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DVD v/s DVB
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<blockquote data-quote="Channel Hopper" data-source="post: 1636" data-attributes="member: 175144"><p>Capacity of disc - my mistake, I am still recovering from yesterdays partying</p><p></p><p>In satellite use, packing more and more data into each transponder for more services - makes the broadcaster more money, as is using less bandwidth (saving money on transponder leasing).</p><p></p><p>The main question over quality from any datastream would not be the capacity of the storage device, but the bitrate the information is sent out at. </p><p></p><p>An average viewer will notice a bitrate of 4 Mbits/s gives rise under scenes of complexity / high movement (ie in an action film) to faults in the playback, regardless of how good the equipment is. In tests it has been shown few people will pick up faults on a stream playing at 6.5 to 7 Mbits/s, so this is set as the maximum required for quality reproduction on the MPEG-2 standard.</p><p></p><p>The amount of data capacity on the DVD disc and the time it has to run will determine the bitrate supplied. The quality of the reproduction will therefore be fixed by how long it has to run. </p><p></p><p>Standard DVDs for a two hour mass pressed film (plus features) will run at a bitrate of between 3.7 and 4.5 Mbit/s.</p><p></p><p>DVB on satellite, however, can be set to almost any type of bitrate the broadcaster wishes, and with a 27.5 Mbits/s transponder symbol rate on the more common satellites (Including Hotbird and Astra 2), there would be enough for four perfect 7 Mbits/s streams. </p><p></p><p>If a DVD played back at the rate of 7Mbit/s you would get only one hour of programme, - half a film. </p><p></p><p>Back to the question - DVD v Multivision</p><p></p><p>Transponder 11662MHz V on Hotbird transmitting seven streams at 27.5 Mbits/s gives a bitrate per film of just under 4Mbit/s (ignoring other factors). Chances then that it would be on par to the better DVDs on todays shelves.</p><p></p><p>By comparison - the Astra 2 transponder, 11.469 MHz Horizontal, symbol rate 27.5 Mbits/s showing at present 11 BSkyB Box Office Movies would mean each stream is delivered at under 2.5 MBits/s per programme stream (not good). </p><p></p><p>The simple comparison between watching a film on Multivision and a DVD therefore would not really be noticeable, however once you start looking at BSKYB transmissions packed like sardines one would have to ask if you are getting what you pay for. </p><p></p><p>Then again to answer the original question from Shahid, present quality of his eyesight and the resultant blur that is 'Emission Impossible' on the screen will have far more impact on the viewing pleasure than the various bitrates between the two mediums.</p></blockquote><p></p>
[QUOTE="Channel Hopper, post: 1636, member: 175144"] Capacity of disc - my mistake, I am still recovering from yesterdays partying In satellite use, packing more and more data into each transponder for more services - makes the broadcaster more money, as is using less bandwidth (saving money on transponder leasing). The main question over quality from any datastream would not be the capacity of the storage device, but the bitrate the information is sent out at. An average viewer will notice a bitrate of 4 Mbits/s gives rise under scenes of complexity / high movement (ie in an action film) to faults in the playback, regardless of how good the equipment is. In tests it has been shown few people will pick up faults on a stream playing at 6.5 to 7 Mbits/s, so this is set as the maximum required for quality reproduction on the MPEG-2 standard. The amount of data capacity on the DVD disc and the time it has to run will determine the bitrate supplied. The quality of the reproduction will therefore be fixed by how long it has to run. Standard DVDs for a two hour mass pressed film (plus features) will run at a bitrate of between 3.7 and 4.5 Mbit/s. DVB on satellite, however, can be set to almost any type of bitrate the broadcaster wishes, and with a 27.5 Mbits/s transponder symbol rate on the more common satellites (Including Hotbird and Astra 2), there would be enough for four perfect 7 Mbits/s streams. If a DVD played back at the rate of 7Mbit/s you would get only one hour of programme, - half a film. Back to the question - DVD v Multivision Transponder 11662MHz V on Hotbird transmitting seven streams at 27.5 Mbits/s gives a bitrate per film of just under 4Mbit/s (ignoring other factors). Chances then that it would be on par to the better DVDs on todays shelves. By comparison - the Astra 2 transponder, 11.469 MHz Horizontal, symbol rate 27.5 Mbits/s showing at present 11 BSkyB Box Office Movies would mean each stream is delivered at under 2.5 MBits/s per programme stream (not good). The simple comparison between watching a film on Multivision and a DVD therefore would not really be noticeable, however once you start looking at BSKYB transmissions packed like sardines one would have to ask if you are getting what you pay for. Then again to answer the original question from Shahid, present quality of his eyesight and the resultant blur that is 'Emission Impossible' on the screen will have far more impact on the viewing pleasure than the various bitrates between the two mediums. [/QUOTE]
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