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<blockquote data-quote="nix_" data-source="post: 13321" data-attributes="member: 802"><p>1)Αλλο λές εσύ,άλλο είπα.Μιλάμε για consumer players και οχι για υπολογιστές.Οι κλασσικές αναλογικές έξοδοι (comsosite,svideo κ.λ.π.) θα πρέπει να είναι pal.Για αυτό έγραψα "όπως το tvout τις κάρτας γραφικών)</p><p>Δεν έγραψα για μετατροπή ανάλυσης σε pc.Αλλο πράγμα.</p><p></p><p>2)Ναι έχεις δίκιο είναι στα 23,97 γιατί:</p><p></p><p><strong><u>3:2 pulldown</u></strong></p><p>The process of converting 24 frame/s material to 29.97 frame/s is known as 3:2 pulldown. It is accomplished in two steps. The first step is to slow down, or "pulldown" the film motion by 0.1%. This speed change is unnoticeable to the viewer, and makes the film travel at 23.976 frame/s.</p><p></p><p>The second step of the 3:2 pulldown is the 3:2 (or 2:3, see below) step. At 23.976 frame/s, there are 4 frames of film for every 5 frames of NTSC video:</p><p></p><p>*βλέπε πινακάκι -2- με την διαίρεση</p><p></p><p>These four frames are "stretched" into five by exploiting the interlaced nature of NTSC video. For every NTSC frame, there are actually two complete images or "fields," one for the odd-numbered lines of the image, and one for the even-numbered lines. There are, therefore, ten fields for every 4 film frames, and the telecine alternately places one film frame across two fields, the next across three, the next across two, and so on. The cycle repeats itself completely after four film frames have been exposed, and in the telecine cycle these are called the "A," "B," "C," and "D" frames, thus:</p><p></p><p>*βλέπε πίνακα -1-</p><p></p><p>Film material on NTSC DVD is usually encoded progressively at 23.976 frame/s, with special flags inserted into the MPEG-2 video stream that instruct the DVD player to repeat certain fields so as to accomplish 2-3 pulldown during playback. Progressive scan DVD players additionally offer output at 480p by using these flags to duplicate frames rather than fields.</p><p></p><p>και πιο συγκεκριμένα</p><p></p><p><strong><u>Film-Mode Deinterlacing</u></strong></p><p></p><p>To display a perfect progressive image from a film-sourced DVD, the player needs to figure out which fields in the MPEG stream go together to make each film frame. In theory, the progressive_frame flag should tell the player that the frames on the disc were originally from a film, and will go together, but as we’ve mentioned, that flag is not always optimized for progressive scan playback.</p><p></p><p>So what the best players do is use a standard MPEG-2 decoder to generate digital interlaced video and then feed that video to a deinterlacing chip. The chip makes decisions constantly about whether the video was originally from film by looking for repeated fields. In the standard 3-2 cadence, the 1st and 3rd fields are identical. If the deinterlacing chip sees a constant stream of 5-field sequences in which the 1st and 3rd fields are identical, it switches to film-mode deinterlacing.</p><p></p><p>Once it’s in film mode, the deinterlacer just combines fields 1 and 2 to make one progressive image, outputs that for 3 progressive frames, then combines fields 4 and 5 to make another progressive image, and outputs that for two frames. Then it repeats the process with the next 5 fields. The player is still outputting frames in a 3-2 pattern, but it’s creating 60 full progressive frames per second instead of 60 fields per second. Once the chip is in film mode, the deinterlacing algorithm is incredibly simple, and the complete film frame is recreated without loss or compromise. Film mode is the one area of deinterlacing that can be objectively perfect.</p><p></p><p></p><p></p><p><strong>Οπως βλέπεις λοιπόν το pulldown έχει ήδη γίνει.Απλώς τα διπλά καρέ δεν αποθηκεύονται στο δίσκο για καλύτερη συμπίεση.</strong></p></blockquote><p></p>
[QUOTE="nix_, post: 13321, member: 802"] 1)Αλλο λές εσύ,άλλο είπα.Μιλάμε για consumer players και οχι για υπολογιστές.Οι κλασσικές αναλογικές έξοδοι (comsosite,svideo κ.λ.π.) θα πρέπει να είναι pal.Για αυτό έγραψα "όπως το tvout τις κάρτας γραφικών) Δεν έγραψα για μετατροπή ανάλυσης σε pc.Αλλο πράγμα. 2)Ναι έχεις δίκιο είναι στα 23,97 γιατί: [B][U]3:2 pulldown[/U][/B] The process of converting 24 frame/s material to 29.97 frame/s is known as 3:2 pulldown. It is accomplished in two steps. The first step is to slow down, or "pulldown" the film motion by 0.1%. This speed change is unnoticeable to the viewer, and makes the film travel at 23.976 frame/s. The second step of the 3:2 pulldown is the 3:2 (or 2:3, see below) step. At 23.976 frame/s, there are 4 frames of film for every 5 frames of NTSC video: *βλέπε πινακάκι -2- με την διαίρεση These four frames are "stretched" into five by exploiting the interlaced nature of NTSC video. For every NTSC frame, there are actually two complete images or "fields," one for the odd-numbered lines of the image, and one for the even-numbered lines. There are, therefore, ten fields for every 4 film frames, and the telecine alternately places one film frame across two fields, the next across three, the next across two, and so on. The cycle repeats itself completely after four film frames have been exposed, and in the telecine cycle these are called the "A," "B," "C," and "D" frames, thus: *βλέπε πίνακα -1- Film material on NTSC DVD is usually encoded progressively at 23.976 frame/s, with special flags inserted into the MPEG-2 video stream that instruct the DVD player to repeat certain fields so as to accomplish 2-3 pulldown during playback. Progressive scan DVD players additionally offer output at 480p by using these flags to duplicate frames rather than fields. και πιο συγκεκριμένα [B][U]Film-Mode Deinterlacing[/U][/B] To display a perfect progressive image from a film-sourced DVD, the player needs to figure out which fields in the MPEG stream go together to make each film frame. In theory, the progressive_frame flag should tell the player that the frames on the disc were originally from a film, and will go together, but as we’ve mentioned, that flag is not always optimized for progressive scan playback. So what the best players do is use a standard MPEG-2 decoder to generate digital interlaced video and then feed that video to a deinterlacing chip. The chip makes decisions constantly about whether the video was originally from film by looking for repeated fields. In the standard 3-2 cadence, the 1st and 3rd fields are identical. If the deinterlacing chip sees a constant stream of 5-field sequences in which the 1st and 3rd fields are identical, it switches to film-mode deinterlacing. Once it’s in film mode, the deinterlacer just combines fields 1 and 2 to make one progressive image, outputs that for 3 progressive frames, then combines fields 4 and 5 to make another progressive image, and outputs that for two frames. Then it repeats the process with the next 5 fields. The player is still outputting frames in a 3-2 pattern, but it’s creating 60 full progressive frames per second instead of 60 fields per second. Once the chip is in film mode, the deinterlacing algorithm is incredibly simple, and the complete film frame is recreated without loss or compromise. Film mode is the one area of deinterlacing that can be objectively perfect. [B]Οπως βλέπεις λοιπόν το pulldown έχει ήδη γίνει.Απλώς τα διπλά καρέ δεν αποθηκεύονται στο δίσκο για καλύτερη συμπίεση.[/B] [/QUOTE]
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