Intensity bypassing the HDV compression chip?

[Ian Maclean]

I’d also like to confirm that using any of the camcorders mentioned above, and recording to hard drive / card / dvd, then playing back to Intensity through HDMI output will have lost the 4:2:2 space when the AVCHD compression was done. Even if decompressed into 4:2:2 for playback, my impression is that the colorspace will have, essentially, been ‘up-rezed.’ Do I understand this right?

I”m also guessing that the camera manufacturers don’t really want to encourage this workflow as it would have to eat into the market for their higher end cameras. Any thoughts?

[Ian Maclean]

I’ve been emailed the following from a Blackmagic rep, and wonder if there are any video / electrical engineers that can verify her statement about one of the new Sony cameras. There are a ton of schematics in the PDF, and I don’t know where to start:

“>To check you can download the service
>manual of the Sony HDr-HC5 and HC7 from this page:
>
>
>https://www.humanvalues.net/hdv/Sony_HDR-HC5_HDR-HC5E_HDR-HC7_HDR-HC7E_Service_Manual.pdf
>
>
>This will clearly show the signal path of
>the video which goes from the lens to the HDMI output.”

[Ian Maclean]

Interesting: Sony’s new HDR-SR7 (Expected to ship on or before July 13, 2007), comes with an Optional HDMI Cable – 30ft. (VMC-30MHD). Can there be any other purpose than tethered, live capture? To the Intensity card?

in the Optional Accessories: https://www.sonystyle.com/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/SY_DisplayProductInformation-Start?CategoryName=dcc_DICamcorders_HighDefinitionVideo&ProductSKU=HDRSR7&TabName=specs&var2=

[Ian Maclean]

Hm. Not a lot of give and take on this topic. Got another response to a question from Blackmagic, and here it is, with an explanation of the signal path on the Sony camera from the PDF service manual link above:

—————

– I am also unclear about …advertised claims such as “With Intensity, you can now capture AND [my caps] play back full resolution HDTV uncompressed video for true broadcast and feature film quality editing.” We seem to agree that, if the cameras work the way you claim, capturing live / direct is capable of film-quality 4:2:2 colorspace, but can the same be said of ‘play back?’ What is ‘played back’ is compressed footage, and my understanding of the AVCHD codec is that it is 8-bit, 4:2:0, which nobody would call ‘film quality.’

-The HDMI output is just like the component outputs or SDI outputs from other cameras. It is unlike the data output of firewire which is merely the transfer of of bits and bytes from the DV or HDV tape to the computer drive. When you send a signal out of the HDMI port, it is an actual 4:2:2 uncompressed video signal in either YUV or RGB colour space. When you capture ‘live’ from the camera, it bypasses the HDV compression chip on the camera going straight out of the component as well as HDMI outputs of the camera, this is why you don’t see a delay in the video unlike using firewire. This can be seen in the block diagram of the service manual I’ve sent you as well as from tests carried out by us when developing the product. Simply capture HDMI off the camera ‘live’ and then the same video off the tape and you will see the quality difference.

When the video is already recorded to tape, the output is still uncompressed video as the camera processes and upsizes the video in order to send out full resolution HD video. You do lose a bit of quality as some data is thrown away after going onto tape but it is still better than working in AVCHD natively.

Now, let’s take about the capturing process on the Mac. We allow you to capture, with Intensity, to the Apple Uncompressed 8-bit codec. This is a uncompressed workflow running at 120MB/sec of datarate. The video goes in uncompressed and when you edit the video, you play out via the HDMI port of the Intensity card, uncompressed video at its full resolution. This is the ‘played back’ part of the equation. True uncompressed video monitoring of your HD timeline out via HDMI.

…I thought I’ll try and explain the signal flow diagram in the service manual.

Let’s the take the Sony HC5 camera for example. We start off on page 38 and the top left corner of the page where the signal starts at the camera iris and then into the CMOS IMAGER. You’ll need to follow the green video lines here. It then goes into page 39 where the signal flows to the right of the page into BASE BAND SIGAL PROCESSOR (IC2101 (1/5)). Page 40 then shows the signal output from