Hi, I'd like to propose to implement in PJMEDIA library such codec features as Speex VBR (variable bit-rate) and ABR (average bit-rate). In order to make one little step forward I propose the patch with basic implementation of these features. The patch has just one new API function: pjmedia_codec_speex_vbr_init(). This function, in comparison with pjmedia_codec_speex_init(), receives two additional optional parameters: - float vbr_quality - int abr_bitrates[3] (three average bitrates values for narrowband, wideband and ultra-wideband mode in this order). I see that this patch maybe looks like a quick and somewhat dirty hack, but it retains PJMEDIA backward compatibility, and I keep the hope that it can become a base of the new functionality. -- Roman Imankulov roman@netangels.ru

Hi all, please be careful in checking that speex VBR is not compatible with SRTP as there are well known security vulnerability that affect SRTP when used with VBR enabled codec. If VBR is introduced please also add that kind of check to the code, SRTP & VBR feature cannot be enabled at the same time because of security risks: http://www2.computer.org/portal/web/csdl/doi/10.1109/SP.2008.21 A new internet-draft for SRTP modification for supporting without security risks VBR features is in progress: http://bgp.potaroo.net/ietf/idref/draft-perkins-avt-srtp-vbr-audio/ Fabio Pietrosanti Roman Imankulov wrote: > Hi, > > I'd like to propose to implement in PJMEDIA library such codec > features as Speex VBR (variable bit-rate) and ABR (average bit-rate). > In order to make one little step forward I propose the patch with > basic implementation of these features. > > The patch has just one new API function: > pjmedia_codec_speex_vbr_init(). This function, in comparison with > pjmedia_codec_speex_init(), receives two additional optional parameters: > > - float vbr_quality > - int abr_bitrates[3] (three average bitrates values for narrowband, > wideband and ultra-wideband mode in this order). > > I see that this patch maybe looks like a quick and somewhat dirty > hack, but it retains PJMEDIA backward compatibility, and I keep the > hope that it can become a base of the new functionality. > > ------------------------------------------------------------------------ > > _______________________________________________ > Visit our blog: http://blog.pjsip.org > > pjsip mailing list > pjsip@lists.pjsip.org > http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org

Hi, Fabio Pietrosanti (naif) wrote: > Hi all, > > please be careful in checking that speex VBR is not compatible with SRTP > as there are well known security vulnerability that affect SRTP when > used with VBR enabled codec. > > If VBR is introduced please also add that kind of check to the code, > SRTP & VBR feature cannot be enabled at the same time because of > security risks: > http://www2.computer.org/portal/web/csdl/doi/10.1109/SP.2008.21 > > A new internet-draft for SRTP modification for supporting without > security risks VBR features is in progress: > http://bgp.potaroo.net/ietf/idref/draft-perkins-avt-srtp-vbr-audio/ Thanks, very illuminative. Interesting that the referenced IETF draft also suggests to disable VAD with SRTP as extreme form of VBR. -- Roman Imankulov roman@netangels.ru