HDMI in HDV and AVCHD Camcorders

[David Ziegelheim]

Originally Posted by Steve Mullen

HDMI is not ONLY 1920x1080. It carries any digital resolution or frame-rate.

Originally Posted by HDMI Spec

6.2.1 Format Support Requirements
Some of the following support requirements are in addition to those specified in EIA/CEA-861B.
• An HDMI Source shall support at least one of the following video format timings:
• 640x480p @ 59.94/60Hz
• 720x480p @ 59.94/60Hz
• 720x576p @ 50Hz
• An HDMI Source that is capable of transmitting any of the following video format timings using any other component analog or uncompressed digital video output, shall be capable of transmitting that video format timing across the HDMI interface.
• 1280x720p @ 59.94/60Hz
• 1920x1080i @ 59.94/60Hz
• 720x480p @ 59.94/60Hz
• 1280x720p @ 50Hz
• 1920x1080i @ 50Hz
• 720x576p @ 50Hz
• An HDMI Sink which accepts 60Hz video formats shall support the 640x480p @ 59.94/60Hz and 720x480p @ 59.94/60Hz video format timings.
• An HDMI Sink which accepts 50Hz video formats shall support the 640x480p @ 59.94/60Hz and 720x576p @ 50Hz video format timings.
• An HDMI Sink which accepts 60Hz video formats, and which supports HDTV capability, shall support 1280x720p @ 59.94/60Hz or 1920x1080i @ 59.94/60Hz video format timings.
• An HDMI Sink which accepts 50Hz video formats, and which supports HDTV capability, shall support 1280x720p @ 50Hz or 1920x1080i @ 50Hz video format timings.
• An HDMI Sink that is capable of receiving any of the following video format timings using any other component analog or uncompressed digital video input, shall be capable of receiving that format across the HDMI interface.
• 1280x720p @ 59.94/60Hz
• 1920x1080i @ 59.94/60Hz
• 1280x720p @ 50Hz
• 1920x1080i @ 50Hz

That doesn't seem to be "any"

[Mike Schell]

A couple of notes of clarification:
1) I certainly agree that the most common application for HDMI will be in post production ingest. But, there will be some occasional uses in live-capture, where you certainly avoid all the issues of MPEG compression.

2) HDMI does specify a clearly defined set of video rates and resolutions (over 35!). For most professional video applications, the 6 most common formats (1080i50, 1080i60, 720p50, 720p60, 480i, and 576i) are all that really matter. HDMI does not support 24p formats.

3) Since HDV (as implemented by Sony and Canon) is fundamentally 1440x1080, I think Sony placed a horizontal upscaler prior to the HDMI transmitter (and analog component encoder). They can use the same data path for capture or playback and connect this bus to the input of the MPEG2 encoder and the output of the MPEG2 decoder. It seems a little odd, but it would be the easiest implementation

4) The HDMI stream out of the camcorder is 1920x1080i YCbCr 4:2:2 in all modes (at least for the HC3 camcorder). I suspect you'll get the same resolution from all Sony HDV camcorders.

Mike Schell

[Mike Schell]

Hi David-
I think Sony does some digtial processing of the 1920x1080p image off the CMOS sensors followed by the downscale to 1440x1080i just before sending the video stream to the MPEG2 encoder. Since the output from the MPEG2 decoder (when operating in playback mode) is also 1440x1080i it is simplier to just put an horizontal upscaler in the path to the HDMI trasmitter. With this design you can use the upscaler in either capture or playback modes. Yes, it may not be the ideal design for live-capture applications, but it does simplify some of the processing circuits in the camera.

I assume the digital processing circuit which follows the CMOS sensor A/D converters may process the video in 12 bit resolution, although I don't know any of the specific details. I am certain that the output is 1440x1080i 8-bit, which is then fed to the MPEG2 encoder and the HDMI upscaler.

Mike Schell