m4a.c

video linux conference

/*****************************************************************************
 * m4a.c : MPEG-4 audio demuxer
 *****************************************************************************
 * Copyright (C) 2002-2004 VideoLAN
 * $Id: m4v.c 7754 2004-05-23 14:43:14Z fenrir $
 *
 * Authors: Gildas Bazin <[e-mail]>
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <stdlib.h>                                      /* malloc(), free() */

#include <vlc/vlc.h>
#include <vlc/input.h>
#include "vlc_codec.h"

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );

vlc_module_begin();
    set_category( CAT_INPUT );
    set_subcategory( SUBCAT_INPUT_DEMUX );
    set_description( _("MPEG-4 audio demuxer" ) );
    set_capability( "demux2", 110 );
    set_callbacks( Open, Close );
    add_shortcut( "m4a" );
    add_shortcut( "mp4a" );
    add_shortcut( "aac" );
vlc_module_end();

/*****************************************************************************
 * Local prototypes
 *****************************************************************************/
struct demux_sys_t
{
    vlc_bool_t  b_start;
    es_out_id_t *p_es;

    decoder_t   *p_packetizer;
};

static int Demux( demux_t * );
static int Control( demux_t *, int, va_list );

#define M4A_PACKET_SIZE 4096

/*****************************************************************************
 * Open: initializes demux structures
 *****************************************************************************/
static int Open( vlc_object_t * p_this )
{
    demux_t     *p_demux = (demux_t*)p_this;
    demux_sys_t *p_sys;
    uint8_t     *p_peek;
    int         b_forced = VLC_FALSE;

    if( p_demux->psz_path )
    {
        int i_len = strlen( p_demux->psz_path );

        if( i_len > 4 && !strcasecmp( &p_demux->psz_path[i_len - 4], ".aac" ) )
        {
            b_forced = VLC_TRUE;
        }
    }

    if( !p_demux->b_force && !b_forced )
    {
        return VLC_EGENERIC;
    }

    /* peek the begining (10 is for adts header) */
    if( stream_Peek( p_demux->s, &p_peek, 10 ) < 10 )
    {
        msg_Err( p_demux, "cannot peek" );
        return VLC_EGENERIC;
    }
    if( !strncmp( p_peek, "ADIF", 4 ) )
    {
        msg_Err( p_demux, "ADIF file. Not yet supported. (Please report)" );
        return VLC_EGENERIC;
    }

    p_demux->pf_demux  = Demux;
    p_demux->pf_control= Control;
    p_demux->p_sys     = p_sys = malloc( sizeof( demux_sys_t ) );
    p_sys->p_es        = NULL;
    p_sys->b_start     = VLC_TRUE;

    /*
     * Load the mpeg 4 audio packetizer
     */
    p_sys->p_packetizer = vlc_object_create( p_demux, VLC_OBJECT_PACKETIZER );
    p_sys->p_packetizer->pf_decode_audio = NULL;
    p_sys->p_packetizer->pf_decode_video = NULL;
    p_sys->p_packetizer->pf_decode_sub = NULL;
    p_sys->p_packetizer->pf_packetize = NULL;
    es_format_Init( &p_sys->p_packetizer->fmt_in, AUDIO_ES,
                    VLC_FOURCC( 'm', 'p', '4', 'a' ) );
    es_format_Init( &p_sys->p_packetizer->fmt_out, UNKNOWN_ES, 0 );
    p_sys->p_packetizer->p_module =
        module_Need( p_sys->p_packetizer, "packetizer", NULL, 0 );

    if( p_sys->p_packetizer->p_module == NULL)
    {
        vlc_object_destroy( p_sys->p_packetizer );
        msg_Err( p_demux, "cannot find mp4a packetizer" );
        free( p_sys );
        return VLC_EGENERIC;
    }

    return VLC_SUCCESS;
}

/*****************************************************************************
 * Close: frees unused data
 *****************************************************************************/
static void Close( vlc_object_t * p_this )
{
    demux_t     *p_demux = (demux_t*)p_this;
    demux_sys_t *p_sys = p_demux->p_sys;

    module_Unneed( p_sys->p_packetizer, p_sys->p_packetizer->p_module );
    vlc_object_destroy( p_sys->p_packetizer );

    free( p_sys );
}

/*****************************************************************************
 * Demux: reads and demuxes data packets
 *****************************************************************************
 * Returns -1 in case of error, 0 in case of EOF, 1 otherwise
 *****************************************************************************/
static int Demux( demux_t *p_demux)
{
    demux_sys_t *p_sys = p_demux->p_sys;
    block_t *p_block_in, *p_block_out;

    if( ( p_block_in = stream_Block( p_demux->s, M4A_PACKET_SIZE ) ) == NULL )
    {
        return 0;
    }

    p_block_in->i_pts = p_block_in->i_dts = p_sys->b_start ? 1 : 0;
    p_sys->b_start = VLC_FALSE;

    while( (p_block_out = p_sys->p_packetizer->pf_packetize(
                                          p_sys->p_packetizer, &p_block_in )) )
    {
        while( p_block_out )
        {
            block_t *p_next = p_block_out->p_next;

            if( p_sys->p_es == NULL )
            {
                p_sys->p_packetizer->fmt_out.b_packetized = VLC_TRUE;
                p_sys->p_es = es_out_Add( p_demux->out,
                                          &p_sys->p_packetizer->fmt_out);
            }

            es_out_Control( p_demux->out, ES_OUT_SET_PCR, p_block_out->i_dts );

            p_block_out->p_next = NULL;
            es_out_Send( p_demux->out, p_sys->p_es, p_block_out );

            p_block_out = p_next;
        }
    }
    return 1;
}

/*****************************************************************************
 * Control:
 *****************************************************************************/
static int Control( demux_t *p_demux, int i_query, va_list args )
{
    if( i_query == DEMUX_SET_TIME ) return VLC_EGENERIC;
    else return demux2_vaControlHelper( p_demux->s, 0, -1,
                                        0, 1, i_query, args );
}