OK well, not a schizophrenic reply to myself, but if it may be useful for someone, I found a part of the solution : the MXF OP1a I need is an Omneon MXF, and I managed to get one with FlipFactory.
Now I have another question : is there other softwares able to export Omneon MXF files ?
I’m not in charge of the softwares purchases in the company, and FlipFactory is kind of a big software, too big for us. We do not need all the workflow manager stuff and so one. We only need to transcode our file into MXF. I’m still looking for it, but as time passes, if someone knows and can share his knowledges, it would be wonderful.
Thanks !
Nicolas.