Mpg1 Mpg2 black levels

RichR wrote on 4/10/2003, 2:15 PM

When using the main concept encoders to encode dv video to mpg1 and 2, the black levels rise to 13% when starting with a black of 7.5%. Is there a reason for this? Is there a setting to keep the black to 7.5, or should it go to 13% for these formats?

Comments

john-beale wrote on 4/10/2003, 3:13 PM

As far as I can tell, the MainConcept encoder always assumes your video starts off with the full 0-255 intensity range and so it must reduce the range and add 16 counts of offset (6.2%) to conform to the 16-235 intensity range expected for DVD (ITU-R BT.601). Of course, DV video already starts out at 16-235 so adding another offset just washes out the contrast. That's one reason I don't think MainConcept is suitable for professional work. If I'm wrong and there is such an encoding option available, I'd like to learn about it!

Some other encoders, for example CinemaCraft and TMPGEnc, offer two intensity level transfer options. In CCE there is a choice called "Luminance: 16-235 or 0-255", and if you start with DV, which has the 16-count offset already you should choose 0-255 so CCE doesn't add it's own offset. Likewise in TMPGEnc, with DV source material you should choose under MPEG setting/Quantize Matrix, the Special Setting "Output YUV data as Basic YCbCr not CCIR601" for the same effect.

If you don't do this, your output will appear washed out with no true blacks. You can fix this cosmetically by adjusting your TV set contrast but it's not the "right" way to do it.

Rain Mooder wrote on 4/10/2003, 5:28 PM

I know the SOFO people are at NAB but if anyone could comment
definitively on the MainConcept 16-235 issue I would love to
hear it. I was guessing that by V4 they would have this stuff
all figured out but I've plopped down by $48 for TMPG. Is it
known for sure that the DV files that V4 outputs are 16-235 so
I can just set the Basic YCbCr option in TMPG?

watson wrote on 4/10/2003, 6:15 PM

Does anyone know if with TMPGEnc I could encode a DV avi to 624x384 Mpeg-1 file ?

Thank you
W

RichR wrote on 4/10/2003, 9:14 PM

thanks for your input. when i left the studio today, i set up TMPGEnc to encode a dv clip. Tommorrow I'll bring it into Vegas and see what I've got. I'll also try one using JBeales settings and see what happens there also.