I assume you meant 5,000 kb/s? As 5,000 kB/s is ~39 Mb/s which is of 1080p MPEG2 level of bitrate, overkill for a Dreamcast for sure. The main limitation is the optical drive. The DC reads GD-Roms at max 12x and CD-R at 4x IIRC. That means hard limits on max bitrates of 12 * 150 kB/s * 8 b/B = 14,400 kb/s for a GD-Rom and 4 * 150kB/s * 8 b/B = 4,800 kb/s for a CD-R. But that's only the read speed at the outer rim on the disc because of CAV. Any large file can only reach those speeds near its end, and only if it's at the end of the disc. GDEMU could probably help then! But you might get CPU limited at one point. Try the kvcd pack, it gives good results most of the time. You can change the bitrate in the script, default is 1,500 kb/s IIRC.