GR-PD1 Recording Modes
The PD1 records, according to JVC, 625 lines of vertical resolution.
If you use the component cable, you might be able to get the full vertical image out of the video camera (UNTESTED – will test soon), although you’ll get an analog signal.
If you use (as I do) the firewire output, then the camera outputs an ~19Mbps MPEG2 data stream to your computer. This stream’s content depends on the recording mode you selected.
There seems to be a lot of confusion regarding the camera’s recording modes, specially when compared to it’s US brother, the GR-HD1. I suspect both cameras are very very similar (if not equal) hardware-wise, so their main differences should be about the firmware.
This raises the interesting question of whether you could turn a PD1 onto a HD1 (or vice versa), or even change them so that we can take the best out of both worlds. My educated guess would be that theoretically this could be possible, but that also, most probably NO, you really can’t turn a PD1 onto an HD1, most probably because of internal clock restrictions (many PAL and NTSC electronic systems inherit different quartz settings depending on their regions – even though they’re really fed thru continuous DC power from a battery and not from the mains AC)
Anyway, according to the JVC manual the camera has 3 video recording modes:
- When the camera is in the HI-RES mode, it uses an effective 1280x659 pixels area of the CCD (which is very high and the main reason why JVC PD1/HD1 footage in well-lit conditions falls so short behind real 3CCD cameras), and samples 25 progressive frames per second in a 16x9 aspect ratio.
- When the camera is in the PS50 mode, it uses either an 941x485 (when in 16x9 mode) or 839x576 (when in 4x3 mode) effective pixels area of the CCD, and samples 50 progressive frames per second.
- When the camera is in DV mode, it uses an effective 839x576 pixels area of the CCD, and samples 50 interlaced frames per second.
HOWEVER, in any of these modes, the firewire signal will always be outputted at 720x576 pixels, independently of the recording mode chosen. How does this make sense? Well, not much, but let’s try to figure it out:
- The HI-RES output stream is a 25fps progressive scan MPEG2 stream, much like in HDV, and has LOADS of color detail – which you can see if you compare a shot in HIRES with PS50 pixel-wise.
- The PS50 output stream manages to crunch 50fps in progressive scan using the same bandwidth than the HI-RES mode, so this immediately tells us that either the HI-RES stream is spoiling bandwidth or there is much less information in the PS50 stream. My pick is the second, and my guess is that there is much less color detail in PS50.
- The DV output stream is regular PAL DV output at 50 fps interlaced. Some users argue that the camera’s DV image is still better than a regular DV camera, since the image gets downsampled from a higher resolution CCD by the camera itself, at the image source. This might hold true, but keep into account that the CCD area in use is not the full CCD but only 839x576 pixels.
So, to make it short,
- HI-RES: firewire 720x576 with 1280x659 effective CCD pixels, 25p
- PS-50: firewire 720x576 with 941x485 (16:9)/839x576 (4:3) effective CCD pixels, 50p
- DV: firewire 720x576 with 839 x 576 effective CCD pixels, 50i
Any comments?
Cheers,
Hugo
If you use the component cable, you might be able to get the full vertical image out of the video camera (UNTESTED – will test soon), although you’ll get an analog signal.
If you use (as I do) the firewire output, then the camera outputs an ~19Mbps MPEG2 data stream to your computer. This stream’s content depends on the recording mode you selected.
There seems to be a lot of confusion regarding the camera’s recording modes, specially when compared to it’s US brother, the GR-HD1. I suspect both cameras are very very similar (if not equal) hardware-wise, so their main differences should be about the firmware.
This raises the interesting question of whether you could turn a PD1 onto a HD1 (or vice versa), or even change them so that we can take the best out of both worlds. My educated guess would be that theoretically this could be possible, but that also, most probably NO, you really can’t turn a PD1 onto an HD1, most probably because of internal clock restrictions (many PAL and NTSC electronic systems inherit different quartz settings depending on their regions – even though they’re really fed thru continuous DC power from a battery and not from the mains AC)
Anyway, according to the JVC manual the camera has 3 video recording modes:
- When the camera is in the HI-RES mode, it uses an effective 1280x659 pixels area of the CCD (which is very high and the main reason why JVC PD1/HD1 footage in well-lit conditions falls so short behind real 3CCD cameras), and samples 25 progressive frames per second in a 16x9 aspect ratio.
- When the camera is in the PS50 mode, it uses either an 941x485 (when in 16x9 mode) or 839x576 (when in 4x3 mode) effective pixels area of the CCD, and samples 50 progressive frames per second.
- When the camera is in DV mode, it uses an effective 839x576 pixels area of the CCD, and samples 50 interlaced frames per second.
HOWEVER, in any of these modes, the firewire signal will always be outputted at 720x576 pixels, independently of the recording mode chosen. How does this make sense? Well, not much, but let’s try to figure it out:
- The HI-RES output stream is a 25fps progressive scan MPEG2 stream, much like in HDV, and has LOADS of color detail – which you can see if you compare a shot in HIRES with PS50 pixel-wise.
- The PS50 output stream manages to crunch 50fps in progressive scan using the same bandwidth than the HI-RES mode, so this immediately tells us that either the HI-RES stream is spoiling bandwidth or there is much less information in the PS50 stream. My pick is the second, and my guess is that there is much less color detail in PS50.
- The DV output stream is regular PAL DV output at 50 fps interlaced. Some users argue that the camera’s DV image is still better than a regular DV camera, since the image gets downsampled from a higher resolution CCD by the camera itself, at the image source. This might hold true, but keep into account that the CCD area in use is not the full CCD but only 839x576 pixels.
So, to make it short,
- HI-RES: firewire 720x576 with 1280x659 effective CCD pixels, 25p
- PS-50: firewire 720x576 with 941x485 (16:9)/839x576 (4:3) effective CCD pixels, 50p
- DV: firewire 720x576 with 839 x 576 effective CCD pixels, 50i
Any comments?
Cheers,
Hugo
posted by Hugo José Pinto at 3:17 PM
6 Comments:
It doesn't seem like it based on the big numbers, but the 25p mode has almost exactly twice the pixels as the 50p mode. That is why they both use the same data rate. There is no more colour information in one mode than the other. Both are 4:2:0 colour space like all HDV.
Ken H.
I'll bookmark this article right away.
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