AdminXP.com: Aspect ratio, FlaskMPEG

Aspect ratio, FlaskMPEG

Aspect ratio

The aspect ratio is important to be mentioned because of different TV screen standards and screen types. Before a film comes to DVD, its input format is usually a classical film or an analog record from a video camera. The output format can be a wide-screen film with aspect ratio of 16:9 or a classical film having aspect ratio of 4:3.
The input format specifies the internal aspect ratio, while the output format can specify the external aspect ratio. The output format is also dependent on the screen type - classical monitors display the image recorded in the 16:9 aspect ratio deformed, not complete or with black bands at the top or/and at the bottom of the picture area.
Within the world, you can find two main standards: PAL - ( 720x576) and 25 images/s (1:1,25 - 5:4) and NTSC - ( 720x480) and 30 images/s (1:1,5 - 6:4)
Display's abilities: Monitor - 4:3 and (1:1,33), classical TV - 4:3 and (1:1,33), TV with the 16:9 format - 16:9 and (1:1,77)
DVD usually provides the format of 16:9 - the image on classical TVs and monitors contains then black bands at the top and at the bottom of the picture area. When updating, it is advisable to trim these black bands, because the player adds them automatically, and then they waste too much of the display capacity. Some films already contain these bands, some do not.
Besides these standard formats you can also meet some other ones - the difference is compensated by black bands in necessary size.
Unfortunately, some players tend to stretch the trimmed format out the whole screen, so the aspect ratio is not kept and the image gets deformed. E. g. the player from ATI does this in the fullscreen mode, on the other hand, Windows Media Player and MicroDVD are well-tried as for this topic.
The trim size can differ for each film according to the format in which it is stored (16:9 or 4:3) and different position of black bands stored together with the film.

Example of setup for DVD output in the FlasKMPEG program

When setting up the trim, first choose an output format and then select desired trim by using buttons. There is a very useful option for setting the left and the upper edges (this option is missing in DVD2AVI-Gui)...
Trim - use buttons to set the output size that is displayed by help of a white dashed line in the preview.
Upper offset - trimming the upper part.
Height - size of the output image.
Left offset - trimming the left part. Beware of trimming essential parts of the film.
Width - size of the output image.
Output size - changes the output resolution.
LetterBox - adds black bands to both sides of the picture area.
Keep aspect Ratio - keeps the right aspect ratio
The limitation lies in numbers divisible by number 16. When setting up the trim, you can encounter a problem with black bands or lose several lines or columns.
Recommended trim for a 4:3 film - 528 x 320 - 544x432
Recommended trim for a 16:9 film - 528 x 320 - 544x304

Custom procedure of DVD films transfer

Copying and decoding files from a DVD disk to hard disk (e. g. SmartRipper). The output files on the disk are already decoded, so they are not equal to those on the DVD disk.
Dividing film into particular parts - video, audio, subtitles.
Converting the parts of the film, the sound tracks and subtitles into a new format. Film, sound and subtitles are converted separately, then the film and the sound are put together into a complete film.
Storing on one or more CDs.

Basic parameters influencing the total size and quality of the film

Resolution - affects number of picture points on the screen. The lesser resolution, the better compression. But there is another factor that crucially affects the total time of the video - data stream.
Data stream - defines the maximum compression level. Demands on the size rise with details displayed on the screen (standing and moving objects in the film require each different compression).
Audio format - MP3 codec is most frequently used for audio compression. However, an hour film can have several dozens of MB in the final size. There exist some data stream settings, most often 128kbps and lower.

Examples of compression demands

A random sequence of a film having 15000 picture (10 minutes) processed on a computer with CPU AMD 1Ghz.
Conversion of a two-hour film including audio and codec setup to 2pass takes usually more than 10 hours on a CPU 1Ghz.
656x360 - 672x496 - bitrate 800 - 1pass - Divx codec 4.12 = 63.825.408b (16 minutes 32s) - video only
656x360 - 672x496 - bitrate 800 - 2pass - Divx codec 4.12 = 55.365.120b (33 minutes) - video only
656x360 - 672x496 - bitrate 800 - 2pass - Divx codec 4.12 = 67.551.232b - with 112mp3 audio

Flask MPEG

Advantages: great amount of settings that are easy to control, lucid settings for trimming, option for building subtitles in the video (not recommended, however, a lot of users still use this), easy settings for different output filters for sound and video.
Disadvantages: much time needed for processing caused by displaying particular pictures when coding.
Must be emphasized before using that this program can be added with different modules. The basic version of this program can be quite too simple and having very few functions. E. g. some original versions of the program cannot read the IFO files...

Program cannot read the IFO files....

Solution: download files ending *.flask and containing support of another language environment (lang directory) and able to read the IFO files (main directory and "thunder.mism.flask" or "css.mism.flask" modules).... or functions extending coding options...

Starting compilation

Menu File - Open - choose a directory containing the copied DVD and select an IFO file.
You are in graphic environment - select video, sound and subtitles if needed.
A video player that has a lots of functions will be started...

Besides standard player buttons, there are another controls: scroll bar, another 7 buttons and a white task window. The mentioned 7 buttons enable to create and delete tasks. Current task (a film sequence) is always marked with a blue line in the scroll bar. The starting value is one task - a whole film. But if you want to e. g. remove subtitles at the beginning or at the end of a film, it is advisable to change this task.
" |_ " button - marks the beginning of the task
" _| " button- marks the end of the task
" |_<< " button - jumps to the beginning of the task
" >>_| " button - jumps to the end of the task
Add - adds a task
Delete - deletes chosen tasks
Delete All - deletes all tasks
Using the "FlasK it!" button you will start coding to a chosen format
Select Output - here you select the AVI Output and in the player´s menu you can choose and configure the Divx codec by help of Output Format Options and the Video Select Codecs button.

Choosing format

Configure - this option you will find in the player´s menu, or in the program´s menu - Global Options. Here are 4 bookmarks available.
Video - it is advisable only to change the resolution, other parameters should remain without changes.
Audio - options for processing audio tracks - Do not process, Process with output plugins setup, Save sound track into a file.
Post Processing - recommended to leave the default settings and to go to trim configuration (Show Output PAD)..
Files - setting up the destination for files
General - options for adjusting the film´s length and turning off the computer after finishing the compilation.

Related coding tools

DVD2AVI (1.74) - arbor.ee.ntu.edu.tw/~jackei/dvd2avi
DVD2AVI_Gui (1.08Pre) (go.to/dvd2avi_gui)
FlasKMPEG (0.60) - www.flaskmpeg.net
VirtualDub (1.48) - www.virtualdub.org
NanDub (1.0rc1) - www.nandub.org