Whitepaper-WebBasedCourses With Video v2

8/14/2019 Whitepaper-WebBasedCourses With Video v2

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Whitepaper

Web Based Courses with Video

Authored by:

Chirag Solanki, Ashish Majumdar, Amitabh Jain, Shubhadeep Ghosh, Venkatesh C

Dated:

July 3rd, 2007

Please post your views, comments, queries, suggestions on this whitepaper on:

http://videooverweb.blogspot.com/
http://videooverweb.blogspot.com/http://videooverweb.blogspot.com/


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Acknowledgement

We would like to thank Jon Pollack and Vishal Dube for their valuable inputs during theprocess of this research.

Disclaimer

This document is for information sharing purpose only and is created from various sources on

the internet and our internal test lab results. No information from this document may be usedor produced for any commercial purpose. We do not hold the responsibility of validity ofsourced data. The purpose of this document is not to highlight or promote or relegate any ofthe products studied during the research or mentioned in this document.


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Table of Content

1 Background and Purpose ............................................................................................ 4

2 Basics of Video (terms and terminologies) ................................................................. 4

2.1 Video standards: NTSC and PAL ....................................................................... 42.1.1 Frame size ................................................................................................... 4

2.1.2 Frame rate ................................................................................................... 5

2.1.3 Pixel aspect ratio ......................................................................................... 52.1.4 Interlaced and progressive video ................................................................ 5

2.2 Bit rate/Data rate ................................................................................................. 6

2.3 Keyframes ........................................................................................................... 6

2.4 Codec .................................................................................................................. 62.5 Encoding Methods .............................................................................................. 7

3 Flash Video ................................................................................................................. 7

3.1 FLV (Flash Video) Formats ................................................................................ 73.2 Codecs supported by Adobe Flash Players ......................................................... 7

3.3 Encoders/Compression Suites ............................................................................. 8

3.4 Video Delivery methods in Flash ....................................................................... 8

3.4.1 Embedding video within SWF files ............................................................ 83.4.2 Progressive download ................................................................................. 8

3.4.3 Streaming video .......................................................................................... 9

3.5 Comparison of various Flash video delivery techniques .................................... 94 Best Practices for using Flash video ......................................................................... 12

4.1 Input video Specifications................................................................................. 12

4.1.1 Source Quality .......................................................................................... 12

4.1.2 Frame Motion............................................................................................ 134.2 Encoding Best practices .................................................................................... 13

4.2.1 Considerations When Encoding ................................................................ 13

4.2.2 Recommended Flash Video Encoder Specifications ................................ 144.3 Brainvisa Test Lab results ................................................................................. 15

4.3.1 Recommended Flash Video Encoder Specs with VP6 Codec: High-Motion

Video 154.3.2 Recommended Flash Video Encoder Specs with VP6 Codec: Low-Motion

Video 16

4.4 References ......................................................................................................... 17


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1 Background and Purpose

Delivery of Video over web has been one of the requirements and challenges thatvarious corporations in the world have been working towards. Some have been ableto surge ahead and develop solutions & best practices for themselves for the

implementation of the same. However, still, there are quite a few organizationswhich find themselves lost and longing for basic collated information &recommendations on the strategies to be adopted to fulfill their needs.

Through this whitepaper, the authors have attempted collation of relevantinformation, best practices and exhaustive test lab results, to help various entities

interested in creating Flash-based courses with video content. It is aimed at giving

an overview of the Basic concepts of Video media, Flash video concepts, deliverymethods and recommendations.

2 Basics of Video (terms and terminologies)2.1 Video standards: NTSC and PAL

The leading formats in use today are NTSC (National Television System Committee)and PAL (Phase Alternating Line). Generally speaking, NTSC is the standard used in

the Americas and Japan, whereas PAL is used in Europe, Australia, the Middle East,and Asia.

Table: Video standard differences

Frame size Frame rate Aspect ratio Display

NTSC 720 x 480 29.97 D1 Interlaced

PAL 720 x 576 25 D1 Interlaced

Computer Varies(much larger)

Square Progressive

2.1.1 Frame size

Conventional television screens are made up of horizontal lines, while computermonitors consist of a series of horizontal and vertical pixels. The standard lineresolution for an NTSC television is 525 lines; for PAL, it is 576 lines. Most modern

computer monitors have much higher vertical resolutions (measured in pixels), suchas 768 or 720, requiring vertical up-scaling during playback in order to fill themonitor.

For NTSC video images, the SMPTE 259 M professional standards specifies that the

525 lines be represented as 720 x 480that is, 720 horizontal pixels by 480 verticalpixels.

For PAL video images, frames are always 720 x 576 pixels, regardless of videosource.


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This default video size is commonly known as D1.

2.1.2 Frame rate

Video is essentially a sequence of images flashed on the screen in rapid succession,

giving the illusion of motion. The number of frames displayed every second is knownas the frame rate, and the speed of the movie's playback is measured in frames persecond (fps). The higher the frame rate, the more frames per second will be used todisplay the sequence of images, resulting in smoother motion. The trade-off,

however, is that higher frame rates require a larger amount of data to display thevideo, and therefore require more bandwidth.

NTSC video is usually said to run at 30 fps, and PAL runs at 25 fps. When workingwith compressed video in a format like Flash video, frame rate can affect the qualityof the video in hard-to-predict ways depending on how the video and its specific

content is encoded. Lower frame rates ostensibly provide less content to encode,

which theoretically improves quality or decreases file size. At the same time,however, it makes it more likely that there are noticeable changes in the pixels from

one frame to the next, which requires more data to encode. If the frame rate is

lowered and the data rate is left unchanged, the video may appear to stutter andmotion may look less fluid than desired.

2.1.3 Pixel aspect ratio

The D1/DV NTSC and PAL specifications specify non-square pixels (often called D1aspect ratio), while computer monitor pixels are square (1:1). D1 pixels arevertically shorter. For this reason, when one looks at a D1 video image on a

computer monitor, the images appear to be squashed verticallymaking actorsappear to be shorter. When this image is displayed on a broadcast monitor, thepixels are wider than they are tall and appear normal.

2.1.4 Interlaced and progressive video

Video images consist of two interlaced fields that together make up a frame.

Modern video standards for digital television have eschewed interlacing in favor ofprogressive scan display techniques. Progressive scan video cameras usually havethe ability to switch back from progressive scan to interlaced video, and most of

these cameras have a variety of frame rates that can be used with and withoutinterlacing. Typical frame rates are described as 60p (60 fps progressive), 30i (30fps interlaced), 30p (30 fps progressive), and 24p (24 fps progressive). While

working with progressive video footage there is no need to de-interlace the video

clips before deploying them to the web.

More details can be found at:http://www.adobe.com/devnet/flash/articles/video_guide_06.html
http://www.adobe.com/devnet/flash/articles/video_guide_06.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_06.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_06.html


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2.2 Bit rate/Data rate

Bit rate is the amount of data transferred per second. Total bit rate is the summation

of Video and Audio bit rates, associated with the video. While encoding a Flash video,

one can specify a bit rate for the encoding. For example, if most of the users are

likely to be using 56kbps modems, it is not advisable to use a video that is encodedat a bit rate of 2Mbps.

The standard formula for calculating bit rate:frame height x frame width x frame rate (fps) = total bits/sec.

2.3 Keyframes

Flash video is encoded as a sequence of keyframes (full-frame uncompressed images

taken from the video at regular intervals), each of which is followed by informationabout how to change the pixels of the keyframe to produce the delta frames between

that keyframe and the next. During playback, the decoder recreates the delta frames

based on the keyframes.

The keyframe interval is the number of delta frames between keyframes. The greater

the interval between keyframes, the harder it is for the decoder to recreate themissing frames. Also, if the keyframe interval is too great, one does not have a large

enough data rate to compress and transmit the data bits. Therefore, a high-motionvideo clip with a large keyframe interval results in the perception of poorer quality.

With Flash video, keyframes are particularly important if the presentation approach

provides seek or scrub feature, which allows a user to advance the stream duringplayback.

Formula for Keyframe Interval:frame rate (fps) x interval (sec.) = keyframe interval

For more details, please visit:http://www.adobe.com/devnet/flash/articles/video_guide_03.html

2.4 Codec

"Codec" is a technical name for "compression/decompression". It also stands for"compressor/decompressor" and "code/decode". All of these variations mean thesame thing: a codec is a computer program that both shrinks large movie files, and

makes them playable on computer. Codec programs are required for the media

player to play downloaded music and movies.
http://www.adobe.com/devnet/flash/articles/video_guide_03.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_03.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_03.html


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2.5 Encoding Methods

Constant bit rate encoding and variable bit rate encoding are the two options,

available for most streaming packages (including those that compress the FLVformat), for compressing a file within the limit of the data rate ceiling:

Constant bit rate (CBR) encoding keeps the set data rate to initial settingover the whole video clip. CBR is recommended only if the clip contains asimilar motion level across the entire duration.

Variable bit rate (VBR) encoding adjusts the data rate down and to theupper limit set by the developer, based on the data required by thecompressor. VBR takes longer to encode but produces the most favorableresults.

Many compression packages support a two-pass VBR. The first pass allows the

compression package to analyze the video and store information about it before it

starts the encoding process in the second pass. This option increases the time it

takes to compress the video but yields much better results. Both the Flash VideoExporter and Sorenson Squeeze support two-pass VBR encoding.

Reference:http://www.adobe.com/devnet/flash/articles/flv_encoding_03.html

3 Flash Video3.1 FLV (Flash Video) Formats

FLV can come in 1.0 and 1.1 format. FLV 1.0 is supported by Flash 7 and FLV 1.1 is

supported by Flash 8. The only difference between the two is that FLV 1.1 hasmetadata injected into it.

3.2 Codecs supported by Adobe Flash Players

Sorenson Spark or ON2 VP6 are the codecs used for encoding video that is to beplayed on Flash player. Sorenson Spark is supported by Flash player 6 and aboveand ON2 VP6 codec is supported by Flash player 8 and above.

The VP6 video codec is the preferred video codec to use when creating Flash contentthat uses video. VP6 provides the best combination of video quality while maintaininga small file size.

References for further details:

http://www.adobe.com/devnet/flash/articles/video_guide_03.html http://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f2

3110762d6b883b18f10cb1fe1af6-7ca8.html
http://www.adobe.com/devnet/flash/articles/flv_encoding_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_03.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_03.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_03.htmlhttp://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f23110762d6b883b18f10cb1fe1af6-7ca8.htmlhttp://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f23110762d6b883b18f10cb1fe1af6-7ca8.htmlhttp://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f23110762d6b883b18f10cb1fe1af6-7ca8.htmlhttp://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f23110762d6b883b18f10cb1fe1af6-7ca8.htmlhttp://livedocs.adobe.com/flash/9.0/UsingFlash/help.html?content=WSd60f23110762d6b883b18f10cb1fe1af6-7ca8.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_03.html


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3.3 Encoders/Compression Suites

Support for encoding Flash Video files is provided by an encoding tool included with

Adobe's Macromedia Flash Professional 8 product, On2's Flix encoding tools,

Sorenson Squeeze, FFmpeg and other third party tools.

If one wants the advantages of a dedicated Flash 8 video encoding application, the

primary options are On2 Flix Pro 8 and Sorenson Squeeze 4.3. These third-party

encoding software packages offer two-pass VBR encoding. Results from bothproducts look great. In fact, it is difficult to see much difference between video clipsencoded with them.

For further details on these third party encoders, please visit:

http://www.sorensonmedia.com/pages/?pageID=2 http://www.on2.com/products/flix/flix-pro/ http://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.ht

ml

3.4 Video Delivery methods in Flash

The Macromedia Flash MX 2004 products enable one to deliver on-demand video in

any of the following ways:

Using embedded video within SWF files. Using progressive download FLV files. Using Streaming video from a Flash Media Server or from a hosted

server using Flash Video Streaming Services/ or any other streamingservices.

3.4.1 Embedding video within SWF files

In this approach, video content is embedded within SWF files by importing video andplacing it on the Timeline in the Flash authoring tool. When the SWF file is published,the video is fully contained in that file. This approach requires only a normal web

server to deliver the video.

3.4.2 Progressive download

Flash Player 7 introduced a new technique called progressive download, whichenables developers to use ActionScript commands to feed external FLV files into a

SWF file and play them back at runtime. More specifically, one can use the

netConnection and netStream commands to set the FLV file to play back, and tocontrol the Play, Pause, Seek (to a timecode), and Close behaviors and thebuffertime and size for a given video file.
http://www.sorensonmedia.com/pages/?pageID=2http://www.sorensonmedia.com/pages/?pageID=2http://www.on2.com/products/flix/flix-pro/http://www.on2.com/products/flix/flix-pro/http://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder_02.htmlhttp://www.on2.com/products/flix/flix-pro/http://www.sorensonmedia.com/pages/?pageID=2


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3.4.3 Streaming video

The most complete, consistent and robust delivery option is to stream video and

audio files from a server running Flash Media Server. In streaming, each client opens

a persistent connection back to the video server, and there is a tight relationship

between the video being delivered and the client interaction. This approach facilitatesdelivery features such as bandwidth detection to serve up the right size video,quality of service metrics, detailed tracking and reporting statistics, and a wholerange of interactive features along with the video experience.

Customers who do not want the difficulty and expense of buying and maintainingserver hardware and Flash Media Server software can get all the benefits ofstreaming Flash video and MP3 files with the Flash Video Streaming Service. This

service is a load-balanced, redundant deployment of Flash Media Server, hosted by aMacromedia-authorized Content Delivery Network partner.

For more information about the Flash Video Streaming Service, please visit theMacromedia website atwww.macromedia.com/go/fvss.

A lower-cost alternative is Flash Video Streaming Service Lite, which also allows oneto stream Flash Video from a hosted service. However, with Flash Video Streaming

Service Lite, one can author only using the Flash Video extension for Dreamweaver.

In other words, one can't author in Flash for Flash Video Streaming Service Lite, andso it is not possible to new skins, add interactivity, or synchronize the video with text

and graphics. These features are available in the full version of Flash VideoStreaming Service.

3.5 Comparison of various Flash video delivery techniques

Embedded Video ProgressiveDownload Streaming Video

Encoding Video and audio is

encoded on importinto Flash using

the SorensonSpark codec.

Alternately, FLVfiles (encoded

elsewhere) can be

imported andplaced on the

Flash Timeline (re-

encoding is notnecessary).

FLV files are encoded

externally from theFlash authoring

system eitherthrough the Flash

Video Exporter and athird-party nonlinear

editing or encoding

product or a stand-alone video encoding

application such as

Sorenson Squeeze.

Same as progressive

download. In addition,one can capture and

record live video feedsfrom client-side

webcams or DVcameras and control

live encoding variables

such as bit rate, fps,and video playback

size programmatically.

File Size SWF files contain

both the video andaudio streams aswell as the Flash

SWF and FLV files

are kept separate,resulting in a smallerSWF file size.

Same as progressive

download.
http://www.macromedia.com/go/fvsshttp://www.macromedia.com/go/fvsshttp://www.macromedia.com/go/fvsshttp://www.macromedia.com/go/fvss


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Embedded Video Progressive

Download

Streaming Video

interface, resultingin a single, larger

file size.

Start Time Heavy SWF filesoften require users

to wait a long time

before seeing anyvideo. Non-

desirable user

experience.

Starts pretty fast. Immediate. The fastestway to go from Play to

actually seeing the

video.

Timeline

Access

When embedded

in the FlashTimeline, videoappears on

individual

keyframes and can

be treated like anyother object on

the Stage.

Video is played back

only at runtime.Individual keyframesare not visible on the

Stage. Timeline

events can be

triggered at selectedtimes of video

playback.

Same as progressive

download.

Publishing Each time the

Flash movie is

published ortested, the entirevideo file is

republished.Changes to videofiles require

manually re-

importing filesonto the Timeline.

FLV files are only

referenced during

runtime. Publishingto the SWF format ismuch faster than

with embeddedvideo. FLV files canbe updated or

modified without

changing the SWFfiles for a project.

Same as progressive

download. One can

dynamically pull FLVfiles from virtuallocations, such as the

storage area networkor the Flash VideoStreaming Service

content delivery

network.

Frame Rate Video frame rate

and SWF movieframe rate must

be the same.

FLV files can have a

different frame ratethan the SWF files.

Same as progressive

download. Live videocapture has

programmable control

over the frame rate.

ActionScript

Access

Video playback

and control is

achieved bycontrolling the

movie's playbackon the Timeline.

Flash MX 2004includes severalbehaviors for

controlling videoand audio

playback.

The netStream

command can be

used to load, play,and pause through

external FLV files.

Same as progressive

download. Server-side

ActionScript can alsobe used to provide

additional functionalitysuch as

synchronization ofstreams, server-sideplaylists, smart

delivery adjusted toclient connection

speed, and more.


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Embedded Video Progressive

Download

Streaming Video

Components No video-specificcomponents.

Media components(Flash MX

Professional 2004

only) can be used toset up and display

external FLV filestogether with

transport controls(Play, Pause, and

Search).

Same as progressivedownload. Also one

can use Flash Media

Server communicationcomponents for

streaming live andmultiway video.

Seek andNavigation

Ability

Requires theentire SWF file to

be downloadedbefore the usercan seek or

navigate the

video.

User can only seek toportions of the video

that have beendownloaded.

User can seekanywhere at any time.

Web Delivery Entire SWF file

must bedownloaded to theclient and loaded

into memory in

order to play backvideo.

FLV files are

progressivelydownloaded, cached,and then played from

the local disk. The

entire video clip neednot fit in memory.

FLV files are streamed

from Flash MediaServer, played on theclient's machine, and

then discarded from

memory in a play-as-you-go method.

Performance Audio and videosync is limitedafter

approximately 120

seconds of video.Total file durationis limited to

available RAM on

the playbacksystem.

Improvedperformance overembedded SWF

video, with bigger

and longer video andreliable audiosynchronization.

Provides best image

quality, which islimited only by the

amount of available

hard drive space onthe playback system.

Improved efficiencyfrom a web deliveryperspective, with

optimal bit rate

delivery on an as-needed basis to asmany customers as

necessary.

Video Stream

Control

None. None. Full control over what

gets delivered when to

clients.

Live Video

Support

No No Yes

Compatibility Flash Player 6, 7 Flash Player 7 Flash Player 6, 7


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Recommended criteria for selecting Delivery Method

Embedded Progressive Streaming

Clip is under 5 seconds long (assuming

optimal file size)

Clip is 5 to 30 seconds long (assumingoptimal file size)

Clip is over 30 seconds long (assuming

optimal file size)

Low viewership expected

Medium to high viewership expected

Instant start

Intellectual property protection

Live video streams

Variable streaming rates based on visitor'sbandwidth

SMIL (Synchronized multimedia

Integration language) usage to control fileselection

References for further details:

http://www.adobe.com/devnet/flash/articles/flv_download.html http://www.adobe.com/devnet/flash/articles/video_guide.html http://www.adobe.com/devnet/flash/articles/video_guide_05.html

4 Best Practices for using Flash video4.1 Input video Specifications

In addition to the physical properties of the video there are a variety of factors thataffect the efficiency of the encoder and, ultimately, the user experience of the videoplayback. Two factors play a significant role in the encoding process: source quality

and frame motion.

4.1.1 Source Quality

The source quality of video is determined at the trigger of the recording button oncamera. The lower the quality of (or more noise in) the video source, the higher the

data rate required to render a good playback file. The cleaner (or less noise in) thevideo source, the less data rate is required to render a good playback file.

Whenever possible, one should compress a file from its uncompressed form. If a pre-

compressed digital video format is converted into the FLV format, the previousencoder can introduce video noise. The (first) compressor has already performed its

encoding algorithm on the video and has already reduced its quality, frame size, andrate. It may have also introduced some of its own digital artifacts or noise. This
http://www.adobe.com/devnet/flash/articles/flv_download.htmlhttp://www.adobe.com/devnet/flash/articles/flv_download.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_05.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_05.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide_05.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/articles/flv_download.html


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additional noise affects the FLV codec and may require more data rate to play back agood-quality file.

4.1.2 Frame Motion

Frame motion is another factor to consider in the encoding formula: It is thepercentage of pixel change from one frame to another. This change can result fromcharacter (or actor) events, camera effects, or post-production effects:

Character/actor events include someone walking past the lens, treesblowing, cars driving by, or an extreme close up of a face

Camera effects such as camera panning, zooming, or hand-holding willresult in almost 100% pixel change from frame to frame

Postproduction effects such as dissolves, fades, wipes, or complex videoeffects will result in a high percentage of pixel changes from frame to frame

The information that the encoder has to compress is directly proportional to the

percentage of frame motion within the video clip. If the clip is relatively still (such asa talking head video), there isn't much pixel change from frame to frame. The videocompressor uses a method of dropping frames and then encoding a series of fullyuncompressed frames. These uncompressed frames, called keyframes, are used to

calculate and "rebuild" the missing frames during playback. For more details, pleasevisit:

http://www.adobe.com/devnet/flash/articles/flv_encoding_03.html

4.2 Encoding Best practices4.2.1 Considerations When Encoding

Below are some general rules of thumb to follow when compressing video to FlashVideo for delivery over the Internet.

As the target bandwidth (data rate) decreases, reduce the keyframerate.A lower keyframe rate (for example one keyframe every six seconds)will result in a softer or blurrier image but reduces the bandwidth demand.However, as the required bandwidth decreases, lowering the keyframe

interval, for example, from one keyframe per second at 29.97 fps to two

keyframes per second at 29.97 fps, will make the video play back moresmoothly.

As motion increases, one must increase the keyframe rate, the framerate, and the data rate.High-motion clips require more information to flowto the player. They are not good for low-bandwidth delivery because they

require additional uncompressed keyframes to be encoded in the file. Dial-up connections consume almost all of the available bandwidth. Frame rates are calculated at half-rate, quarter-rate, and third-rate

Whenever the frame rate is reduced, it is always a good idea to use an evenly

divisible ratio of the original frame rate. If the source has a frame rate of 24fps, then reduce the frame rate to 12 fps, 8 fps, 6 fps, 4 fps, 3 fps, or 2 fps. If
http://www.adobe.com/devnet/flash/articles/flv_encoding_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_03.html


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the source frame rate is 30 fps, in most cases one can adjust the frame rateto 30 fps, 15 fps, 10 fps, 6 fps, and so on. If the video is more than 10

minutes long, then audio will drift noticeably out of synch if one do not adhereto the 29.97 fps rate or use an accurate even division for lower frame rates

(such as setting the frame rate to 14.98, which is half of 29.97).

Reduce frame size when bandwidth is limited and frame rate andquality are important. Always enable de-interlacing and set the Flash Video encoder to the

upper field.If the video source that one is encoding comes straight from avideo camera, this feature should always be enabled. If the video isinterlaced, selecting this option increases the performance of the video

encoding and playback. Extra video noise in lower quality video requires additional data rate.

For more details, please visit:

http://www.adobe.com/devnet/flash/articles/flv_encoding_02.html

4.2.2 Recommended Flash Video Encoder Specifications

Tables 1 and 2 below give a head start on adjusting the encoding settings. The most

important variable is the amount of movement in the clip. Fast-moving music videos

need a higher bit rate. Talking-head videos can be encoded using the lower bit ratesettings. Audio settings should be adjusted according to how important the audio is

to the project. Music should be in stereo and go higher than 64 Kbps. Speech clipscan be in mono and go as low as 16 Kbps.

Table 1: Recommended Flash Video Encoder Specs with VP6 Codec: High-Motion Video

High-MotionVideo

TotalBit

Rate

VideoBit

Rate

AudioBit

Rate

FrameSize

Frame RateVideo/Film

Source

KeyframeInterval*

Modem

Streaming**

40K 24K 16Kmono

160 x

1207.5/8 fps 8 sec.

Modem Progressive

80K 64K 16Kmono

160 x120

7.5/8 fps 8 sec.

Small 220K 188K 32Kmono

240 x180

15/12 fps 8 sec.

Medium 400K 336K 64Kmono

320 x

24030/24 fps 8 sec.

Large 850K 754K 96K

stereo

480 x

360

30/24 fps 8 sec.

X-Large 1400K 1304K 96Kstereo

640 x480

30/24 fps 8 sec.

* Start with an 8-second frame interval for all, and work down as needed.
http://www.adobe.com/devnet/flash/articles/flv_encoding_02.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_02.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding_02.html


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** No real choice for 56K modem streaming. One must stay under 40K and shouldn'ttake MP3 audio under 16K.

Table 2: Recommended Flash Video Encoder Specs with VP6 Codec: Low-Motion Video

Low-MotionVideo

TotalBit

Rate

VideoBit

Rate

AudioBit

Rate*

FrameSize

Frame RateVideo/Film

Source

KeyframeInterval

Modem Streaming

40K 24K 16Kmono

160 x120

7.5/8 fps 8 sec.

Modem Progressive

50K 34K 16Kmono

160 x120

7.5/8 fps 8 sec.

Small 100K 68K 32Kmono

240 x

18015/12 fps 8 sec.

Medium 180K 132K 48Kmono

320 x

24030/24 fps 8 sec.

Large 350K 286K 64Kmono 480 x360 30/24 fps 8 sec.

X-Large 600K 504K 96Kstereo

640 x480

30/24 fps 8 sec.

4.3 Brainvisa Test Lab results4.3.1 Recommended Flash Video Encoder Specs with VP6 Codec: High-

Motion Video

Modem Streaming**

Modem Progressive

Small Medium Large X-Large

Total Bit Rate 40K 80K 220K 400K 850K 1400K

Video Bit Rate 24K 64K 188K 336K 754K 1304K

Audio Bit Rate 16K mono 16K mono 32Kmono

64Kmono

96Kstereo

96Kstereo

Frame Size 160 x 120 160 x 120 240 x180

320 x240

480 x360

640 x480

Frame Rate Video/FilmSource

10 fps 10 fps 12 fps 30 fps 30 fps 30 fps

Keyframe Interval* 8 sec. 8 sec. 8 sec. 8 sec. 8 sec. 8 sec.

Uncompressed Video of15 Seconds

13.7 MB 13.7 MB 32.4 MB 134 MB 299 MB 530 MB

File Size SorensonSqueeze

108 KB 157 KB 424 KB 767 KB 1.61 MB(Audio -MONO)

2.66 MB(Audio -MONO)

ON2 Flix 82 KB 158 KB 410 KB 785 KB 1.55 MB 2.90 MB

Flash 8Video

Encoder

91 KB 165 KB 433 KB 773 KB 1.58 MB 2.59 MB

QualityRating(Video)(1 is Highest)

SorensonSqueeze

1 1 3 3 1 1


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ON2 Flix 3 2 2 2 2 2

Flash 8Video

Encoder

2 3 1 1 2 3

QualityRating(Video)

(1 is Highest)

SorensonSqueeze

1 1 1 1 2 1

ON2 Flix 2 2 2 2 3 2

Flash 8Video

Encoder

3 3 1 1 1 1

* Start with an 8-second frame interval for all, and work down as needed.

** No real choice for 56K modem streaming. You must stay under 40K and youshouldn't take MP3 audio under 16K.

4.3.2 Recommended Flash Video Encoder Specs with VP6 Codec: Low-Motion Video

Modem Streaming

Modem Progressive

Small Medium Large X-Large

Total Bit Rate 40K 50K 100K 180K 350K 600K

Video Bit Rate 24K 34K 68K 132K 286K 504K

Audio Bit Rate 16K mono 16K mono 32Kmono

48Kmono

64Kmono

96Kstereo

Frame Size 160 x 120 160 x 120 240 x180

320 x240

480 x360

640 x480

Frame Rate Video/FilmSource

10 fps 10 fps 12 fps 30 fps 30 fps 30 fps

Keyframe Interval 8 sec. 8 sec. 8 sec. 8 sec. 8 sec. 8 sec.

Uncompressed Video of15 Seconds

13.7 MB 13.7 MB 32.4 MB 134 MB 299 MB 530 MB

File Size SorensonSqueeze

92 KB 104 KB 214 KB 399 KB 728 KB 1.16 MB

ON2 Flix 84 KB 107 KB 198 KB 354 KB 674 KB 1.12 MB

Flash 8Video

Encoder

91 KB 114 KB 211 KB 377 KB 692 KB 1.16 MB

QualityRating

(1 is Highest)

SorensonSqueeze

2 1 1 1 1 1

ON2 Flix 3 2 2 2 2 1

Flash 8Video

Encoder

1 2 2 3 2 1

QualityRating(Video)(1 is Highest)

SorensonSqueeze 1 1 1 1 1 1

ON2 Flix 1 1 2 2 2 2

Flash 8Video

Encoder

2 2 1 1 1 1


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4.4 References

http://www.adobe.com/devnet/flash/articles/encoding_video_03.html

http://www.adobe.com/devnet/flash/articles/flv_download.html

http://www.adobe.com/devnet/flash/video.html

http://www.adobe.com/devnet/flash/articles/video_guide.html

http://www.adobe.com/devnet/flash/articles/selecting_video_encoder.html

http://www.adobe.com/devnet/flash/articles/flv_encoding.html

http://www.flashvideofaq.com/

http://www.sorensonmedia.com/pages/?pageID=79

http://en.wikipedia.org/wiki/Frame_rate

http://netforbeginners.about.com/od/multimedia/f/codec.htm

http://img157.imageshack.us/img157/2878/sorensonsparkvson2vp6ko6.jpg

http://www.michaeldvd.com.au/Articles/PALvsNTSC/PALvsNTSC.asp

http://www.communitymx.com/content/article.cfm?cid=BD063
http://www.adobe.com/devnet/flash/articles/encoding_video_03.htmlhttp://www.adobe.com/devnet/flash/articles/encoding_video_03.htmlhttp://www.adobe.com/devnet/flash/articles/flv_download.htmlhttp://www.adobe.com/devnet/flash/video.htmlhttp://www.adobe.com/devnet/flash/video.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding.htmlhttp://www.adobe.com/devnet/flash/articles/flv_encoding.htmlhttp://www.flashvideofaq.com/http://www.flashvideofaq.com/http://en.wikipedia.org/wiki/Frame_ratehttp://en.wikipedia.org/wiki/Frame_ratehttp://netforbeginners.about.com/od/multimedia/f/codec.htmhttp://netforbeginners.about.com/od/multimedia/f/codec.htmhttp://img157.imageshack.us/img157/2878/sorensonsparkvson2vp6ko6.jpghttp://img157.imageshack.us/img157/2878/sorensonsparkvson2vp6ko6.jpghttp://www.michaeldvd.com.au/Articles/PALvsNTSC/PALvsNTSC.asphttp://www.communitymx.com/content/article.cfm?cid=BD063http://www.communitymx.com/content/article.cfm?cid=BD063http://www.communitymx.com/content/article.cfm?cid=BD063http://www.michaeldvd.com.au/Articles/PALvsNTSC/PALvsNTSC.asphttp://img157.imageshack.us/img157/2878/sorensonsparkvson2vp6ko6.jpghttp://netforbeginners.about.com/od/multimedia/f/codec.htmhttp://en.wikipedia.org/wiki/Frame_ratehttp://www.flashvideofaq.com/http://www.adobe.com/devnet/flash/articles/flv_encoding.htmlhttp://www.adobe.com/devnet/flash/articles/selecting_video_encoder.htmlhttp://www.adobe.com/devnet/flash/articles/video_guide.htmlhttp://www.adobe.com/devnet/flash/video.htmlhttp://www.adobe.com/devnet/flash/articles/flv_download.htmlhttp://www.adobe.com/devnet/flash/articles/encoding_video_03.html

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