Hello, Sorry for not answering sooner. I could have saved you some time about the WLSB width :-/
First of all, your changes seem correct. Please send me a patch, I'll check if I can integrate your changes in the next release. The increased size is indeed a consequence. You ask the library to be more robust, so it sends more information to achieve that goal. You have to choose a trade-off between a/ compression efficiency and b/ robustness. Did you try to set smaller value for the WLSB width? Maybe 128 provides enough robustness? Maybe 192? Regards, Didier On Tue, 6 Feb 2018 17:31:18 +0300, mehmet sulak <[email protected]> wrote: > After some trials I saw that; > > rohc_comp_set_wlsb_window_width() method is working correctly, the > second parameter is just width of LSB window however I toughed that > it was the number of bits that are for LSB width. > > I set it as 256 to handle large number of problematic cases(by setting > ROHC_WLSB_WIDTH_MAX to 256U). Also I set ROHC_LSB_SHIFT_SN as 128 to > handle delayed packets. > (I defined new enumeration field whose value is 128 by updating > interval.h and setting new value in c_udp.c and d_udp.c files) > > The results are seems to perfect. Rohc decomress errors are seems to > minimized to very small values which stems from loss of initial > context packages. > > The drawback is that 28 byte UDP headers were compressed to 4 bytes > previously but with the solution that I tried they are now compressed > to 7 bytes. > > Is this normal behavior? > > Best Regards.. > > > > 2018-01-30 17:26 GMT+03:00 mehmet sulak <[email protected]>: > > > Thanks for your detailed response first; > > > > First I tried method rohc_comp_set_wlsb_window_width(comp,8) by > > giving 8bits window width but I still observe the following in the > > log files; > > > > rohc_decomp_rfc3095.c:1463 parse_uo0() 4 SN bits = 0xe > > > > So I think it still uses 4 bit window length? If yes did I do > > something wrong? > > > > Secondly I think for UDP packets ROHC_LSB_SHIFT_SN(-1) is used for > > compressor and decompressor which makes parsing delayed packets > > impossible. > > > > So I need to use something half of (2 ^ lsb_width) instead of -1 by > > adding a new enumeration value. > > > > Do have any idea about this parameter? > > > > Best Regards.. > > > > 2018-01-29 22:11 GMT+03:00 Didier Barvaux <[email protected]>: > > > >> Hello, > >> > >> > I am using Rohc comressor/decomressor pair on a lossy > >> > media(sometimes at receiver side some packets are lost) and the > >> > orderings of the UDP packets are not guaranteed.(packets are > >> > not coming in right order all the time). > >> > > >> > I am using Unidirectional mode and observe some decomression > >> > failures about CRC check, malformed packets... > >> > > >> > Any recommendation to overcome these issues? > >> > >> The ROHC protocol provides several ways to handle packet loss or > >> reordering: > >> > >> a/ Increasing the width of the window used by the W-LSB algorithm > >> improves the robustness of the ROHC protocol by sending more > >> bits for changing fields. Given a W-LSB width <wlsb_width>, up to > >> (<wlsb_width> - 1) packets may be lost without causing > >> additional loss. > >> The default width is set to 4 by the ROHC library ; please use > >> the rohc_comp_set_wlsb_window_width() function to change the > >> value ; see [1] for more details. > >> > >> b/ Increasing the number of transmissions N required for a changing > >> static fields or a changing pattern for a dynamic field ensures > >> that the loss of N-1 packets during such a change will cause no > >> additional loss. > >> The default number of transmissions is set to 3 by the ROHC > >> library ; there is no API to change the value at that time, but > >> you may change the value of the constant MAX_IR_COUNT in the > >> source file src/comp/rohc_comp_internals.h and re-build/re-install > >> the library. > >> > >> c/ Same as b/ but for lists of extensions headers (such as IPv6 > >> extension headers, GRE, AH...). Use the function > >> rohc_comp_set_list_trans_nr() to change the value ; the default > >> value is set to 5 ; see [2] for more details. > >> > >> d/ You may enable packet/context repair upon CRC failures, so that > >> the decompressor tries to fix the context or packet if it detects a > >> decompression problem (due to packet loss/reordering for > >> example). The feature is disabled by default. Enable it with the > >> function rohc_decomp_set_features() and the feature > >> ROHC_DECOMP_FEATURE_CRC_REPAIR ; see [3] for more details. > >> > >> Configuring options a-c is easier if you know the largest number of > >> consecutive losses that you may expect and/or you want to be > >> protected against. > >> > >> Let me know if my explanations are clear enough or if you need more > >> details. And, of course, let me know if one of the options solves > >> your problem. > >> > >> Regards, > >> Didier > >> > >> > >> [1] documentation of rohc_comp_set_wlsb_window_width(): > >> https://rohc-lib.org/support/documentation/API/rohc-doc-2.1. > >> 0/group__rohc__comp.html#ga2b68070dddbc038cd55490952a7b3fa4 > >> > >> [2] documentation of rohc_comp_set_list_trans_nr(): > >> https://rohc-lib.org/support/documentation/API/rohc-doc-2.1. > >> 0/group__rohc__comp.html#ga32608bc06e1b0d1656e463eeb1ccbd7f > >> > >> [3] documentation of rohc_decomp_set_features(): > >> https://rohc-lib.org/support/documentation/API/rohc-doc-2.1. > >> 0/group__rohc__decomp.html#ga2298148ca8dc277a1c1905f550f21f7b > >> > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~rohc > >> Post to : [email protected] > >> Unsubscribe : https://launchpad.net/~rohc > >> More help : https://help.launchpad.net/ListHelp > >> > > > > _______________________________________________ Mailing list: https://launchpad.net/~rohc Post to : [email protected] Unsubscribe : https://launchpad.net/~rohc More help : https://help.launchpad.net/ListHelp
