Chris@0: /*
Chris@0:  * libmad - MPEG audio decoder library
Chris@0:  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
Chris@0:  *
Chris@0:  * This program is free software; you can redistribute it and/or modify
Chris@0:  * it under the terms of the GNU General Public License as published by
Chris@0:  * the Free Software Foundation; either version 2 of the License, or
Chris@0:  * (at your option) any later version.
Chris@0:  *
Chris@0:  * This program is distributed in the hope that it will be useful,
Chris@0:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@0:  * GNU General Public License for more details.
Chris@0:  *
Chris@0:  * You should have received a copy of the GNU General Public License
Chris@0:  * along with this program; if not, write to the Free Software
Chris@0:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
Chris@0:  *
Chris@0:  * $Id: frame.c,v 1.29 2004/02/04 22:59:19 rob Exp $
Chris@0:  */
Chris@0: 
Chris@0: # ifdef HAVE_CONFIG_H
Chris@0: #  include "config.h"
Chris@0: # endif
Chris@0: 
Chris@0: # include "global.h"
Chris@0: 
Chris@0: # include <stdlib.h>
Chris@0: 
Chris@0: # include "bit.h"
Chris@0: # include "stream.h"
Chris@0: # include "frame.h"
Chris@0: # include "timer.h"
Chris@0: # include "layer12.h"
Chris@0: # include "layer3.h"
Chris@0: 
Chris@0: static
Chris@0: unsigned long const bitrate_table[5][15] = {
Chris@0:   /* MPEG-1 */
Chris@0:   { 0,  32000,  64000,  96000, 128000, 160000, 192000, 224000,  /* Layer I   */
Chris@0:        256000, 288000, 320000, 352000, 384000, 416000, 448000 },
Chris@0:   { 0,  32000,  48000,  56000,  64000,  80000,  96000, 112000,  /* Layer II  */
Chris@0:        128000, 160000, 192000, 224000, 256000, 320000, 384000 },
Chris@0:   { 0,  32000,  40000,  48000,  56000,  64000,  80000,  96000,  /* Layer III */
Chris@0:        112000, 128000, 160000, 192000, 224000, 256000, 320000 },
Chris@0: 
Chris@0:   /* MPEG-2 LSF */
Chris@0:   { 0,  32000,  48000,  56000,  64000,  80000,  96000, 112000,  /* Layer I   */
Chris@0:        128000, 144000, 160000, 176000, 192000, 224000, 256000 },
Chris@0:   { 0,   8000,  16000,  24000,  32000,  40000,  48000,  56000,  /* Layers    */
Chris@0:         64000,  80000,  96000, 112000, 128000, 144000, 160000 } /* II & III  */
Chris@0: };
Chris@0: 
Chris@0: static
Chris@0: unsigned int const samplerate_table[3] = { 44100, 48000, 32000 };
Chris@0: 
Chris@0: static
Chris@0: int (*const decoder_table[3])(struct mad_stream *, struct mad_frame *) = {
Chris@0:   mad_layer_I,
Chris@0:   mad_layer_II,
Chris@0:   mad_layer_III
Chris@0: };
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	header->init()
Chris@0:  * DESCRIPTION:	initialize header struct
Chris@0:  */
Chris@0: void mad_header_init(struct mad_header *header)
Chris@0: {
Chris@0:   header->layer          = 0;
Chris@0:   header->mode           = 0;
Chris@0:   header->mode_extension = 0;
Chris@0:   header->emphasis       = 0;
Chris@0: 
Chris@0:   header->bitrate        = 0;
Chris@0:   header->samplerate     = 0;
Chris@0: 
Chris@0:   header->crc_check      = 0;
Chris@0:   header->crc_target     = 0;
Chris@0: 
Chris@0:   header->flags          = 0;
Chris@0:   header->private_bits   = 0;
Chris@0: 
Chris@0:   header->duration       = mad_timer_zero;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	frame->init()
Chris@0:  * DESCRIPTION:	initialize frame struct
Chris@0:  */
Chris@0: void mad_frame_init(struct mad_frame *frame)
Chris@0: {
Chris@0:   mad_header_init(&frame->header);
Chris@0: 
Chris@0:   frame->options = 0;
Chris@0: 
Chris@0:   frame->overlap = 0;
Chris@0:   mad_frame_mute(frame);
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	frame->finish()
Chris@0:  * DESCRIPTION:	deallocate any dynamic memory associated with frame
Chris@0:  */
Chris@0: void mad_frame_finish(struct mad_frame *frame)
Chris@0: {
Chris@0:   mad_header_finish(&frame->header);
Chris@0: 
Chris@0:   if (frame->overlap) {
Chris@0:     free(frame->overlap);
Chris@0:     frame->overlap = 0;
Chris@0:   }
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	decode_header()
Chris@0:  * DESCRIPTION:	read header data and following CRC word
Chris@0:  */
Chris@0: static
Chris@0: int decode_header(struct mad_header *header, struct mad_stream *stream)
Chris@0: {
Chris@0:   unsigned int index;
Chris@0: 
Chris@0:   header->flags        = 0;
Chris@0:   header->private_bits = 0;
Chris@0: 
Chris@0:   /* header() */
Chris@0: 
Chris@0:   /* syncword */
Chris@0:   mad_bit_skip(&stream->ptr, 11);
Chris@0: 
Chris@0:   /* MPEG 2.5 indicator (really part of syncword) */
Chris@0:   if (mad_bit_read(&stream->ptr, 1) == 0)
Chris@0:     header->flags |= MAD_FLAG_MPEG_2_5_EXT;
Chris@0: 
Chris@0:   /* ID */
Chris@0:   if (mad_bit_read(&stream->ptr, 1) == 0)
Chris@0:     header->flags |= MAD_FLAG_LSF_EXT;
Chris@0:   else if (header->flags & MAD_FLAG_MPEG_2_5_EXT) {
Chris@0:     stream->error = MAD_ERROR_LOSTSYNC;
Chris@0:     return -1;
Chris@0:   }
Chris@0: 
Chris@0:   /* layer */
Chris@0:   header->layer = 4 - mad_bit_read(&stream->ptr, 2);
Chris@0: 
Chris@0:   if (header->layer == 4) {
Chris@0:     stream->error = MAD_ERROR_BADLAYER;
Chris@0:     return -1;
Chris@0:   }
Chris@0: 
Chris@0:   /* protection_bit */
Chris@0:   if (mad_bit_read(&stream->ptr, 1) == 0) {
Chris@0:     header->flags    |= MAD_FLAG_PROTECTION;
Chris@0:     header->crc_check = mad_bit_crc(stream->ptr, 16, 0xffff);
Chris@0:   }
Chris@0: 
Chris@0:   /* bitrate_index */
Chris@0:   index = mad_bit_read(&stream->ptr, 4);
Chris@0: 
Chris@0:   if (index == 15) {
Chris@0:     stream->error = MAD_ERROR_BADBITRATE;
Chris@0:     return -1;
Chris@0:   }
Chris@0: 
Chris@0:   if (header->flags & MAD_FLAG_LSF_EXT)
Chris@0:     header->bitrate = bitrate_table[3 + (header->layer >> 1)][index];
Chris@0:   else
Chris@0:     header->bitrate = bitrate_table[header->layer - 1][index];
Chris@0: 
Chris@0:   /* sampling_frequency */
Chris@0:   index = mad_bit_read(&stream->ptr, 2);
Chris@0: 
Chris@0:   if (index == 3) {
Chris@0:     stream->error = MAD_ERROR_BADSAMPLERATE;
Chris@0:     return -1;
Chris@0:   }
Chris@0: 
Chris@0:   header->samplerate = samplerate_table[index];
Chris@0: 
Chris@0:   if (header->flags & MAD_FLAG_LSF_EXT) {
Chris@0:     header->samplerate /= 2;
Chris@0: 
Chris@0:     if (header->flags & MAD_FLAG_MPEG_2_5_EXT)
Chris@0:       header->samplerate /= 2;
Chris@0:   }
Chris@0: 
Chris@0:   /* padding_bit */
Chris@0:   if (mad_bit_read(&stream->ptr, 1))
Chris@0:     header->flags |= MAD_FLAG_PADDING;
Chris@0: 
Chris@0:   /* private_bit */
Chris@0:   if (mad_bit_read(&stream->ptr, 1))
Chris@0:     header->private_bits |= MAD_PRIVATE_HEADER;
Chris@0: 
Chris@0:   /* mode */
Chris@0:   header->mode = 3 - mad_bit_read(&stream->ptr, 2);
Chris@0: 
Chris@0:   /* mode_extension */
Chris@0:   header->mode_extension = mad_bit_read(&stream->ptr, 2);
Chris@0: 
Chris@0:   /* copyright */
Chris@0:   if (mad_bit_read(&stream->ptr, 1))
Chris@0:     header->flags |= MAD_FLAG_COPYRIGHT;
Chris@0: 
Chris@0:   /* original/copy */
Chris@0:   if (mad_bit_read(&stream->ptr, 1))
Chris@0:     header->flags |= MAD_FLAG_ORIGINAL;
Chris@0: 
Chris@0:   /* emphasis */
Chris@0:   header->emphasis = mad_bit_read(&stream->ptr, 2);
Chris@0: 
Chris@0: # if defined(OPT_STRICT)
Chris@0:   /*
Chris@0:    * ISO/IEC 11172-3 says this is a reserved emphasis value, but
Chris@0:    * streams exist which use it anyway. Since the value is not important
Chris@0:    * to the decoder proper, we allow it unless OPT_STRICT is defined.
Chris@0:    */
Chris@0:   if (header->emphasis == MAD_EMPHASIS_RESERVED) {
Chris@0:     stream->error = MAD_ERROR_BADEMPHASIS;
Chris@0:     return -1;
Chris@0:   }
Chris@0: # endif
Chris@0: 
Chris@0:   /* error_check() */
Chris@0: 
Chris@0:   /* crc_check */
Chris@0:   if (header->flags & MAD_FLAG_PROTECTION)
Chris@0:     header->crc_target = mad_bit_read(&stream->ptr, 16);
Chris@0: 
Chris@0:   return 0;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	free_bitrate()
Chris@0:  * DESCRIPTION:	attempt to discover the bitstream's free bitrate
Chris@0:  */
Chris@0: static
Chris@0: int free_bitrate(struct mad_stream *stream, struct mad_header const *header)
Chris@0: {
Chris@0:   struct mad_bitptr keep_ptr;
Chris@0:   unsigned long rate = 0;
Chris@0:   unsigned int pad_slot, slots_per_frame;
Chris@0:   unsigned char const *ptr = 0;
Chris@0: 
Chris@0:   keep_ptr = stream->ptr;
Chris@0: 
Chris@0:   pad_slot = (header->flags & MAD_FLAG_PADDING) ? 1 : 0;
Chris@0:   slots_per_frame = (header->layer == MAD_LAYER_III &&
Chris@0: 		     (header->flags & MAD_FLAG_LSF_EXT)) ? 72 : 144;
Chris@0: 
Chris@0:   while (mad_stream_sync(stream) == 0) {
Chris@0:     struct mad_stream peek_stream;
Chris@0:     struct mad_header peek_header;
Chris@0: 
Chris@0:     peek_stream = *stream;
Chris@0:     peek_header = *header;
Chris@0: 
Chris@0:     if (decode_header(&peek_header, &peek_stream) == 0 &&
Chris@0: 	peek_header.layer == header->layer &&
Chris@0: 	peek_header.samplerate == header->samplerate) {
Chris@0:       unsigned int N;
Chris@0: 
Chris@0:       ptr = mad_bit_nextbyte(&stream->ptr);
Chris@0: 
Chris@0:       N = ptr - stream->this_frame;
Chris@0: 
Chris@0:       if (header->layer == MAD_LAYER_I) {
Chris@0: 	rate = (unsigned long) header->samplerate *
Chris@0: 	  (N - 4 * pad_slot + 4) / 48 / 1000;
Chris@0:       }
Chris@0:       else {
Chris@0: 	rate = (unsigned long) header->samplerate *
Chris@0: 	  (N - pad_slot + 1) / slots_per_frame / 1000;
Chris@0:       }
Chris@0: 
Chris@0:       if (rate >= 8)
Chris@0: 	break;
Chris@0:     }
Chris@0: 
Chris@0:     mad_bit_skip(&stream->ptr, 8);
Chris@0:   }
Chris@0: 
Chris@0:   stream->ptr = keep_ptr;
Chris@0: 
Chris@0:   if (rate < 8 || (header->layer == MAD_LAYER_III && rate > 640)) {
Chris@0:     stream->error = MAD_ERROR_LOSTSYNC;
Chris@0:     return -1;
Chris@0:   }
Chris@0: 
Chris@0:   stream->freerate = rate * 1000;
Chris@0: 
Chris@0:   return 0;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	header->decode()
Chris@0:  * DESCRIPTION:	read the next frame header from the stream
Chris@0:  */
Chris@0: int mad_header_decode(struct mad_header *header, struct mad_stream *stream)
Chris@0: {
Chris@0:   register unsigned char const *ptr, *end;
Chris@0:   unsigned int pad_slot, N;
Chris@0: 
Chris@0:   ptr = stream->next_frame;
Chris@0:   end = stream->bufend;
Chris@0: 
Chris@0:   if (ptr == 0) {
Chris@0:     stream->error = MAD_ERROR_BUFPTR;
Chris@0:     goto fail;
Chris@0:   }
Chris@0: 
Chris@0:   /* stream skip */
Chris@0:   if (stream->skiplen) {
Chris@0:     if (!stream->sync)
Chris@0:       ptr = stream->this_frame;
Chris@0: 
Chris@0:     if (end - ptr < stream->skiplen) {
Chris@0:       stream->skiplen   -= end - ptr;
Chris@0:       stream->next_frame = end;
Chris@0: 
Chris@0:       stream->error = MAD_ERROR_BUFLEN;
Chris@0:       goto fail;
Chris@0:     }
Chris@0: 
Chris@0:     ptr += stream->skiplen;
Chris@0:     stream->skiplen = 0;
Chris@0: 
Chris@0:     stream->sync = 1;
Chris@0:   }
Chris@0: 
Chris@0:  sync:
Chris@0:   /* synchronize */
Chris@0:   if (stream->sync) {
Chris@0:     if (end - ptr < MAD_BUFFER_GUARD) {
Chris@0:       stream->next_frame = ptr;
Chris@0: 
Chris@0:       stream->error = MAD_ERROR_BUFLEN;
Chris@0:       goto fail;
Chris@0:     }
Chris@0:     else if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) {
Chris@0:       /* mark point where frame sync word was expected */
Chris@0:       stream->this_frame = ptr;
Chris@0:       stream->next_frame = ptr + 1;
Chris@0: 
Chris@0:       stream->error = MAD_ERROR_LOSTSYNC;
Chris@0:       goto fail;
Chris@0:     }
Chris@0:   }
Chris@0:   else {
Chris@0:     mad_bit_init(&stream->ptr, ptr);
Chris@0: 
Chris@0:     if (mad_stream_sync(stream) == -1) {
Chris@0:       if (end - stream->next_frame >= MAD_BUFFER_GUARD)
Chris@0: 	stream->next_frame = end - MAD_BUFFER_GUARD;
Chris@0: 
Chris@0:       stream->error = MAD_ERROR_BUFLEN;
Chris@0:       goto fail;
Chris@0:     }
Chris@0: 
Chris@0:     ptr = mad_bit_nextbyte(&stream->ptr);
Chris@0:   }
Chris@0: 
Chris@0:   /* begin processing */
Chris@0:   stream->this_frame = ptr;
Chris@0:   stream->next_frame = ptr + 1;  /* possibly bogus sync word */
Chris@0: 
Chris@0:   mad_bit_init(&stream->ptr, stream->this_frame);
Chris@0: 
Chris@0:   if (decode_header(header, stream) == -1)
Chris@0:     goto fail;
Chris@0: 
Chris@0:   /* calculate frame duration */
Chris@0:   mad_timer_set(&header->duration, 0,
Chris@0: 		32 * MAD_NSBSAMPLES(header), header->samplerate);
Chris@0: 
Chris@0:   /* calculate free bit rate */
Chris@0:   if (header->bitrate == 0) {
Chris@0:     if ((stream->freerate == 0 || !stream->sync ||
Chris@0: 	 (header->layer == MAD_LAYER_III && stream->freerate > 640000)) &&
Chris@0: 	free_bitrate(stream, header) == -1)
Chris@0:       goto fail;
Chris@0: 
Chris@0:     header->bitrate = stream->freerate;
Chris@0:     header->flags  |= MAD_FLAG_FREEFORMAT;
Chris@0:   }
Chris@0: 
Chris@0:   /* calculate beginning of next frame */
Chris@0:   pad_slot = (header->flags & MAD_FLAG_PADDING) ? 1 : 0;
Chris@0: 
Chris@0:   if (header->layer == MAD_LAYER_I)
Chris@0:     N = ((12 * header->bitrate / header->samplerate) + pad_slot) * 4;
Chris@0:   else {
Chris@0:     unsigned int slots_per_frame;
Chris@0: 
Chris@0:     slots_per_frame = (header->layer == MAD_LAYER_III &&
Chris@0: 		       (header->flags & MAD_FLAG_LSF_EXT)) ? 72 : 144;
Chris@0: 
Chris@0:     N = (slots_per_frame * header->bitrate / header->samplerate) + pad_slot;
Chris@0:   }
Chris@0: 
Chris@0:   /* verify there is enough data left in buffer to decode this frame */
Chris@0:   if (N + MAD_BUFFER_GUARD > end - stream->this_frame) {
Chris@0:     stream->next_frame = stream->this_frame;
Chris@0: 
Chris@0:     stream->error = MAD_ERROR_BUFLEN;
Chris@0:     goto fail;
Chris@0:   }
Chris@0: 
Chris@0:   stream->next_frame = stream->this_frame + N;
Chris@0: 
Chris@0:   if (!stream->sync) {
Chris@0:     /* check that a valid frame header follows this frame */
Chris@0: 
Chris@0:     ptr = stream->next_frame;
Chris@0:     if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) {
Chris@0:       ptr = stream->next_frame = stream->this_frame + 1;
Chris@0:       goto sync;
Chris@0:     }
Chris@0: 
Chris@0:     stream->sync = 1;
Chris@0:   }
Chris@0: 
Chris@0:   header->flags |= MAD_FLAG_INCOMPLETE;
Chris@0: 
Chris@0:   return 0;
Chris@0: 
Chris@0:  fail:
Chris@0:   stream->sync = 0;
Chris@0: 
Chris@0:   return -1;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	frame->decode()
Chris@0:  * DESCRIPTION:	decode a single frame from a bitstream
Chris@0:  */
Chris@0: int mad_frame_decode(struct mad_frame *frame, struct mad_stream *stream)
Chris@0: {
Chris@0:   frame->options = stream->options;
Chris@0: 
Chris@0:   /* header() */
Chris@0:   /* error_check() */
Chris@0: 
Chris@0:   if (!(frame->header.flags & MAD_FLAG_INCOMPLETE) &&
Chris@0:       mad_header_decode(&frame->header, stream) == -1)
Chris@0:     goto fail;
Chris@0: 
Chris@0:   /* audio_data() */
Chris@0: 
Chris@0:   frame->header.flags &= ~MAD_FLAG_INCOMPLETE;
Chris@0: 
Chris@0:   if (decoder_table[frame->header.layer - 1](stream, frame) == -1) {
Chris@0:     if (!MAD_RECOVERABLE(stream->error))
Chris@0:       stream->next_frame = stream->this_frame;
Chris@0: 
Chris@0:     goto fail;
Chris@0:   }
Chris@0: 
Chris@0:   /* ancillary_data() */
Chris@0: 
Chris@0:   if (frame->header.layer != MAD_LAYER_III) {
Chris@0:     struct mad_bitptr next_frame;
Chris@0: 
Chris@0:     mad_bit_init(&next_frame, stream->next_frame);
Chris@0: 
Chris@0:     stream->anc_ptr    = stream->ptr;
Chris@0:     stream->anc_bitlen = mad_bit_length(&stream->ptr, &next_frame);
Chris@0: 
Chris@0:     mad_bit_finish(&next_frame);
Chris@0:   }
Chris@0: 
Chris@0:   return 0;
Chris@0: 
Chris@0:  fail:
Chris@0:   stream->anc_bitlen = 0;
Chris@0:   return -1;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	frame->mute()
Chris@0:  * DESCRIPTION:	zero all subband values so the frame becomes silent
Chris@0:  */
Chris@0: void mad_frame_mute(struct mad_frame *frame)
Chris@0: {
Chris@0:   unsigned int s, sb;
Chris@0: 
Chris@0:   for (s = 0; s < 36; ++s) {
Chris@0:     for (sb = 0; sb < 32; ++sb) {
Chris@0:       frame->sbsample[0][s][sb] =
Chris@0:       frame->sbsample[1][s][sb] = 0;
Chris@0:     }
Chris@0:   }
Chris@0: 
Chris@0:   if (frame->overlap) {
Chris@0:     for (s = 0; s < 18; ++s) {
Chris@0:       for (sb = 0; sb < 32; ++sb) {
Chris@0: 	(*frame->overlap)[0][sb][s] =
Chris@0: 	(*frame->overlap)[1][sb][s] = 0;
Chris@0:       }
Chris@0:     }
Chris@0:   }
Chris@0: }