DNxHR LB is similar to ProRes Proxy as a very low bitrate option within the same codec family (LB is short for Low Bandwidth). It's not really intended as a capture codec for final-deliverable quality. For example, one workflow using the codec is to capture in something like DNxHR HQ, but then create DNxHR LB versions of all the clips for editing. This allows for editing in the same resolution as the final deliverable, but requires much lower storage requirements during the edit process (so more footage can be kept on a high performance local drive, for example). Then for the final deliverable, you would export using the DNxHR HQ clips.
But since DNxHR LB is intended as an edit-friendly codec, it uses intra-frame compression. And this is a good example of just how much less efficient intra-frame compression is compared to the inter-frame compression typically used in H.264. The data rate for DNxHR LB at 2160p25 is 143 Mb/s which is actually a bit more than the 100 Mb/s internal codec. But the more efficient inter-frame compression of the internal codec means that it ends up looking better overall.
For comparison, the data rate for DNxHR SQ at 2160p25 is 459 Mb/s. Still intra-frame compression, but now more than 4x the bitrate of the internal codec. Which seems to be about the minimum to get decent quality. And if you consider the 1080p internal recording modes on the DVX200, the intra-frame (ALL-I) mode clocks in at 200 Mb/s which again is 4x the bitrate of the 50 Mb/s inter-frame codec (the lowest bitrate the camera offers for 1080p MP4 recording).
But since DNxHR LB is intended as an edit-friendly codec, it uses intra-frame compression. And this is a good example of just how much less efficient intra-frame compression is compared to the inter-frame compression typically used in H.264. The data rate for DNxHR LB at 2160p25 is 143 Mb/s which is actually a bit more than the 100 Mb/s internal codec. But the more efficient inter-frame compression of the internal codec means that it ends up looking better overall.
For comparison, the data rate for DNxHR SQ at 2160p25 is 459 Mb/s. Still intra-frame compression, but now more than 4x the bitrate of the internal codec. Which seems to be about the minimum to get decent quality. And if you consider the 1080p internal recording modes on the DVX200, the intra-frame (ALL-I) mode clocks in at 200 Mb/s which again is 4x the bitrate of the 50 Mb/s inter-frame codec (the lowest bitrate the camera offers for 1080p MP4 recording).