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There are a few calculators for conversion parameters such as constant bitrate or proportional resizing. There are a few others applications programmed for this. I hope, that at least a JavaScript fans like this page.
This page uses a JavaScript 1.1 technology. All present significient browsers honor it. The site should works also off-line.
Properties and parameters of converted sequence we can found at VirtualDub on dialog under menu File > File Information. It is true, that this information gives us also a player, or - at worse case - later mentioned freeware util AVICodec. But, the fact, that we can play video does not mean necessary we can convert it into this codec. Most of codecs is playback only! You can not create a video using them. If VirtualDub returns an error, nothing help us - even Microsoft Windows Media Encoder or TMPGEncoder with redefined filters priority. We just have to download appropriate codec.
Pic. 1 - Information about video-file at VirtualDub (collage).
The links can be found e.g. here. Very helpful can be mentioned utility AVICodec. It has a direct link to more than 50 codecs and recognize a few hundred others.
In case of missing sound codec (e.g. AC3) we can try the following camouflage:
We just deceive system and hardware - even that this is a camouflage in its true meaning. It is not the only one way, how to deal with DirectX only codecs, but it works always. Whole converting should take no more than 10% of clip minutage.
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This calculator is de facto meaning less, because when the particullar sequences are added to VirtualDub, the overall time is updated automatically. However, if you are lazy to calculate at babylonian numeric system:
Assume, we have got a cinema-wide movie with 576 x 320 pxls size. Even this size is unnecessary luxus: it is too big to preserve details and sharpness at rational data bit-rates. Generally, the size should be choosen to not cross 150 000 pxls at all area. 200 000 at maximum. Normally, all internet media use canvas up to 80 000 pxls.
Vertical size: from 240 pxl to 384 pxl. The most common size are: 240, 288, 320 a 384. On the other site, horizontal size: from 320 to 720 pxl. Common values are: 320, 352, 480, 512, 576, 640, 704 a 752.
Size 352 and 752 should be prefered, because you can easily expand them to DVD players standard sizes by padding with black stripes. MPEG-4 and internet videos has standard size 320 x 240 pxls. Summa summarum, universal compromise is 352 x 288 pxls.
And this is also alpha and omega at following calculator. After enter the input sizes and choosing the one(only one!) which is desired - you can also enter a different custom value - the other one is calculated. If it is possible to expand it to standard DVD letter-box (352 x 288, or 752 x 576), it will propose it. De facto, it is not so important for computers, because most of codecs can do this adjust on fly during playback. Sometimes even without borring the user. Both sizes should be dividable by 8 or 16 - this restriction comes from principle of JPEG-DCT transformation. Most of modern MPEG-4 or MJPEG codecs has no restriction for sizes (except that must be greater than 0). By the way, even or prime size is often use as preventive technique to avoid grabbing video through TV card hardware directly to MPEG-I, or MPEG-II. But this is only technique of amateurs or semi-professionals. I suppose, dear reader is not one of them. Back to sizes: we can leave them as they are. However, when they will be divideable, we can spare us a few annoying surprises later.
When to resize video? I mean reduce their size, to be strict. Only when you really need to dramatically reduce file-size. Generally, you can take as good starting point fact, that there should be 120 minutes of MPEG-4 video on single CD. Here is the calculator:
There is a special Resize filter at VirtualDub. Choose menu Video > Filters :: Add. You can find all installed filter at dialog window. Resize 2:1 is quickest and returns the most quality result for the most common situation: conversion from full-size to half-size format. Beside this, we choose an universal filter Resize and method Lancozs3 (the most quality), ev. Bicubic precise A = 1.0 (a little bit faster).
Fig. 2 - Setting post-process filters for video-stream (collage). At dialog box Filters click Add and choose desired filter - presented is Resize - which you can later set. Then we can add the next filter - here it is Sharpen. The filters will be applied in this order. Result preview is achieved through menu File > Preview Filtered.
Bitrate, or data-stream-rate, is a balance between size and quality. Overall bitrate is sum of two individual bitrates: one for video and one for sound. Usually we set a bitrate for sound - or we will ignore it at all - and later we calculate bit-rate for video. It is a meaning less to calculate bit-rate for other processes than one-pass constant bit-rate encoding!
As for sound, it is usually quite enough to set bit-rate at interval from 64 kbps to 96 kbps. If there is accustically demanding music at video (orchester, choir, etc.), you can set 128 kbps. Bit-rate over 192 kbps are meaning less because they need really special and costly hardware to heard a difference. As it is at previous calculator, you can copy value from listbox or enter a custom value.
The standard medium is CD-R 80 / 700 MBy. Classic musical CD-R 74 with capacity 650 MBy, as well as CD-R 99 with capacity 870 MBy are already/still rare. CD-(bussiness-)cards are too small for videosequences longer than a few seconds. "Overbooked medium" with extended capacity (712, 671 a 896 MBy) is presently the most sure way how to destroy a CD mechanics! This is also a reason why I ignore them. The same is valid also for a special CD-R VCD medium, which are not normed by ISO. Consequently, they also can destroy a mechanism. The value 736279247 By, which is preseted to calculations is the real capacity of CD-R80 medium (it is a slightly less than declared 703 MBy). As usually, this value can be changed by custom capacity.
As the result we will get a bit-rater for video. There is a safety margin for calculation: compression is not an exact process and additionally, there are also a files with subtitles which we are going to burn together with video-file. So, by my opinion, it is a better to low slightly capacity or final bitrate, than helplessly rage after a few hours long converssion, because the result file is a 200 kBy larger than medium capacity. Audio stream should not be greater than 15% of overall bit-rate, or file-size.
A subtitles tip: when you want to easily switch among a few subtitles (of the same movie, say Movie.avi) with different languages, use a multi-extension. E.g. Movie.EN.srt, Movie.SP.sub, Movie.SK.txt. All three will be loaded by stream switcher and you can easily switch between them. It is a legendary bug of Microsoft Windows which is widely missused by e-mail's viruses.
Anywhere, we set at codec parameters (VirtualDub: Video > Full Processing, Video > Compression) a One-Pass Constant Bit Rate method (sometimes is shortened to 1P-CBR). Our calculations result is the second parameter - i.e. the concrete level of bit-rate. The same we have to do also at audio (VirtualDub: Audio > Full Processing, Audio > Compression) - according to value we set.
The quality is very subjective term, so the commentary should be taken with (a lot of) tolerance. It is my fiction - or invention - based on my experiences and customer reactions during post-process advert video-sequences to CD-cards, presentations and web domains. The value after word-quality-judgement is a percentage at interval length: when the calculated data-bit-rate is e.g. 600 kbps, the quality is "acceptable" and because appropriate interval is 500 kbps to 700 kbs, the quality factor will be 50% For e.g. 700 kbps, the quality is "ordinary" and factor 0%.
These two values are calculated according to the following table, which is also my fiction. However, based on facts and my experiences:
By my subjective judgement, the differencies between MPEG-4 videos quality with overall bit-rate 900 kbps and over are impssible to notice on (usually) dusty and wacky (thumby) computer screen. What about sound? 96 kbps is quite enough. When one has enough money for home-cinema, he has enough money also for original DVD.
Fig. 3 - Settings for video-stream compression (collage). Audio codec and compression is set by the same way. First, we have to check Full processing mode! Then we can choose codec - here it is XviD MPEG-4 - click Configure and we can set. The most important is Encoding Mode - the labels are changing from codec to codec, but their meaning stay. Unless we are creating an archive copy or work copy, we set CBR (constant-bit-rate) one-pass. Finally we enter a calculated value to Bitrate. Two-pass encoding for archivation are usually labeled as 2P, or Low & High Pass. For work copy we should use a one-pass quality--based mode, with quality at least 85%.
This calculator proceed a reverse calculations than previous one. It is meaning less also - as the first one - because all applications for video-editing can divide whole video to a smaller parts (chapters) with desired length (VirtualDub: File > Save segmented AVI). However, it can be useful for preliminary calculations.
You have to enter both bit-rates (video and audio) and medium capacity (choose from list-box or enter directly). As the result, you will get a maximum sequence length (at minutes and seconds) at defined quality which can be compressed into.
AVICodec: is freeware utility for analyzing AVI, RM and WMV files at binary level as well as operating system. It is only for Microsoft Windows. Its purposse is identify exactly which codecs have been used for creating the file. Based on our system analyze we can figure out, what we will need for succesful conversion.
abcAvi: is MPEG-7 information editor for RIFF / MPEG files: I mean e.g. producent, autor of music, release date, genre, age restriction and a few dozen other information. It is a freeware too, but top-quality. Application does not support any DRM system - in fact, it is not necessary.
AVI/(X)(S)VCD Kalkulačka: is also freeware programmed by Tomáš Závodný. It realize calculations like any simillar product - or my before last calculator. I mention it here, because it has very valuable hints at pop-up'ed bubles. The calculator works "on the edge", so you should low down its result, e.g. 920 kbps to 0.995 x 920 = 915 kbps.
GSpot: is professional but still free utility for analyzing AVI and Ogg's files (*.ogm, *.ogg) with possibility of editing a chunks. So something as AVICodec and abcAvi together. Application uses a binary level of analyze (it can by-pass DirectX) so you can use it for checking your whole system. It can really press on a video playback and editing hot-spots - sometimes Microsoft Windows (mostly DirectX) loose its mind. Highly recommended.
VirtualDub: it is probably the oldest and surely one of the most powerful freeware project. For those, who do not known it, it is an editor for non-linear video-sequences processes. It means, that it wil not necessary works at real-time, however, one of contidion to get an approbation from ISO for MPEG-4 compatible is, that codec will works rel-time. But it touches only coding/encoding, not applying the filters. There are a lot of external filters - both for sound as well as for video. Verssion with postfix AI is not so user-friendly, however, if you are professional or you can spend a time to familiar, you can achieve a batch-based results in shorter time. It has direct support for free-licensed codecs (XviD, AC3, OggVorbis).
AVIPreview: is freeware player which should be - for now - an integral part of Kazza Lite ++. As its name suggest, it can play files before the download is completing. To explain, AVI has index at end of the file. The most important is, that it does not intervere to inner file structure and it can find header anywhere. So it can be used not only for previewing during download - it is not rare, that file name and its content does not match at Peer2Peer nets - but also to quick check during conversion. All other players will be stoped by Microsoft Windows, because they will want to reach a file which is already in use. Besides AVI, it can handle all MPEGs (MPEG-I, MPEG-II, MPEG-I Layer III).
DataRelate: is a small util based on Microsoft Access database which can converts "data-relate" untis (transport, archiving, etc.). Its author Jim Singh programmes a few functions additionaly (IP address, colors, hexadecimal converssion), which can be priceless occassionaly. What is the most valuable, it is a detailed description of all untis.
Codecs: http://www.FourCC.org/ This web site is specialized for video and audio codecs. If you have any troubles to find appropriate codec for download, or are you just interesting about them, surf here. You will not be dissapointed. It contains also a few high-tech articles and a few links for other than Microsoft Windows systems (like Apple QuickTime). A light version is here, or you can download it zipped here.
VCD/DVD: http://www.VCDHelp.com/ this domain offers a lot of all kind of tutorials, materials, experiences or FAQs for creating a DVD-players' compatible discs. A specially, the site about particular medium kinds and their real capacity under different burning modes is excellent.
DivX, video in general: http://www.doom9.org/, http://www.DivX-Digest.com/, http://dvd.box.sk/ these domains contains mostly concrete tutorials and extranal links for software (including a few codecs). The biggest is DivX Digest, where also some cinema trailers can be found. The most detailed tutorials and richest forum is at Doom9. DVDBox is the best source for titles and for software. All have a member section - free for real e-mail.
Internet video-stream: http://www.souxin.com/ It is a chinesse web-site specialized for internet streaming video. There are only a few English tutorials. But, there is also the richest archive of software tools. Not only for publishing a streaming video to net. And I will finish on that - I have already gave a link, which is a form of distribution.
If you are wondering about used JavaScripts, please download this archive. There is one more site about panaromatic photos equations used at Apple QuickTime or Ulead Cool360 panoramas. Text is in Slovak, but all calculators are also at English. You will get more examples. You should download also a Cookies' archive (java-scripts considered mainly on time) and Arles templates (java-script for protect a web-page content).
Marián Stach, 2004-04-26
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Marián Stach Prešov, Slovakia Central Europe 2004-04-28