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547 lines
20 KiB
547 lines
20 KiB
/*****************************************************************************
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* mpeg_audio.c: parse MPEG audio sync info and packetize the stream
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*****************************************************************************
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* Copyright (C) 2001-2003 VideoLAN
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* $Id: mpeg_audio.c,v 1.9 2003/01/28 23:55:57 massiot Exp $
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*
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* Authors: Laurent Aimar <fenrir@via.ecp.fr>
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* Eric Petit <titer@videolan.org>
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* Christophe Massiot <massiot@via.ecp.fr>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* 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
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
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*****************************************************************************/
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/*****************************************************************************
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* Preamble
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*****************************************************************************/
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#include <stdlib.h> /* malloc(), free() */
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#include <string.h> /* strdup() */
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#include <vlc/vlc.h>
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#include <vlc/aout.h>
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#include <vlc/decoder.h>
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/*****************************************************************************
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* dec_thread_t : decoder thread descriptor
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*****************************************************************************/
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typedef struct dec_thread_t
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{
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/*
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* Thread properties
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*/
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vlc_thread_t thread_id; /* id for thread functions */
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/*
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* Input properties
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*/
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decoder_fifo_t * p_fifo; /* stores the PES stream data */
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bit_stream_t bit_stream;
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/*
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* Output properties
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*/
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aout_instance_t * p_aout; /* opaque */
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aout_input_t * p_aout_input; /* opaque */
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audio_sample_format_t output_format;
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} dec_thread_t;
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#define MAX_FRAME_SIZE 10000
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/* This isn't the place to put mad-specific stuff. However, it makes the
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* mad plug-in's life much easier if we put 8 extra bytes at the end of the
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* buffer, because that way it doesn't have to copy the aout_buffer_t to a
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* bigger buffer. This has no implication on other plug-ins, and we only
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* lose 8 bytes per frame. --Meuuh */
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#define MAD_BUFFER_GUARD 8
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/****************************************************************************
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* Local prototypes
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****************************************************************************/
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static int Open ( vlc_object_t * );
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static int RunDecoder ( decoder_fifo_t * );
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static void EndThread ( dec_thread_t * );
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static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
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unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
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unsigned int * pi_frame_length,
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unsigned int * pi_current_frame_length,
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unsigned int * pi_layer );
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/*****************************************************************************
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* Module descriptor
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*****************************************************************************/
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vlc_module_begin();
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set_description( _("MPEG audio layer I/II/III parser") );
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set_capability( "decoder", 100 );
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set_callbacks( Open, NULL );
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vlc_module_end();
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/*****************************************************************************
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* OpenDecoder: probe the decoder and return score
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*****************************************************************************/
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static int Open( vlc_object_t *p_this )
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{
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decoder_fifo_t *p_fifo = (decoder_fifo_t*) p_this;
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if( p_fifo->i_fourcc != VLC_FOURCC( 'm', 'p', 'g', 'a') )
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{
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return VLC_EGENERIC;
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}
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p_fifo->pf_run = RunDecoder;
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return VLC_SUCCESS;
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}
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/*****************************************************************************
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* RunDecoder: this function is called just after the thread is created
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*****************************************************************************/
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static int RunDecoder( decoder_fifo_t *p_fifo )
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{
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dec_thread_t * p_dec;
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audio_date_t end_date;
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unsigned int i_layer = 0;
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byte_t p_sync[MAD_BUFFER_GUARD];
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mtime_t pts;
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int i_free_frame_size = 0;
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/* Allocate the memory needed to store the thread's structure */
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p_dec = malloc( sizeof(dec_thread_t) );
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if( p_dec == NULL )
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{
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msg_Err( p_fifo, "out of memory" );
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DecoderError( p_fifo );
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return -1;
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}
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/* Initialize the thread properties */
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p_dec->p_aout = NULL;
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p_dec->p_aout_input = NULL;
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p_dec->p_fifo = p_fifo;
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aout_DateSet( &end_date, 0 );
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/* Init the bitstream */
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if( InitBitstream( &p_dec->bit_stream, p_dec->p_fifo,
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NULL, NULL ) != VLC_SUCCESS )
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{
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msg_Err( p_fifo, "cannot initialize bitstream" );
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DecoderError( p_fifo );
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free( p_dec );
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return -1;
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}
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/* Init sync buffer. */
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NextPTS( &p_dec->bit_stream, &pts, NULL );
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GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
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/* Decoder thread's main loop */
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while ( !p_dec->p_fifo->b_die && !p_dec->p_fifo->b_error )
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{
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int i_current_frame_size;
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unsigned int i_rate, i_original_channels, i_frame_size, i_frame_length;
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unsigned int i_new_layer, i_bit_rate;
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uint32_t i_header;
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aout_buffer_t * p_buffer;
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int i;
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/* Look for sync word - should be 0xffe */
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if ( (p_sync[0] != 0xff) || ((p_sync[1] & 0xe0) != 0xe0) )
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{
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msg_Warn( p_dec->p_fifo, "no sync - skipping" );
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/* Look inside the sync buffer. */
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for ( i = 1; i < MAD_BUFFER_GUARD - 1; i++ )
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{
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if ( (p_sync[i] == 0xff) && ((p_sync[i + 1] & 0xe0) != 0xe0) )
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break;
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}
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if ( i < MAD_BUFFER_GUARD - 1 )
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{
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/* Found it ! */
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memmove( p_sync, &p_sync[i], MAD_BUFFER_GUARD - i );
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GetChunk( &p_dec->bit_stream, &p_sync[MAD_BUFFER_GUARD - i],
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i );
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}
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else
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{
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if ( p_sync[MAD_BUFFER_GUARD - 1] == 0xff
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&& ShowBits( &p_dec->bit_stream, 3 ) == 0x3 )
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{
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/* Found it ! */
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p_sync[0] = p_sync[MAD_BUFFER_GUARD - 1];
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GetChunk( &p_dec->bit_stream,
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&p_sync[1], MAD_BUFFER_GUARD - 1 );
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}
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else
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{
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/* Scan the stream. */
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while ( ShowBits( &p_dec->bit_stream, 11 ) != 0x07ff &&
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(!p_dec->p_fifo->b_die) &&
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(!p_dec->p_fifo->b_error) )
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{
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RemoveBits( &p_dec->bit_stream, 8 );
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}
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if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error )
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break;
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NextPTS( &p_dec->bit_stream, &pts, NULL );
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GetChunk( &p_dec->bit_stream,p_sync, MAD_BUFFER_GUARD );
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}
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}
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}
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if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error ) break;
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/* Set the Presentation Time Stamp */
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if ( pts != 0 && pts != aout_DateGet( &end_date ) )
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{
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aout_DateSet( &end_date, pts );
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}
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/* Get frame header */
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i_header = (p_sync[0] << 24) | (p_sync[1] << 16) | (p_sync[2] << 8)
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| p_sync[3];
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/* Check if frame is valid and get frame info */
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i_current_frame_size = SyncInfo( i_header,
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&i_original_channels, &i_rate,
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&i_bit_rate, &i_frame_length,
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&i_frame_size, &i_new_layer );
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if ( !i_current_frame_size )
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i_current_frame_size = i_free_frame_size;
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if ( i_current_frame_size == -1 )
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{
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msg_Warn( p_dec->p_fifo, "syncinfo failed" );
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/* This is probably an emulated startcode, drop the first byte
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* to force looking for the next startcode. */
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memmove( p_sync, &p_sync[1], MAD_BUFFER_GUARD - 1 );
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p_sync[MAD_BUFFER_GUARD - 1] = GetBits( &p_dec->bit_stream, 8 );
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continue;
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}
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if ( (unsigned int)i_current_frame_size > i_frame_size )
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{
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msg_Warn( p_dec->p_fifo, "frame too big %d > %d",
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i_current_frame_size, i_frame_size );
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memmove( p_sync, &p_sync[1], MAD_BUFFER_GUARD - 1 );
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p_sync[MAD_BUFFER_GUARD - 1] = GetBits( &p_dec->bit_stream, 8 );
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continue;
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}
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if( (p_dec->p_aout_input != NULL) &&
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( (p_dec->output_format.i_rate != i_rate)
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|| (p_dec->output_format.i_original_channels
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!= i_original_channels)
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|| (p_dec->output_format.i_bytes_per_frame
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!= i_frame_size + MAD_BUFFER_GUARD)
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|| (p_dec->output_format.i_frame_length != i_frame_length)
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|| (i_layer != i_new_layer) ) )
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{
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/* Parameters changed - this should not happen. */
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aout_DecDelete( p_dec->p_aout, p_dec->p_aout_input );
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p_dec->p_aout_input = NULL;
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}
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/* Creating the audio input if not created yet. */
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if( p_dec->p_aout_input == NULL )
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{
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i_layer = i_new_layer;
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if ( i_layer == 3 )
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{
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p_dec->output_format.i_format = VLC_FOURCC('m','p','g','3');
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}
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else
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{
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p_dec->output_format.i_format = VLC_FOURCC('m','p','g','a');
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}
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p_dec->output_format.i_rate = i_rate;
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p_dec->output_format.i_original_channels = i_original_channels;
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p_dec->output_format.i_physical_channels
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= i_original_channels & AOUT_CHAN_PHYSMASK;
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p_dec->output_format.i_bytes_per_frame = i_frame_size
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+ MAD_BUFFER_GUARD;
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p_dec->output_format.i_frame_length = i_frame_length;
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aout_DateInit( &end_date, i_rate );
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p_dec->p_aout_input = aout_DecNew( p_dec->p_fifo,
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&p_dec->p_aout,
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&p_dec->output_format );
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if ( p_dec->p_aout_input == NULL )
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{
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p_dec->p_fifo->b_error = 1;
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break;
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}
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}
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if ( !aout_DateGet( &end_date ) )
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{
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byte_t p_junk[MAX_FRAME_SIZE];
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int i_skip = i_current_frame_size - MAD_BUFFER_GUARD;
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/* We've just started the stream, wait for the first PTS. */
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while( i_skip > 0 )
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{
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int i_read;
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i_read = __MIN( i_current_frame_size - MAD_BUFFER_GUARD, MAX_FRAME_SIZE );
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GetChunk( &p_dec->bit_stream, p_junk, i_read );
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i_skip -= i_read;
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}
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NextPTS( &p_dec->bit_stream, &pts, NULL );
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GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
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continue;
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}
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p_buffer = aout_DecNewBuffer( p_dec->p_aout, p_dec->p_aout_input,
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i_frame_length );
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if ( p_buffer == NULL )
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{
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p_dec->p_fifo->b_error = 1;
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break;
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}
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p_buffer->start_date = aout_DateGet( &end_date );
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p_buffer->end_date = aout_DateIncrement( &end_date,
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i_frame_length );
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/* Get the whole frame. */
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memcpy( p_buffer->p_buffer, p_sync, MAD_BUFFER_GUARD );
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if ( i_current_frame_size )
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{
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GetChunk( &p_dec->bit_stream, p_buffer->p_buffer + MAD_BUFFER_GUARD,
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i_current_frame_size - MAD_BUFFER_GUARD );
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}
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else
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{
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/* Free bit-rate stream. Peek at next frame header. */
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i = MAD_BUFFER_GUARD;
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for ( ; ; )
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{
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int i_next_real_frame_size;
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unsigned int i_next_channels, i_next_rate, i_next_bit_rate;
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unsigned int i_next_frame_length, i_next_frame_size;
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unsigned int i_next_layer;
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while ( ShowBits( &p_dec->bit_stream, 11 ) != 0x07ff &&
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(!p_dec->p_fifo->b_die) &&
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(!p_dec->p_fifo->b_error) &&
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i < (int)i_frame_size + MAD_BUFFER_GUARD )
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{
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((uint8_t *)p_buffer->p_buffer)[i++] =
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GetBits( &p_dec->bit_stream, 8 );
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}
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if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error
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|| i == (int)i_frame_size + MAD_BUFFER_GUARD )
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break;
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i_header = ShowBits( &p_dec->bit_stream, 8 );
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i_next_real_frame_size = SyncInfo( i_header,
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&i_next_channels, &i_next_rate,
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&i_next_bit_rate, &i_next_frame_length,
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&i_next_frame_size, &i_next_layer );
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if ( i_next_real_frame_size != 0 ||
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i_next_channels != i_original_channels ||
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i_next_rate != i_rate ||
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i_next_bit_rate != i_bit_rate ||
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i_next_frame_length != i_frame_length ||
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i_next_frame_size != i_frame_size ||
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i_next_layer != i_new_layer )
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{
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/* This is an emulated start code, try again. */
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continue;
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}
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i_free_frame_size = i;
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break;
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}
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if ( p_dec->p_fifo->b_die || p_dec->p_fifo->b_error )
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break;
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if ( i == (int)i_frame_size + MAD_BUFFER_GUARD )
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{
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/* Couldn't find the next start-code. This is sooo
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* embarassing. */
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aout_DecDeleteBuffer( p_dec->p_aout, p_dec->p_aout_input,
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p_buffer );
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NextPTS( &p_dec->bit_stream, &pts, NULL );
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GetChunk( &p_dec->bit_stream, p_sync, MAD_BUFFER_GUARD );
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continue;
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}
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}
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if( p_dec->p_fifo->b_die )
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{
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aout_DecDeleteBuffer( p_dec->p_aout, p_dec->p_aout_input,
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p_buffer );
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break;
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}
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/* Get beginning of next frame. */
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NextPTS( &p_dec->bit_stream, &pts, NULL );
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GetChunk( &p_dec->bit_stream, p_buffer->p_buffer + i_current_frame_size,
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MAD_BUFFER_GUARD );
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memcpy( p_sync, p_buffer->p_buffer + i_current_frame_size,
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MAD_BUFFER_GUARD );
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p_buffer->i_nb_bytes = i_current_frame_size + MAD_BUFFER_GUARD;
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/* Send the buffer to the aout core. */
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aout_DecPlay( p_dec->p_aout, p_dec->p_aout_input, p_buffer );
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}
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if( p_dec->p_fifo->b_error )
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{
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DecoderError( p_dec->p_fifo );
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}
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EndThread( p_dec );
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return 0;
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}
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/*****************************************************************************
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* EndThread : thread destruction
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*****************************************************************************/
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static void EndThread( dec_thread_t * p_dec )
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{
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if ( p_dec->p_aout_input != NULL )
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{
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aout_DecDelete( p_dec->p_aout, p_dec->p_aout_input );
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}
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CloseBitstream( &p_dec->bit_stream );
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free( p_dec );
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}
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|
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/*****************************************************************************
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* SyncInfo: parse MPEG audio sync info
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*****************************************************************************/
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static int SyncInfo( uint32_t i_header, unsigned int * pi_channels,
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unsigned int * pi_sample_rate, unsigned int * pi_bit_rate,
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unsigned int * pi_frame_length,
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unsigned int * pi_frame_size, unsigned int * pi_layer )
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{
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static const int pppi_mpegaudio_bitrate[2][3][16] =
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{
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{
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/* v1 l1 */
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{ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384,
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416, 448, 0},
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/* v1 l2 */
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256,
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320, 384, 0},
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/* v1 l3 */
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{ 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224,
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256, 320, 0}
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},
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{
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/* v2 l1 */
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192,
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224, 256, 0},
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/* v2 l2 */
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128,
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144, 160, 0},
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/* v2 l3 */
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128,
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144, 160, 0}
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}
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};
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static const int ppi_mpegaudio_samplerate[2][4] = /* version 1 then 2 */
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{
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{ 44100, 48000, 32000, 0 },
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{ 22050, 24000, 16000, 0 }
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};
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int i_version, i_mode, i_emphasis;
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vlc_bool_t b_padding, b_mpeg_2_5;
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int i_current_frame_size = 0;
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int i_bitrate_index, i_samplerate_index;
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int i_max_bit_rate;
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|
|
b_mpeg_2_5 = 1 - ((i_header & 0x100000) >> 20);
|
|
i_version = 1 - ((i_header & 0x80000) >> 19);
|
|
*pi_layer = 4 - ((i_header & 0x60000) >> 17);
|
|
/* CRC */
|
|
i_bitrate_index = (i_header & 0xf000) >> 12;
|
|
i_samplerate_index = (i_header & 0xc00) >> 10;
|
|
b_padding = (i_header & 0x200) >> 9;
|
|
/* Extension */
|
|
i_mode = (i_header & 0xc0) >> 6;
|
|
/* Modeext, copyright & original */
|
|
i_emphasis = i_header & 0x3;
|
|
|
|
if( *pi_layer != 4 &&
|
|
i_bitrate_index < 0x0f &&
|
|
i_samplerate_index != 0x03 &&
|
|
i_emphasis != 0x02 )
|
|
{
|
|
switch ( i_mode )
|
|
{
|
|
case 0: /* stereo */
|
|
case 1: /* joint stereo */
|
|
*pi_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
|
|
break;
|
|
case 2: /* dual-mono */
|
|
*pi_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
|
|
| AOUT_CHAN_DUALMONO;
|
|
break;
|
|
case 3: /* mono */
|
|
*pi_channels = AOUT_CHAN_CENTER;
|
|
break;
|
|
}
|
|
*pi_bit_rate = pppi_mpegaudio_bitrate[i_version][*pi_layer-1][i_bitrate_index];
|
|
i_max_bit_rate = pppi_mpegaudio_bitrate[i_version][*pi_layer-1][14];
|
|
*pi_sample_rate = ppi_mpegaudio_samplerate[i_version][i_samplerate_index];
|
|
|
|
if ( b_mpeg_2_5 )
|
|
{
|
|
*pi_sample_rate >>= 1;
|
|
}
|
|
|
|
switch( *pi_layer )
|
|
{
|
|
case 1:
|
|
i_current_frame_size = ( ( i_version ? 6000 : 12000 ) *
|
|
*pi_bit_rate / *pi_sample_rate
|
|
+ b_padding ) * 4;
|
|
*pi_frame_size = ( ( i_version ? 6000 : 12000 ) *
|
|
i_max_bit_rate / *pi_sample_rate + 1 ) * 4;
|
|
*pi_frame_length = 384;
|
|
break;
|
|
|
|
case 2:
|
|
i_current_frame_size = ( i_version ? 72000 : 144000 ) *
|
|
*pi_bit_rate / *pi_sample_rate
|
|
+ b_padding;
|
|
*pi_frame_size = ( i_version ? 72000 : 144000 ) *
|
|
i_max_bit_rate / *pi_sample_rate + 1;
|
|
*pi_frame_length = 1152;
|
|
break;
|
|
|
|
case 3:
|
|
i_current_frame_size = ( i_version ? 72000 : 144000 ) *
|
|
*pi_bit_rate / *pi_sample_rate
|
|
+ b_padding;
|
|
*pi_frame_size = ( i_version ? 72000 : 144000 ) *
|
|
i_max_bit_rate / *pi_sample_rate + 1;
|
|
*pi_frame_length = i_version ? 576 : 1152;
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
return -1;
|
|
}
|
|
|
|
return i_current_frame_size;
|
|
}
|
|
|
|
|