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ryan knight

7D recording to Uncompressed Recorder

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Does anyone know if you can record Uncompressed HD to a recorder (like the AJA I/O Express) via the 7D's HDMI?

 

RK.

 

...or to SATA 3.0?

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Does anyone know if you can record Uncompressed HD to a recorder (like the AJA I/O Express) via the 7D's HDMI?

 

RK.

Yes you can, but it is interlaced 1080 60i with a letterbox and you have to crop out the red recording dot, so the final resolution is something like 720. Also, it doesn't really fix the aliasing and rolling shutter issues. But you will have a more robust recording for grading purposes.

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Yes you can, but it is interlaced 1080 60i with a letterbox and you have to crop out the red recording dot, so the final resolution is something like 720. Also, it doesn't really fix the aliasing and rolling shutter issues. But you will have a more robust recording for grading purposes.

 

 

That makes no sense. Have you tried it yourself sats? If so, did you make sure you were doing it 100% correctly? I don't mean to question you like that, but it seems rediculous that aja wouldn't have considered those things.

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I believe that the HDMI output on the 7D is always 60i - which frankly is what I'd have done, given that it is probably the most compatible of all HDMI picture formats. You could probably extract the 24p from that if it's just 3:2'd up to 60i, but the superimposed dot is a bit of an issue.

 

But um - surely the red dot isn't going to be there when the camera isn't recording to its internal storage. And if you're recording to external storage, you won't have the camera in record. Are there other GUI graphics that are unavoidably superimposed on the HDMI out?

 

P

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I believe that the HDMI output on the 7D is always 60i - which frankly is what I'd have done, given that it is probably the most compatible of all HDMI picture formats. You could probably extract the 24p from that if it's just 3:2'd up to 60i, but the superimposed dot is a bit of an issue.

 

But um - surely the red dot isn't going to be there when the camera isn't recording to its internal storage. And if you're recording to external storage, you won't have the camera in record. Are there other GUI graphics that are unavoidably superimposed on the HDMI out?

 

P

 

phil, so you can hit record on your device (AJA or Blackmagic, etc) and capture data without having to hit record on the camera?

 

sats, is the red dot in such a place that it can be cropped out in a 2.40 matte?

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It's not worth doing this. Noise and artifacts are already present in the HDMI output, so you aren't avoiding that. And the H.264 files that the 7D records to have a generous bitrate of around 45 megabits per second. In other words, they already look about as good as they can, even though they are compressed. Capturing through HDMI and having to crop the image is a big tradeoff for little, if any, gain.

 

 

Marco

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the 7d and the 5d don't output a clean uncompressed HDMI signal any ways... so you would be getting an SD signal which is technically a down conversion from the native H.264 compression.

 

Thats why you would try rock this with an EX3 instead. In which case you can get 180Mb/s @ 4:2:2.

 

check it out here: http://philipbloom.co.uk/2009/10/12/conver...igns-nanoflash/

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And the H.264 files that the 7D records to have a generous bitrate of around 45 megabits per second. In other words, they already look about as good as they can, even though they are compressed.

 

Pish. The bitrate is generous, but it's very poorly applied - Canon DSLR footage is rotten with artefacts. A better h.264 compressor (which I certainly wouldn't expect to see on a DSLR) could do far more with it. An uncompressed recording would have a lot of advantages, although I'd expect the aliasing to become comparatively more objectionable.

 

P

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Pish. The bitrate is generous, but it's very poorly applied - Canon DSLR footage is rotten with artefacts. A better h.264 compressor (which I certainly wouldn't expect to see on a DSLR) could do far more with it. An uncompressed recording would have a lot of advantages, although I'd expect the aliasing to become comparatively more objectionable.

 

P

 

oh no, i agree. It would have a lot of advantages. If the HDMI output was clean uncompressed HD.

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