Click here to Skip to main content
15,896,111 members
Articles / Desktop Programming / MFC

VLCWrapper - A Little C++-wrapper Around libvlc

Rate me:
Please Sign up or sign in to vote.
4.91/5 (49 votes)
12 Mar 2012CPOL3 min read 464.5K   25.9K   169  
An article on wrapping libvlc (VLC media player) in a C++-class
/*****************************************************************************
 * vlc_demux.h: Demuxer descriptor, queries and methods
 *****************************************************************************
 * Copyright (C) 1999-2005 VLC authors and VideoLAN
 * $Id: 2ae2f841961977db764eef08ea502b60a07c160b $
 *
 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

#ifndef VLC_DEMUX_H
#define VLC_DEMUX_H 1

/**
 * \file
 * This files defines functions and structures used by demux objects in vlc
 */

#include <vlc_es.h>
#include <vlc_stream.h>
#include <vlc_es_out.h>

/**
 * \defgroup demux Demux
 * @{
 */

struct demux_t
{
    VLC_COMMON_MEMBERS

    /* Module properties */
    module_t    *p_module;

    /* eg informative but needed (we can have access+demux) */
    char        *psz_access;
    char        *psz_demux;
    char        *psz_location;
    char        *psz_file;

    /* input stream */
    stream_t    *s;     /* NULL in case of a access+demux in one */

    /* es output */
    es_out_t    *out;   /* our p_es_out */

    /* set by demuxer */
    int (*pf_demux)  ( demux_t * );   /* demux one frame only */
    int (*pf_control)( demux_t *, int i_query, va_list args);

    /* Demux has to maintain them uptodate
     * when it is responsible of seekpoint/title */
    struct
    {
        unsigned int i_update;  /* Demux sets them on change,
                                   Input removes them once take into account*/
        /* Seekpoint/Title at demux level */
        int          i_title;       /* idem, start from 0 (could be menu) */
        int          i_seekpoint;   /* idem, start from 0 */
    } info;
    demux_sys_t *p_sys;

    /* Weak link to parent input */
    input_thread_t *p_input;
};


/* demux_meta_t is returned by "meta reader" module to the demuxer */
typedef struct demux_meta_t
{
    VLC_COMMON_MEMBERS
    demux_t *p_demux; /** FIXME: use stream_t instead? */
    input_item_t *p_item; /***< the input item that is being read */

    vlc_meta_t *p_meta;                 /**< meta data */

    int i_attachments;                  /**< number of attachments */
    input_attachment_t **attachments;    /**< array of attachments */
} demux_meta_t;

enum demux_query_e
{
    /* I. Common queries to access_demux and demux */
    /* POSITION double between 0.0 and 1.0 */
    DEMUX_GET_POSITION,         /* arg1= double *       res=    */
    DEMUX_SET_POSITION,         /* arg1= double arg2= bool b_precise    res=can fail    */

    /* LENGTH/TIME in microsecond, 0 if unknown */
    DEMUX_GET_LENGTH,           /* arg1= int64_t *      res=    */
    DEMUX_GET_TIME,             /* arg1= int64_t *      res=    */
    DEMUX_SET_TIME,             /* arg1= int64_t arg2= bool b_precise   res=can fail    */

    /* TITLE_INFO only if more than 1 title or 1 chapter */
    DEMUX_GET_TITLE_INFO,       /* arg1=input_title_t*** arg2=int*
                                   arg3=int*pi_title_offset(0), arg4=int*pi_seekpoint_offset(0) can fail */
    /* TITLE/SEEKPOINT, only when TITLE_INFO succeed */
    DEMUX_SET_TITLE,            /* arg1= int            can fail */
    DEMUX_SET_SEEKPOINT,        /* arg1= int            can fail */

    /* DEMUX_SET_GROUP only a hit for demuxer (mainly DVB) to allow not
     * reading everything (you should not use this to call es_out_Control)
     * if you don't know what to do with it, just IGNORE it, it is safe(r)
     * -1 means all group, 0 default group (first es added) */
    DEMUX_SET_GROUP,            /* arg1= int, arg2=const vlc_list_t *   can fail */

    /* Ask the demux to demux until the given date at the next pf_demux call
     * but not more (and not less, at the precision available of course).
     * XXX: not mandatory (except for subtitle demux) but I will help a lot
     * for multi-input
     */
    DEMUX_SET_NEXT_DEMUX_TIME,  /* arg1= int64_t *      can fail */
    /* FPS for correct subtitles handling */
    DEMUX_GET_FPS,              /* arg1= double *       res=can fail    */

    /* Meta data */
    DEMUX_GET_META,             /* arg1= vlc_meta_t **  res=can fail    */
    DEMUX_HAS_UNSUPPORTED_META, /* arg1= bool *   res can fail    */

    /* Attachments */
    DEMUX_GET_ATTACHMENTS,      /* arg1=input_attachment_t***, int* res=can fail */

    /* RECORD you are ensured that it is never called twice with the same state
     * you should accept it only if the stream can be recorded without
     * any modification or header addition. */
    DEMUX_CAN_RECORD,           /* arg1=bool*   res=can fail(assume false) */
    DEMUX_SET_RECORD_STATE,     /* arg1=bool    res=can fail */


    /* II. Specific access_demux queries */
    /* PAUSE you are ensured that it is never called twice with the same state */
    DEMUX_CAN_PAUSE = 0x1000,   /* arg1= bool*    can fail (assume false)*/
    DEMUX_SET_PAUSE_STATE,      /* arg1= bool     can fail */

    DEMUX_GET_PTS_DELAY,        /* arg1= int64_t*       cannot fail */

    /* DEMUX_CAN_CONTROL_PACE returns true (*pb_pace) if we can read the
     * data at our pace */
    DEMUX_CAN_CONTROL_PACE,     /* arg1= bool*pb_pace    can fail (assume false) */

    /* DEMUX_CAN_CONTROL_RATE is called only if DEMUX_CAN_CONTROL_PACE has returned false.
     * *pb_rate should be true when the rate can be changed (using DEMUX_SET_RATE)
     * *pb_ts_rescale should be true when the timestamps (pts/dts/pcr) have to be rescaled */
    DEMUX_CAN_CONTROL_RATE,     /* arg1= bool*pb_rate arg2= bool*pb_ts_rescale  can fail(assume false) */
    /* DEMUX_SET_RATE is called only if DEMUX_CAN_CONTROL_RATE has returned true.
     * It should return the value really used in *pi_rate */
    DEMUX_SET_RATE,             /* arg1= int*pi_rate                                        can fail */

    DEMUX_CAN_SEEK,            /* arg1= bool*    can fail (assume false)*/
};

VLC_API int demux_vaControlHelper( stream_t *, int64_t i_start, int64_t i_end, int64_t i_bitrate, int i_align, int i_query, va_list args );

/*************************************************************************
 * Miscellaneous helpers for demuxers
 *************************************************************************/

VLC_USED
static inline bool demux_IsPathExtension( demux_t *p_demux, const char *psz_extension )
{
    if( !p_demux->psz_file )
        return false;

    const char *psz_ext = strrchr ( p_demux->psz_file, '.' );
    if( !psz_ext || strcasecmp( psz_ext, psz_extension ) )
        return false;
    return true;
}

VLC_USED
static inline bool demux_IsForced( demux_t *p_demux, const char *psz_name )
{
   if( !p_demux->psz_demux || strcmp( p_demux->psz_demux, psz_name ) )
        return false;
    return true;
}

/**
 * This function will create a packetizer suitable for a demuxer that parses
 * elementary stream.
 *
 * The provided es_format_t will be cleaned on error or by
 * demux_PacketizerDestroy.
 */
VLC_API decoder_t * demux_PacketizerNew( demux_t *p_demux, es_format_t *p_fmt, const char *psz_msg ) VLC_USED;

/**
 * This function will destroy a packetizer create by demux_PacketizerNew.
 */
VLC_API void demux_PacketizerDestroy( decoder_t *p_packetizer );

/**
 * This function will return the parent input of this demux.
 * It is retained. Can return NULL.
 */
VLC_API input_thread_t * demux_GetParentInput( demux_t *p_demux ) VLC_USED;

/* */
#define DEMUX_INIT_COMMON() do {            \
    p_demux->pf_control = Control;          \
    p_demux->pf_demux = Demux;              \
    p_demux->p_sys = calloc( 1, sizeof( demux_sys_t ) ); \
    if( !p_demux->p_sys ) return VLC_ENOMEM;\
    } while(0)

/**
 * @}
 */

#endif

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Technical Lead HERE, a Nokia Business
Germany Germany
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions