System information

If you store a recording in several formats (such as WAV, GSM, etc.), Asterisk will
determine the least costly format
§
to use when a channel requires that recording.
Table 2-7. Format interpreters
Name Plays files stored in Popularity/Status
format_g723 G.723 .g723 Insignificant
format_g726 G.726 .g726 Insignificant
format_g729 G.729 .g729 Useful
format_gsm RPE-LTP (original GSM codec) .gsm Usable
format_h263 H.263—video .h263 Usable
format_h264 H.264—video .h264 Usable
format_ilbc Internet Low Bitrate Codec .ilbc Insignificant
format_jpeg Graphic file .jpeg .jpg Insignificant
format_ogg_vorbis Ogg container .ogg Usable
format_pcm Various Pulse-Coded Modulation
formats: .alaw, .al, .alw, .pcm, .ulaw, .ul, .mu, .ulw, .g722, .au
Useful
format_siren14 G.722.1 Annex C (14 kHz) .siren14 New
format_siren7 G.722.1 (7 kHz) .siren7 New
format_sln16 16-bit signed linear .sln16 New
format_sln 8-bit signed linear .sln .raw Useful
format_vox .vox Insignificant
format_wav .wav Useful
format_wav_gsm GSM audio in a WAV container .WAV, .wav49 Usable
Dialplan Functions
Dialplan functions, listed in Table 2-8, complement the dialplan applications (see
“Applications” on page 12). They provide many useful enhancements to things like
string handling, time and date wrangling, and ODBC connectivity.
Table 2-8. Dialplan functions
Name Purpose Popularity/Status
func_aes Encrypts/decrypts an AES string Useful
func_audiohookinherit Allows calls to be recorded after transfer Useful
func_base64 Encodes/decodes a base-64 string Usable
func_blacklist Writes/reads blacklist in astdb Useful
§ Some codecs can impose a significant load on the CPU, such that a system that could support several hundred
channels without transcoding might only be able to handle a few dozen when transcoding is in use.
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