Yes, that was my conclusion earlier. IMHO it makes the most sense to simply encode the original progressive content, then add standard 2:3 telecine flags for playback, because most TV's can detect that and it is losslessly reversible. AFAIK most movies are encoded in this way (though other video content often must be encoded differently). Does anyone know if all HD-DVD and Blu-Ray movies are created in this basic way?
I don't understand the hype for 1080p/24 output
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Yes, that was my conclusion earlier. IMHO it makes the most sense to simply encode the original progressive content, then add standard 2:3 telecine flags for playback, because most TV's can detect that and it is losslessly reversible. AFAIK most movies are encoded in this way (though other video content often must be encoded differently). Does anyone know if all HD-DVD and Blu-Ray movies are created in this basic way?
The source is the 35mm negative, it can't be ruined in any way unless you phisically ruin it. A 24p output would be more usefull because it would display all the original frames as they are without introducing an additional compression.
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A 24p output would be more usefull because it would display all the original frame as they are.
I was referring to the encoded video when I said "source". If I understand Colourless correctly, he was saying that some movies are filtered with a deflicker filter prior to encoding, which would make the original frames unrecoverable in any mode.
However, perhaps he was saying that deflicker is done after encoding, and just before telecined output, but not in a 24p output mode. Is that right?
You can also make 24p dvds and let the dvd player add the 3:2 pulldown , so you save space and can go with an higer bitrate.
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You're using the word "compression" far too much. There is no compression involved. You just take the right lines from the right fields and recombine them. That has nothing at all to do with (lossy) (de)compression. If the data shuffling is done for the purpose of immediately displaying the stuff (like the logic in a TV set), there's no point and no need to repackage the data into another MPEG stream or whatever.
Ah, ok i get what you mean.
Well, the telecined material is the uncompressed master from when you do all the encoding to wharever format you want, so i think you should not add any kind of filer on it...or , like you said, it would ruin the quality of everything originated from it.
What i guess is you add some kind of filter only when you make the encoding from 24p to 60i to make it lok smooter.
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Sorry, I'm mis-using some of the terms out of habit. When I say "telecine", I'm generally referring to 2:3 pulldown.
Btw, zeckensack is right, and that is what I was trying to explain to your earlier. There is no de/recompression during the Inverse Telecine stage, as you seem to think.
Btw, zeckensack is right, and that is what I was trying to explain to your earlier. There is no de/recompression during the Inverse Telecine stage, as you seem to think.
There is need of a decompression process to recover the frame C and this is a fact, i am not going to go back on this point as it percetcly explained here
By the way, i dont think you have any rights on the word "compression" so i think i should be fine.
Well is not just my "think", it is common knowledge for a filmmaker and i have provided a realiable article with the technical explanation about it , if you want to debate it and telling me where it is wrong please do, because i am absolutly open to the discussion.
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And I had though that I explained how this differs between progressive and interlaced encoding. That link of yours is talking about video that has undergone 2:3 pulldown, then encoded (compressed). As it says, the intraframe compression method used (DV) renders the C frame unreversible. As I explained, video which is encoded progressively with pulldown applied at playback (which you yourself admitted can be done) doesn't have this problem, and is reversible without quality loss, compression, recompression, whatever else.
From your own Wiki link about 24p
The link talk about a 24p stream recorded on the fly with a 3:2 pulldown to a 60i tape, the
result is exactly the same as 24p film transfered to video at 60i, and the same of a dvd player that convert a 24p source into a 60i source, mpeg2 use intraframe compression too.
It doeas not change anything, when the player apply the 3:2 pulldown and output a 60i stream , the C frame in the 60i stream is splitted and if it is displayed at 60i you are not reversing the video so you are fine, but if the Tv deinterlace the 60i stream to 24p again , it do a reverse telecine and the Tv will introduce image degradation and artifacts because can only guess what is the right 3:2 pulldown pattern.
Edit: But you are right in saiying there is no recompression when it done with uncompressed signal...
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No, your link was specific to DV recording, and not applicable to Hollywood movies mastered to DVD or HD-DVD, etc.
The order of pulldown and encoding is important to determine whether the pulldown can be properly reversed.
The movie is still pulled-down and output at 60i, for compatibility with interlaced displays. Progressive devices like many DVD players, HDTV's, etc, then Inverse Telecine (reverse pulldown) to get back the progressive frames. The only decompression that happens in this case is from MPEG-2, to decode the frames. The Inverse Telecine is done after decoding and only involves selectively matching fields, as zeckensack described. Once again, the stream is UNCOMPRESSED raw fields when it gets to the Inverse Telecine stage of the TV. No further de/compression needs to be done! Only combining fields with selective weaves, as I've tried to explain before. Your link is only relevant when talking about video that has been compressed AFTER the pulldown stage, not BEFORE!
Edit:
Actually, your link is extremely DV specific. Look at this part:
It is talking about actually converting a pulled-down 60i DV compressed file to a 24p compressed DV file. This is all about editing has nothing at all directly to do with outputting video to a display device. This is where your misconception is coming from, I think.
The order of pulldown and encoding is important to determine whether the pulldown can be properly reversed.
The movie is still pulled-down and output at 60i, for compatibility with interlaced displays. Progressive devices like many DVD players, HDTV's, etc, then Inverse Telecine (reverse pulldown) to get back the progressive frames. The only decompression that happens in this case is from MPEG-2, to decode the frames. The Inverse Telecine is done after decoding and only involves selectively matching fields, as zeckensack described. Once again, the stream is UNCOMPRESSED raw fields when it gets to the Inverse Telecine stage of the TV. No further de/compression needs to be done! Only combining fields with selective weaves, as I've tried to explain before. Your link is only relevant when talking about video that has been compressed AFTER the pulldown stage, not BEFORE!
Edit:
Actually, your link is extremely DV specific. Look at this part:
It is talking about actually converting a pulled-down 60i DV compressed file to a 24p compressed DV file. This is all about editing has nothing at all directly to do with outputting video to a display device. This is where your misconception is coming from, I think.
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hollywood movies all have DTC in their codecs .
This simply cant be done in the same way because decompressing the 60i stream you lose the flags that the Tv would have need to recreate a perfect 24p , so you would get a worst result then a native 24p output from the player for sure, and here we answare your first question of why it is better to have a 24 stream from the output instead of a 60i output.
The 3:2 pulldown process explained here work in this way for any kind of compressed codec DTC based , an hd-dvd source is still a compressed video with the same multigeneration rendering quality loss degradation.
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The flags are for determining the pulldown pattern after decompression. The TV only has to recognize this pattern to reverse it, which is easy with the standard 2:3 or 3:2.
Can't you just accept what I'm saying? If you dealt with encoding and re-encoding DVD video you would already know all of this.
You clearly don't even understand your own link. You do not need to convert from compressed format to compressed format when simply viewing DVD video! Nothing needs to be recompressed! The fact that Mpeg-2, DV, etc, are DCT-based codecs doesn't matter when the video being encoded is pure progressive because no frames have mixed fields!
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If the source has flags that the unit understands, in the
MPEG-2 stream then the unit will utilize it and produce the best picture setup, period. Once you decompress the mpeg2 stream and output to the tv, the flas are gone.
Sorry but as a movie director i dealt with more than simply encoding and recoding and what you say is aganist what i see working with film and video
This is what you need to do in order to remove a 3:2 pulldown with an mpeg2 stream, it's math, deal with it.
You are repeating the same things again and again, this is not a case where you have a reverse telecine, if the video is alredy progressive, then you have no need to do any reverse telecine.
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Yes, the decoding unit (ie. the DVD player), NOT the display unit (TV).
Sorry but as a movie director i dealt with more than simply encoding and recoding and what you say is aganist what i learned working with film and video
I'm sorry that you were taught incorrectly
That's totally wrong. You are misunderstanding a great deal.
Yes, and I've already made it clear that it is no longer compressed by the time it is converted to interlaced form via pulldown.
But I'm failing to convince you of this, so this is going nowhere, fast. Anyone else want to chime in?
Why the big discussion here?
1080p24 is favourable to trying to convert 24fps material (like ALL movies) to 1080p60 signals through 3:2 simply because it's closer to the original framerate and doesn't need to go through pull-down or conversions or whatnot. Every original frame is mapped to a frame (two actually) on your screen, giving no motion issues (except it being low framerate, but at least it's 100% stable).
When TVs or processors try to convert 24fps material to 60Hz, they can be more or less successful, meaning that sometimes you get issues with motion. Sometimes they're fine, but it would just be preferrable to have each frame mapped to a frame on the screen. It's actually two frames, which it's much better than trying to slot one frame in there every so often...
That's that really.
Pretty much like all other things in the digital world: when what you see is closer to the original source, without going through conversions and filtering, it tends to be better.
1080p24 is favourable to trying to convert 24fps material (like ALL movies) to 1080p60 signals through 3:2 simply because it's closer to the original framerate and doesn't need to go through pull-down or conversions or whatnot. Every original frame is mapped to a frame (two actually) on your screen, giving no motion issues (except it being low framerate, but at least it's 100% stable).
When TVs or processors try to convert 24fps material to 60Hz, they can be more or less successful, meaning that sometimes you get issues with motion. Sometimes they're fine, but it would just be preferrable to have each frame mapped to a frame on the screen. It's actually two frames, which it's much better than trying to slot one frame in there every so often...
That's that really.
Pretty much like all other things in the digital world: when what you see is closer to the original source, without going through conversions and filtering, it tends to be better.
Fruitfrenzy
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Sorry but as a movie director i dealt with more than simply encoding and recoding and what you say is aganist what i learned working with film and video
I fail to see why a "movie director" would need to know anything about the mechanics of 3:2 pulldown. The fact is that as Bohdy stated, no recompression is involved during playback of a DVD.
The compressed video is decoded and can either be output in the native NTSC or PAL that the DVD specification mandates or the DVD player can use the flags in the MPEG2 stream to extract the original 24 fps progressive source and output that. If it outputs the original then the TV can choose to deinterlace that by trying to detect the cadence but it is always going to be an inferior solution to the DVD player doing it.
Despite what was stated earlier DVDs can not store 24fps video. They can however store NTSC format 30fps video the is encoded as progressive frames with the flags "repeat_first_field" and "top_field_first". The MPEG2 decode process includes the processing of these flags to generate a 30fps sequence from 24fps input. The sequence frame rate is defined as the rate at the output of the decoder which will be 30fps for a compliant decoder.
If a DVD player knows it is decoding to a progressive display it can choose to skip the final stage of the decode and leave the video at 24fps but this lies outside of the MPEG2 specification.
But surely any TV with IVTC logic can handle a standard 3:2 sequence perfectly?
Yes, if you dont pretend the Tv of doing the 3:2 pulldown removal, you are fine with the dvd player doing this.
I'm sorry that you were taught incorrectly
it would be everithing as simple as you make it i would be really happy...but, it does not work like this
He he i so wish i was wrong...it would make dealing with mpeg2 not a so pain in the ass...it would really made all simplier for me
You have not failed to convince me that it is uncompressed once it gets out of the dvd player, and i agree that in that case the Tv is working with uncompressed video, however the quality will not be the same as having the original mpeg2 24p stream.
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