Frameserve quicktime video: which colorspace ?

[varunb]

For frameserving quicktime h.264 videos using avisynth, which colorspace shud i use: converttorgb32(matrix="rec709")
or converttoyv12() ? I will b converting those movie trailers (downloaded from apple) to avi(xvid) using TMPGEnc 3.0 Xpress.

My 2nd question is that is "rec709" the default matrix used in converttoyv12() ?

[IanB]

Rec601 is the default matrix in all AviSynth RGB <-> YUV conversions. It is best to avoid any unnecessary RGB <-> YUV conversions where possible.

YUY2 <-> YV12 conversions do not make any changes to the YUV encoding levels, they only adjust the chroma subsampling. XVID internally stores it's data as YV12.

Most XVID players assume REC.601 encoding of the data stream, If you believe Apple has used Rec.701 for these clips then see the ColorMatrix filter (thread in this forum) for changing YUV coefficients within the YUV colour space.

Rec.601 presentation of Rec.709 data causes excessive contrast in the blues.

[varunb]

Thanx Ianb for ur reply! So u mean to say that i need not to put any colorspace mode(converttorgb,yv12) while frameserving .mov videos to Xpress ?

[IanB]

Perhaps some test encodes of a short segment to ensure you are completely happy with the results.

Another option might be to just change the container format from quicktime. Use search to find reference to appropriate tools.

[Blue_MiSfit]

mkvtoolnix will do nicely ;)