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vmix_core/playmix.inc

Application to local playback buffer import routine for vmix (FP)

Description

#ifdef CONFIG_OSS_VMIX_FLOAT

This file is part of Open Sound System.

Copyright (C) 4Front Technologies 1996-2008.

This this source file is released under GPL v2 license (no other versions). See the COPYING file included in the main directory of this source distribution for the license terms and conditions.

Mixing function for virtual devices 


vmix_mixer_t *mixer = portc->mixer;
vmix_engine_t *eng = &mixer->play_engine;

dmap_t *dmap = audio_engines[portc->audio_dev]->dmap_out;

int frame_size;

int inptr, inmax;
int used_channels;
int i, ch, nch;
double vol;

Initial setup 


frame_size = sizeof (*inp);

inmax = dmap->bytes_in_use / frame_size;
inptr = portc->play_dma_pointer / frame_size;

inp = (BUFFER_TYPE) dmap->dmabuf;

used_channels = portc->channels;
if (used_channels > eng->channels)
  used_channels = eng->channels;

/* ignored_channels = portc->channels - used_channels; */

Handle mono playback by playing the mono stream twice (for left and right ch) 

nch=used_channels;
if (nch<2)nch=2;

Do the mixing 

for (ch = 0; ch < nch; ch++)
  {
    int ip = inptr + (ch%used_channels);
    double vu = portc->vu[ch % 2];
    float *chbuf = eng->chbufs[ch+portc->play_choffs];

    i = portc->volume[ch%2];
    vol = vmix_db_table[i / 5];

    vu = vu / 255.0;

    for (i = 0; i < nsamples; i++)
      {
	double tmp;

#if 0 && defined(SINE_DEBUG)
	if (ch > 1)
	  tmp = 0.0;
	else
	  tmp = sine_table[sine_phase[ch]];
	sine_phase[ch] = (sine_phase[ch] + 1) % SINE_SIZE;
#else

Convert the sample to right endianess. 

	tmp = VMIX_BYTESWAP (inp[ip]);
	tmp = tmp * range;
#endif
	tmp = tmp * vol;

	*chbuf++ += tmp;
	ip = (ip + portc->channels) % inmax;

	/* VU meter */
	if (tmp < 0.0)
	  tmp = -tmp;
	if (tmp > vu)
	  vu = tmp;
      }

    if (ch < 2)
      {				/* Save left/right VU meters */
	vu = vu * 255.0;
	portc->vu[ch] = (int)vu;
      }
  }

Finally save the state variables 


portc->play_dma_pointer =
  (portc->play_dma_pointer +
   nsamples * frame_size * portc->channels) % dmap->bytes_in_use;
#else
#include "playmix_int.inc"
#endif
Copyright (C) 4Front Technologies, 2007. All rights reserved.

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Copyright (C) 4Front Technologies, 2007. All rights reserved.
Back to index OSS web site