There are two think I wld like to know.
In samsung- 32in series 5 & 6,Samsung has Full HD,24 true cinema but they are only 50 Hzs.
Spirovious,
You have thrown a lot of different specs and terminology together and got confused in the process. So let us try to understand the terminology, and how they are relevant.
spirovious said:
Whereas Panasonic LX800 is 100Hzs,it can play 24 pic but not full HD. In Pan manual,24 frm play & 24 frm true pic are the two ways of playing Blue ray. LX800 has 24 playback not the true one.I dont understand the term.Is it bcos its not full HD, but can accept 1080p?
First the Panasonic LX 800 is 1,366 x 768-pixel resolution. This cannot display 1080p (Full HD) under any circumstance. If you want a Full HD display you have to get a TV that has 1920x1080 pixel screen. This is irrespective of every other specification, and whether you connect it to a Blu-Ray or not.
24P
Now coming to 24. You have used many terms here - 24 pic, 24frm, 24 true pic, 24 playback.... etc.
The correct terms are 24p and 24fps (FRAMES PER SECOND).
24fps comes from movies that you see in cinema hassle. These are shot on film rolls that are moved across a projector to display motion. Each frame has a slightly different still photograph from the previous frame that is an indication of motion. The projector moves the reel across the light source and lens at the rate of 24 frames for every one second. When these still pictures are projected on the screen at that speed, your eyes see that as motion. Now a film is also called
progressive scanning as each still picture fills the entire frame. This is called progressive source. This means that the frame rate is the number of individual full pictures. In the came of film this is exactly 24.
When a movie is converted to DVD, it is always stored as 24 frames per second.
Now a TV system works in a completely different fashion. Basically there are two systems - NTSC and PAL and both these systems are based upon the CRT. In a CRT, an image is displayed by scanning a electron beam across the screen. Each frame of a film is broken into two halves called
FIELDS. The CRT first scans even numbered lines such a 1,2,4,6 and so on. It thus forms half an image. It then scans the odd numbered lines such a 3,5,6,7, and so on to form the second half of the image. These two half images are interleaved or
interlaced to form the full image.
Since a TV display technology forms two half images and then interlaces them to form a full frame, it is called interlacing. So all TV displays have two aspects - scanning lines and frame rate, The field rate is always double the frame rate.
NTSC uses a Frame consisting of 486 horizontal lines in the active area and a frame rate of 29.97 frames per second (fps). The frame is interlaced, meaning it's composed of two individual fields with a Field rate of 59.94fps, usually referred to as 60fps. (fields per second)
The PAL (Phase Alternating Line) TV standard was introduced in the early 1960's in Europe. It has better resolution than NTSC, having 576 lines in the active area of the frame. The frame rate is 25fps, much closer to the 24 fps frame rate of a reel film.
Now when you take a film standard at 24 fps whi9ch is progressively scanned, it can never be displayed on either NTSC or PAL directly. So the frame rate is converted.
In NTSC, the conversion is done by periodically playing a selected frame twice. The difference in frame rates can be corrected by showing every 4th frame of film twice, although this does require the sound to be handled separately to avoid "skipping" effects. A more convincing technique is to use "2:3 pull down", which turns every other frame of the film into three fields of video, which results in a much smoother display.
In PAL, a similar system called "2:2 pull down is used. Theatrical film originally shot at 24 frame/s are simply sped up by 4% to 25 frame/s. This speeding up does not make too much difference to the video. The audio on the other hands is affected by an increase in audio note by one semitone. A recent innovation called pitch shifter handles this. The system is good enough for the human ear, but one can notice the difference if the sound with shifted pitch is played along with the original sound.
What we discussed till now is an analogue system.
Modern TV such as LCDs are both digital and analogue. What this means is that they can display both interlaced as well as progressively scanned images. Why is this needed? Simply because all your TV production is mostly still using analogue interlaced system. Though digital TV cameras are there, transmitting progressive images needs very high bandwidth, and TV companies, because of their investments, still use NTSC and PAL systems.
When a TV manufacturer says his TV is 24p, all it means is that the TV can display images at 24 frames per second without any conversion. This has
nothing to do with Full HD. You can display at 24p but still display images at 480p or 720p resolution. So a 24p does not guarantee 1080p.
Secondly the 24p is relevant only for DVD (SD DVD or Blu-Ray). TV transmission still do not use 24p.
Hz
The Hz in TVs refer to what is called refresh rate. This is the number of times the TV draws from the data that is presented to it by a DVD or a TV source.
When the CRT was developed in the 1920s, the TVs were run at the same speed as AC line frequency used for power. So US CRTs were run at 60 Hz, and European CRTs at 50 Hz. These rates thus formed the basis for the NTSC (60 Hz) and PAL & SECAM (50 Hz) sets used today. The 50 Hz refresh rate gave the CRT more time to scan the detail. Thus PAL system had higher resolution and detail as compared to NTSC. But the scanning rate can introduce some flicker mostly in high speed motion.
Modern TVs have increased refresh rates to avoid flicker. Refresh rates have to be multiple of 24, as that is the frame rate. So refresh rates such as 48, 72, 96, and 120 Hz are needed to display motion properly.
Again the refresh rate has nothing to do with Full HD. Even used at 720p, a TV with higher refresh rate will display smoother motion.
spirovious said:
Secondly dealer told me upscaling can be done only from HDMI connection only.Tatasky which was already playing through composite can not be upscaled by both TVs.So are those both capable of upscaling composite signal to HD?
As far as I aware, most TVs restrict scaling to de-interlacing. This is converting an interlaced image to a progressive image at the same resolution. In other words, if the TV receives a 720i signal, it converts it to 720p. In addition, scalers built into most HDTVs are very basic and do not have advanced processing to eliminate scaling artifacts, such as jagged edges, motion adaptive noise reduction, mosquito noise, and detection of various video and film cadences.
Scaling to a higher resolution such as 1080p is usually done by the AVR or DVD Player.
Scaling or conversion to a higher resolution is done by TVs which specifically mention these in their specs. If a TV says it is Full HD, it does not mean it does scaling or upconversion. All it means is that it can accept and display a 1080p image.
Technically, component cable is capable of carrying 480i, 480p, 576i, 576p, 720p, 1080i and 1080p signals. Many TVs though do not support 1080p through component video.
Composite cables cannot carry high resolution signals. They are best at 480p. After that the data starts getting gets corrupted.
If you want a TV signal to be scaled, it has to be done by an external scaler such as an AVR.
spirovious said:
I even read some where 800 has native resolution of 720p.So will 1080p be downscaled to 720p? What abt samsung?
Any TV that has a native resolution of 720 cannot display anything more than that. So it will have no option but to downscale higher resolution images to its native capability. This has nothing to do with the brand.
spirovious said:
So personally I liked Pan but not full HD & sam full HD but 50 Hz. Sam can play 24 true pic,pan can accept but dont know what it meens. So looking at future Blueray which will be better buy? (considering 100Hz over Full HD and 24 pic for 32in only)
If you are planning for a Blu-ray system down the line, you have to look for a TV that is minimum 42" in size, has a pixel resolution of 1920x1080, and a refresh rate of 100Hz at a minimum. Amongst brands, these are the minimum specs you have to look for and then start short listing after auditioning.
Cheers