1 /*****************************************************************************
2 * lpcm.c: lpcm decoder/packetizer module
3 *****************************************************************************
4 * Copyright (C) 1999-2003 VideoLAN
5 * $Id: lpcm.c,v 1.21 2004/01/25 18:20:12 bigben Exp $
7 * Authors: Samuel Hocevar <sam@zoy.org>
8 * Henri Fallon <henri@videolan.org>
9 * Christophe Massiot <massiot@via.ecp.fr>
10 * Gildas Bazin <gbazin@netcourrier.com>
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
25 *****************************************************************************/
27 /*****************************************************************************
29 *****************************************************************************/
31 #include <vlc/decoder.h>
33 /*****************************************************************************
34 * decoder_sys_t : lpcm decoder descriptor
35 *****************************************************************************/
39 vlc_bool_t b_packetizer;
44 audio_date_t end_date;
51 * - private stream ID (16 bits) == 0xA0 -> not in the bitstream
53 * - frame number (8 bits)
54 * - unknown (16 bits) == 0x0003 ?
56 * - current frame (4 bits)
58 * - frequency (2 bits) 0 == 48 kHz, 1 == 32 kHz, 2 == ?, 3 == ?
60 * - number of channels - 1 (3 bits) 1 == 2 channels
61 * - start code (8 bits) == 0x80
64 #define LPCM_HEADER_LEN 6
66 /*****************************************************************************
68 *****************************************************************************/
69 static int OpenDecoder ( vlc_object_t * );
70 static int OpenPacketizer( vlc_object_t * );
71 static void CloseDecoder ( vlc_object_t * );
73 static void *DecodeFrame ( decoder_t *, block_t ** );
75 /*****************************************************************************
77 *****************************************************************************/
80 set_description( _("Linear PCM audio decoder") );
81 set_capability( "decoder", 100 );
82 set_callbacks( OpenDecoder, CloseDecoder );
85 set_description( _("Linear PCM audio packetizer") );
86 set_capability( "packetizer", 100 );
87 set_callbacks( OpenPacketizer, CloseDecoder );
91 /*****************************************************************************
92 * OpenDecoder: probe the decoder and return score
93 *****************************************************************************/
94 static int OpenDecoder( vlc_object_t *p_this )
96 decoder_t *p_dec = (decoder_t*)p_this;
99 if( p_dec->fmt_in.i_codec != VLC_FOURCC('l','p','c','m')
100 && p_dec->fmt_in.i_codec != VLC_FOURCC('l','p','c','b') )
105 /* Allocate the memory needed to store the decoder's structure */
106 if( ( p_dec->p_sys = p_sys =
107 (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
109 msg_Err( p_dec, "out of memory" );
114 p_sys->b_packetizer = VLC_FALSE;
115 aout_DateSet( &p_sys->end_date, 0 );
117 /* Set output properties */
118 p_dec->fmt_out.i_cat = AUDIO_ES;
119 p_dec->fmt_out.i_codec = VLC_FOURCC('s','1','6','b');
122 p_dec->pf_decode_audio = (aout_buffer_t *(*)(decoder_t *, block_t **))
124 p_dec->pf_packetize = (block_t *(*)(decoder_t *, block_t **))
130 static int OpenPacketizer( vlc_object_t *p_this )
132 decoder_t *p_dec = (decoder_t*)p_this;
134 int i_ret = OpenDecoder( p_this );
136 if( i_ret != VLC_SUCCESS ) return i_ret;
138 p_dec->p_sys->b_packetizer = VLC_TRUE;
140 p_dec->fmt_out.i_codec = VLC_FOURCC('l','p','c','m');
145 /*****************************************************************************
146 * DecodeFrame: decodes an lpcm frame.
147 ****************************************************************************
148 * Beware, this function must be fed with complete frames (PES packet).
149 *****************************************************************************/
150 static void *DecodeFrame( decoder_t *p_dec, block_t **pp_block )
152 decoder_sys_t *p_sys = p_dec->p_sys;
154 unsigned int i_rate = 0, i_original_channels = 0, i_channels = 0;
158 if( !pp_block || !*pp_block ) return NULL;
161 *pp_block = NULL; /* So the packet doesn't get re-sent */
163 /* Date management */
164 if( p_block->i_pts > 0 &&
165 p_block->i_pts != aout_DateGet( &p_sys->end_date ) )
167 aout_DateSet( &p_sys->end_date, p_block->i_pts );
170 if( !aout_DateGet( &p_sys->end_date ) )
172 /* We've just started the stream, wait for the first PTS. */
173 block_Release( p_block );
177 if( p_block->i_buffer <= LPCM_HEADER_LEN )
179 msg_Err(p_dec, "frame is too short");
180 block_Release( p_block );
184 i_header = p_block->p_buffer[4];
185 switch ( (i_header >> 4) & 0x3 )
201 i_channels = (i_header & 0x7);
202 switch ( i_channels )
205 i_original_channels = AOUT_CHAN_CENTER;
208 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
211 /* This is unsure. */
212 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT | AOUT_CHAN_LFE;
215 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
216 | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT;
219 /* This is unsure. */
220 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
221 | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT
225 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
226 | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT
227 | AOUT_CHAN_CENTER | AOUT_CHAN_LFE;
230 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
231 | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT
232 | AOUT_CHAN_CENTER | AOUT_CHAN_MIDDLELEFT
233 | AOUT_CHAN_MIDDLERIGHT;
236 i_original_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT
237 | AOUT_CHAN_REARLEFT | AOUT_CHAN_REARRIGHT
238 | AOUT_CHAN_CENTER | AOUT_CHAN_MIDDLELEFT
239 | AOUT_CHAN_MIDDLERIGHT | AOUT_CHAN_LFE;
243 /* Check frame sync and drop it. */
244 if( p_block->p_buffer[5] != 0x80 )
246 msg_Warn( p_dec, "no frame sync" );
247 block_Release( p_block );
251 /* Set output properties */
252 if( p_dec->fmt_out.audio.i_rate != i_rate )
254 aout_DateInit( &p_sys->end_date, i_rate );
255 aout_DateSet( &p_sys->end_date, p_block->i_pts );
257 p_dec->fmt_out.audio.i_rate = i_rate;
258 p_dec->fmt_out.audio.i_channels = i_channels + 1;
259 p_dec->fmt_out.audio.i_original_channels = i_original_channels;
260 p_dec->fmt_out.audio.i_physical_channels
261 = i_original_channels & AOUT_CHAN_PHYSMASK;
263 i_frame_length = (p_block->i_buffer - LPCM_HEADER_LEN) /
264 ( p_dec->fmt_out.audio.i_channels * 2 );
266 if( p_sys->b_packetizer )
268 p_block->i_pts = p_block->i_dts = aout_DateGet( &p_sys->end_date );
270 aout_DateIncrement( &p_sys->end_date, i_frame_length ) -
273 /* Just pass on the incoming frame */
278 aout_buffer_t *p_aout_buffer;
279 p_aout_buffer = p_dec->pf_aout_buffer_new( p_dec, i_frame_length );
280 if( p_aout_buffer == NULL ) return NULL;
282 p_aout_buffer->start_date = aout_DateGet( &p_sys->end_date );
283 p_aout_buffer->end_date =
284 aout_DateIncrement( &p_sys->end_date, i_frame_length );
286 memcpy( p_aout_buffer->p_buffer,
287 p_block->p_buffer + LPCM_HEADER_LEN,
288 p_block->i_buffer - LPCM_HEADER_LEN );
290 block_Release( p_block );
291 return p_aout_buffer;
295 /*****************************************************************************
296 * CloseDecoder : lpcm decoder destruction
297 *****************************************************************************/
298 static void CloseDecoder( vlc_object_t *p_this )
300 decoder_t *p_dec = (decoder_t*)p_this;
301 free( p_dec->p_sys );