1080i Conversion for Broadcast?

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ImActuallyAMusician
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1080i Conversion for Broadcast?

Post by ImActuallyAMusician » Wed Feb 28, 2018 2:29 pm

Hi there. I'm needing a little help with file conversion for television broadcast in the USA.

I'm about to do a single day shoot for a small project that has the potential of turning into a bigger project, and I want to make sure I'm broadcast safe in case it ever comes to that.

My main camera will shoot at 1080i/60, which is what I plan to do. My issue is with my 2nd camera. It will shoot at both 30 and 60 frames a second, but both of which are at 720p and 1080p, not 1080i.

I was wondering if there is an acceptable way to convert any of that footage to a broadcast safe format? Or am I going to have to ditch the second camera?

I did a lot of searching, but I couldn't seem to find an answer to my question.

My apologies if this is an idiotic question, and any help is greatly, greatly appreciated! :)

Signed,
A musician that's somehow doing video now

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NECRAT
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Re: 1080i Conversion for Broadcast?

Post by NECRAT » Thu Mar 01, 2018 2:07 pm

If the two devices are being used in a live shoot into a video switcher, you can use a simple cross converter.

They range from a couple of hundred bucks to high end several thousand dollar models.

For your money, especially if you are going into a switcher, you could get one of the Lynx boxes that do cross conversion and are referenced.
(So the cameras remain in sync).

If you are recording, most video software will cross convert for you.
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PID_Stop
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Re: 1080i Conversion for Broadcast?

Post by PID_Stop » Thu Mar 01, 2018 4:14 pm

To add a couple thoughts to what Mike just said: if you're simply recording in each camera and putting the show together with editing software, you might want to have both cameras recording 1080p... and when you've done the editing, render the final product in the broadcast format you want to use (1080i, for instance). The advantage to this is that if the program is distributed in other formats (over the internet, for instance), you can render a separate full 1080p version with little additional effort. Also, if you are doing something like sports that includes slow motion, making the original footage 1080p will give you much cleaner slo-mo without all of the de-interlacing artifacts.

Jeff

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Re: 1080i Conversion for Broadcast?

Post by ImActuallyAMusician » Thu Mar 01, 2018 7:51 pm

I guess I should have been a little more clear. I am indeed shooting to edit later.

I would love to shoot at 1080p as per your suggestion, Jeff, though my issue is that my main camera only shoots at 1080i/60, or 1080p/24, and from my understanding shooting at 24fps isn't a good move for broadcast? Thus my wanting to convert from 1080p at 30 or 60fps from my B camera into 1080i/60.

Please do correct me if I'm totally wrong, as standards for television broadcast is a pretty foreign subject to me. (I liked this project better when it was web only. :lol: )

I really appreciate the information. Any further suggestions or sources for information are greatly appreciated!

(One other thing to note: My shoot day is this coming Sunday the 4th, and budget is currently non-existent, so purchases/rentals aren't viable at this point.)

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Re: 1080i Conversion for Broadcast?

Post by PID_Stop » Fri Mar 02, 2018 9:12 am

You could do 24fps, and some people do so intentionally to get a "film look" (which in this instance is 3:2 pulldown... it alludes to a trick used in telecine projectors to repeat film frames periodically so that the video camera would be shown a frame every 30th of a second, even though the film itself was moving at normal speed).

Chances are, this isn't an effect you are looking for... so going with 1080i sounds like your best option.

Cheers!

Jeff

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Re: 1080i Conversion for Broadcast?

Post by ImActuallyAMusician » Fri Mar 02, 2018 12:34 pm

Thanks Jeff! That makes a lot of sense. So it looks like 1080i is what I'll be shooting then.

I guess that does bring me back around to my original problem, though. For my second camera, should I shoot 1080p/30 or 1080p/60 for best results for 1080i/60 conversion?

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Re: 1080i Conversion for Broadcast?

Post by Sesse » Thu May 10, 2018 1:52 pm

1080p60, definitely. Everything else will look oddly jerky when played back in i60.

You can think of i60 as a sort-of odd compression technique that has as much motion as p60 but occasionally has significantly less resolution.

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Re: 1080i Conversion for Broadcast?

Post by PID_Stop » Thu May 10, 2018 2:36 pm

Sesse wrote:
Thu May 10, 2018 1:52 pm
1080p60, definitely. Everything else will look oddly jerky when played back in i60.
Bear in mind that broadcast television in the United States does not currently support 1080p -- just 1080i and 720p.
You can think of i60 as a sort-of odd compression technique that has as much motion as p60 but occasionally has significantly less resolution.
The resolution for both 1080i and 1080p is a fixed constant that is the same for each: 1,920 x 1,080 pixels. The actual difference is that 1080p transmits 59.94 complete frames every second, whereas 1080i transmits 59.94 fields per second. A field is half of one frame; odd frames contain only the odd horizontal lines, and even frames contain the even horizontal lines. The field pairs interleave, hence the "i" in 1080i.

The issue with interleaved formats and motion is twofold: first and most generally, a higher frame rate is going to handle motion more smoothly than a lower frame rate. Second, if you intend to do slow motion or a still frame of moving video, there will be visible horizontal jitter because the two fields that make up the frame are captured about a thirtieth of a second apart in time.

Jeff

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Re: 1080i Conversion for Broadcast?

Post by Sesse » Thu May 10, 2018 2:47 pm

Yes, indeed. I intended to answer the question “if downconverting to 1080i, do I want to record in 1080p30 or 1080p60”? Everything you're saying is correct, of course.

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