diff options
Diffstat (limited to 'third_party/gsm/man/gsm.3')
| -rw-r--r-- | third_party/gsm/man/gsm.3 | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/third_party/gsm/man/gsm.3 b/third_party/gsm/man/gsm.3 new file mode 100644 index 00000000..e465762b --- /dev/null +++ b/third_party/gsm/man/gsm.3 @@ -0,0 +1,105 @@ +.\" +.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische +.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for +.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. +.\" +.PU +.TH GSM 3 +.SH NAME +gsm_create, gsm_destroy, gsm_encode, gsm_decode \(em GSM\ 06.10 lossy sound compression +.SH SYNOPSIS +.PP +#include "gsm.h" +.PP +gsm gsm_create(); +.PP +void gsm_encode(handle, src, dst) +.br +gsm handle; +.br +gsm_signal src[160]; +.br +gsm_frame dst; +.PP +int gsm_decode(handle, src, dst) +.br +gsm handle; +.br +gsm_frame src; +.br +gsm_signal dst[160]; +.PP +void gsm_destroy(handle) +.br +gsm handle; +.br +.SH "DESCRIPTION" +Gsm is an implementation of the final draft GSM 06.10 +standard for full-rate speech transcoding. +.PP +gsm_create() initializes a gsm pass and returns a 'gsm' object +which can be used as a handle in subsequent calls to gsm_decode(), +gsm_encode() or gsm_destroy(). +.PP +gsm_encode() encodes an array of 160 13-bit samples (given as +gsm_signal's, signed integral values of at least 16 bits) into +a gsm_frame of 33 bytes. +(gsm_frame is a type defined as an array of 33 gsm_bytes in gsm.h.) +.PP +gsm_decode() decodes a gsm_frame into an array of 160 13-bit samples +(given as gsm_signals), which sound rather like what you handed to +gsm_encode() on the other side of the wire. +.PP +gsm_destroy() finishes a gsm pass and frees all storage associated +with it. +.SS "Sample format" +The following scaling is assumed for input to the algorithm: +.br +.nf + 0 1 11 12 + S..v..v..v..v..v..v..v..v..v..v..v..v..*..*..* +.nf +.br +Only the top 13 bits are used as a signed input value. +The output of gsm_decode() has the three lower bits set to zero. +.\" .SH OPTIONS +.SH "RETURN VALUE" +gsm_create() returns an opaque handle object of type gsm, or 0 on error. +gsm_decode() returns -1 if the passed frame is invalid, else 0. +.SH EXAMPLE +.nf +#include "gsm.h" + +gsm handle; +gsm_frame buf; +gsm_signal sample[160]; +int cc, soundfd; + +play() { /* read compressed data from standard input, write to soundfd */ + + if (!(handle = gsm_create())) error... + while (cc = read(0, (char *)buf, sizeof buf)) { + if (cc != sizeof buf) error... + if (gsm_decode(handle, buf, sample) < 0) error... + if (write(soundfd, sample, sizeof sample) != sizeof sample) + error... + } + gsm_destroy(handle); +} + +record() { /* read from soundfd, write compressed to standard output */ + + if (!(handle = gsm_create())) error... + while (cc = read(soundfd, sample, sizeof sample)) { + if (cc != sizeof sample) error... + gsm_encode(handle, sample, buf); + if (write(1, (char *)buf, sizeof buf) != sizeof sample) + error... + } + gsm_destroy(handle); +} +.nf +.SH BUGS +Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de. +.SH "SEE ALSO" +toast(1), gsm_print(3), gsm_explode(3), gsm_option(3) |