If I want to edit and color grade mpeg2 clips in Premiere Pro CS3, it is best to transcode them to other formats ?
Importing mpeg2 clips in premiere pro, without transcoding, will cause problems when editing or color grading ?
Also, if transcoding the mpeg2 clips is recommended, or is a better workflow, what intermediate/editing-oriented formats are used for transcoding mpeg2 sd footage ?
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Last edited by codemaster; 26th Apr 2012 at 15:28.
Regaring grading only , the reason why some people transcode to intermediate formats like cineform, DNxHD, is that chroma upsampling is better from 4:2:2 (even when upsampled from a 4:2:0 source) in premiere. The end result is less blocky color edges compared to native grading 4:2:0 footage. The other reason is there maybe some better precision when using 10bit or more intermediate , and some filters work better on 10bit footage (even when transcoded from 8bit source). It may reduce the banding and artifacts you introduce if you really push the footage during grading
It's not a night & day huge difference - sometimes you can barely see the difference until you zoom in. But do some tests for yourself - you have to decide yourself if you are willing to take the extra steps, time, HDD space to see if it's worth it for you
The other reasons for trancoding are for smoother editing experience and perhaps better compatibility with I-frame format, but editing SD MPEG2 usually isn't an issue on modern hardware. CS3 might have problems, but CS4-6 are ok with native MPEG2 import
Also, you're asking a lot of questions about frameserving into PP
You should be aware that AVS Import Plugin for PP frameserves RGB32 - so this means if you don't correct for your undershoots / overshoots before frameserving in (e.g fix levels in the script, or convert using full range), they will be clipped in premiere
Premiere treats some formats as YUV and others as RGB. Most native camera formats are treated as YUV (e.g. DV, XDCAM, HDV, AVC Intra, etc..). The distinction is important for retaining superbrights/darks. They are recoverable by YUV filters in the former, and clipped in the latter. e.g. something like lagarith, huffyuv for a YUV intermediate which are normally considered "lossless" - they are clipped because they are treated as RGB, not YUV. So they actually aren't truly lossless in Premiere (because of colorspace conversion) . Cineform and DNxHD are "visually" lossless (high bitrates, but not as high as lossless codecs) , but are treated as YUV - so they are not clipped
poisondeathray, you are saying that just by importing the mpeg2 clips in premiere, all illegal levels (<0.3V and >1.0V for PAL) will be clipped ? I didn't noticed that, and in the waveform monitor, blacks go below 0.3 V and whites go over 1.0 V, and only when I apply the RGB Color Correction (the filter with sliders like pedestal, gain and gamma) everything below 0.3V and above 1.0V is clipped, but if I apply RGB Curves, then there is no clipping involved.
Or this is not the kind of clipping that you were talking about ?
I didn't know that it is possible to frameserve the mpeg2 clips to premiere, via avisynth and AVS Import Plugin. What does it mean to correct levels in avisynth ? Do you know if there is any documentation that explains the adjustments that have to be applied to the clips before importing them into premiere pro ?
Last edited by codemaster; 26th Apr 2012 at 17:06.
In CS3, some filters are RGB some are YUV. For example "fast color corrector" works on YUV, so you can recover values beyond 0-100IRE or Y<16, Y>235 on digital scale . In CS5 they are labelled "YUV" filters
Or, If you specifed full range matrix for conversion to RGB, this "maps" Y' 0 => RGB 0,0,0 , Y'255=> RGB 255,255,255
In normal range "Rec" matrices Y' 16=> RGB 0,0,0 , Y'235=> RGB 255,255,255 . (Similarly for CbCr 16-240) . You see, values below 16 and greater than 235 (240 for CbCr) are lost