Specs on HDcam?

stephen lamb · May 9, 2006

Hey all,

Can someone tell me what the compression specs are like on an HDcam tape? I have searched aorund some, but haven't had any luck. I am prepping for a project in the future where I will have the ability to use HDcam as my transfer medium from Super16mm. I have read some sorts of complaining on other topics about how "crappy" HD cam tape is, especially considering that i will be pulling mattes and doing a fair bit of compositing. The best video format i have previously used has been DVCproHD. how do the two compare? Thanks,

Steve

Phil Rhodes · May 9, 2006

Hi,

HDCAM tape (not HDCAM SR) takes a 1920-pixel-wide HD image and scales it down to 1440, then throws away two thirds of the colour information, then compresses the result around 7:1. This is a lot of information to lose and the format is considered suboptimal, especially if you are doing compositing.

DVCPROHD stores the whole 1280x720 image, but at a slightly higher ratio of compression and having thrown out half of the colour information.

Neither format is really ideal for high end post work, although both have been applied to it. The best solution would be to do your transfer to a hard disk recorder and walk away with data, but few places are willing to do that - probably to protect their six figure investments in Sony VT equipment.

Phil

Joshua Reis · May 9, 2006

HDCAM

Color Sampling = 3:1:1, Bandwidth = 143 Mb/s, Compression 7.1:1, Precision = 8 bit, 1440x1080

HDCAM SR (two modes)

Color Sampling = 4:2:2, Bandwidth = 440 Mb/s, Compression 2.7:1, Precision = 10 bit, 1920x1080

Color Sampling = 4:4:4, Bandwidth = 880 Mb/s, Compression 4.2:1, Precision = 10 bit, 1920x1080

D5 (two modes)

Color Sampling = 4:2:2, Bandwidth = 250 Mb/s, Compression 4:1, Precision = 8 bit, 1440x1080

Color Sampling = 4:2:2, Bandwidth = 250 Mb/s, Compression 5:1, Precision = 10 bit, 1440x1080

DVCPRO100 (1080)

Color Sampling = 4:2:2, Bandwidth = 100 Mb/s, Compression 6.7:1, Precision = 8 bit, 1280x1080

(720)

Color Sampling = 4:2:2, Bandwidth = 100 Mb/s, Compression 6.7:1, Precision = 8 bit, 960x720

HDV (1080)

Color Sampling = 4:2:0, Bandwidth = 25 Mb/s, Compression 22.5:1, Precision = 8 bit, 1440x1080

(720)

Color Sampling = 4:2:0, Bandwidth = 25 Mb/s, Compression 22.5:1, Precision = 8 bit, 1280x720

David Cox · May 10, 2006

Although the HD CAM compression figures make for frightening reading, the truth is that for straight, normal images there are amazingly few artefacts.

You are right though to point out the limitations for post, particularly blue / green screen comps. This is because the colour part of the signal is effectively recorded at 1/4 HD resolution, so the images you are pulling your mattes from are fundamentally low res.

Where we have been faced with projects where producers have "had to use HD CAM for budgetary reasons", we suggest getting the blue screen stuff transferred separately, ideally to uncompressed 4:4:4 file. Failing that HD CAM SR in 4:4:4 mode or failing that HD D5 - although this still gives half res colour for your mattes.

For grading, at least agree your contrast settings in telecine before going to tape to avoid banding being introduced by expanding the contrast from the data on the HD tape.

David Cox

Baraka Post Production

DetroitDIT · May 10, 2006

Stephen Lamb said:
Hey all,
Can someone tell me what the compression specs are like on an HDcam tape? I have searched aorund some, but haven't had any luck. I am prepping for a project in the future where I will have the ability to use HDcam as my transfer medium from Super16mm. I have read some sorts of complaining on other topics about how "crappy" HD cam tape is, especially considering that i will be pulling mattes and doing a fair bit of compositing. The best video format i have previously used has been DVCproHD. how do the two compare? Thanks,

Steve

My suggestion would be to shoot a test and see how you like Super16mm transfered to HDCAM. Even do a little compositing. No matter what anyone says about this ratio and that ratio it all comes down to two things. 1) Does the footage look great? 2) Do you like it? I believe that you would be very happy with the results. Your not trying to reinvent the wheel here, this has been done with a great amount of success in the past. Just ask Kodak.

Great success with your production.