diffrence between NTSC and NTSC Film?

[M7D7G7]

could someone please explain the diffrence. i have the spider-man mpg and was wondering which is better to encode it to?

[g0dZpr0fi7]

Only difference is the framerate.
It is best to stick with the framerate of the source.

[fantomlord]

could someone please explain the diffrence. i have the spider-man mpg and was wondering which is better to encode it to?

if you have the mpeg, why are you encoding it?
or is it bcz it's PAL(25fps)?
if that's the case, try playing it without encoding/converting it...it may work. if it is bcz it's PAL, search for PAL to NTSC for how to convert properly...it's not an easy task

[Macros746]

I would have to agree with fantom....the only reason to worry about NTSC film is if you are converting a DVD to VCD or SVCD...then NTSC supposedly gives you slightly better quality and a smaller file size (although this has been debated on this forum many times)


Macros746

[adam]

Macros746 the quality improvements of ntscfilm over ntsc are not up for debate and they are definitely not slight. Just do a web search on telecine and inverse telecine and you'll understand why.

g0dZpr0fi7 gave the best advice. Keep your framerate the same as the source. This is exactly why its best to use ntscfilm when encoding a dvdrip, because the material on almost all commercial dvds is stored as film.

[AntnyMD]

If your MPEG file is MPEG-1 and encoded at 24, 25, or 29.97 fps, all of these are valid framerates for VCD 2.0. If the audio/video bitrate does not exceed 1.15Mbps, you do not need to re-encode this file.

If your MPEG file is MPEG-1 and encoded at 25 or 29.97 fps, these are valid framerates for DVD. If the audio/video bitrate does not exceed 1.8Mbps, you do not need to re-encode this file.

[kjmacke]

Another thing to think about. My apex doesn't like ntsc film. It seems to skip now and then. I have always converted ntsc film to ntsc 29.97 and they played perfect. I know your player is supposed to convert it fine but my player doesn't so that's why I make everything 29.97. Just my 2 cents worth.

[adam]

kjmacke, just to make sure...You are talking about vcds correct? If so then that is true, some dvd players do not correctly telecine the vcd to 29.97fps. In this case all you can do is re-encode your mpg to ntsc. However, every Apex dvd player I have ever tested seems to have no problem with ntscfilm vcds.

If you are talking about ntscfilm encoded svcds then you did include the 3:2 pulldown flag correct? If not then no wonder its skipping, 23.976fps is not a valid framerate for svcds.

[kjmacke]

Adam I am just doing vcd's. Like I said above in my player 23.976 doesn't do as well as 29.97. My apex is ad-660.

[M7D7G7]

alrighty...i got it all figured out....thanks so much for your help guys!!

--mike

[69moons]

Hey, I know what you're talking about kjmacke. My Apex won't play ntscfilm VCDs correctly either. I mean they are watchable but every few minutes or so they do the speed-up slow-motion thing for a couple of seconds. I have an Apex AD-1500. I brought this topic up a few days ago here and one of the moderators told me that making 30fps VCDs from a 24fps source results in a 20% loss in quality. In other words when you convert a DIVX file with a framerate of 23.976 into a VCD using the NTSC template instead of the NTSCfilm template in TMPGEnc, you lose a lot of quality. I can't believe this to be true. I mean the resulting VCDs don't look any different. I tried them side by side on one disc and I couldn't tell the difference.

And another funny thing is that after hearing about the quality loss, I decided to give NTSCfilm one more try and so I encoded SHREK using the NTSCfilm template. And it played fine! No glitches whatsoever. So I thought, well, maybe I was doing something wrong before so I decided to stay with NTSCfilm on all my future VCDs. Wouldn't you know it, the very next movie I do, Monsters Ball is full of speedups and slowdowns. AAARRRGHHH!

Does anyone out there know if there truly is a 20% loss in quality? And if so, can they explain why that's true. I mean I know that the difference from 24 to 30 is 20% but I know that it's just not that simple.

And does anyone else out there with an Apex AD-1500 NOT have this problem? Because I'm wondering if maybe my computer is to blame. I'm using a slow computer, AMD K6-2 500Mhz, which sort of pushes the minimum requirements for TMPGEnc. Because the only reason I can think of as to why Shrek would come out fine and none of the other movies would is that Shrek is a computer animation with maybe not as much variation in color which might make it easier to encode.

And also I was thinking if the problem really is that my Apex has a hard time with real time telecine conversion, then why aren't the glitches more random? They are all in the exact same places in the movie every time I play it back, no matter where I start the playback.

Oh well, until I get some more clarification on the subject and a possible solution, I'm just going to use the NTSC template.

I wish I would have never even thought about this issue because it just makes me feel that every VCD I make is not as good as it could be. Frustrating.

Thanks All.

[kjmacke]

I have never noticed quality loss by changing frame rate. Like I said before because of my player I always encode to 29.97. To up the quality I just up my bitrate and put movies on two cd's. They look find to me but I could just be blind also.

[adam]

Does anyone out there know if there truly is a 20% loss in quality? And if so, can they explain why that's true. I mean I know that the difference from 24 to 30 is 20% but I know that it's just not that simple.

This has been answered literally dozens of times on this forum. Film originates at 24fps and in order to comply with the ntsc standard it must be telecined to 30fps. The frames are split into fields and some of those fields are repeated to increase the framerate. Frames are literally being added that weren't there before. At 29.97fps you have %20 more frames every second than you started with. Bitrates is the amount of bits every second of your movie gets...so your bitrate is now being distributed over %20 more frames. You have effectively lost %20 of your bitrate and with an already highly lossy format such as vcd or svcd, that basically translates to a %20 loss in quality. You would achieve the eact same result it you encoded in ntscfilm and just lowered your bitrate by %20. Whether you see the difference in quality or not I can assure you that it is always there. Furthermore, since vcds do not support interlaced material you either have to throw away half of your fields or you have to blend them together. Either case is not desirable and results in further quality loss.

69moons how are you reaching 23.976fps? You cannot simply encode to this framerate. If your source is 29.97fps you must do an inverse telecine. Remember those fields were added, you need to remove them in the same way they were added. If you simply convert to 23.976fps then the encoder will throw away random frames which will result in jumpy playback.

Assuming you encoded and authored correctly and assuming that your dvd player just cannot handle the real time telecine, it makes perfect sense that the glitches are consistent. Your dvd player is not performing the telecine its simply outputting the video at 29.97fps. I don't know what physically is occuring because of this. Perhaps it is pausing on that 24th frame for another 5 frames, perhaps after so many seconds it just has to play catch up, regardless whatever your dvd player is doing it is doing it consistently every second. The resulting playback problems will result at the exact same intervals everytime.

If your dvd player truly cannot handle the real time telecine of vcds then yes your vcds are not as high quality as they can be. That doesn't mean they aren't perfectly acceptable as they are and this is definitely not something you should beat yourself up about.

[69moons]

Adam, thanks for the clarification. And I did earlier deduce that this was what you meant when you said I was losing 20% quality by encoding a 24fps source into a 30fps mpeg. The same bitrate is now being spread over 20% more frames but when I compared the two finished products and couldn't really see the difference, I thought about how video is encoded digitally. I mean isn't one of the compression techniques used when compressing video using the same information for pixels or areas that do not change in the following frame? Therefore, if a duplicate frame is being added every fifth frame, then it stands to reason that that fifth frame is an exact duplicate of the fourth. And if this is true, then the information needed for the fifth frame is minimal because there is no change in the makeup of the 5th frame from the 4th. I don't know. I'm no expert but that's why I was doubting the 20% quality loss. But maybe that logic is flawed for mpegs with a constant bit rate. And either way, you're knowledge on the matter I'm sure is far more extensive than mine so I'll just take your word for it.

In any case, bottom line is that I still have to keep encoding 23.976 fps sources using the NTSC template.

Thanks again for taking the time to post a response to my queries.

[adam]

Actually no mpeg encoding doesnt work like that, it would be nice if it did though.