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720p @ 25fps or 29.97fps is not a supported frame rate?
I’m in a dilema, looking for a breakout box I’ve noticed that none of the major brands, AJA, BlackMagic Design or Matrox support 720p HD video @ 25fps or 29.97fps.
Why is this? Is anything less than 720p @ 50fps not an “official” frame rate for this HD format? Could someone please explain this to me. I understand about progressive and interlaced frame rates, such as 50Hz and 60Hz which is supported as 720p but as a progressive format there should be 25fps support, or am I wrong in thinking this? Thanks in advanced!
AJA doesn’t support 720p @ 25fps either.
525i 29.97
625i 25
720P 50, 59.94, 60
1080i 25, 29.97, 30
1080PsF 23.98, 24
1080p 23.98, 24, 25, 29.97, 30https://www.aja.com/en/products/io-express#techspecs
nor does Matrox
NTSC/PAL/NTSC-EIAJ
720P 50/59.94
1080I 50/59.94
1080P 23.98/24/25/29.97/30
1080PsF 23.98/24/25/29.97/30
https://www.matrox.com/video/en/products/mxo2_le/specs/or BlackMagic Design
HD Format Support
720p50, 720p59.94, 720p60, 1080PsF23.98, 1080p23.98, 1080PsF24, 1080p24, 1080PsF25, 1080p25, 1080PsF29.97, 1080p29.97, 1080PsF30, 1080p30, 1080i50, 1080p50, 1080i59.94, 1080p59.94, 1080i60, and 1080p60.https://www.blackmagicdesign.com/products/ultrastudiothunderbolt/techspecs
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2 Replies
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[Anthony Cox] “I’m in a dilema, looking for a breakout box I’ve noticed that none of the major brands, AJA, BlackMagic Design or Matrox support 720p HD video @ 25fps or 29.97fps. Why is this? Is anything less than 720p @ 50fps not an “official” frame rate for this HD format?”
I’m not sure what the actual standard is, but in practice, there is no such thing as 720p25 or 720p29.97.
I don’t think it has to be a big deal, though — 720p50 carries 720p25 perfectly by duplicating frames, and 720p59.94 carries 720p29.97 perfectly by duplicating frames.
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
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Those listed framerates for 720p are the signal standards. I’ve not gone super deep analyzing this but I’d wager it’s that because 720p50 has pretty much the same bit-rate as 1080i25.
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