I read about and understand how NTSC gets 60 FPS via the 2 fields in each frame @30 FPS, and that to capture all the "frames" I should capture at 30 FPS with 480 lines of resolution. My question is... when encoding the final MPEG, do I encode it at 480 lines of resolution at 30 FPS or do I deinterlace it and make a 60 FPS MPEG? Does the DVD player automatically deinterlace the frames of a 30 FPS MPEG just as it normally would? Please clarify. Thanks for your help.
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Thread: 60 FPS vs 30... please clarify
It takes two fields to make one frame. So, NTSC is 30 frames per second, or 60 fields (half frames) per second. When you capture at 480, you capture filed one (240) and field 2 (240) making a full 480 frame. There are only 30 480 frames per second, or 60 240 fields per second. So, to capture full NTSC, you capture 30 frames at x480 pixels, not 60 frames.
Thank you for replying... I assume then your answer is that the final MPEG should be encoded at 30 FPS (or 29.97) at 720x480 resolution. Is that correct?
Well not neccessarily, it depends on what you are trying to make. Most NTSC DVDs are truly encoded at 23.97 fps, but have a "2:3 when playback" flag inserted in the stream to tell the player to play it at 29.97. Im not up on the "capturing process", so Im not sure if you have to specify a fps to capture at, but if you do, I would capture at 23.97 if possible, encoded at that fps as well. Then insert pulldown flags when you need 29.97.
This is the actual table that I copied from the DVD specs. Notice the frame rate of 29.97, thats what you capture and encode at. You capture using and interlace and encode using interlace. Also note your size is not restricted to 720x480. You can use any multiple of 16 but for practical purposes as outlined in the table, they are confined.
These specifications are what DVD set top players are designed around.
Deviating from the following standards may cause improper playback in your set top player. I would not recommend capturing at a framerate of 23.97. If your capture equipment is does not have a setting for interlace or none still capture at 29.97 and set the encoder to interlace. It will perform the needed magic.
Coded representation MPEG-1 (SIF combo)
MPEG-2 (Main Profile @ Main Level)
Frame rate 29.97 or 25 Hz
TV system 525/60 or 625/50
Aspect ratio 4:3 (all video formats)
16:9 (all formats except 352 pixels/line)
Display Mode pan & scan, letterbox
User_data closed caption
Coded frame sizes 525/60: 720x480, 704x480, 352x480, 352x240
625/50: 720x576, 704x576, 352x576, 352x288
(MPEG-1 is allowed only in 352x240 or 352x288 res).
GOP size max 36 fields or 18 frames (NTSC)
max 30 fields or 15 frames (PAL)
Buffer size 1.8535008 Mbits (MPEG-2)
max 327689 bits (MPEG-1)
Transfer method VBR, CBR (MPEG-2)
only CBR for MPEG-1
Maximum bitrate 9.8 Mbit/sec
Low_delay NOT permitted !!!!
capture at 30, encode at 29.97, your dvd player will do the rest.
also MPEG-1 is not restricted to 352x240 or 352x288 in some players.
Apex (example) can do 720x480 MPEG-1 (only at 29.97 fps)
Just depends on your player.
VCD is limited to 352x240 MPEG video=1150kbit/s and audio=224kbit/s. You can change any of these settings and make an xVCD. Not all stand alones will play xVCDs (check the DVD Players list to the left).
If you're working w/ a DVD rip I'd recommend 352x480 or 480x480 to get both fields. No need to step up to 720x480 as at the low bitrates this 'can' result in lower picture quaility, plus the human eye can't tell the difference.
For even better results, lower the audio bitrate to 128kbit/s, and raise the video bitrate. I find that ~60min/80min CDR (video bitrate = 1650kbit/s & audio = 128kbit/s) 3pass VBR in CCE or 2pass VBR & motion search = high in TMPGenc, produces encodes are damn near DVD quaility. 60min/cdr works out that most movies need 2 discs (i don't encode the credits).
Vejita-sama- so what your saying is if i rip a DVD and encode to 480X480, both fields will play in my DVD player? when i capture at 480X480 i get the interlace lines and when i convert at 480X480 i have to deinterlace to get rid of the lines. this is for Mpeg1. my question is, is it different for DVD rips?????
Jeff303 - For capturing, you must capture at the FPS of the stream, 29.xx. If high-quality source, doing an Inverse Telecine will reduce framerate to 23.xx. Your bitrate now applies to 20% less frames, giving either better quality for same rate or smaller movie for same quality. Use either pulldown.exe or 2:3 pulldown on playback in TMPGenc to apply flag which tells player to perform fps conversion.
For low-quality source, IVTC introduces too many frame skips for me. Many say deinterlace for PC display, not necessary for TV, but I find deinterlace better looking on both.
Yes, back in the old days, the frame rate was chosen to match the AC cycle to lower interference. 50 Hz in Europe and 60 Hz in the US. 59.94 Hz was introduced when color TV started in NTSC format, to lower interference between horizontal scan line frequency and color subcarrier frequency.
Here are a couple of pages that might help clarify everything that everyone is saying.
Capture at 29.97 frames at 640x480. This will prevent noise problems and give you both fields during the reduction.
I recommend reading both pages so you have an understanding for yourself of the telecline.