SSB_HighSpeed_Modem/modem/audio.c

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2020-10-31 20:21:52 -04:00
/*
* High Speed modem to transfer data in a 2,7kHz SSB channel
* =========================================================
* Author: DJ0ABR
*
* (c) DJ0ABR
* www.dj0abr.de
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* audio.c ... functions to handle audio in/out via a soundcard
* uses the "BASS" library
*
* captures samples from the sound card.
* Samples are 32-bit floats in a range of -1 to +1
* get these samples from the thread safe fifo: cap_read_fifo(&floatvariable)
*
* plays samples to the sound card
* Samples are 32-bit floats in a range of -1 to +1
* play the samples by calling the thread save function: pb_write_fifo(floatsample)
*
*/
#include "qo100modem.h"
//BOOL CALLBACK RecordingCallback(HRECORD handle, const void *buffer, DWORD length, void *user);
DWORD CALLBACK WriteStream(HSTREAM handle, float *buffer, DWORD length, void *user);
int pb_read_fifo(float *data, int elements);
void close_audio();
#define CHANNELS 1 // no of channels used
HRECORD rchan = 0; // recording channel
BASS_INFO info;
HSTREAM stream = 0;
int init_audio()
{
close_audio();
printf("init audio, caprate:%d\n",caprate);
// check the correct BASS was loaded
if (HIWORD(BASS_GetVersion()) != BASSVERSION)
{
printf("An incorrect version of BASS was loaded\n");
return -1;
}
/*
// initalize default recording device
if (!BASS_RecordInit(-1))
{
printf("Can't initialize recording device\n");
return -1;
}
*/
// initialize default output device
if (!BASS_Init(-1, caprate, 0, NULL, NULL))
{
printf("Can't initialize output device\n");
return -1;
}
/*
// set capture callback
rchan = BASS_RecordStart(caprate, CHANNELS, BASS_SAMPLE_FLOAT, RecordingCallback, 0);
if (!rchan) {
printf("Can't start capturing\n");
return -1;
}
*/
// set play callback
BASS_GetInfo(&info);
stream = BASS_StreamCreate(info.freq, CHANNELS, BASS_SAMPLE_FLOAT, (STREAMPROC*)WriteStream, 0); // sample: 32 bit float
BASS_ChannelSetAttribute(stream, BASS_ATTRIB_BUFFER, 0); // no buffering for minimum latency
BASS_ChannelPlay(stream, FALSE); // start it
return 0;
}
void close_audio()
{
if(stream != 0)
{
//BASS_RecordFree();
int r = BASS_Free();
if(!r)
printf("Bass_free error: %d\n", BASS_ErrorGetCode());
stream = 0;
}
}
/*
// capture callback
// length: bytes. short=2byte, 2channels, so it requests samples*4
BOOL CALLBACK RecordingCallback(HRECORD handle, const void *buffer, DWORD length, void *user)
{
//printf("captured %ld samples\n",length/sizeof(float));
float *fbuffer = (float *)buffer;
//printf("w:%ld ",length/sizeof(float));
for(int i=0; i<(length/sizeof(float)); i+=CHANNELS)
{
//printf("%f\n",fbuffer[i]);
cap_write_fifo(fbuffer[i]);
}
return TRUE; // continue recording
}
*/
// play callback
// length: bytes. float=4byte, 2channels, so it requests samples*8
DWORD CALLBACK WriteStream(HSTREAM handle, float *buffer, DWORD length, void *user)
{
int ret = pb_read_fifo(buffer,length/sizeof(float));
if(ret == 0)
{
// fifo empty, send 00
memset(buffer,0,length);
}
return length;
}
// ================ thread safe fifo for audio callback routines ===============
pthread_mutex_t cap_crit_sec;
pthread_mutex_t pb_crit_sec;
#define CAP_LOCK pthread_mutex_lock(&cap_crit_sec)
#define CAP_UNLOCK pthread_mutex_unlock(&cap_crit_sec)
#define PB_LOCK pthread_mutex_lock(&pb_crit_sec)
#define PB_UNLOCK pthread_mutex_unlock(&pb_crit_sec)
#define AUDIO_BUFFERMAXTIME 2 // fifo can buffer this time in [s]
#define AUDIO_PLAYBACK_BUFLEN (48000 * 10) // space for 10 seconds of samples
/*#define AUDIO_CAPTURE_BUFLEN (48000*CHANNELS*AUDIO_BUFFERMAXTIME*UPSAMPLING)
int cap_wridx=0;
int cap_rdidx=0;
float cap_buffer[AUDIO_CAPTURE_BUFLEN];
*/
int pb_wridx=0;
int pb_rdidx=0;
float pb_buffer[AUDIO_PLAYBACK_BUFLEN];
/*
// write one sample into the fifo
// overwrite old data if the fifo is full
void cap_write_fifo(float sample)
{
CAP_LOCK;
cap_buffer[cap_wridx] = sample;
if(++cap_wridx >= AUDIO_CAPTURE_BUFLEN) cap_wridx = 0;
CAP_UNLOCK;
}
int cap_read_fifo(float *data)
{
CAP_LOCK;
if (cap_rdidx == cap_wridx)
{
// Fifo empty, no data available
CAP_UNLOCK;
return 0;
}
*data = cap_buffer[cap_rdidx];
if(++cap_rdidx >= AUDIO_CAPTURE_BUFLEN) cap_rdidx = 0;
CAP_UNLOCK;
return 1;
}
*/
void pb_write_fifo(float sample)
{
PB_LOCK;
// check if there is free space in fifo
if(pb_fifo_freespace(1) == 0)
{
PB_UNLOCK;
printf("************* pb fifo full\n");
return;
}
pb_buffer[pb_wridx] = sample;
if(++pb_wridx >= AUDIO_PLAYBACK_BUFLEN) pb_wridx = 0;
PB_UNLOCK;
//printf("write: pbw:%d pbr:%d\n",pb_wridx,pb_rdidx);
}
int pb_fifo_freespace(int nolock)
{
int freebuf = 0;
if(nolock == 0) PB_LOCK;
/*freebuf = AUDIO_PLAYBACK_BUFLEN - ((pb_wridx+AUDIO_PLAYBACK_BUFLEN+1 - pb_rdidx)%AUDIO_PLAYBACK_BUFLEN);
freebuf %= AUDIO_PLAYBACK_BUFLEN;*/
int elemInFifo = (pb_wridx + AUDIO_PLAYBACK_BUFLEN - pb_rdidx) % AUDIO_PLAYBACK_BUFLEN;
freebuf = AUDIO_PLAYBACK_BUFLEN - elemInFifo;
if(nolock == 0) PB_UNLOCK;
//printf("fifolen:%d check: pbw:%d pbr:%d freebuf:%d\n",AUDIO_PLAYBACK_BUFLEN,pb_wridx,pb_rdidx,freebuf);
return freebuf;
}
// read elements floats from fifo or return 0 if not enough floats are available
int pb_read_fifo(float *data, int elements)
{
//printf("pb read fifo: %d\n",elements);
PB_LOCK;
int e = AUDIO_PLAYBACK_BUFLEN - pb_fifo_freespace(1);
//if (pb_rdidx == pb_wridx)
if(e < elements)
{
// Fifo empty, no data available
PB_UNLOCK;
//printf("pb fifo empty, need:%d have:%d size:%d\n",elements,e,AUDIO_PLAYBACK_BUFLEN);
return 0;
}
for(int i=0; i<elements; i++)
{
data[i] = pb_buffer[pb_rdidx];
if(++pb_rdidx >= AUDIO_PLAYBACK_BUFLEN) pb_rdidx = 0;
}
//printf("read %d floats\n",elements);
PB_UNLOCK;
return 1;
}