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Compression Quality Comparison HDCAM – Decklink
How does the Quality of HDCAM / HDCAM SR Compare to BMD Systems?
Sony says that:
– HDCAM is 8Bit, 4:2:2 @ 18 MB /s
– HDCAM SR is 10Bit, 4:4:4 @ 55 MB /sBMD Systems are running at much higher Datarates (132MB/s and up), does this mean BMD Codecs are much higher Quality than HDCAM ???
Would AppleProRes 422 (27MB/s) have a similar Quality like HDCAM ?
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1 Reply
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Yes. BM captures 10 or 12bit uncompressed (YUV or RGB), so it is superior quality to any of the HD tape formats. HDCAM and SR both compress on tape, reducing the image quality. You can use a Sony camera’s HDSDI out directly into th Decklink to bypass the compression, which is what I try to do when I have a choice.
Your spec on SR is in the “SQ” mode… newer decks can do “HQ” mode which doubles the data rate to 880mbit/sec (ie. 110MByte/Sec). ProRes HQ’s data rate is 220mbit/sec, so it is throwing away much more information than SR. Both are 10bit.
HDCAM is really an old HD format and seriously compromises image quality. Besides the low 144mbit/sec data rate, it is only 8bit, and throws away 1/3 the chroma working in 3:1:1 color space. Even the low end pro-res is 4:2:2 10bit. Pus pro-res is using better compression algorithms.
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