3:2 Pulldown

[VCDHunter]

Am I right in thinking this is for MPEG2 only ? If I try this on MPEG1 I get terrible interlacing.

[SLK001]

Am I right in thinking this is for MPEG2 only ? If I try this on MPEG1 I get terrible interlacing.

If your MPEG1 file is at 23.976fps, then it will also need to be "pulled down" to 29.97fps.

[VCDHunter]

If your MPEG1 file is at 23.976fps, then it will also need to be "pulled down" to 29.97fps.

No, its a DivX at 23.976 fps, but when I attempt to convert to VCD format using the 3:2 Pulldown it gets "interlaced" ( terrible horizontal lines across screen ). Do I have to unlock and adjust some settings in Tmpgenc to enable this to work properly ? When I load the NTSCFilm template and click the 3:2 Pulldown the encode becomes interlaced.

[dphirschler]

You don't want to click that setting. Instead select the "3:2 pulldown on playback" under "encode mode". Also make sure you have loaded the (S)VCD film template.


Darryl

[FOO]

MPEG1 doesn't support pulldown flags

[VCDHunter]

MPEG1 doesn't support pulldown flags

Any chance of a further explanation here Are you saying that the 3:2 pulldown option IS for MPEG2 only ? In so much as everytime I tick that option in Tmpgenc the video will never encode correctly ?

[adam]

VCDs support 23.976fps (NTSCfilm) natively. You do not need to convert to 29.97fps (via the 3:2 pulldown filter) and you do not need to apply the 3:2 pulldown flag (via the video tab- actually its not even possible with mpeg1.) The 3:2 pulldown flag ONLY applies to mpeg2 video. Just use the default NTSCfilm VCD template. Your file will be encoded at 23.976fps but it will play back at 29.97fps.

The reason you are seeing interlacing when using the 3:2 pulldown filter is because it is telecining the video to 29.97fps. It is splitting the frames into fields and repeating them in a 3:2 pattern to increase the framerate. If you view this on your tv it should disply correctly, though this is a much lower quality way to encode versus keeping it NTSCfilm and progressive. If you play it on your computer you may or may not see the interlacing depending on the software player you are using.

[adam]

To clarify, there are two options labeled 3:2 pulldown. The one on the advanced tab is a filter. It performs a hard telecine. It physically converts your file from 23.976fps to 29.97fps. Honestly, you would almost never need to do this.

The 3:2 pulldown while playback option on the video tab is used to perform a soft telecine. It inserts a flag in the stream, which instructs the DVD player to perform the telecine to 29.97fps in real time as the movie plays. The video itself is still 23.976fps, its just played back at 29.97fps. This is ONLY possible and only required for mpeg2. Mpeg1 can be encoded at 23.976fps and as long as its authored as a compliant VCD it will be played back at 29.97fps.

[VCDHunter]

VCDs support 23.976fps (NTSCfilm) natively. You do not need to convert to 29.97fps (via the 3:2 pulldown filter) and you do not need to apply the 3:2 pulldown flag (via the video tab- actually its not even possible with mpeg1.) The 3:2 pulldown flag ONLY applies to mpeg2 video. Just use the default NTSCfilm VCD template. Your file will be encoded at 23.976fps but it will play back at 29.97fps.

Thanks - I kinda was of this opinion but not 100% Sure

The reason you are seeing interlacing when using the 3:2 pulldown filter is because it is telecining the video to 29.97fps. It is splitting the frames into fields and repeating them in a 3:2 pattern to increase the framerate. If you view this on your tv it should disply correctly, though this is a much lower quality way to encode versus keeping it NTSCfilm and progressive. If you play it on your computer you may or may not see the interlacing depending on the software player you are using.

I've not tried this encode on a TV yet as Intervideo WinDVD shows the interlacing quite badly.

[VCDHunter]

Mpeg1 can be encoded at 23.976fps and as long as its authored as a compliant VCD it will be played back at 29.97fps.

Thanks - the DVD player does the telecine of this or simply speeds up playback ? If it does the telecine if I encode at 23.976 and its played back as 29.976 whats the point of the soft 3:2 you mentioned ? Or am I getting confused and should just shut up and go post in off topic for a bit ?

[darkwunder]

Deleted, as the previous posts said it way better than I did. I really need to learn to type faster

[adam]

Video is never sped up from 23.976fps to 29.97fps. Everything would move in super high speed and everyone would sound like a chipmunk. The 3:2 pulldown flags instruct the DVD player to perform a real time telecine to 29.97fps. Its the same process as TMPGenc does via its 3:2 pulldown filter, it just happens during playback rather then encoding.

The benefits of doing a soft telecine versus a hard telecine are numerous. You only have to encode 23.976 frames every second rather than 29.97 frames. This means slightly faster encode times, but more importantly it means that you have now freed up 20% of your bitrate. Every frame you encode has to have bits assigned to it. Less frames means more bits per remaining frames, which translates directly to an increase in quality.

Possibly even more important is the fact that 23.976fps, as used in application with the 3:2 pulldown, is inherantly progressive and properly telecined 29.97fps footage is inherantly interlaced. Progressive footage is much simpler to encode than interlaced footage, and pretty much any encoder will provide better quality with progressive input and output than vice versa. In regards to VCDs its an entirely different problem, which is MUCH worse. Mpeg1 does not support interlacing. So after making the conversion to 29.97fps half of the fields are simply thrown out. You have literally just lost half of the data of your movie.

Finally, storing the video as 23.976fps keeps it closer to its original film source. This is especially beneficial if you have a progressive scan playback device and a progressive scan DVD player. It still undergoes a telecine process of sorts, but it is substantially higher quality than if you encoded at 29.97fps. But this doesn't really apply so much for VCDs.

Pretty much all commercial NTSC DVDs are encoded at 23.976fps and are soft telecined at playback to 29.97fps. Its the perfect work around for about 90% of the faults of the NTSC standard.