When you first asked about which to select for "Conversion for 4:3 Input video", I already guessed that you will also ask about the difference.

The old TV display standard is still being used in many countries which is the full-screen 4:3 (or 1.33:1) format.

There are 3 commonly used screen formats being used eventhough different countries may use slightly different ratios.

I believe a picture is worth a thousand words so I have prepared some sample pics to add to my explanations.

3 screen ratios commonly used...

a) Full Screen 4:3 (or 1.33:1) > As used by traditional old TV for the old SD TV channels.
b) HD Television Standard Wide Screen 16:9 (or 1.77:1) > As used by all LCD/LED/Plasma HD TV.
c) Cinema Standard Anamorphic Wide Screen, Aproximately 22:10 (or 2:39:1) > As used by Cinemas.

Of course there are other different ratios used such as the (35mm, 65mm, 70mm) formats, Todd-AO format, the IMAX large screen theatres, etc BUT I used only these 3 commonratio sizes to make my explanations simpler.

Sample Pictures (inside spoilers)...


As you can see from the sample pics above, if the same hieght is used as a comparison, the shortest is (a) and the longest is ©.

When 3 such different screen ratio sizes are used, there will be a problem in trying to get the "best fit" for our TV. Why ? Because, generally there are 2 common TV types being used to receive the TV channels.

2 common types of TV screen size used...

a) The old CRT TV which can only accept SD resolution... Screen size ratio : Full Screen 4:3
b) The new generaton thin HD TV which accepts HD/SD resolution... Screen size ratio : Wide Screen 16:9

Ok... lets talk about each of the 2 TV types.

For CRT TV
Its screen size is "full screen 4:3". No problem to fill the entire screen for videos that are originally 4:3.

But how to fit the videos that was filmed in (1) Wide Screen 16:9 and (2) Cinema ~22:10 which are "wider in ratio" to this TV Full Screen 4:3 size ? Well, the answer is simple. Reduce the video screen size to fit the 4:3 TV screen.

Here's the sample pics of fitting and preserving different videos in correct ratios to the Full Screen 4:3 TV...


As you can see, the 2 Wide Screen videos have been reduced in size to fit the TV 4:3 screen BUT there will be top and bottom black bars that appear on the screen.

These black bars are what the movie industry people refer to as... "Widescreen In Letterbox Format", hehe.

Because the Cinema ~22:10 is much much wider, you will notice that the black bars will be much bigger and many people don't like this, hehe.

I have heard of many people's complains before so it doesn't surprise me when someone tells me... "Why ? I have an old 29 inch TV and I don't like to watch movies which look soooo small now, why don't they show it on the entire TV screen"... BUT in order to do that... they have to cut-off a lot of the left and righ side of the movie and zoom in to fit the 4:3 TV screen losing a LOT of important video details... can you imagine cutting of 2 persons talking to each other and each person standing at the extreme left and right screen area and then you will hear them talking but see no people in the screen.

Many times they can do cut-off the left and right side of the video screen and used a process called "Pan And Scan" technique which involve moving the screen area left and right according to what is important or who is talking.

Ok, to partly answer your question for Byond box connected to old CRT TV, the Byond do NOT have setting for "Conversion of 16:9 Input video". It will always refit Wide Screen videos (HD TV and Cinema formats) to "LETTERBOX" with black bars at top and bottom.

For Widescreen HD TV
Its screen size is "Wide Screen 16:9". No problem to fill the entire screen for videos that are originally 16:9.

Well... so how do videos that was filmed in (1) Full Screen 4:3 (old TV films) (2) Cinema ~22:10 fit into this Wide Screen HD TV 16:9 ?

Again, to preserve the correct ratio size, they can choose to use LETTERBOX again but this time the black bars appear at left and right for 4:3 videos.

Here's the sample pics of fitting and preserving different videos in correct ratios to the Wide Screen 16:9 TV...


The Byond Conversion Settings

Ok, to finally answer your question, your Byond box have 3 settings to change the way Full Screen 4:3 and Cinema ~22:10 original-size programs fit into the HD TV screen area.

The 3 Byond "Conversion for 4:3 Input video" settings for Wide Screen 16:9 HD TV...
1) Pillar Box
2) LB Expand
3) Fit to screen

Sample pics of the conversion on the Wide Screen 16:9 TV...

Pillar Box
For "Full Screen 4:3" source programs, the original ratio is preserved so black bars will appear. Good... scenes in video appear correct shape, people appear in original shape. Bad... picture appear smaller with side black bars.

For "Cinema ~22:10" source programs, same thing but black bars appear at top and bottom.

LB Expand
For "Full Screen 4:3" source programs, the video is stretched to fill the screen vertically and horizontally to preserve same ratio and black bars do NOT appear. This is actually "zooming" the entire screen until no black bars appear. Good... no more side black bars and everything appear in correct shape. Bad... scenes in video are zoomed in until a lot of screen areas at top and bottom disappear outside the TV screen and picture sharpness reduced.

For "Cinema ~22:10" source programs, no change or maybe very slight change to fill the small top and bottom black bar. Screen may be zoomed slightly.

Fit to screen
For "Full Screen 4:3" source programs, the video is stretched horizontally only left and right to fill the screen. the original ratio is NOT preserved so that black bars do not appear. Good... no more left and right black bars. Bad... scenes in video appear out of shape, people and everything appear fatter, picture not so sharp due to stretching.

For "Cinema ~22:10" source programs, no change is size. Black bars still appear at top and bottom.

So you need to ask yourself just what you think is the best choice !

Do you want the entire screen area of your HD TV to be "filled up" with no black bars ? If so, choose "Fit to screen" but not good to choose "LB Expand". Well... people will appear "out of shape", hehe.

Do you want everything in the video to appear in their correct original shape, not fat or thin ? If so, choose "Pillar Box" but not good to choose "LB Expand".

In my personal opinion, "LB Expand" is the worst choice because of too much zooming on the wide screen HD TV which makes the picture more blur AND lots of video area at top and bottom "missing"... sometimes can see peoples heads with eyes missing at the top... very ugly. This setting works better on CRT TV (4:3)

Mmm... I have explained enough. I hope I did not confuse you, hehe.

I appreciate your compliments.

Sorry if I am a bit confused about what you mean by "source play". If you are referring to the "source programmes" used by each different channels, then its difficult for me to answer.

The "source programmes" are those movies, TV shows, TV documentaries, TVB dramas, etc. For example... HBO HD Channel 433 always broadcast in 16:9 format but can choose to broadcast the movie "Transformers: Dark Side Of The Moon" in actual 22:10 cinema ratio which will show as letterbox with some black bars on top/bottom... However, HBO HD have chosen to reformat that movie into 16:9 by cutting off a liitle bit of the left and right side of the movie so the movie is shown as full 16:9 without letterbox.

Sometimes letterbox cannot be avoided depending on what source each channel operator have chosen to broadcast. If the channel operator chose to "cut-off" left and right parts of a 22:10 movie, then will get full 16:9. Some channels... example... KIX HD chose to use original source programs in 4:3, reconvert it by expanding left and right to fit 16:9 so everything in the screen will appear fatter and will be slightly more blur picture so it sucks.

It does NOT matter what "source materials" each channel chose to broadcast. You will not be able to avoid poor PQ due to upscaling from SD source, letterbox, screen image appearing "fatter", etc. This happens for ALL satellite broadcasters, not only for Astro.

Ok, to make it simpler, I think this is what you want to know ...

The actual ratio used by Astro for broadcast
1) For all SD channels... in 4:3 format.
2) For all HD channels... in 16:9 format which is the standard adopted by all High Definition TV broadcasters.

You cannot have the best of everything when you choose which Byond setting to use.

Since all the HD channels are broadcast in 16:9, people with Widescreen HDTV will have NO problems viewing HD channels when the source movie/TV show is originally in 16:9... so setting to "Pillar Box" or "Fit to screen" makes NO difference. Aah... there will be letterbox when the source movie is in 22:1 Cinema format.

BUT since all the SD channels are broadcast in 4:3, setting to "Pillar Box" or "Fit to screen" will definitely have difference.

Ask yourself these questions...

a) Do you want to watch all the SD and HD channels in the correct ratio (no fat image) and can accept letterbox with black bars ?
b) Do you hate to see the letterboxed black bars and don't like a smaller picture screen due to black bars and wants the entire TV screen area to be used ?

If you have a Widescreen 16:9 HDTV
Answer to (a)... "Pillar Box" is the suitable choice. This will cause ALL SD channels (4:3) to be shown with letterbox, left and right black bars.

Answer to (b)... "Fit to screen" is the suitable choice. This will cause ALL SD channels (4:3) to be shown "fatter".

If you have an old CRT TV (SD screen 4:3)
Answer to (a)... "Pillar Box" is the suitable choice. This will cause ALL HD channels (16:9) to be shown with letterbox, top and bottom black bars.

Answer to (b)... "Fit to screen" is the suitable choice. This will cause ALL HD channels (16:9) to be shown "thinner". Hehe... not sure about this as I have not tested it on an old CRT TV.

In my opinion, I don't recommend "LB Expand" for Widescreen HDTV because too much area is cut-off from the top and bottom for ALL SD channels. Even the channel logo at the top may go missing ! Well... some people may disagree with me on this and love "LB Expand"... so everyone have the right to choose whatever one feels and believe is the best. After all, its each person's viewing experience that is important, my opinion is not necessarily right for everyone.

Oh... I really don't know how to answer you on how to check the ratio format for any "programme source" when it is playing in any channel. I think you will "sense" that something is wrong, for example... when you see people's face appearing fatter BUT its not accurate because you will get used to it after watching for a long time.

Many people got used to watching SD 4:3 channels when "Fit to screen" is used for Widescreen HDTVs and did NOT notice that everything in the programme appear fatter and happily watch people with fat faces without any complaints. But when changed to "Pillar Box", THEN they complained about the smaller screen area with BIG black side bars on their Widescreen HDTVs !!! LOL !!! 

Speaking for myself only, I prefer "Pillar Box" for my Widescreen 16:9 HDTV because I like the original shape and don't mind the smaller screen area for the SD channels. 

Kakakaka...hehehehehe... the Screen Ratio Choice ! Nobody wins and nobody is right.   

Bingo ! All yes.

The only change is when any channel operator reconvert any source programmes original screen ratio into a different one. For example ... KIX HD sometimes reconvert some programmes from the original 4:3 by expanding the black side bars to become 16:9... eventhough you set to "Pillar Box" for your HDTV, you will still get "fat faces".

That means if the channel operator did not reconvert or meddle with the original source program ratio, then you will get exactly the same result as you mentioned above.

It is the same situation for the Byond subtitle settings. Eventhough I set the Byond subtitle setting to "Disable" which shut off all subtitles, the Bahasa or English or Chinese or whatever subtitle will still appear for some programmes. Many times the channel operator can "hard-code" the subtitle into a programme. Whatever I do to the Byond subtitle setting... if they "hard-coded" Bahasa Malaysia subtitle, then I will ALWAYS see the Bahasa Malaysia subtitle.

Subtitles that can be changed or follow according to the Byond settings are called "Soft-coded" subtitles. Of course there will be no subtitle when the programme did not come with any, hehe.