Hi Leighton,
I'm not sure to understand what you mean, so here it is :
Until revision r4264 of webrtc trunk, there were a ViEFileRecorder class. As soon as the ViEChannel got a frame, it feeds the recorder with it. (And quite the same for audio)
This interface has been removed. (Nonetheless there is interesting stuff is the 'new_include' part, perhaps that's why.)
So no, it is not directly from the RTP packet, it has to be decoded into a I420Frame (=YUV) before being reencoded. But this is part of the WebRTC and not a code of mine.
Actually I don't think you can do it from stream without decoding / encoding, as there is video AND audio. I'm not even sure that you can do it for video or audio only.. But I'm not an expert at all.
If this is possible, please tell me, it could help here.
Regards,
Z.