[FFmpeg-user] Is there a CodecID for stream copy? What if codec support isn't compiled in?

[Thomas Worth]

I want to take a file and do a stream copy, that is bypass decoding
and encoding. This may need to be done without the actual codec
compiled into avcodec. Since no decoding or encoding takes place, what
would I specify as the CodecID? Since avformat_write_header() requires
an AVCodec argument, what would the codec be if it's not compiled in?
Can I just set the AVCodec fields manually?