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Home: Inactive Forums: Casablanca Users:
Casablanca DV image quality

X-AD
Imported Account

Jun 7, 1999, 11:38 AM

Post #1 of 3 (739 views)
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Casablanca DV image quality	Can't Post

I am still confused about the basic image quality of the Cassie unit when DV footage is used.I am not discussing the processing needed for editing but only the pure in/out performance .It is told that DV data is digitally converted to MJPEG, being the internal compression format.To my knowledge the DV setting on the unit remains with the 5:1 (same amount of data as for the DV footage).Given the fact that MJPEG compaires to DV as about 3to5 (MJPEG 3:1 results is about the same subjective quality as a 5:1 DV), I think there must be quality loss even under the ideal conversion conditions (e.g starting from the DV DCT values)
Did anyone evaluate this issue?
Andre

X-Phil_Handler
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Jun 8, 1999, 12:02 AM

Post #2 of 3 (739 views)
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Re: Casablanca DV image quality	Can't Post

If the question is a mathematical one, then I can not answer it, but if it is a qualitative evaluation of the image which comes in via firewire and goes back out to DV after being edited on the Cassie, then I can assure you that the quality is for all practical purposes, imperceptable from that which was input. Assuming you actually show the material on a lower quality format, then the quality depends on the ability to dub with good fidelity.
Bottom line is, the output is as awesome as the material you input via Firewire, regardless of what you might read into the fact that MJPEG is being used to edit.

: I am still confused about the basic image quality of the Cassie unit when DV footage is used.I am not discussing the processing needed for editing but only the pure in/out performance .It is told that DV data is digitally converted to MJPEG, being the internal compression format.To my knowledge the DV setting on the unit remains with the 5:1 (same amount of data as for the DV footage).Given the fact that MJPEG compaires to DV as about 3to5 (MJPEG 3:1 results is about the same subjective quality as a 5:1 DV), I think there must be quality loss even under the ideal conversion conditions (e.g starting from the DV DCT values)
: Did anyone evaluate this issue?
: Andre

X-Andre_De_Clercq
Imported Account

Jun 8, 1999, 8:12 AM

Post #3 of 3 (739 views)
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Re: Casablanca DV image quality [In reply to]	Can't Post

My question relates indeed more to technical stuff than to the subjective image performance, which depends indeed on the basic footage quality and image content,and also on the display performance and viewing conditions.I no way i am blaming MJPEG as a codec.It could even be much better than DV if a lower compression ratio is used. The only thing is that DV uses some aditional "tricks" like variable Q tables and adaptive field processing. All this has been added purely for getting the best possible quality in a 5:1 intraframe codec.The difference must be convincing otherwise DV could never have been "sold" against the existing (M)JPEG concept.
Andre

: If the question is a mathematical one, then I can not answer it, but if it is a qualitative evaluation of the image which comes in via firewire and goes back out to DV after being edited on the Cassie, then I can assure you that the quality is for all practical purposes, imperceptable from that which was input. Assuming you actually show the material on a lower quality format, then the quality depends on the ability to dub with good fidelity.
: Bottom line is, the output is as awesome as the material you input via Firewire, regardless of what you might read into the fact that MJPEG is being used to edit.

: : I am still confused about the basic image quality of the Cassie unit when DV footage is used.I am not discussing the processing needed for editing but only the pure in/out performance .It is told that DV data is digitally converted to MJPEG, being the internal compression format.To my knowledge the DV setting on the unit remains with the 5:1 (same amount of data as for the DV footage).Given the fact that MJPEG compaires to DV as about 3to5 (MJPEG 3:1 results is about the same subjective quality as a 5:1 DV), I think there must be quality loss even under the ideal conversion conditions (e.g starting from the DV DCT values)
: : Did anyone evaluate this issue?
: : Andre