How To Make Small Non-interlaced AVIs From Video Using Speed Razor 3.51

1/ TEMPORAL RESOLUTION: It is often important to deinterlace a full resolution interlaced video clip to prevent blurring between the two fields wherever there is motion (called destruction of temporal resolution). You usually should turn off one of the fields (when making small AVIs such as 320X240). It's usually not a bad idea to do the same for 640X480 AVIs intended for playback on computer screens, unless the aliasing on graphics is more undesirable than the blurring of motion between fields. There are 3 ways to turn off one of the fields. You can put one of the repeat field effects under any video clips that are being converted to AVIs, or you can go under Project/Editing Settings/Setup & set Playback to Field 1 or 2, but don't forget to set it back to Frame when you're done. The third, most often used way is if you use the "Import Scale" feature to trim off excess black from the sides of the picture (usually required for PVR users when making small AVIs), then you should also have "Source is fielded" X ON. Use only one of these methods, usually the last one.

2/ IMPORT SCALE: When making AVIs from PVD clips, the import scale function is usually necessary to trim the black edges off the PVD clip. The import scale function may also be necessary to trim lines below the head switching point at the bottom of the screen or for trimming off closed captioning, VITC & other data that may be at the top of the picture. The import scale function will considerably increase your rendering times because it causes Speed Razor to scale TWICE (i.e. scales it from the trimmed version, up to 720 pixels wide by 480 pixels wide for a PVR, then scales it down to your final size, often 320 X 240 pixels). When in:sync programmed the "Import Scale" feature, they were not thinking in terms of the final file width being anything other than the width that your video card puts out (i.e. 720 X 480 pixels). The ideal solution would be if in:sync programmed Speed Razor so that the "Narrow Image" feature could be used when making small AVIs. That would only require one scaling (not two) so the image quality might be slight better & the rendering time for AVIs would be dramatically less (almost half). To be as versatile as the "Import Scale" feature, the "Narrow Image" feature should be redesigned so that you can trim a different amount off each edge.

3/ GAMMA CURVE: When making AVIs from NTSC video in Speed Razor, only the 7.5 to 100 IRE luma range is normally used (superblack off), so make sure no black detail is below 7.5 IRE when capturing. Most of the AVI codecs have a NONLINEAR GAMMA CURVE that is a little different than video (video is 2.2), so it will cause the detail in the blacks to be clipped or crushed (some detail in black areas will seem too dark or gone altogether). Depending on the picture content, you may want to countercorrect for this in Speed Razor by putting the Gamma effect under the video clip & doing a black stretch. For a mild black stretch of about 4 IRE set the effect at 0.9. For a medium black stretch of about 5-7 IRE set the effect at 0.8 (I recommend this setting). For a heavy black stretch of about 8-11 IRE set the effect at 0.7. Here is my preset for the Speed Razor gamma effect.

4/ AVI AUDIO OUT OF SYNC: It has been my experience when making small AVIs from PVDs using "in:sync's" Speed Razor, that the AVI audio & video are consistently "out of sync" by about 7 or 8 frames (based on 30 frames/second) with all Indeo & Cinepak codecs when played back on the old version 4.0 Microsoft Media Player in NT, or about 3 to 4 frames off using the Microsoft Media Player in Windows 95. Were not talking about audio drift, but a consistent offset of the AVI audio to video from the beginning of the clip to the end, regardless of length. The audio occurs before the video. I don't think this is a problem with Speed Razor, but I'm pretty sure it is a problem with the Microsoft Media Player version 4.0. If you play the same AVI file back using the Active Movie Player (or the even newer Windows Media Player Version 6), it seems to be in sync. There are two workarounds to bring it back in sync if you have to play it back using the old Microsoft Media Player 4.0. If your original PVD & WAV files are single clips, separate the audio from the video & slide the audio to the right along the timeline by about 7 or 8 frames. If your original is many clips, render the small AVI as you normally would, then pull the AVI back into SR (after changing the settings to edit an AVI), separate the audio from the video & slide the audio to the right along the timeline by about 7 or 8 frames, then export it to a file. If the AVI is in 14.985 frames per second mode, just remember that each frame now really represents two frames, so only move the audio clip 4 frames to the right. There will be no quality loss when exporting AVI to AVI since it is only copying the file.

5/ COLOR BIT DEPTH: In Speed Razor, use 24 bit AVIs because 16 bit doesn't seem to work right (at least for Indeo codecs). Actually, I don't think 24 bit AVIs really are 24 bit (16.7 million colors). I've recently learned that some AVI codecs use YUV9 color space which makes them less than 24 bit. I'd like to learn more about this area because I suspect this is one of the reasons that small AVIs aren't particularly efficient with data size.

6/ FRAME SIZE: 320X240 is the usual pixel size for an AVI for CD/kiosk applications & it fits the correct screen ratio of 4:3 so that the picture is geometrically correct. Smaller sizes (i. e. 160x120 or smaller) are sometimes used when extremely small data rates are required such as for internet downloads of AVIs. 640X480 AVIs are more likely to skip frames during playback unless you have a very powerful CPU, a defragmented hard drive, are using the Active Movie Player or new Windows Media Player 6.0 & have little or nothing else running at the same time. Older codecs like Cinepak & Indeo 3.2 don't require as much CPU power & are less likely to skip on 640X480 X 15 frames.

7/ FRAME RATES: If you decide to use a lower frame rate than the original video, set it at EXACT divisible numbers of the original frame rate so you don't get any black frames or unevenness of motion. For example, if the original frame rate was 29.97 for NTSC, set it at 14.985 (not 15) if you want to have new frames half as often. If there isn't much motion, you might be able to get away with a frame rate of 9.99 (not 10). Most clients seem to find a frame rate of 14.985 per second to be a reasonable compromise (& it halves the video data size of the AVI). Sometimes the frame rate will revert to an earlier setting if you enter/exit the "AVI compression setup" area, so verify before clicking OK in the "export file settings box".

8/ EXPORT FIELD RENDER OFF: In the Export File settings area, it is VERY important to turn OFF "Field Rendering" when making non interlaced small AVIs. This should not be confused with the Import Scale area where "Source is fielded" should be left ON. The combination of these two different field settings are interactive & the position you should set them to will vary depending the frame rate (i.e. 29.97 Vs 14.985), the size of image (i.e. 640X480 Vs 320X240) & whether you want to blend the two fields together or not.

9/ TYPES OF CODECS: The Intel Indeo Video INTERACTIVE 4.3 & 5.06 AVI codecs are the best AVI codecs by a country mile (especially for lower data rates)(very similar in quality to the Sorenson codec for Quicktime), but they do require significantly more CPU processing power to play back without flaws (a 486 at 33 MHz isn't fast enough for 320X240 X15 frame/sec & even a low end Pentium may not be enough for some Indeo INTERACTIVE AVIs). These INTERACTIVE codecs are not included in NT 4.0, but you can download them for free at http://www.intel.com/ial/indeo/video/driver.htm   Intel now has a 5.06 version with additional improvements. The Intel codecs may also be freely distributed with your product for the benefit of those who can't download them (the free QuickTime player needs a license if you distribute it). If you don't know what processing power will be used to playback, then it is often safest to use Cinepak (newest version is 1.10.0.26) or Indeo 3.2 codecs which are built into every Windows operating system. Cinepak is a more universal codec, but Indeo 3.2 has skin colors that look more natural (more red) & a bit higher contrast. Indeo 3.2 can look extremely blocky on solid luma levels in the 57 to 95 IRE range (try a 85 IRE solid white screen & you'll see what I mean). Cinepak doesn't have this problem, but the original version (1.8.0.12) that ships with each PC operating system does have a known bug at 100% of data rate that can cause objectionable large pixels blocks in areas with slight gradations or flat colors (such as faces). Cinepak has slightly greener skin colors, lower color saturation (especially for subtle colors), better anti-aliasing at low data rates, but it also looks a bit blockier & has noticeably more noise (or granularness). The Quicktime3 player on the Mac or PC will only play Cinepak AVIs not (Intel Indeo 3.2 AVIs), however the newer Quicktime4 player will play Indeo 3.2. The Quicktime3 player on the PC (not the Mac) will also play Indeo 4 versions but not 5.

If you are producing an AVI to be imported into another utility for further processing & compression (say MPEG-1 or Quicktime3), choose "Uncompressed RGB" so it doesn't suffer additional quality loss from compressing & uncompressing another generation. This will create a very large file (about 3.46 meg/sec without audio for a 320X240 X15 frames/sec AVI) so make sure you have enough hard drive space. Since AVIs currently have a 2 gig limitation, you will only be able to create an uncompressed 320X240 X15 AVI of about 9:38 minutes (8:25 minutes if 22 kHz 16 bit mono audio is used).

There are newer paid Windows Cinepak codec versions available at http://www.cinepak.com/begin.html   The readme file for the new version says "This version improves compression quality, adds some new modes to improve playback in different bit depths and formats, improves the quality of larger frames, reduces the codec's memory footprint, and fixes a few obscure GPFs."

You should be aware that if you take an RGB uncompressed AVI into QuickTime3 Pro for exporting to a Cinepak .mov file, this QuickTime3 version of Cinepak is really just an AVI file. If you rename it from FileName.mov to FileName.avi it will play on PC systems that are not updated with QuickTime3 but have the new Windows Media Player (recent attempts to rename a QuickTime3 Cinepak to an AVI on movies made with Media Cleaner Pro 4.0 did not work). Unfortunately you cannot take a Cinepak AVI created in Speed Razor & rename it to a .mov for use in the QuickTime3 player. That's too bad because it would save having to do the second render & the newer Windows Cinepak codec (version 1.10.0.24) doesn't have the pixel block bug mentioned above. While the older version of Cinepak for QuickTime3 does have that pixel block bug, I found the picture to be a little less posterized than AVIs made with the newer Windows Cinepak codec.

10/ DATA RATES: About the lowest "fixed" data rate that I found acceptable for 320X240 AVIs at 14.985 frames per second, with no audio & a key frame every frame, was 250 k/second. If space is not a problem & you are playing back from hard drives, or if you are including audio, use a higher data rate. This is a very subjective thing & the data rate needed will vary depending on the codec used, the detail in the picture, key framing used & the amount of motion from frame to frame. You have a choice of setting a "fixed" data rate per second which includes any audio you might use (X data rate box & fill in desired data rate) or a percentage of the compression quality that the chosen AVI codec can handle (85% or higher is usually pretty good for Indeo codecs). Choosing a percentage will end up using "variable" data rates depending on how much the subject material needs, which is a more efficient use of data & hence your data size will probably be lower overall while your picture quality in high detailed scenes might be higher. I prefer the percentage setting, unless you have a situation where a spike in the data rate above a predetermined point might cause problems. If you need to conform to a minimum data rate such as 2X CD-ROM speeds (with no spikes above that rate) then you might want to fix the data rate rather than use a compression quality percentage. At 2X CD-ROM speeds, a fixed data rate will probably lower your overall picture quality compared to a percentage that results in the same total data size, but a fixed data rate would be less likely to skip frames on a 2X CD-ROM playback. You'll have to experiment to get the best results for your material & playback hardware. At low data rates, it's always compromise.

The percentage settings are rather logarithmic for Indeo codecs & relatively linear for the Cinepak codec. In other words, the percentage setting using the Cinepak codec is more relative to the data rate used. A percentage setting of 85% may yield adequate results for Indeo. The same 85% for the Cinepak codec doesn't drop the data rate as radically when you set a lower percentage. Both Intel Indeo 3.2 & Cinepak codecs give about the same quality at a given data rate (but not at a given percentage). The Intel Indeo 4.3 & 5.06 INTERACTIVE codecs will give better quality at a given data rate, but not every computer has a powerful enough CPU to play back these codecs without skipping frames. You will have to experiment to find the data rate settings that are suitable for your project.

If you are playing back from CD-ROM, you will be limited to the data rate of the CD-ROM player your client is using. Even though most computers have fast CD-ROMs (4X or faster), the slowest is likely a 2X CD-ROM which has a theoretical speed of 344 kilobytes/sec, but in practice shouldn't be expected to exceed more than about 2/3rds (or about 230 kilobytes/sec) without skipping frames, because the CPU uses system time to uncompress the file & because CD players seldom deliver their rated speed across the whole surface of the disc. Since it is difficult to deliver quality movies at 2X CD-ROM speeds using older AVI codecs & since most modern computers are equipped with at least a 4X CD-ROM player or faster, I would recommend suggesting to your client that the minimum requirement be 4X CD-ROM players (try not to exceed 460 kilobytes/sec).

It should be pointed out that some CD-R burners do not make very good players for AVI & QuickTime movies even though they may be rated as high as 16X play speed (like my Yamaha CRW4416SX). In theory they should play back movie files with no trouble, but in reality they often cause serious skipping problems. I really don't know why CD-ROM burners have problems playing movies (if you know why, please let me know). Usually any current cheap play only CD-ROM will play movies without a problem.

11/ KEY FRAMING: If you really need to get the data rates down so your AVI will play off a 2X CD-ROM without skipping frames, or so the AVI will more quickly download off a web site, or just to save hard drive space, experiment with setting your KEY FRAME every 4 or 7 frames (rather than every frame). If you set key frames at 4, what this does is store a full frame every 4th frame & it just stores the difference data for the other 3 frames in between. It is a pretty good compromise when you want to keep the resolution up & the data rate down. The artifact that this causes is low resolution in the 1 - 3 frames after a change in scenes, until you get to the next key frame. Most clients don't even notice this if your key frames aren't too far apart (i.e.. key frame every 4th frame at 14.985 frames per second, or key frame every 7th frame at 29.97 frames per second). To demonstrate how effective changing the key frame can be, I was able to get the data rate of an AVI file from 352 k/sec, down to 169 k/sec by changing the key framing from every frame, to every 4th frame & the client thought they looked the same. The particulars were Indeo 3.2 codec, 320X240 X 24 bit, 14.985 frames per second, audio at 16 bit mono 22 kHz. If your key framing is left on, do not set it to zero as this will cause only the first frame to be keyed & the image may get progressively poorer in quality the further you play into the file.

When using keyframes of higher values it also limits whether you can look at specific frames in applications like Microsoft Media Player. i.e. keyframing set to 15 only allows you to stop at every 15th frame. Speed Razor can look at each frame regardless of key frame frequency.

12/ PADDING: If your AVIs will be playing back from hard drives, set the padding to meet byte boundary on 512 & if it's playing back from CD-ROM set it at 2048. If you're not sure which it will be playing back from, set padding to 2048 (for Indeo 3.2 & Cinepak). Indeo 4.3 video INTERACTIVE should almost never be set at 2048 as it may adversely affect playback quality.

13/ AUDIO DATA RATE: You will have to determine which audio quality is suitable for the material you have. Changing stereo 44 kHz 16 bit audio 176,404 bytes per second (172.27 kilobytes/second) to mono, cuts the audio data rate to half (about 86.1 KB/sec). Changing the sampling rate from 44.1 kHz to 22 kHz will cut the data rate by half again (about 43.06 KB/sec) & will handle audio analogue frequencies almost up to 11 kHz, which is not a serious compromise even for music. After this you start to make serious compromises in your audio. Cutting the sampling rate to 11 kHz will cut the frequency response to 5.5 kHz which is about telephone voice quality and cuts off high frequency music (about 21.53 KB/sec data rate size). Cutting 16 bit back to 8 bit approx. halves your data rate again (about 10.76 KB/sec) but it has such few samples that 8 bit audio sometimes has an objectionable noise floor when the audio is quiet. I recall someone saying that if you use 8 bit audio, you can clean it up a bit so the noise floor doesn't sound so staticy, in sound programs like Sound Forge or Cool Edit. If you use audio when making AVIs, make sure you turn on "Interleave audio with video" when exporting to a file so you don't get a separate audio file.

Intel Indeo 4 & 5 version codecs now also have an audio compression codec version 2.05 which can considerably reduce the size needed for audio data, however you must make sure that the target audience also has the codec on their system.

14/ BATCH PROCESSING: If you need to batch process a bunch of short PVDs to AVIs since there is no batch processor in Speed Razor, the best way is to render all your PVDs to one huge AVI file, then bring that AVI file into SR as a new project & chop it into the original lengths. You can then "Export to a file selected area" to make individual AVI files (use load settings from file). AVI to AVI at matched settings can be rendered (copied) in faster than real-time & there is no quality deterioration. Try to make your original clip length in even number of frames if you're reducing the frame rate in half.

15/ PLAYING AVIs IN SPEED RAZOR: If you cannot get the AVI to play in real-time on the computer screen (while editing in Speed Razor), this is no longer a DPS codec bug (since PVR codec 2.53 July 96). All you have to do is open the "Perception AVI Codec Configure" & unX "Play to Video Monitor". In Speed Razor under Project/Editing Settings, change the video device to Video (*.avi), then click on "Load settings from file" & reference it to the file you're editing.

16/ DO A TEST. If your video (PVD) to AVI render is a real long one, do a short "Export to a file" test first to make sure it looks right, as rendering times can be pretty long.

17/ SKIPPING FRAMES: The Microsoft Media Player 4.0 in NT 4.0 will not tell you if an AVI file is skipping video frames when the hard drive can't keep up because of fragmentation (& you might not notice this). If you play the AVI file in Speed Razor, it will give you a message whenever it's skipping frames because it uses a different player. Higher AVI data rates (often above 300 k/sec) will often skip frames if the drive is fragmented or if the software codec can't uncompress fast enough, so if this is happening, defragment the drive or copy the AVI to an empty partition. If you download the free new Microsoft Windows Media Player version 6.0 at www.microsoft.com/windows/mediaplayer/download/default.asp you will find this a much better player & it can tell you if the movie file is skipping frames (under View/Statistics).

18/ AVI AUDIO DRIFT: The AVI player in Speed Razor is different than the Microsoft Media Player 4.0 in Windows NT 4.0 & audio will frequently drift out of sync with the video when playing from Speed Razor (audio plays too slowly & won't be finished by the time the video is finished). The larger the data rate, the more it drifts (starts to be noticeable on a 30 second AVI clip above 150 k/sec) Audio does not usually drift out of sync in the Microsoft Media Player (instead it drops video frames). I was using a Pentium 133 & padding to meet byte boundary of 2048. Your results may vary. This AVI audio drift is not to be confused with the 8 frame consistent audio offset sync problem mentioned earlier.

19/ GRAPHICS CARD RESOLUTION & BIT DEPTH. Having a high quality graphics card with acceleration will help display the AVI files without skipping frames. Make sure your graphics card has the latest graphics drivers. If support for Microsoft's "Direct Draw" is available, install it. It is preferable to run your computer screen color depth at more than 256 colors (8 bit) as the picture could look more posterized at only 256 colors, especially if the graphics card doesn't do a real good conversion from the 24 bit AVI. 65,000 colors (16 bit) or 16 million colors (24 bit) will make your AVI look better.

20/ RECOMPRESS I do not fully understand the "Recompress always" & Recompress to match data rate" features, so the follow statement in from Christopher Bond. "I believe recompress always means that when creating a clip it will recompress everything when compressing your files. An example is say you open a 30 sec AVI clip and you change the audio and reoutput it; if you recompress the video will degrade. This also [at least] was an option in animator studio, and you could force it to not recompress some portions of the video that didn't have changes - i.e. an AVI clip where half had a new layer added [composite] it wouldn't recompress the frames before the new stuff was added - which meant better quality during that first portion, but the compression wouldn't match."

There are many other pieces of advice that could be given for processing small non interlaced AVI files but these should get you on your way. Other users might wish to pontificate on the "Recompress always" & "Recompress to match data rate". If you have corrections or improvements to this tutorial, please forward them to me.

By Doug Hembruff.
Last updated June 14/2000