Amount of Video that is cropped out when a VCD is played in a standalone?greenspun.com : LUSENET : Video CD : One Thread
Hello. Since I'm only burning standard NTSC VCDs at 352x240, I'm curious of exactly how much of that original MPEG is being cropped when the burned VCD is played on a standalone DVD player? I decide to play several of the original MPEGs on my PC, while playing the burned VCDs on the standalone. As I watched both at the same time, I could see that the TV was showing less of the actual video than the PC playback of the MPEG. It clearly showed that the DVD standalone cut off portions of both sides, as well as the top and bottom. 5%?, 10%?, I can't tell. This is the reason for my question, and if anyone knows of a "magic formula" that will disclose how much is lost, then please post that info here.
Also, since this obviously happens to all VCDs, does anyone do anything to make the original MPEGs play in full frame on their DVD player? Such as, adding borders before burning, or re-encoding everything in WS format?
-- Jeremiah (Jeremiah@noemail.com), June 11, 2002
This is what is called safe-area. In conventional analogue video NTSC there are 525 vertical scan lines of which only 480 is supposed to be visible, the remainder spent for vertical interval lines, and unused video lines (not really unused; the broadcaster or whatever can put reference signals, close-captioning signals, copy-protect pulses, and time code on them). On a new, properly calibrated TV still only about 450 of the 480 will be seen because the TV is deliberately overscanned to reflect such. As a TV gets older the picture shrinks because the high-voltage slightly goes down. To avoid the possibility of making visible the unwanted lines I mentioned above as it ages so overscanning when new is done. Of course u can see all the 480 lines on the PC monitor and compare and see that indeed 5 to 10% is not visible on a TV. NLE program (Premiere and MediaStudio among others) users are made aware of and have to contend with this all the time.
-- Mehmet Tekdemir (email@example.com), June 11, 2002.
Thanks for the reply. So, are you saying that this is always just accepted? If this is the case, why not re-encode everything to a size that would allow the entire video to be displayed on a TV? Encoding it is such a way so that the "safe area" only consist of borders and not the actual video? Why then, is 352x240 the standard size for NTSC VCDs? Wouldn't 310x210 be the approximate proper size then of the visible picture? If the remainder were always borders, then I think that we would always see the full video?
For example, let's say I cap a CNN interview. As you know, CNN runs a newsbug across the very bottom of the screen throughout the day. So if it is encoded to 352x240, then the newsbug would not be visible when that MPEG is then burned to a disc and played back on a standalone DVD player. Of course, the newsbug WOULD still be visible when playing the MPEG on the PC, just not when the VCD is played on the TV. What if I wanted that newsbug to be displayed when I play back the VCD?
So is this just accepted? Obviously, most action doesn't appear on the very top or bottom of the screen, but often the top of heads would be cut off during this process. Just curious if this is simply accepted as the "way it is" and no one does anything to work around it.
-- Jeremiah (Jeremiah@noemail.com), June 11, 2002.
When creating something for TV the mindset is of invisible borders within the frame and any noteworthy thing you want guaranteed to appear on TV later is deliberately not placed outside this frame. For example TV logos are placed about 10% down and left of the upper- righthand corner; on TV they appear snugly in the corner but on the PC or any other display device where all pixels can be seen there are swathes of space around it. The borders are there all along but instead of a deliberate rectangle they are invisible. If you will use Premiere you will see on creating titles a dashed-line safe area where what you will put will be guaranteed seen on TV later. Personally I like to see a whole cropped picture (because of the borders/overscan) than to see deliberate 'black' borders around. This is why we nowadays deliberately have 16:9 screens, so that we avoid having to contend with the black bars on top and bottom of a 16:9 program on a 4:3 screen. And the newsbug WOULD STILL be visible even if you captured that CNN segment, encoded to MPEG and created a VCD with it: in the exact same manner you saw it earlier. Try it.
-- Mehmet Tekdemir (firstname.lastname@example.org), June 12, 2002.
there are areas that dont show up on tv intentially, but the vcds are copys of what appeared on the tv. I hvae episodes of a tv show, captured then put into vcd. when i watch the episodes when they are on, i see the same picture that i see when watching the vide on my comp. so its not supposed to be cropped, you follow?.
-- James (email@example.com), September 14, 2003.