Basically DNxHD 120, 185 and 185X were effectively identical to the source
clip. DNxHD 36 was very very good also, I couldn't see any differences
visually, and those I could detect were minimal. I also tested XDCAM EX
(35Mb/s) and XDCAM HD422 (50Mb/s) with strong results, again both appeared
visually identical in my tests.
It seems that the detail retained in the H.264 is easily simple enough to be
effectively compressed into other codecs with minimal variance or loss,
especially where those codecs are of significantly higher baseline quality.
I blogged it -
http://dylanreeve.com/videotv/avid/2010/transcoding-canon-dslr-footage.html
On Tue, Jun 15, 2010 at 7:38 PM, Dylan Reeve <dylan@dylanreeve.com> wrote:
> In theory there should be no quality differences in decode methods. The
> only real differences should be in terms of decode time - I'm not sure how
> each of the applications do it, but I'd assume Adobe's apps are doing it a
> little differently as I believe their Mercury engine improves the decode
> times, using the power of the GPU.
>
> Canon's DSLR files confuse me, they are a pretty high bitrate (around
> 46Mb/s) but deliver pretty poor performance for that amount of data. They
> are 8bit and 4:2:0 sampled and tend to exhibit pretty noticable quantization
> artifacts. I'd tend to assume that any of the "full" DNxHD codec are more
> than capable of fully representing all the recorded image data (120, 185 or
> 220).
>
> I'm fairly certain, however, that H.264 at such high bitrates should be
> able to do a lot better. If MPEG2 can deliver the quality it does with
> 50Mbit/s in XDCAM HD422, then H.264 at almost the same bitrate can surely be
> better?
>
>
> On Tue, Jun 15, 2010 at 4:13 PM, nat jencks <natjencks.lists@gmail.com>wrote:
>
>>
>>
>> In the course of researching various methods for processing 5Dmk2 and 7D
>> footage as dailies I have hit two questions for the lists collective wisdom.
>>
>> 1) Is there any difference between the various tools (Mpeg Streamclip, FCP
>> log and transfer, Magic Bullet Grinder, Adobe CS5, Neo Scene, etc) on the
>> DECODE side of things?
>>
>> From the research that I have done, all of these tools use the underlying
>> quicktime framework to decode the H.264, and any differences in transcoding
>> are the result of different types of encoding.
>> Possible exceptions are Neo Scene, and CS5, but even these may use the
>> same quicktime framework to decode?
>>
>> 2) On the ENCODE side of things, what is people's real world experience
>> regarding what type of datarate you need to go with to get ALL the
>> information out of these source files...
>> Prores HQ? Prores444? Uncompressed DPX? Obviously the safe thing to do is
>> go for an offline/online workflow with ProresLT for offline and Uncompressed
>> DPX for online, but if ProresHQ would capture all the source data without
>> introducing compression artifacts it would be nice to avoid offline/online
>> scenarios.
>>
>> Thanks in advance!
>>
>> Best-
>> -Nat
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>
>
>
> --
> Dylan Reeve
> http://dylanreeve.com/
>
--
Dylan Reeve
http://dylanreeve.com/
[Non-text portions of this message have been removed]
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