git.sesse.net Git - vlc/blob - src/input/input_ext-dec.c

   1 /*****************************************************************************
   2  * input_ext-dec.c: services to the decoders
   3  *****************************************************************************
   4  * Copyright (C) 1998, 1999, 2000 VideoLAN
   5  *
   6  * Authors:
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  21  *****************************************************************************/
  22
  23 /*****************************************************************************
  24  * Preamble
  25  *****************************************************************************/
  26 #include "defs.h"
  27
  28 #include "config.h"
  29 #include "common.h"
  30 #include "threads.h"
  31 #include "mtime.h"
  32
  33 #include "intf_msg.h"
  34
  35 #include "stream_control.h"
  36 #include "input_ext-dec.h"
  37 #include "input.h"
  38
  39 /*****************************************************************************
  40  * InitBitstream: initialize a bit_stream_t structure
  41  *****************************************************************************/
  42 void InitBitstream( bit_stream_t * p_bit_stream, decoder_fifo_t * p_fifo )
  43 {
  44     p_bit_stream->p_decoder_fifo = p_fifo;
  45     p_bit_stream->pf_next_data_packet = NextDataPacket;
  46
  47     /* Get the first data packet. */
  48     vlc_mutex_lock( &p_fifo->data_lock );
  49     while ( DECODER_FIFO_ISEMPTY( *p_fifo ) )
  50     {
  51         if ( p_fifo->b_die )
  52         {
  53             vlc_mutex_unlock( &p_fifo->data_lock );
  54             return;
  55         }
  56         vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
  57     }
  58     p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
  59     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
  60     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
  61     p_bit_stream->fifo.buffer = 0;
  62     p_bit_stream->fifo.i_available = 0;
  63     vlc_mutex_unlock( &p_fifo->data_lock );
  64 }
  65
  66 /*****************************************************************************
  67  * NextDataPacket: go to the next data packet
  68  *****************************************************************************/
  69 void NextDataPacket( bit_stream_t * p_bit_stream )
  70 {
  71     WORD_TYPE           buffer_left;
  72     /* FIXME : not portable in a 64bit environment */
  73     int                 i_bytes_left;
  74     decoder_fifo_t *    p_fifo = p_bit_stream->p_decoder_fifo;
  75
  76     /* Buffer used at the end of a decoder thread, to give it zero
  77      * values if needed. */
  78     static byte_t       p_zero[64] = { 0, 0, 0, 0, 0, 0, 0,
  79                                        0, 0, 0, 0, 0, 0, 0,
  80                                        0, 0, 0, 0, 0, 0, 0,
  81                                        0, 0, 0, 0, 0, 0, 0,
  82                                        0, 0, 0, 0, 0, 0, 0,
  83                                        0, 0, 0, 0, 0, 0, 0,
  84                                        0, 0, 0, 0, 0, 0, 0,
  85                                        0, 0, 0, 0, 0, 0, 0 };
  86
  87     /* Put the remaining bytes (not aligned on a word boundary) in a
  88      * temporary buffer. */
  89     i_bytes_left = p_bit_stream->p_end - p_bit_stream->p_byte;
  90     buffer_left = *((WORD_TYPE *)p_bit_stream->p_end - 1);
  91
  92     /* We are looking for the next data packet that contains real data,
  93      * and not just a PES header */
  94     do
  95     {
  96         /* We were reading the last data packet of this PES packet... It's
  97          * time to jump to the next PES packet */
  98         if( p_bit_stream->p_data->p_next == NULL )
  99         {
 100             /* We are going to read/write the start and end indexes of the
 101              * decoder fifo and to use the fifo's conditional variable,
 102              * that's why we need to take the lock before. */
 103             vlc_mutex_lock( &p_fifo->data_lock );
 104
 105             /* Is the input thread dying ? */
 106             if( p_fifo->b_die )
 107             {
 108                 vlc_mutex_unlock( &p_fifo->data_lock );
 109                 p_bit_stream->p_byte = p_zero;
 110                 p_bit_stream->p_end = &p_zero[sizeof(p_zero) - 1];
 111                 return;
 112             }
 113
 114             /* We should increase the start index of the decoder fifo, but
 115              * if we do this now, the input thread could overwrite the
 116              * pointer to the current PES packet, and we weren't able to
 117              * give it back to the netlist. That's why we free the PES
 118              * packet first. */
 119             p_fifo->pf_delete_pes( p_fifo->p_packets_mgt,
 120                                    DECODER_FIFO_START( *p_fifo ) );
 121             DECODER_FIFO_INCSTART( *p_fifo );
 122
 123             while( DECODER_FIFO_ISEMPTY( *p_fifo ) )
 124             {
 125                 vlc_cond_wait( &p_fifo->data_wait, &p_fifo->data_lock );
 126                 if( p_fifo->b_die )
 127                 {
 128                     vlc_mutex_unlock( &p_fifo->data_lock );
 129                     p_bit_stream->p_byte = p_zero;
 130                     p_bit_stream->p_end = &p_zero[sizeof(p_zero) - 1];
 131                     return;
 132                 }
 133             }
 134
 135             /* The next byte could be found in the next PES packet */
 136             p_bit_stream->p_data = DECODER_FIFO_START( *p_fifo )->p_first;
 137
 138             /* We can release the fifo's data lock */
 139             vlc_mutex_unlock( &p_fifo->data_lock );
 140         }
 141         else
 142         {
 143             /* Perhaps the next data packet of the current PES packet contains
 144              * real data (ie its payload's size is greater than 0). */
 145             p_bit_stream->p_data = p_bit_stream->p_data->p_next;
 146         }
 147     } while ( p_bit_stream->p_data->p_payload_start
 148                == p_bit_stream->p_data->p_payload_end );
 149
 150     /* We've found a data packet which contains interesting data... */
 151     p_bit_stream->p_byte = p_bit_stream->p_data->p_payload_start;
 152     p_bit_stream->p_end  = p_bit_stream->p_data->p_payload_end;
 153
 154     /* Copy remaining bits of the previous packet */
 155     *((WORD_TYPE *)p_bit_stream->p_byte - 1) = buffer_left;
 156     p_bit_stream->p_byte -= i_bytes_left;
 157 }