fixed.c 7.84 KB
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/*****************************************************************************
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 * fixed.c: Fixed-point audio format conversions
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 *****************************************************************************
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 * Copyright (C) 2002, 2006 the VideoLAN team
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 * $Id$
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 *
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 * Authors: Jean-Paul Saman <jpsaman _at_ videolan _dot_ org>
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 *          Marc Ariberti <marcari@videolan.org>
 *          Samuel Hocevar <sam@zoy.org>
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 *
 * 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
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/

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#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

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#include <vlc/vlc.h>
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#include <vlc_aout.h>
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/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
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static int  Create_F32ToS16    ( vlc_object_t * );
static void Do_F32ToS16( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
                         aout_buffer_t * );
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static int  Create_S16ToF32    ( vlc_object_t * );
static void Do_S16ToF32( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
                         aout_buffer_t * );

static int  Create_U8ToF32    ( vlc_object_t * );
static void Do_U8ToF32( aout_instance_t *, aout_filter_t *, aout_buffer_t *,
                         aout_buffer_t * );
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/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
vlc_module_begin();
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    set_description( _("Fixed point audio format conversions") );
    add_submodule();
        set_callbacks( Create_F32ToS16, NULL );
        set_capability( "audio filter", 10 );
    add_submodule();
        set_callbacks( Create_S16ToF32, NULL );
        set_capability( "audio filter", 15 );
    add_submodule();
        set_callbacks( Create_U8ToF32, NULL );
        set_capability( "audio filter", 1 );
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vlc_module_end();

/*****************************************************************************
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 * F32 to S16
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 *****************************************************************************/
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static int Create_F32ToS16( vlc_object_t *p_this )
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{
    aout_filter_t * p_filter = (aout_filter_t *)p_this;

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    if ( p_filter->input.i_format != VLC_FOURCC('f','i','3','2')
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          || p_filter->output.i_format != AOUT_FMT_S16_NE )
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    {
        return -1;
    }

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    if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
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    {
        return -1;
    }

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    p_filter->pf_do_work = Do_F32ToS16;
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    p_filter->b_in_place = 1;

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    return VLC_SUCCESS;;
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}

/*****************************************************************************
 * support routines borrowed from mpg321 (file: mad.c), which is distributed
 * under GPL license
 *
 * mpg321 was written by Joe Drew <drew@debian.org>, and based upon 'plaympeg'
 * from the smpeg sources, which was written by various people from Loki Software
 * (http://www.lokigames.com).
 *
 * It also incorporates some source from mad, written by Robert Leslie
 *****************************************************************************/

/* The following two routines and data structure are from the ever-brilliant
     Rob Leslie.
*/

#define VLC_F_FRACBITS  28

# if VLC_F_FRACBITS == 28
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#  define VLC_F(x) ((vlc_fixed_t) (x##L))
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# endif

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# define VLC_F_ONE VLC_F(0x10000000)
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/*****************************************************************************
 * s24_to_s16_pcm: Scale a 24 bit pcm sample to a 16 bit pcm sample.
 *****************************************************************************/
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static inline int16_t s24_to_s16_pcm(vlc_fixed_t sample)
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{
  /* round */
  sample += (1L << (VLC_F_FRACBITS - 16));

  /* clip */
  if (sample >= VLC_F_ONE)
    sample = VLC_F_ONE - 1;
  else if (sample < -VLC_F_ONE)
    sample = -VLC_F_ONE;

  /* quantize */
  return (sample >> (VLC_F_FRACBITS + 1 - 16));
}

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static void Do_F32ToS16( aout_instance_t * p_aout, aout_filter_t * p_filter,
                         aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
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{
    int i;
    vlc_fixed_t * p_in = (vlc_fixed_t *)p_in_buf->p_buffer;
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    int16_t * p_out = (int16_t *)p_out_buf->p_buffer;
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    for ( i = p_in_buf->i_nb_samples
               * aout_FormatNbChannels( &p_filter->input ) ; i-- ; )
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    {
        /* Fast Scaling */
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        *p_out++ = s24_to_s16_pcm(*p_in++);
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    }
    p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
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    p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes / 2;
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}
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/*****************************************************************************
 * S16 to F32
 *****************************************************************************/
static int Create_S16ToF32( vlc_object_t *p_this )
{
    aout_filter_t * p_filter = (aout_filter_t *)p_this;

    if ( p_filter->output.i_format != VLC_FOURCC('f','i','3','2')
          || p_filter->input.i_format != AOUT_FMT_S16_NE )
    {
        return -1;
    }

    if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
    {
        return -1;
    }

    p_filter->pf_do_work = Do_S16ToF32;
    p_filter->b_in_place = 1;

    return 0;
}

static void Do_S16ToF32( aout_instance_t * p_aout, aout_filter_t * p_filter,
                         aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
{
    int i = p_in_buf->i_nb_samples * aout_FormatNbChannels( &p_filter->input );

    /* We start from the end because b_in_place is true */
    int16_t * p_in = (int16_t *)p_in_buf->p_buffer + i - 1;
    vlc_fixed_t * p_out = (vlc_fixed_t *)p_out_buf->p_buffer + i - 1;

    while( i-- )
    {
        *p_out = (vlc_fixed_t)( (int32_t)(*p_in) * (FIXED32_ONE >> 16) );
        p_in--; p_out--;
    }

    p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
    p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes
            * sizeof(vlc_fixed_t) / sizeof(int16_t);
}


/*****************************************************************************
 * U8 to F32
 *****************************************************************************/
static int Create_U8ToF32( vlc_object_t *p_this )
{
    aout_filter_t * p_filter = (aout_filter_t *)p_this;

    if ( p_filter->input.i_format != VLC_FOURCC('u','8',' ',' ')
          || p_filter->output.i_format != VLC_FOURCC('f','i','3','2') )
    {
        return -1;
    }

    if ( !AOUT_FMTS_SIMILAR( &p_filter->input, &p_filter->output ) )
    {
        return -1;
    }

    p_filter->pf_do_work = Do_U8ToF32;
    p_filter->b_in_place = VLC_TRUE;

    return 0;
}

static void Do_U8ToF32( aout_instance_t * p_aout, aout_filter_t * p_filter,
                        aout_buffer_t * p_in_buf, aout_buffer_t * p_out_buf )
{
    int i = p_in_buf->i_nb_samples * aout_FormatNbChannels( &p_filter->input );

    /* We start from the end because b_in_place is true */
    uint8_t * p_in = (uint8_t *)p_in_buf->p_buffer + i - 1;
    vlc_fixed_t * p_out = (vlc_fixed_t *)p_out_buf->p_buffer + i - 1;

    while( i-- )
    {
        *p_out = (vlc_fixed_t)( (int32_t)(*p_in - 128) * (FIXED32_ONE / 128) );
        p_in--; p_out--;
    }

    p_out_buf->i_nb_samples = p_in_buf->i_nb_samples;
    p_out_buf->i_nb_bytes = p_in_buf->i_nb_bytes * sizeof(vlc_fixed_t);
}