Converting 23.976 fps to 29.97 fps using CCE and Avisynth.

[digicube]

Hi, this is my situtation. i have a Divx/Xvid file (23.976 fps) which I want to convert to VCD (29.97 fps) using CCE and Avisynth. In my script I added the line ChangeFPS(29.97). The resulting MPEG-1 videos are in sync with the audio when I play them on the PC but I have no DVD player or VCD player to try them out. I have heard from some people what I shouldn't have use this code and should have use telecide() and decimate() from the decomb.dll instead. Does anyone know how to use this code to change my fps? What would generally be the code used?

[adam]

Why would you want to convert 23.976fps to 29.97fps for VCD output? All that would do would make the quality much worse. VCDs support 23.976fps, and that is the preferred framerate to use. If you encode and author at 23.976fps then the dvd player will do the conversion to 29.97fps for you, but since you only have 23.976fps every second, you have less total frames to encode. Given the same bitrate, less frames to encode means more bits per frames and thus higher quality. There are many other reasons why 23.976fps is higher qualtiy than 29.97fps as well. Trust me, always keep it 23.976fps if that is what your source is.

[digicube]

That is because I'm trying to create a NTSC VCD which must be 29.97 fps, am I right?

[adam]

No. NTSC VCD supports both 29.97fps and 23.976fps, and like I said, 23.976fps is much preferred because of its quality advantages.

23.976fps is called NTSCfilm and it is played back at 29.97fps thus complying with the NTSC standard at playback.

[digicube]

CCE states this in the manual.
Video CD
Outputs Video CD compatible stream. This mode can be selected
only if the frame size is 352×240 and frame rate is 29.97
or frame size is 352 × 288 and frame rate is 25 fps.

[digicube]

Yah you're right I guess it must be CCE who can't accept 23.976 fps for NTSC VCD.

[digicube]

Deleted post.

[adam]

The CCE manual is referring to a specific mode it offers. Its an option, its not the rule. I assume it just configures the GOP structure for you to comply with the VCD spec, because really there's not much else to it. You can still encode VCD compliant video at 23.976fps in CCE, you just can't use that option, you will have to make all other settings and adjustments manually.

I don't use RecordNow Max so I can't comment, but I have authored many VCDs at 23.976fps in Nero with no problems. Perhaps there is something else non-compliant about your VCD or perhaps this is a limitation of your particular build of Nero.

[digicube]

Yeah I just have to know how to tweak CCE. Nero do have an option to turn off standard compliance of VCD 2.0 and continue adding the files encoded by CCE. Maybe CCE only encodes to VCD complain video at 29.97 fps.

[digicube]

CCE staff told the video have to be 29.97 fps if I want to convert to VCD. As for now I'll change the frame rate to 29.97 using Avisynth until someone can tell me how to tweak CCE so I can use 23.976 fps for VCD. Changing the frame rate doesn't really degrade anything right? I watch it on a VCD player and cannot see any difference.

[adam]

Either you misunderstood Custom Technology's information they gave you or they are only referring to the VCD option in CCE. I have the IEC specs for VCD and you can check any technical documents on the VCD standard that you wish, believe me 23.976fps is well within the standard. I can also assure you that CCE can produce VCD compliant video streams encoded at 23.976fps just fine. I have done so numerous times in the past and I have verified their compliance with Philip's verification software (they invented the standard.) Perhaps Custom Technology's statements are referring to outputted PROGRAM streams, meaning if you encode both audio and video together it will only be multiplexed according to VCD specifications if you use 29.97fps. The solution is to only encode the video in CCE, which most people do anyway for numerous reasons, and then multiplex your audio and video streams afterward using different software.

Yes, taking a 23.976fps source and converting it to 29.97fps will result in a fairly substantial decrease in quality. First off, you now have about %20 more frames per second. This is effectively like lowering your bitrate by about that amount. A ~%15-20 drop in bitrate makes a huge difference in quality when your bitrate is already so limited such as with the VCD standard.

Furthermore, the only way to get from 23.97fps to 29.97fps is to perform a telecine which requires that the video be interlaced. (Each frame split into 2 fields.) The problem with this is that mpeg1, which VCDs use, does not support interlacing. So you have to either throw out half of your fields (you literally lose half of your temporal information which means less smooth motion and drastically decreased detail) or you blend your two fields into a progressive frame (makes the image substantially blurrier and can lead to interlace artifacts.)

Whether you encode at 23.976fps or 29.97fps you will literally get IDENTICAL playback on the television. If stored at 23.976fps the dvd player does the telecine for you but you avoid all the downsides to the conversion. 29.97fps is rarely used for digital video because of its inefficiency. It is generally only used for analogue media and for video which did not originate as film, ie: DV or camcorders which film in pure NTSC.

I strongly suggest you simply load your video into CCE as is without adjusting the framerate. You do NOT need to enable the VCD option in CCE to get VCD compliant output. Indeed, my version of CCE does not even have this option and I think it probably only refers to how the file is multiplexed. Encode only the video in CCE, and use the encoder of your choice for audio. Then multiplex the streams using something like TMPGenc or BBmpeg. If you are set on Nero than it should work fine with 23.976fps encoded material, I have no problems with it, but you must first ensure that your program stream is properly multiplexed, and this is probably where CCE is failing you. Honestly, I feelVCDEasy (frontend for VCDimager) is a much better and more compliant way to author VCDs than Nero.

[digicube]

Thanks I downloaded VCDEasy and it says the MPEG file require autopadding. My Divx file is 640x480 23.976 fps, I still need to make a script to resize it. Let me try encoding in CCE again retaining the same fps. Do you use CCE? If so maybe I can tell you my settings.

[digicube]

Looks like CCE does not have a profile for VCD NTSCFilm, only VCD NTSC is available. So does this mean I can't make a VCD NTSC Film using CCE? Is there a website that gives the right settings for making VCD NTSC Film using CCE?

[digicube]

yes you're right. I encoded using CCE to seperate audio and video files and multiplex them together using TMPGEnc and NERO accepted it. Thanks. However the purpose for me using CCE is to make things easier and go faster, since I'm not getting it I'll stick with TMPGEnc.

[adam]

Well considering that CCE is at least twice as fast as TMPGEnc, I doubt you will speed up your process by sticking to TMPGenc. Also, TMPGenc has had a long standing bug where it does not correctly mulitplex when exporting a program stream, apparantly just like CCE. The simple fact is that it is much more compatible to encode to elementary streams and then multiplex to a program stream.

As for making VCD compliant settings in CCE, it is an encoder. It will take your source and output it to an mpg stream using whatever settings your source used. So if your source avi does not conform to VCD spec then you will have to resize it through your frameserver. You can use Avisynth, VirtualDub, or even TMPGenc to frameserve to CCE and adjust things such as resolution. This, however, does complicate your process quite a bit so I could understand wanting to simply things with TMPGenc. Yes you can definitely make a compliant NTSCfilm VCD with CCE, you just have to resize to 352x240/288 through frameserving.

If you want faster encoding times and an overall much faster process, then you are going to have to learn how to properly frameserve to CCE or you will have to move to another mpg encoder like Mainconcept. TMPGenc is by far one of the slowest commercial mpg encoders on the market.

[digicube]

Is there a software that can do BATCH multiplex and demuliplex? I like to "set it and forget it" then Zzzzzzz.

[digicube]

Found one. it's a commercial program for businesses. http://www.pixeltools.com/transmux.html and it costs $1000