audio_output.h 7.29 KB
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/*****************************************************************************
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 * audio_output.h : audio output thread interface
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 *****************************************************************************
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 * Copyright (C) 1999, 2000 VideoLAN
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 * $Id: audio_output.h,v 1.50 2002/07/31 20:56:50 sam Exp $
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 *
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 * Authors: Michel Kaempf <maxx@via.ecp.fr>
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 *          Cyril Deguet <asmax@via.ecp.fr>
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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.
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 * 
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 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
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 *
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 * 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
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 *****************************************************************************/

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/*****************************************************************************
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 * aout_increment_t
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 *****************************************************************************
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 * This structure is used to keep the progression of an index up-to-date, in
 * order to avoid rounding problems and heavy computations, as the function
 * that handles this structure only uses additions.
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 *****************************************************************************/
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typedef struct aout_increment_t
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{
    /* The remainder is used to keep track of the fractional part of the
     * index. */
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    int i_r;
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    /*
     * The increment structure is initialized with the result of an euclidean
     * division :
     *
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     *  i_x           i_b
     * ----- = i_a + -----
     *  i_y           i_c
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     *
     */
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    int i_a, i_b, i_c;
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} aout_increment_t;

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/*****************************************************************************
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 * aout_fifo_t
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 *****************************************************************************/
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struct aout_fifo_t
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{
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    /* See the fifo formats below */
    int                 i_format;
    int                 i_channels;
    int                 i_rate;
    int                 i_frame_size;

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    vlc_bool_t          b_die;
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    int                 i_fifo;      /* Just to keep track of the fifo index */
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    vlc_mutex_t         data_lock;
    vlc_cond_t          data_wait;
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    u8 *                buffer;
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    mtime_t *           date;
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    /* The start frame is the first frame in the buffer that contains decoded
     * audio data. It it also the first frame in the current timestamped frame
     * area, ie the first dated frame in the decoded part of the buffer. :-p */
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    int                 i_start_frame;
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    vlc_bool_t          b_start_frame;
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    /* The next frame is the end frame of the current timestamped frame area,
     * ie the first dated frame after the start frame. */
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    int                 i_next_frame;
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    vlc_bool_t          b_next_frame;
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    /* The end frame is the first frame, after the start frame, that doesn't
     * contain decoded audio data. That's why the end frame is the first frame
     * where the audio decoder can store its decoded audio frames. */
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    int                 i_end_frame;
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    /* Current index in p_aout->buffer */
    int                 i_unit;
    /* Max index in p_aout->buffer */
    int                 i_unit_limit;
    /* Structure used to calculate i_unit with a Bresenham algorithm */
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    aout_increment_t    unit_increment;
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    /* The following variable is used to store the number of remaining audio
     * units in the current timestamped frame area. */
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    int                 i_units;
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};
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#define AOUT_FIFO_ISEMPTY( fifo ) \
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  ( (fifo).i_end_frame == (fifo).i_start_frame )
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#define AOUT_FIFO_ISFULL( fifo ) \
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  ( ((((fifo).i_end_frame + 1) - (fifo).i_start_frame) & AOUT_FIFO_SIZE) == 0 )

#define AOUT_FIFO_INC( i_index ) \
  ( ((i_index) + 1) & AOUT_FIFO_SIZE )
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/* List of known fifo formats */
#define AOUT_FIFO_NONE    0
#define AOUT_FIFO_PCM     1
#define AOUT_FIFO_SPDIF   2
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/*****************************************************************************
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 * aout_thread_t : audio output thread descriptor
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 *****************************************************************************/
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struct aout_thread_t
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{
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    VLC_COMMON_MEMBERS
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    vlc_mutex_t         fifos_lock;
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    aout_fifo_t         fifo[ AOUT_MAX_FIFOS ];

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    /* Plugin used and shortcuts to access its capabilities */
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    module_t *   p_module;
    int       ( *pf_setformat )  ( aout_thread_t * );
    int       ( *pf_getbufinfo ) ( aout_thread_t * , int );
    void      ( *pf_play )       ( aout_thread_t * , byte_t *, int );
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    void *              buffer;
    /* The s32 buffer is used to mix all the audio fifos together before
     * converting them and storing them in the audio output buffer */
    s32 *               s32_buffer;

    /* The size of the audio output buffer is kept in audio units, as this is
     * the only unit that is common with every audio decoder and audio fifo */
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    int                 i_units;
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    /* date is the moment where the first audio unit of the output buffer
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     * will be played */
    mtime_t             date;
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    /* The current volume */
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    int                 i_volume;
    int                 i_savedvolume;
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    /* Format of the audio output samples, number of channels, and
     * rate and gain (in Hz) of the audio output sound */
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    int                 i_format;
    int                 i_channels;
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    int                 i_rate;

    /* Latency of the audio output plugin, in bytes */
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    int                 i_latency;
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    /* there might be some useful private structure, such as audio_buf_info
     * for the OSS output */
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    aout_sys_t *        p_sys;
};
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/* Those are from <linux/soundcard.h> but are needed because of formats
 * on other platforms */
#define AOUT_FMT_U8          0x00000008
#define AOUT_FMT_S16_LE      0x00000010           /* Little endian signed 16 */
#define AOUT_FMT_S16_BE      0x00000020              /* Big endian signed 16 */
#define AOUT_FMT_S8          0x00000040
#define AOUT_FMT_U16_LE      0x00000080                 /* Little endian U16 */
#define AOUT_FMT_U16_BE      0x00000100                    /* Big endian U16 */
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#define AOUT_FMT_AC3         0x00000400                 /* Dolby Digital AC3 */

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#ifdef WORDS_BIGENDIAN
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#define AOUT_FMT_S16_NE      AOUT_FMT_S16_BE
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#else
#define AOUT_FMT_S16_NE      AOUT_FMT_S16_LE
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#endif

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/* Number of samples in an AC3 frame */
#define AC3_FRAME_SIZE      1536

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/* Size of a frame for spdif output */
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#define SPDIF_FRAME_SIZE    6144
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/*****************************************************************************
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 * Prototypes
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 *****************************************************************************/
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aout_thread_t * aout_CreateThread       ( vlc_object_t *, int, int );
void            aout_DestroyThread      ( aout_thread_t * );
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#define aout_CreateFifo(a,b,c,d,e,f) __aout_CreateFifo(VLC_OBJECT(a),b,c,d,e,f)
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VLC_EXPORT( aout_fifo_t *, __aout_CreateFifo,  ( vlc_object_t *, int, int, int, int, void * ) );
VLC_EXPORT( void,            aout_DestroyFifo, ( aout_fifo_t *p_fifo ) );
            void             aout_FreeFifo     ( aout_fifo_t *p_fifo );
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