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PostPosted: Sun Aug 04, 2019 4:37 am 
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rana wrote:
Recently, I learnt a few tricks and discovered a few characteristics of some videos. Still, I'm no expert and it will have to be a collective effort to figure out currently available content in various formats.

If enough interest, we can start a discussion here.
yes let's do it


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PostPosted: Thu Sep 05, 2019 4:44 pm 
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rana wrote:
Ragz wrote:
Mr. Rana, I have noticed that YouTube's technical details list frame rate for most videos, and it seems accurate for most times. However, the songs of Amrapali run at film speed (my inference is based on the pitch of audio compared to the previous field averaged versions of the film) however, labeled as "25" in the attribute section. What are the odds here?!

https://www.youtube.com/watch?v=yIlCqg__Nvg

Let's see what's going on in this clip. I brought this youtube video into my VLC player. VLC's video info clearly states 25 fps. You said, audio is 4% slower than 25 fps field averaged DVD video.

And yet, both statements can be true. I'm not 100% sure but most likely my findings will be same as any one else's (Of course video tech who mastered this video, knows for sure). I tried to frame advance frame by frame. Somehow VLC video timer did not advance (other videos, it does). And, many frame advance you advance one frame but many are repeat frames, sometimes 3 at a time. So, if the played audio at normal speed and inserted frames and filled up 25 fps, you do get no 4% speed up as well as normal audio speed. Ingenious! I do not know if there is auto program for that or if they did it painstakingly, frame by frame.
Now, as far as lyp sinc is concerned, if a frame gets repeated 5-6 times in a one second period, you won't get the lyp sinc problem.

I'll look into other clips later on, one by one.

--------------------------------------------
BTW, filling up frames technique can also be used to replace/ add damaged frames with repeated frames. Only 14 frames are required per second to fool the eye. 24 frames film standard was used for cushion.

Your insights and observations make so much sense. I'm glad to have the mystery solved, and I feel ashamed that this hadn't occurred to me earlier!
I apologize for not replying earlier as I most likely lost the notification of this. Thank you!


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PostPosted: Wed Sep 18, 2019 4:52 pm 
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Many videos on youtube look much better than their DVD versions, although it's the same video. Difference is internet videos are direct film to 25 fps while DVDs if mastered in India were film to 25 fps to NTSC (60 fields per sec) field averaged.
It was the greed/ ignorance that they transferred Indian films to PAL but to capture a wider market, they converted PAL material to NTSC, mostly by field averaging.
With the internet videos or with modern day TV screens, there is no such restriction that they can't play 24, 25, 30 or 60 Hz material. So, no need to transfer from 25 Hz to NTSC (or any other frequency transfer).


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