CTC GPU support

[Hibbert-pku]

Very happy to see CTC in #tensorflow! #32
My question is:
Is someone working on CTC GPU implement internal? Or is it 'contribution welcomed'?
Baidu has a CTC GPU implement:

https://github.com/baidu-research/warp-ctc

[zheng-xq]

As Eugene and Vijay commented, it is currently on the contrib directory. And once it matures enough, it will be moved to the core directory.

As always, contributions are welcome. For any significant code changes, it is optional to announce it first, so people would notice and avoid replicated work.

[Hibbert-pku]

Sorry to bother you again, can you point the ctc .cu.cc file, please? I can't find it.
@zheng-xq

[cjh9]

+1, CTC GPU support would be awesome for handwritten text recognition, speech recognition etc. May key applications here!! 🎉 😀

[Hibbert-pku]

I've merged tensorflow and baidu's warp-ctc in:
https://github.com/Hibbert-pku/tensorflow/tree/only-ctc
maybe it's useful for you.(pls ignore the latest commits, I just want to add a travisCI for it but failed.)
@cjh9

[igormq]

Is there any news?

[zheng-xq]

Adding @ebrevdo to comment on the status of CTC GPU implementation.

[ebrevdo]

Very much a "contributions welcome"; @Hibbert-pku has what looks like an implementation in their own github. It includes some nvidia code which probably cannot be merged into the main tensorflow repository, and a lot of cleanup would have to happen before we could merge a pull request.

[lingz]

Maybe we could open this issue back up then, so it's visible?

[andykitchen]

I would also find a GPU implementation of CTC loss very helpful!