Hi, Is it possible to make "ROHC_WLSB_WIDTH_MAX 256U" in the next release so that a wide range of width values can be used in rohc_comp_set_wlsb_window_ width() method?
Is it possible to make "rohc_lsb_shift_t" values parametric in next release ? I mean to make lsb shift values parametric so that users can set any shift value from a related parameter? Final one is; is it possible to change lsb_width and shift values dynamically while related compressor/decompressors are in progress? Best Regards... 2018-02-12 14:39 GMT+03:00 mehmet sulak <[email protected]>: > Hi , > > Thank you for your response, > > Here are my changes; > > in file interval.h > //#define ROHC_WLSB_WIDTH_MAX to 64U (comment out) > #define ROHC_WLSB_WIDTH_MAX 256U (new definition) > > also added new enum value at "rohc_lsb_shift_t" > > ROHC_LSB_SHIFT_UDP_SN = 128 > > to be used in UDP traffic. > > also in files c_udp.c and d_udp.c > > instead of using "ROHC_LSB_SHIFT_SN" which is -1 > > I used newly defined "ROHC_LSB_SHIFT_UDP_SN" value > > > For the trade-off between compression efficiency and robustness I > observed that for configurations > > higher then lsb_w = 32 and p=16 makes UDP/IP header to 7 bytes. So I > choose the lsb_w=256 and p = 128 for greatest coverage. > > Best Regards... > > > 2018-02-08 17:17 GMT+03:00 Didier Barvaux <[email protected]>: > >> 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 >> > >
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