There is no on the air 1080p broadcasting:
Digital television in the United States - Wikipedia, the free encyclopedia
1080p - Wikipedia, the free encyclopedia
Format standards
Main article: High-definition television in the United States
The five main ATSC formats of DTV currently broadcast in the U.S. are:
* Standard definition - 480i, to maintain compatibility with existing NTSC sets when a digital television broadcast is converted back to an analog one[citation needed] - either by a converter box or a cable/satellite operator's proprietary equipment
* Enhanced definition - 480p, about the same quality as current DVDs
* High definition - 720p
* High definition - 1080i
* High definition - 1080p (only in use by a few cable operators, currently no OTA broadcasts available in 1080p format).
Main article: High-definition television in the United States
The five main ATSC formats of DTV currently broadcast in the U.S. are:
* Standard definition - 480i, to maintain compatibility with existing NTSC sets when a digital television broadcast is converted back to an analog one[citation needed] - either by a converter box or a cable/satellite operator's proprietary equipment
* Enhanced definition - 480p, about the same quality as current DVDs
* High definition - 720p
* High definition - 1080i
* High definition - 1080p (only in use by a few cable operators, currently no OTA broadcasts available in 1080p format).
Broadcasts
In the United States, the ATSC standard allows 1080p24 and 1080p30 video. In practice, all major networks use a 60 Hz format in the MPEG-2 header -- either 720p60 or 1080i60. But that only dictates the formal output of the MPEG-2 decoding process, not the actual means of encoding the frames.
For material that originated from a 24 frame/s source (such as film), MPEG-2 allows the video to be coded as 1080p24, irrespective of the final output format. The progressively-coded frames are then tagged with metadata (literally, fields of the PICTURE header) instructing a decoder how to perform a 3:2 pulldown to interlace them. While the formal output of the MPEG-2 decoding process from such stations is 1080i60, the actual content is coded as 1080p24 and can be viewed as such. That is to say, twenty-four progressively-coded frames per second are present in the bitstream; it is the decoder that turns them into 60 interlaced fields per second. NBC is known to use this method with some stations.[citation needed]
Even for content that has not been encoded in this fashion, it is still usually possible to extract the original 24 source frames from a 1080i60 broadcast of 24 frame/s material, since no information is lost even when the broadcaster (as opposed to the receiver) performs the 3:2 pulldown.[citation needed]
In the United States, the ATSC standard allows 1080p24 and 1080p30 video. In practice, all major networks use a 60 Hz format in the MPEG-2 header -- either 720p60 or 1080i60. But that only dictates the formal output of the MPEG-2 decoding process, not the actual means of encoding the frames.
For material that originated from a 24 frame/s source (such as film), MPEG-2 allows the video to be coded as 1080p24, irrespective of the final output format. The progressively-coded frames are then tagged with metadata (literally, fields of the PICTURE header) instructing a decoder how to perform a 3:2 pulldown to interlace them. While the formal output of the MPEG-2 decoding process from such stations is 1080i60, the actual content is coded as 1080p24 and can be viewed as such. That is to say, twenty-four progressively-coded frames per second are present in the bitstream; it is the decoder that turns them into 60 interlaced fields per second. NBC is known to use this method with some stations.[citation needed]
Even for content that has not been encoded in this fashion, it is still usually possible to extract the original 24 source frames from a 1080i60 broadcast of 24 frame/s material, since no information is lost even when the broadcaster (as opposed to the receiver) performs the 3:2 pulldown.[citation needed]
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