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Old September 10th, 2008, 09:55 PM   #1
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50 Mbs vs 100 Mbs

Hi guys,

I would appreciate your input in the following:
How significant is the difference in image quality between 50Mbs and 100Mbs.
Since the 100Mbs is basically not available in progressive right now I will have to go 50Mbs.
Will it be less attractive to broadcasters to use footage obtained at 50Mbs (I use Sony Z7 and Sony EX3 ) ?

Thanks,
Ofer Levy
Ofer Levy Nature Photographer

Last edited by Ofer Levy; September 10th, 2008 at 11:28 PM.
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Old September 11th, 2008, 02:04 AM   #2
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Dear Ofer,

One of Sony's very nice professional cameras, the 700 model uses 50 Mb. It is my understanding that quite a few of these cameras were used at the 2008 Olympics.

I think that you will find 50 Mb to be very acceptable and very high quality.

There is a difference between 50 Mb and 100 Mb for some footage. And 100 Mb is very close to uncompressed. As more units get in the field, I expect more people to share their experiences and opinions. I expect 50 Mb to be used quite often for professional work.

At this moment, you have 1080i 50 Mb and 100 Mb options available for your cameras.

For 720p, you are currently limited to 50 Mb, but this is only temporary.

I do not know, at this moment, if our current firmware locks out the 720p 100 Mb mode or not. I think it is still available, but you are cautioned against using it, especially for high motion footage.

I do not foresee any broadcaster rejecting your footage due to it being recorded in the 50 Mb mode. I doubt if any broadcaster would reject the quality of the images produced at the latest Olympics since they were mainly recorded at 50 Mb (to the best of my knowledge).

Remember that we have a few things in our favor:

1. The Sony module is the latest and greatest of Sony's substantial investment in MPEG2 encoders/decoders. This may be Sony's sixth generation of chips or modules.

2. This Sony module is used in the Sony 700 camera.

3. The same Sony module is used in the Flash XDR / nanoFlash units.
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Old September 11th, 2008, 07:39 AM   #3
 
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I've recently been involved in a super16 film project. The film was telecined to HDCAM SR and Avid DNX115(which is 115Mbps for anyone unfamiliar with DNxHD codecs) I've been working with a 65Mbps proxy file for editing. The difference between 65mbps and 115mbps is quite striking, at least when viewed on a production monitor. There is considerably more noise in the shadow areas with the higher compression inherent in the DNX65.


edit: I would add that DNX175 comes very close to the quality of HDCAM SR. DNX175 becomes difficult to process on a conventional machine, particularly due to I/O time. At this level, the differences in image are detectable only with a production monitor. On a standard computer LCD, I can't tell the diff between DNX175 and DNX100.

None of my experience, of course, relates to improvements in motion artifacts resulting from lower compression ratios. My biggest hope is that I will see improvements in motion artifacts inherent in 35mbps HQ mode in the EX1.
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Old September 11th, 2008, 07:52 AM   #4
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Dear Bill,

Thank you for sharing your experience.

From our limited experience, I would recommend 100 Mb for critical work. I feel that this is a great balance between file size and quality. I would definitely use 100 Mb for green screen work.

For routine work, but still providing a high level of quality, some may choose the 50 Mb option. One reason to choose 50 Mb is that it doubles the recording time versus 100 Mb.

Looking to the future:

I am looking forward to our current and future users of the units reporting in as to which options they choose for various situations.

I also look forward for our users expressing, in their own words, their evaluations of the two options.
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