Forward Error Correction #7
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…ransmitter to match receiver
…eholders for future integration of Raptor FEC
…ebug mode by default, small fixes in readme,cmakelists,gitignore
…ding symbols to_payload() functions
…uct since its too difficult to directly replace it
…based on fec scheme in use
…and file, cleaned up cmakelistst for raptor build case
…on for all FEC transformers
…s to allocate the file buffer themselves
…isabled or ssl doesnt define ex2 on ubu20
…] instead of delete
…or calls in FEC + updated readme
dsilhavy
requested changes
Jun 9, 2023
Remove an unnecessary #ifdef in Receiver.h, and fix error messages in AlcPacket.cpp
autumn-traveller
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@autumn-traveller : @kuehnhammer is currently working on the FEC integration and harmonizing our two implementations (one of these is yours). Then we should be ready to merge. |
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Overview
This PR adds support for forward error correction. Firstly, an abstract class for FEC schemes of any kind is added ("FEC Transformer"), which can be used to encode individual files and source blocks. Secondly, an instance of the class for a raptor-based FEC scheme is added. The mechanism used is very similar to the Raptor FEC encoding scheme but differs in the generation of random numbers for selecting symbol degrees, and in not generating Half symbols. The scheme used only generates LDPC symbols during the intermediate symbol generation.
Full list of Changes:
This PR (unintentionally) addresses Issue #1
Building with FEC
The library used for FEC is in a git submodule in another repository. To pull and build the raptor changes you need to pull the other submodule and then rebuild. Pull using
git submodule update --initif you are in a previously checked out repsitory.When building, raptor is enabled by default (but can be turned off) so build as usual.
Testing the changes
To test that everything works you need an environment with packet loss. One way to do this is to modify the loopback device so that it experiences packet loss. There is a script included -
setup_packet_loss_on_loopbackwhich uses thetccommand to adjust the loopback device to experience packet loss, as well as adding a routing entry for the default mulitcast address used by libflute to make it go via the lo device. After testin you can rever the changes with thesetup_packet_loss_on_loopbackscript.