [EVSmain] [videos] [this page]

Video streaming testbed and tech. notes

By Steve Draper,   Department of Psychology,   University of Glasgow.

This page is only a few points I had to pick up for myself and may as well store here as anywhere. No guarantee of accuracy. For more and better information, you need to go elsewhere.

First, here is a set of test cases to work with (return to my main video page for more cases).

Test cases
File download Streaming 1 Streaming 2
Quicktime .mov (Macs) 650 kbytes our trailer John's demo Calum
Windows media .wmv (PCs) 554 kbytes our trailer (may not work) our trailer 2 Jack's demo

  • LTDF streaming video seminars

    URLs look like:
    Quicktime: rtsp://www.psy.gla.ac.uk/steve/streaming/sample_300kbit.mov
    Windows AVI/.wmv: http://130.209.38.90/commemorationday.asx which calls "mms://commsvs1.cent.gla.ac.uk/Psychology/PRS/PRS-Clip-LAN.wmv"

    The indirection via a .asx file allows information on titles, copyright etc. to be added (although these are also usually encoded in the .wmv file); and may allow CompServ to move servers around without disturbing people's bookmarks to the .asx files.


    Temporary test

    Test file download:
    qt
    qt
    wmf
    wmf.czc
    avi

    web header get

  • http://www.dcs.gla.ac.uk/~mitchell/hdr.cfm

  • web server logs

    Points about configuring your machine

    If you want to test machines on their ability to play videos, particularly streaming videos, and to reconfigure them to do so, then you want to:

    Hardware

    One page to look at on hardware requirements: (to support latest Windows player)

    At least for some player software, the sound hardware must be enabled even if you don't want to play the sound, or else the player refuses to work.

    Operating system patches / extensions

    I have heard that on a PC, a widely available OS patch is needed to get Quicktime to work.

    Movie player

    Player software is mostly free; and there seem to be versions of each player for both Mac and PCs.


    Quicktime players: Download page   (General website) At least for my video, you seem to need at least version 6.x Otherwise you get it playing sound but no picture.

    Windows Media player. At least for my video, you seem to need at least version 7.x Otherwise the error message says it can't download the right codec.

    Real player

    Browser protocols

    For Quicktime streaming video, your browser must handle the rtsp (as well as http) protocols. For WMV streaming video, your browser must handle the mms (as well as http) protocols.

    Problems / symptoms

    Symptoms Actual problem, solutions
    Windows player on a PC refused to play the vision because no sound on machine. Fix: change OS to make it at least look as if there were sound.
    Movie plays sound but no vision (quicktime) Upgrade Quicktime from v.4 to v.6
    Movie plays sound but no vision (wmv) Upgrade Windows Media Player e.g. from v.7 to v.9 In Player, choose File menu, Get Info and it shows you the codecs used in that movie being played. In the Apple menu, About Media Player it shows you the version number of the player.
    Movie plays vision but no sound. (Small PC) I seen this, but dunno the details or the solution
    Errors about unable to download a codec (Windows movie) Later version of Windows player needed: at least v.7
    IE browser wouldn't play streaming QT Manually add a protocol helper for RTSP -> Quicktime player
    "Can't do this format" when quicktime Open command on file is attempted ?? Actually: just Mac file type not set on file
    Hangs silently when trying to play QT streaming video Protocol failure in browser. Set its mappings so that rtsp protocol handled by something e.g. Quicktime plugin
    Browser download fails: no apparent result Need upgrade of quicktime to v.6
    IE Browser error page "This page cannot be displayed" followed by "page may be missing". But this is not in fact an error page from the server but from the browser. Although it looks like a missing page / bad URL error page, this is actually a browser (not server) error page saying it cannot understand what was sent. It means it can't do the rtsp protocol: you need to install the quicktime plugin and/or change the settings to point to it.
    Netscape: Page missing page from server Actually, browser unable to do quicktime streaming (rtsp protocol)
    Download (of wmv) fails: displays garble as text IE fix: edit config to use mime type text/plain and suffix wmv mapped to Windows player
    But don't work in netscape because that "mime type taken"
    "The playlist format not recognised" from Windows player for WMF streaming video (in IE on mac) In fact an obscure failure of the WMP plugin to parse .asx files and also do http redirection. Solution: configure browser helper to redirect .asx to the WMP (windows player).
    "Switching transports" message on QT player: Mac OS-X, MAG, IE, streaming opens QT but never does it. ? newer QT?; McClure fix to browser page?
    "connecting..." browser message, but never does. IE, Stuart's machine, attempt to download .wmv file. Machine recognises file suffix type, but browser doesn't: probably MIME type doesn't.
    xx yy

  • Sound not working on a machine that actually had it.
  • Page not found: actually, PC browser unable to do quicktime streaming.
  • On Mac OS9 IE browser wouldn't play streaming QT. Fix: manually add a protocol helper for RTSP -> Quicktime player. On second attempt that got streaming quicktime to work.
  • On res.rm PC in IE, must say "yes" to "do you want to reassign mime types"; and must say "yes" to "do you want to play the movie inside the browser".

    Server stats on viewing the streaming video versions

    Windows streaming

  • http://www.gla.ac.uk/services/computing/video/reports/Report26/
    Hit the link "video content" e.g. http://www.gla.ac.uk/services/computing/video/reports/Report26/Week21Mar2004/VideoContent.html

    Quicktime streaming


    DVD higher level structure

    DVDs are divided into "titles", and then into "chapter points". However their movie parts may be divided into separate "cells", with user interaction (typically on graphics screens with active link points) deciding which cell to play next. In fact I understand there is essentially a programming language for these control flows, with branch and test, access to some parameter values and to a clock for timing, and 16 registers (variables) to use e.g. for keeping a score, counting the number of attempts at something, etc.

    Thus it would be possible to build a piece of CAL (Computer Assisted Learning): play a segment of movie; ask a question (in text or sound or both), and which button the user chooses to press determines which cell they get next e.g. "Rubbish", "Good", explanations of what was wrong, try again, etc.


    Tech. Facts

    MPEG 1 MPEG 2
    CD
    650Mbytes 74 mins
    DVD
    4.38 Gbytes (15.9) 75 mins at max. quality
    PAL or NTSC, but not both
    Quarter area TV screen size/resolution
    352 X 288 720 X 576 frame size
    1.5Mbps (bits) 10 Mbps (bits)

    Picture sizes

    NTSC vs. PAL

    Windows format has neither (and no interlacing). Both MPEGs, and so quicktime, has either NTSC or PAL built in (and with it, resolution and frame rates). However QT can play any QT file on any computer. The problem is probably only with domestic equipment feeding to a TV monitor without much conversion.

    Presumably then a DVD (which definitely is either NTSC or PAL) would play on a laptop regardless, but not on a domestic/specialised DVD player.

    Other things

    CD disks: good for both macs and PCs at once
    Quicktime seems much better at compression than WMF

    DVDs hold files with 3 extenstion types:
    .IFO (control flow data)
    .BUP (backup duplicates of the .IFO files)
    .VOB (the video chunks)
    The VOBs are actually a subspecies of MPEG2 file.


    More wider points

    GIF movie (Netscape only??): press.

    OS "edge" movie:
    original page

    < img src="http://www.g-intelligence.co.uk/emails/select/150104/email/i/2.jpg" alt="" border="0" width="393" height="144" />xx

    still only

    The code: < img src="http://www.g-intelligence.co.uk/emails/select/150104/email/i/vid.jpg" alt="" border="0" width="192" height="144" dynsrc="http://www.g-intelligence.co.uk/emails/select/150104/email/bike.mal" codectype="raolb" xrate="15" cntval="true" />

    local relink

    Web site logical path: [www.psy.gla.ac.uk] [~steve] [EVSmain] [videos] [this page]
    [Top of this page]