很多人不知道HDCAM只能錄1440X1080
大多數人以為HDCAM錄下來就是1920X1080的full HD畫面,但實際上,包括可以錄24p的Cine Alta級HDCAM F900等HDCam,
雖然CCD畫素是1920X1080,
但在錄影時"偷吃步",並未使用上所有CCD畫素,
因為HDCAM的Codec只能錄下1440X1080,
因此真正錄下的訊源原始已pre-filterd成1440X1080,
隨後播出過帶編輯時才upsample成1920X1080給VTR,
因此嚴格來說,不能說是"真正"的1920X1080,
HDcam SR才是...
http://en.wikipedia.org/wiki/HDCAM
HDCAM, introduced in 1997, is an HD version of Digital Betacam, using an 8-bit DCT compressed 3:1:1 recording, in 1080i-compatible downsampled resolution of 1440×1080 , and adding 24p and 23.976 PsF modes to later models. The HDCAM codec uses non-square pixels and as such the recorded 1440×1080 content is upsampled to 1920×1080 on playback. The recorded video bitrate is 144 Mbit/s. Audio is also similar, with 4 channels of AES/EBU 20-bit/48 kHz digital audio.
http://cinetaur.googlepages.com/hd2...matographylinks
The most commonly used cameras for 8-bit image capture are Sony's Alta Vista F900 and Panasonic's Varicam. The F900 records in 1440x1080/24P , the Varicam in 720/24P - but has a variable frame rate (12-60).
http://www.hd-cinema.com/camera_comparison.html
Sony HDW-F900,
1920x1080p three 2/3" CCDs...2.1 Mega Pixel imager, frame rates up to 60i;
F900 records to HDCAM tape at 1440x1080 resolution 144 Mbs
http://hd24.com/panasonic_v_sony.htm
Panasonic Varicam has a 1 million pixel imager. Sony has 2.1 million pixel imager (both cameras do not use all of the pixels) Varicam records 960x720 pixels of luminence detail Sony 1440x1080 pixels of lumence. On playback vtrs convert the image up to 1920x1080 pixels. HDCAM samples the original 1920x1080 to 1440x1080 whereas the Varicam samples 1220x720 to 960x720. So comparing the two is a apple and oranges comparison. 是的，
這還導致HDCAM的色彩取樣總量，還低於XDCAM EX (HQ) ！
只能說HDCAM機身的CCD、訊號處理及Codec很優秀，再加上高碼流，淹蓋了這部分的減損。
Brian 原帖由 <i>terry</i> 於 2009-1-12 17:16 發表 <a href="http://www.hd.club.tw/redirect.php?goto=findpost&pid=215239&ptid=18488" target="_blank"><img src="http://www.hd.club.tw/images/common/back.gif" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open('http://www.hd.club.tw/images/common/back.gif');}" onmousewheel="return imgzoom(this);" alt="" /></a><br />
大多數人以為HDCAM錄下來就是1920X1080的full HD畫面,<br />
但實際上,包括可以錄24p的Cine Alta級HDCAM F900等HDCam,<br />
雖然CCD畫素是1920X1080,<br />
但在錄影時"偷吃步",並未使用上所有CCD畫素,<br />
因為HDCAM的Codec只能錄下1440X ... <br />
前不久去紀錄片工會得知,有些經費拍攝一定要1920x1080 才行,聽說會有一台儀器測量才能夠知道他的原始格式！
所以有些hd是不能過關的....
DVCPRO HD是真正的FULL HD 嗎?
原帖由 terry 於 2009-1-12 17:16 發表 http://www.hd.club.tw/images/common/back.gif大多數人以為HDCAM錄下來就是1920X1080的full HD畫面,
但實際上,包括可以錄24p的Cine Alta級HDCAM F900等HDCam,
雖然CCD畫素是1920X1080,
但在錄影時"偷吃步",並未使用上所有CCD畫素,
因為HDCAM的Codec只能錄下1440X ...
大多數人以為DVCPRO HD錄下來就是1920X1080的full HD畫面,
但實際上,包括可以錄最高階的VAIRCAM級AJ-HPX3700,
雖然CCD畫素是1920X1080,
且在錄影時雖未偷吃步, 使用上所有CCD畫素,
但因為DVCPRO HD的VTR只能錄下1280X1080,
因此真正錄下的訊源原始已Downsampled成1280x1080,
隨後播出過帶編輯時才upsample成1920X1080給VTR,
因此嚴格來說,也不能說是"真正"的1920X1080,
HDcam SR才是...
資料來源:
http://www.mediacollege.com/video/format/dv/dvcprohd.html
[ 本帖最後由 Shammy42 於 2009-4-16 08:50 編輯 ]
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