HDSDI and HDV frame grabs

[Alister Chapman]

I have been playing with the HDSDI on my H1. I have been capturing uncompressed video to my PC with my Decklink HD card. By the way the H1 also plays back HDV tapes via the SDI connection, making it a really cheap DV/HDV deck with SDI/HDSDI output.

There are 3 frame grabs from the same frame.

The first one is from the HDSDSI stream recorded on the PC.
http://www.ingenioustv.co.uk/tests/sdichicks1.jpg

This one is from the m2t stream recorded on the camera tape.
http://www.ingenioustv.co.uk/tests/m2tchicks1.jpg

and the last one is a grab form a cineform clip, taken from the m2t.
http://www.ingenioustv.co.uk/tests/cineformchicks1.jpg

I was surprised at how small the difference is. Next time I'll do a test with some more saturated colours.

[Mike Marriage]

Originally Posted by Alister Chapman

...I was surprised at how small the difference is. Next time I'll do a test with some more saturated colours.

Could you do one with a lot of movement and detail to. That is more likely to show the differences. Also, to really compare them you need to post uncompressed image files, otherwise it is hard to tell what is MPEG2 compression and what is .jpeg.

Did you buy your H1 from Creative Video?

Thanks.

[Steve Connor]

Alister,

When did you start keeping chickens!

[Dylan Pank]

Originally Posted by Mike Marriage

Could you do one with a lot of movement and detail to. That is more likely to show the differences. Also, to really compare them you need to post uncompressed image files, otherwise it is hard to tell what is MPEG2 compression and what is .jpeg.

Did you buy your H1 from Creative Video?

Thanks.

Thing is we can at least assure that the JPEG compression is applying equally (or similarly) to all of them, so you can at least make some assessment. For example, look at the cockerel's crest (that's the rooster's crest for all our North American friends). Definitely it's sharper in the SDI capture. However some uncompressed frames would definitely be preferable.

Just to clarity, was the SDI capture live from the Cam to the PC, or from recorded HDV tape?

[Paul Doherty]

A very interesting comparison. I would agree the uncompressed is very slightly ahead of the others, and to my eyes the m2t shot is fractionally ahead of the cineform one.

To the man in the street they're identical!

[Vincent Rozenberg]

Originally Posted by Alister Chapman

By the way the H1 also plays back HDV tapes via the SDI connection, making it a really cheap DV/HDV deck with SDI/HDSDI output.

But.. Can you get timecode and audio as wel with this? To do some proper editing this is a must.

[Alister Chapman]

I used as little JPEG compression as photoshop would allow, otherwise each frame would be 5Mb.

The SDI capture was direct, "Live" from the camera to the PC.

I would love to post the actual video clips but the uncompressed clips would be a silly size.

There is no audio or timecode via the SDI. However audio and timecode are output from the analog outputs so if you were feeding a deck you could feed the audio and timecode via analog connections and the video via SDI.

We have had the chickens for 6 months, and the one with the big crest is a big hen that lays giant sized eggs, not a rooster. LOL.

Yes I got my H1 from creative video.

[Alister Chapman]

For those that want to see the uncompressed images I have created a Photoshop PSD file that has the images on 3 layers. The background layer is the HDSDI image, layer 2 is the cineform image and layer 3 is the m2t. By clicking the layers on and off in photoshop you can flick between them and thats when you can really see the differences. The SDI grab is clearly sharper than the other two, interestingly the colours are different on the m2t image, maybe something to do with the mpeg codec (mainconcept).

Right click on the link below and select "save target as" and save the zip file to you PC then unzip and open in photoshop, it's a big file at 19mb.

http://www.ingenioustv.co.uk/tests/sdichicks1.zip

[Dylan Pank]

We have had the chickens for 6 months, and the one with the big crest is a big hen that lays giant sized eggs, not a rooster. LOL

DOH!

Guess I'll stick to Video then and stay out of poultry farming.

[David Newman]

Interesting that the CineForm conversion for the M2T actually looks more like the uncompressed than the M2T file. Check out the M2T files color shift in the red rooster's crest, also the aspect ratio shift of the M2T decode. CineForm AVI correctly displays all the contents of the M2T, as it handles the 709 color sapce better than the MPEG decoder use to creater these images. The M2T data is clearly softer than the uncompressed, so there is good reason to use the HD-SDI, particularly directly into Prospect HD or a Wafian HR-1 to maintain ALL that resolution/definition at a 6:1 compression ratio.

[Vincent Rozenberg]

Thanks for the answer.

Sorry for going a bit off-topic, but I've got some more questions 'bout the SDI capturing.

For example, you've shot something in the 24F mode can you capture this with your Aja or Blackmagic set to 30i/p or (because i'm a European Dutchy) 25i/p and edit without any problems?

[Alister Chapman]

Don't know Vincent.. I am off on a shoot tomorrow so won't be able to try until Thursday. I'll give 25F a go then (have not had the camera modded for 24/60 yet).

Dave Newman: Am i correct in saying that the regular cineform codec (not 10 bit prospect) is optimised for 1440x1080? If I wanted to convert my uncompressed files to Cineform should I create 1920x1080 cineform files or 1440x1080? I Guess if I was editing mixed uncompressed and HDV in premiere I would be best using Cineform 1440x1080 otherwise I'll have two different sized images.

[David Newman]

Alister,

Aspect HD is only licensed up to 1440x1080 images 8-bit. Prospect HD support 1920x1080 10-bit. So to convert your uncompressed 1920 files to CineForm with Aspect HD you may need to scale your output.

[Alister Chapman]

Thanks Dave, That's kind of what I suspected. For $1999 I can add another 2 or 3 Tb of storage so I wouldn't really need prospect as I can already edit uncompressed in real time. I expect I'll end up getting Aspect 4 for Premiere Pro 2. I currently just have Connect HD which has to have been the best $199 I have spent.

[David Newman]

Alister, you are thinking of an older workflow. We have customers posting feature films and completely bypassing the off-line stage. 2-3Tb of data would be only enough space for posting a short film uncompressed. People can now store 40+ hours of HD source material on disk space that will cost only around $1000, no elborate RAID required. Plus you get for more real-time options in a compressed system (more channels, even across GigE, great for collabrative workflows.) When a customer thinks about the real workflow benefits they will realize purchasing Prospect HD will actually save you money, plus get you production out faster. I glad you have discovered benefits from Connect HD; we offer the same workflow gains with Prospect HD (it is worth the increased price.) Of course if you only need 8-bit processing, Aspect HD and as you have Connect HD are also bargins.