1080p from High-Definition DVDs?

takisot

Μέλος Δ.Σ.
Staff member
17 June 2006
24,573
Παλλήνη
Επειδη εχει γινει αρκετος ντόρος για το κατα πόσον τα HD-DVD και BLU-RAY θα εχουν 1080P υλικο αλλα και πως θα ειναι δυνατο να φτασει ως το πανι μας με τις λιγοτερες δυνατες προσαρμογες, παραθετω ενα πολυ ενδιαφερον αρθρο του Eric Steward, το οποιο νομιζω οτι θα ξεκαθαρισει λιγο το θολο τοπιο:

1080p from High-Definition DVDs?


Now debuting: two, count 'em, two, mutually incompatible formats for high-definition DVDs: HD DVD and Blu-ray. These are the first two commercially available standards for video discs whose players (not the old-style DVD players we have now) will play the new discs into a suitable HDTV with all the resolution the TV can reproduce.

As long as, that is, the HDTV does not utilize the gold standard of high-definition television display: 1080p resolution. The initially available HD DVD players don't output 1080p. And it's not absolutely clear which, if any, of the Blu-ray players we're eagerly awaiting over the next few months are going to deliver 1080p.

In the last year or so, TVs whose "native" resolution is 1080p have sprung up, big as life, and taken a noticeable slice of the market. Their screens offer fully 1,080 rows of 1,920 pixels each, yielding the best spatial resolution available in consumer video history: roughly two million pixels overall on the screen.

1080i, the standard in use by many over-the-air HDTV broadcasters, has the same number of pixels as 1080p, but only half of them actually change with each screen update: first the odd-numbered rows, and then, a fraction of a second later, the even-numbered rows. This alternation of scan lines is "interlaced scanning," the origin of the "i" in 1080i.

In 1080p — "p" for "progresive scanning" — the entire pixel array gets updated, every time. Motion is smoother. Jaggies at the edges of moving objects, "twittering" scan lines, and now-you-see-it-now-you-don't tiny details — symptoms experts call "interlace artifacts" — are pretty much history.

So, do HD DVD and Blu-ray support 1080p?

The answer is, alas, complicated. In order to get 1080p to your eyeballs, you need at least four things:

a disc encoded at 1080p
a DVD player that can output 1080p to the TV
a TV that can receive 1080p from the player
1080p native resolution at the TV screen

Reportedly, most HD DVD and Blu-ray discs encode their main content, usually a movie, at 1080p, so no worry there.

Any TV which is advertised as 1080p-capable must have that as its native screen resolution, so this is not a huge problem (as long as you happen to own such a TV).

But most of the initial crop of "1080p" TVs cannot actually receive 1080p signals; 1080i is their maximum input capability. (That situation may have changed with the most recently introduced 1080p TVs, however.)

What's more, few if any of the initial HD DVD players actually output 1080p. (That may not be as true for Blu-ray; see below.) They convert the 1080p on the disc to 1080i, and ouptut that. The 1080p-native TV receives the signal as 1080i and deinterlaces it for display on the screen. The interlace-deinterlace sequence can introduce pesky artifacts.

Foolish, right, for HD DVD players not to support full-fledged 1080p output from the get-go? Well, part of the reason for the foolishness is that 1080p must travel between the player and the TV, if at all, along an HDMI cable. HDMI is a standard for the transmission of video data, audio, and other digital goodies between source devices such as DVD players and TVs. It uses HDCP copy protection to keep anyone from intercepting the digital stream and diverting it to their own (illegal) advantage — so it's very, very complicated.

But HDMI/HDCP's originally-strictly-optional ability to transmit and receive 1080p is just now actually appearing in consumer electronics gear for the first time. The initial HD DVD players are meanwhile sticking with an older, non-1080p implementation of HDMI.

For instance, one of the very first HD DVD players is the Toshiba HD-A1. According to Amazon.com, it can output either 720p or 1080i at its HDMI connection. No 1080p.

As for Blu-ray, it looks as if at least some of the initial player models will output 1080p on HDMI. For example, the yet-to-arrive (as of early June, 2006) Sony BDP-S1 will reportedly do so.

Another complicating factor: there are different flavors of 1080p, distinguished by their frame rates. How many frames of video per second are going to be transmitted? There are at least three popular answers: 24, 30, and 60.

24 fps (frames per second) matches the rate at which movies are shot. Hence, most HD DVD and Blu-ray discs are encoded at 1080p/24.
30 fps is typical of television broadcasts, both standard definition and high. If they're 1080i hi-def, as opposed to 720p, they are more precisely 1080i/60, not 1080i/30, since there are two interlaced "fields" per frame, one for the odd-numbered scan lines and one for the even. With interlaced transmission the number after the '/' is the field rate, not the frame rate ... and by the way, often the '/' is omitted: you'll see "1080p24," "1080i60," etc., instead of designations with slashes.

So the frame rate of 1080i/60 is actually 30 fps. 720p high-definition television (1,280 pixels across the screen by 720 vertically) doubles that frame rate to 60 fps: 720p/60. In 720p there are fewer pixels per frame than either 1080i or 1080p, but they're updated twice as often as 1080i/60. 720p is excellent for fast-action sports.

1080p/60, with 60 full frames every second, is another flavor of 1080p. Some current and/or soon-to-come "1080p" TVs apparently will accept 1080p/60 input, which can happen if the DVD player converts 1080p/24 to 1080p/60.

(Today, it's not easy to find out such precise frame-rate details about TVs and DVD players. Here's hoping that changes soon.)

What if the TV can only display 1080p at 30 fps or 60 fps, not at 24 fps, and what's on the disc is 1080p/24? Then either the player or the TV (typically the player) must perform a conversion. Again, as with any type of scan conversion, there is a potential for visible artifacts to result.

In this situation, the main reason for artifacting is that 60 is not an even multiple of 24. Neither is 30, for that matter. If 1080p/24 on DVD is converted to 1080p/60, or 1080p/30, or even 1080i/60, some frames in the output video will necessarily be interdigitated hybrids of two source frames, which can lead to ragged edges on moving objects. Or else the 24 input frames per second will be parceled out to varying numbers of output frames, some to one and others to two, making for jerky motion.

To avoid such motion artifacts, the TV ought to be able to operate at a 1080p frame rate that is an exact multiple of what's on the disc: say, 72 fps. 48 fps would work, too. And incidentally, the rate at which the TV "paints" frames on the screen is its "refresh rate," and is stated in Hertz or cycles per second. 48 frames per second is 48 Hz. 72 fps is 72 Hz.

A 24-Hz refresh rate with a one-to-one correspondence of output frames to incoming 1080p/24 frames would not work well, unfortunately. It would produce annoying flicker on any bright video display screen. (The reasoning is similar to why motion pictures are projected with each frame illuminated twice in 1/24 of a second.)

Ideally, the player would supply the TV with 1080p/24, and the TV could convert it to, say, 1080p/72 (or 1080p/48) to avoid the flicker common when bright video displays use a 24-fps refresh rate. The conversion from 24 to 72 frames per second is straightforward and does not produce visible artifacts.

Just the ability to learn such details about 1080p-native HDTVs and the initial crop of HD DVD and Blu-ray players ain't easy. And let's face it, the ideal hookup as I envision it will look only a smidgen better than converting 1080p/24 on the disc to 1080i/60 for HDMI transmission to the TV, assuming the TV could handle it, and then to (say) 1080p/30 for display on the TV screen at its native resolution. You'd have to be some kind of purist to even care, right?

Well ... as the incipient high-definition DVD format war heats up, we shall see whether people really do care, shall we not?

After all, all the early adopters who spend the big bucks now, at the dawn of hi-def DVD, may find later that waiting a few months, while all the pieces fall in place for an end-to-end 1080p DVD experience without unnecessary artifacts, would have given them a better picture for little if any extra cost.

They're sure to be miffed, right?
Don't say I didn't warn them.


Πηγή:http://whatsonhdtv.blogspot.com/
 

GeonX

Μέλος Σωματείου
17 June 2006
2,747
Τάκη, είναι κατανοητό σε όλους ότι οι μπροστάρηδες θα γίνουν πάλι τα πειραματόζωα…
Σε τελευταίο ταξίδι μου βρήκα το χρόνο και πέρασε ένα δίωρο με το Toshiba HD Drive,
OK η εικόνα καλή (κάτι σαν τα HD Clips τις MS) από την άλλη αργό στο φόρτωμα της ταινίας, μικρή διαθεσιμότητα λόγο προβλημάτων (τα παιδία στο κατάστημα έλεγαν ότι δεν το σπρώχνουν γιατί τα περισσότερα γύριζαν πίσω με προβλήματα κατασκευαστικά η συμβατότητας με τα υπόλοιπα μηχανήματα του αγοραστή (άρε Αμερική με το money return policy…) λίγη τίτλοι και ακριβοί για τα αμερικανικά δεδομένα (29-35 USD όταν οι νέες κυκλοφορίες στα DVD πάνω κάτω στα 20…) Κάποια στιγμή ο Μπάμπης θα με συγχωρέσει που δε του έφερα ένα κομμάτι αλλά μέχρι τότε θα μου τα χώνει όποτε με βλέπει… ας μη μιλήσουμε ποτέ θα δούμε Greek subtitles… καλό 2008 και βαλε ίσως… κάτσε να δούμε το PS3 στο Ελλαντα (μέσα Νοέμβρη ?)…
 
17 June 2006
1,230
Ατύχησες!...

GeonX said:
Κάποια στιγμή ο Μπάμπης θα με συγχωρέσει που δε του έφερα ένα κομμάτι αλλά μέχρι τότε θα μου τα χώνει όποτε με βλέπει…


Και να σε συγχωρέσει ο στρατηγός μας Γιώργο, δεν θα σε συγχωρήσουμε οι υπόλοιποι! :mad: Καταλαβαίνεις τι ζημιά μας έκανες; Θα μπορούσαμε στο επόμενο συγκριτικό να τα βάλουμε δίπλα δίπλα με το bluray της Samsung και να γίνει παραπαμπέρομ! :D
 

Andronidis Akis

AVClub Addicted Member
17 June 2006
2,996
Voula - Greece
Παιδια το αθρο δεν λεει τιποτα αλλο απο συνεχεις ασυμβατοτητες που μπορουν να προκυψουν απο τον απλο συνδιασμο tv, 1080p player και hdmi.

Κουφαθικα διαβαζοντας γιατα 1080p/24, 30, 60 και τα προβληματα που μπορουν να δημιουργηθουν !!!

Οποτε ειναι πολυ νωρις γιανα αγορα πηγης. Λεει ομως οτι καλο ειναι να βλεπουμε αν οι tv που αγοραζουμε 1920χ1080 υποστηριζουν 1080p ασχετα απο το ι.
 

Andronidis Akis

AVClub Addicted Member
17 June 2006
2,996
Voula - Greece
Πραγματικα μου θιμιζει τις πρωτες ασυμβατητες που υπηρχαν με το πρωτοκολο HDMI/DVI.
Αλλα εδω οπως τα γραφει τα προβληματα ειναι ακομα μεγαλυτερα.
 

mezzanine

AVClub Enthusiast
19 June 2006
744
Γεια χαρά και απο εμένα, και καλορίζικο το νέο forum.

Πάντως μέχρι τώρα όσοι HD-DVD και Blu-Ray τίτλοι βγήκαν είναι 1080p.
Μπορείτε να δείτε μερικά reviews εδώ: http://www.highdefdigest.com/

Η μεγάλη απογοήτευση είναι που το Blu-Ray χρησιμοποιεί MPEG2 compression που ακόμα και τα 20MBits/sec εμφανίζουν arifacts σε δύσκολες σκηνές. Αν βγούν ταινίες 1080p με AVC η ποιότητα θα είναι τρελή ακόμα και με 10-15Gb.
 
Last edited:

Babis K.

Super Moderator
Staff member
17 June 2006
24,419
Αθήνα
GeonX said:
Κάποια στιγμή ο Μπάμπης θα με συγχωρέσει που δε του έφερα ένα κομμάτι αλλά μέχρι τότε θα μου τα χώνει όποτε με βλέπει…

Επειδή γουστάρω να στα "χώνω", κάποια στιγμή παρακάλαγα να μην το φέρεις για νάχω να λέω...:D :D
 
17 June 2006
1,230
Κάτι δεν πάει καλά εδώ!...

mezzanine said:
Γεια χαρά και απο εμένα, και καλορίζικο το νέο forum.

Πάντως μέχρι τώρα όσοι HD-DVD και Blu-Ray τίτλοι βγήκαν είναι 1080p.
Μπορείτε να δείτε μερικά reviews εδώ: http://www.highdefdigest.com/

Η μεγάλη απογοήτευση είναι που το Blu-Ray χρησιμοποιεί MPEG2 compression που ακόμα και τα 20MBits/sec εμφανίζουν arifacts σε δύσκολες σκηνές. Αν βγούν ταινίες 1080p με AVC η ποιότητα θα είναι τρελή ακόμα και με 10-15Gb.


Βλέπω κι εγώ στο link ότι η Sony ανακοίνωσε π.χ. το Silent Evil με εικόνα στα 1080p. Αλλά βρε παιδιά, ο αλγόριθμος MPEG2 δεν υποστηρίζει σήμα 1080p, παρά μόνο 1080i, κι αυτό είναι απολύτως σίγουρο. :confused: Άρα;

Πιστεύω απλά ότι η Sony αθέτησε ήδη την υπόσχεσή της, ότι δηλαδή δεν θα χρησιμοποιούσε τον αλγόριθμο VC1. :D
 

takisot

Μέλος Δ.Σ.
Staff member
17 June 2006
24,573
Παλλήνη
ΠΑΝΑΓΙΩΤΗΣ ΒΟΓΙΑΤΖΑΚΗΣ said:
Αλλά βρε παιδιά, ο αλγόριθμος MPEG2 δεν υποστηρίζει σήμα 1080p, παρά μόνο 1080i, κι αυτό είναι απολύτως σίγουρο. :confused: Άρα;
. :D

Πανο, που το διαβασες αυτο?? Εισαι σιγουρος? Τι σχεση εχει ο αλγορυθμος συμπιεσης με το αν μια ταινια θα βγει σε interlaced ή progressive format?:confused:
 
17 June 2006
1,230
Κι όμως...

Τακης Σωτηροπουλος said:
Πανο, που το διαβασες αυτο?? Εισαι σιγουρος? Τι σχεση εχει ο αλγορυθμος συμπιεσης με το αν μια ταινια θα βγει σε interlaced ή progressive format?:confused:



Τάκη, τα 1080p είναι εκτός των επίσημων τεχνικών προδιαγραφών του αλγόριθμου MPEG2, για τους ψηφιακούς δίσκους το ταβάνι είναι τα 1080i. Δες εδώ, φαντάζομαι να αποδέχεσαι ότι πρόκειται για το πιο έμπειρο site τεχνικών προδιαγραφών:
en.wikipedia.org/wiki/MPEG-2



MPEG-2 Profiles
Abbr. Name Frames YUV Streams Comment
SP Simple Profile P, I 4:2:0 1 no interlacing
MP Main Profile P, I, B 4:2:0 1
422P 4:2:2 Profile P, I, B 4:2:2 1
SNR SNR Profile P, I, B 4:2:0 1–2 SNR: Signal to Noise Ratio
SP Spatial Profile P, I, B 4:2:0 1–3 low, normal and high quality decoding
HP High Profile P, I, B 4:2:2 1–3

MPEG-2 Levels
Abbr. Name Pixel/line Lines Framerate (Hz) Bitrate (Mbit/s)
LL Low Level 352 288 30 4
ML Main Level 720 576 30 15
H-14 High 1440 1440 1152 30 60
HL High Level 1920 1152 30 80

Profile @ Level Resolution (px) Framerate max. (Hz) Sampling Bitrate (Mbit/s) Application
[email protected] 176 × 144 15 4:2:0 0.096 Wireless handsets
[email protected] 352 × 288 15 4:2:0 0.384 PDAs
320 × 240 24
[email protected] 352 × 288 30 4:2:0 4 Set-top boxes (STB)
[email protected] 720 × 480 30 4:2:0 15 (DVD: 9.8) DVD, SD-DVB
720 × 576 25
[email protected] 1440 × 1080i 30 4:2:0 60 (HDV: 25) HDV
1280 × 720p 30
[email protected] 1920 × 1080i 30 4:2:0 80 ATSC 1080i, 720p60, HD-DVB (HDTV)
1280 × 720p 60
[email protected] 4:2:2
[email protected] 720 × 512 30 4:2:2 50 Sony IMX using I-frame only, Broadcast "contribution" video (I&P only, extra horizontal resolution for VBI information)
720 × 608 25
[email protected] 1440 × 1080i 30 4:2:2 80 Potential future MPEG-2-based HD products from Sony and Panasonic
1280 × 720p 60
[email protected] 1920 × 1080i 30 4:2:2 300 Potential future MPEG-2-based HD products from Panasonic
1280 × 720p 60
[edit]

DVD
The DVD standard uses MPEG-2 video, but imposes some restrictions:
 Allowed Resolutions
 720 × 480, 704 × 480, 352 × 480, 352 × 240 pixel (NTSC)
 720 × 576, 704 × 576, 352 × 576, 352 × 288 pixel (PAL)
 Allowed Aspect ratio (image) (Display AR)
 4:3
 16:9 (2.21:1 also specified but little if ever used)
 Allowed Frame rates
 29.97 frame/s (NTSC)
 25 frame/s (PAL)
Note: By using a pattern of REPEAT_FIRST_FIELD flags on the headers of encoded pictures, pictures can be displayed for either two or three fields and almost any picture display rate (minimum 2/3 of the frame rate) can be achieved. This is most often used to display 23.976 (approximately film rate) video on NTSC.
 Audio+video bitrate
 Buffer average maximum 9.8 Mbit/s
 Peak 15 Mbit/s
 Minimum 300 Kbit/s
 YUV 4:2:0
 Additional subtitles possible
 Closed captioning (NTSC only)
 Audio
 Linear Pulse Code Modulation (LPCM): 48 kHz or 96 kHz; 16- or 24-bit; up to six channels (not all combinations possible due to bitrate constraints)
 MPEG Layer 2 (MP2): 48 kHz, up to 5.1 channels (required in PAL players only)
 Dolby Digital (DD, also known as AC-3): 48 kHz, 32–448 kbit/s, up to 5.1 channels
 Digital Theater Systems (DTS): 754 kbit/s or 1510 kbit/s (not required for DVD player compliance)
 NTSC DVDs must contain at least one LPCM or Dolby Digital audio track.
 PAL DVDs must contain at least one MPEG Layer 2, LPCM, or Dolby Digital audio track.
 Players are not required to playback audio with more than two channels, but must be able to downmix multichannel audio to two channels.
 GOP structure
 Sequence header must be present at the beginning of every GOP
 Maximum frames per GOP: 18 (NTSC) / 15 (PAL), i.e. 0.6 seconds both
 Closed GOP required for multiple-angle DVDs
[edit]

DVB
Application-specific restrictions on MPEG-2 video in the DVB standard:
Allowed resolutions for SDTV:
 720, 640, 544, 480 or 352 × 480 pixel, 24/1.001, 24, 30/1.001 or 30 frame/s
 352 × 240 pixel, 24/1.001, 24, 30/1.001 or 30 frame/s
 720, 704, 544, 480 or 352 × 576 pixel, 25 frame/s
 352 × 288 pixel, 25 frame/s
For HDTV:
 720 x 576 x 50 frames/s progressive (576p50)
 1280 x 720 x 25 or 50 frames/s progressive (720p50)
 1440 or 1920 x 1080 x 25 frames/s progressive (1080p25 - film mode)
 1440 or 1920 x 1080 x 25 frames/s interlace (1080i25)
1920 x 1080 x 50 frames/s progressive (1080p50) possible future H.264/AVC format
[edit]

ATSC
Allowed resolutions:
 1920 × 1080 pixel, 30 frame/s (1080i)
 1280 × 720 pixel, 60 frame/s (720p)
 720 × 576 pixel, 25 frame/s (576i, 576p)
 720 or 640 × 480 pixel, 30 frame/s (480i, 480p)
Note: 1080i is encoded with 1920 × 1088 pixel frames, but the last 8 lines are discarded prior to display.


Όπως βλέπεις, στη γραμμή που σου έχω τονισμένη, 1080p με MPEG2 προβλέπεται μελλοντικά και μόνο για μετάδοση μέσω δορυφόρου και μόνο στα 50 frames, με τη χρήση του νέου αλγόριθμου Η.264/AVC. H Sony από την άλλη μεριά είχε δεσμευτεί ότι δεν θα χρησιμοποιούσε τον VC1 αλγόριθμο, οπότε το υλικό στα bluray δισκάκια αναγκαστικά θα ήταν αποθηκευμένο στα 1080i.
 

takisot

Μέλος Δ.Σ.
Staff member
17 June 2006
24,573
Παλλήνη
Απάντηση: Κι όμως...

ΠΑΝΑΓΙΩΤΗΣ ΒΟΓΙΑΤΖΑΚΗΣ said:
Τάκη, τα 1080p είναι εκτός των επίσημων τεχνικών προδιαγραφών του αλγόριθμου MPEG2, για τους ψηφιακούς δίσκους το ταβάνι είναι τα 1080i. Δες εδώ, φαντάζομαι να αποδέχεσαι ότι πρόκειται για το πιο έμπειρο site τεχνικών προδιαγραφών:
en.wikipedia.org/wiki/MPEG-2



MPEG-2 Profiles
Abbr. Name Frames YUV Streams Comment
SP Simple Profile P, I 4:2:0 1 no interlacing
MP Main Profile P, I, B 4:2:0 1
422P 4:2:2 Profile P, I, B 4:2:2 1
SNR SNR Profile P, I, B 4:2:0 1–2 SNR: Signal to Noise Ratio
SP Spatial Profile P, I, B 4:2:0 1–3 low, normal and high quality decoding
HP High Profile P, I, B 4:2:2 1–3

MPEG-2 Levels
Abbr. Name Pixel/line Lines Framerate (Hz) Bitrate (Mbit/s)
LL Low Level 352 288 30 4
ML Main Level 720 576 30 15
H-14 High 1440 1440 1152 30 60
HL High Level 1920 1152 30 80

Profile @ Level Resolution (px) Framerate max. (Hz) Sampling Bitrate (Mbit/s) Application
[email protected] 176 × 144 15 4:2:0 0.096 Wireless handsets
[email protected] 352 × 288 15 4:2:0 0.384 PDAs
320 × 240 24
[email protected] 352 × 288 30 4:2:0 4 Set-top boxes (STB)
[email protected] 720 × 480 30 4:2:0 15 (DVD: 9.8) DVD, SD-DVB
720 × 576 25
[email protected] 1440 × 1080i 30 4:2:0 60 (HDV: 25) HDV
1280 × 720p 30
[email protected] 1920 × 1080i 30 4:2:0 80 ATSC 1080i, 720p60, HD-DVB (HDTV)
1280 × 720p 60
[email protected] 4:2:2
[email protected] 720 × 512 30 4:2:2 50 Sony IMX using I-frame only, Broadcast "contribution" video (I&P only, extra horizontal resolution for VBI information)
720 × 608 25
[email protected] 1440 × 1080i 30 4:2:2 80 Potential future MPEG-2-based HD products from Sony and Panasonic
1280 × 720p 60
[email protected] 1920 × 1080i 30 4:2:2 300 Potential future MPEG-2-based HD products from Panasonic
1280 × 720p 60
[edit]

DVD
The DVD standard uses MPEG-2 video, but imposes some restrictions:
 Allowed Resolutions
 720 × 480, 704 × 480, 352 × 480, 352 × 240 pixel (NTSC)
 720 × 576, 704 × 576, 352 × 576, 352 × 288 pixel (PAL)
 Allowed Aspect ratio (image) (Display AR)
 4:3
 16:9 (2.21:1 also specified but little if ever used)
 Allowed Frame rates
 29.97 frame/s (NTSC)
 25 frame/s (PAL)
Note: By using a pattern of REPEAT_FIRST_FIELD flags on the headers of encoded pictures, pictures can be displayed for either two or three fields and almost any picture display rate (minimum 2/3 of the frame rate) can be achieved. This is most often used to display 23.976 (approximately film rate) video on NTSC.
 Audio+video bitrate
 Buffer average maximum 9.8 Mbit/s
 Peak 15 Mbit/s
 Minimum 300 Kbit/s
 YUV 4:2:0
 Additional subtitles possible
 Closed captioning (NTSC only)
 Audio
 Linear Pulse Code Modulation (LPCM): 48 kHz or 96 kHz; 16- or 24-bit; up to six channels (not all combinations possible due to bitrate constraints)
 MPEG Layer 2 (MP2): 48 kHz, up to 5.1 channels (required in PAL players only)
 Dolby Digital (DD, also known as AC-3): 48 kHz, 32–448 kbit/s, up to 5.1 channels
 Digital Theater Systems (DTS): 754 kbit/s or 1510 kbit/s (not required for DVD player compliance)
 NTSC DVDs must contain at least one LPCM or Dolby Digital audio track.
 PAL DVDs must contain at least one MPEG Layer 2, LPCM, or Dolby Digital audio track.
 Players are not required to playback audio with more than two channels, but must be able to downmix multichannel audio to two channels.
 GOP structure
 Sequence header must be present at the beginning of every GOP
 Maximum frames per GOP: 18 (NTSC) / 15 (PAL), i.e. 0.6 seconds both
 Closed GOP required for multiple-angle DVDs
[edit]

DVB
Application-specific restrictions on MPEG-2 video in the DVB standard:
Allowed resolutions for SDTV:
 720, 640, 544, 480 or 352 × 480 pixel, 24/1.001, 24, 30/1.001 or 30 frame/s
 352 × 240 pixel, 24/1.001, 24, 30/1.001 or 30 frame/s
 720, 704, 544, 480 or 352 × 576 pixel, 25 frame/s
 352 × 288 pixel, 25 frame/s
For HDTV:
 720 x 576 x 50 frames/s progressive (576p50)
 1280 x 720 x 25 or 50 frames/s progressive (720p50)
 1440 or 1920 x 1080 x 25 frames/s progressive (1080p25 - film mode)
 1440 or 1920 x 1080 x 25 frames/s interlace (1080i25)
1920 x 1080 x 50 frames/s progressive (1080p50) possible future H.264/AVC format
[edit]

ATSC
Allowed resolutions:
 1920 × 1080 pixel, 30 frame/s (1080i)
 1280 × 720 pixel, 60 frame/s (720p)
 720 × 576 pixel, 25 frame/s (576i, 576p)
 720 or 640 × 480 pixel, 30 frame/s (480i, 480p)
Note: 1080i is encoded with 1920 × 1088 pixel frames, but the last 8 lines are discarded prior to display.


Όπως βλέπεις, στη γραμμή που σου έχω τονισμένη, 1080p με MPEG2 προβλέπεται μελλοντικά και μόνο για μετάδοση μέσω δορυφόρου και μόνο στα 50 frames, με τη χρήση του νέου αλγόριθμου Η.264/AVC. H Sony από την άλλη μεριά είχε δεσμευτεί ότι δεν θα χρησιμοποιούσε τον VC1 αλγόριθμο, οπότε το υλικό στα bluray δισκάκια αναγκαστικά θα ήταν αποθηκευμένο στα 1080i.

Πανο, το wikipedia.org δεν ειναι τεχνικο site αλλα Online εγκυκλοπαιδια (στυλ Δομη) η οποια γραφεται απο χρηστες.
Ακομα ομως και σε αυτο υπαρχει ξεκαθαρη αναφορα στο ζητημα.
Αυτο που μου εχεις κανει bold, δεν σημαινει σε καμια περιπτωση οτι ο αλγορρυθμος MPEG2 ειναι ασυμβατος με το 1080p.
Αντιθετως! Εδω απλα αναφερονται οι επισημες προδιαγραφες ψηφιακης ή αναλογικής δορυφορικης τηλεοπτικης μετάδοσης(DVB και ATSC) στις οποιες, για λογους bandwidth, δεν συμφερει να χρησιμοποιειται ο αλγορυθμος συμπιεσης MPEG-2 για αναλυσεις πανω απο 1080p50 και ειναι προτιμοτερος ενας πιο efficient αλγορυθμος οπως ο Η.264!
Σε καμια περιπτωση δεν υπαρχει ανικανοτητα του MPEG-2 να συμπιεσει το πρωτογενες υλικο υπερυψηλης αναλυσης απο το master σε φορμα 1080p για χρηση σε blu-ray και Hd-dvd! Αποδειξη, οτι η Sony το χρησιμοποιει στους πρωτους της τιτλους για blu-ray σε 1080P.
Δες ακριβως τι λεει το Wikipedia και θα καταλαβεις:

Broadcasting standards

Due to bandwidth limitations of broadcast frequencies, the ATSC and DVB have standardized only the frame rates of 24, 25, and 30 frames per second (1080p24, 1080p25, 1080p30). 1080p30 is currently the most bandwidth-intensive video mode supported. If the standard MPEG-2 compression is used, versions with higher frame rate such as 1080p50 and 1080p60 could only be sent over higher-bandwidth channels; to send these over normal-bandwidth channels, a more modern codec such as the H.264/MPEG-4 AVC codec must be used. Higher frame rates such as 1080p50 and 1080p60 are currently for private or internal use only, and are not part of the broadcasting standard.
The ATSC is considering amending its standard to allow the incorporation of the newer codecs for optional usage like the DVB Consortium already has done with DVB-S2. However, this is not expected to result in widespread consumer availability of broadcast 1080p programming, since most of the existing digital television sets, or external digital receivers would still only be capable of decoding the older, less-efficient MPEG-2 codec, while the bandwidth limitations do not allow for broadcasting two simultaneous streams (i.e. both a 1080i or 720p MPEG-2 stream alongside a 1080p MPEG-4 stream) on the same broadcast channel.
 
Last edited:

mezzanine

AVClub Enthusiast
19 June 2006
744
Χωρίς να ξέρω σίγουρα δεν νομίζω το MPEG-2 να μην μπορεί να κάνει encode σε 1080p. Αλλα όπως και να έχει εάν τελικά τα Blu-Ray κρατήσουν σαν standard το MPEG-2 για video compression την πατήσαμε.
Αν όμως οι τίτλοι που θα βγούν στο μέλλον είναι 1080p σε codec Η.264/AVC (πολύ καλύτερο απο το WMV που χρησιμοποιούν τα HD-DVD) η εικόνα θα είναι απίθανη.
 

Emilot

AVClub Fanatic
18 June 2006
32,853
Εξάρχεια
Mezzanine, δεν την πατήσαμε εμείς αυτοί την πάτησαν....χε χε!!

Και από ότι βλέπω η Sony δεν αλλάζει ρότα....καλαααααάαα!!!:cool: