FreeSwitch明明已经设置了H264，为什么通话时还是别的格式（如VP8）

检查有哪些CODEC

show codecs

freeswitch@telecom> show codecs

type,name,ikey
codec,ADPCM (IMA),mod_spandsp
codec,AMR / Bandwidth Efficient,mod_amr
codec,AMR / Octet Aligned,mod_amr
codec,B64 (STANDARD),mod_b64
codec,G.711 alaw,CORE_PCM_MODULE
codec,G.711 ulaw,CORE_PCM_MODULE
codec,G.722,mod_spandsp
codec,G.723.1 6.3k,mod_g723_1
codec,G.726 16k,mod_spandsp
codec,G.726 16k (AAL2),mod_spandsp
codec,G.726 24k,mod_spandsp
codec,G.726 24k (AAL2),mod_spandsp
codec,G.726 32k,mod_spandsp
codec,G.726 32k (AAL2),mod_spandsp
codec,G.726 40k,mod_spandsp
codec,G.726 40k (AAL2),mod_spandsp
codec,G.729,mod_g729
codec,GSM,mod_spandsp
codec,LPC-10,mod_spandsp
codec,PROXY PASS-THROUGH,CORE_PCM_MODULE
codec,PROXY VIDEO PASS-THROUGH,CORE_PCM_MODULE
codec,RAW Signed Linear (16 bit),CORE_PCM_MODULE
codec,Speex,CORE_SPEEX_MODULE
codec,VP8 Video,CORE_VPX_MODULE
codec,VP9 Video,CORE_VPX_MODULE

没有看到H264。为什么呢？

freeswitch@telecom> load mod_av
2020-07-04 18:22:42.470632 [INFO] switch_stun.c:897 External ip address detected using STUN: 180.112.27.205
2020-07-04 18:22:42.730632 [INFO] switch_stun.c:897 External ip address detected using STUN: 180.112.27.205
2020-07-04 18:22:42.870636 [INFO] mod_enum.c:884 ENUM Reloaded
2020-07-04 18:22:42.870636 [INFO] switch_time.c:1430 Timezone reloaded 1750 definitions

+OK Reloading XML
-ERR [module load file routine returned an error]

2020-07-04 18:22:42.870636 [CRIT] switch_loadable_module.c:1785 Error Loading module /usr/local/freeswitch/mod/mod_av.so
**/usr/local/freeswitch/mod/mod_av.so: undefined symbol: avfilter_link**

　　加载失败。编译链接时没有加上相应的库。解决这个错误即可。