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diff --git a/audio_codec/libmad/frame.c b/audio_codec/libmad/frame.c new file mode 100644 index 0000000..e588d5c --- a/dev/null +++ b/audio_codec/libmad/frame.c @@ -0,0 +1,525 @@ +/* + * libmad - MPEG audio decoder library + * Copyright (C) 2000-2004 Underbit Technologies, Inc. + * + * 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 02111-1307 USA + * + * $Id: frame.c,v 1.29 2004/02/04 22:59:19 rob Exp $ + */ + +# ifdef HAVE_CONFIG_H +# include "config.h" +# endif + +# include "global.h" + +# include <stdlib.h> + +# include "bit.h" +# include "stream.h" +# include "frame.h" +# include "timer.h" +# include "layer12.h" +# include "layer3.h" + +static +unsigned long const bitrate_table[5][15] = { + /* MPEG-1 */ + { + 0, 32000, 64000, 96000, 128000, 160000, 192000, 224000, /* Layer I */ + 256000, 288000, 320000, 352000, 384000, 416000, 448000 + }, + { + 0, 32000, 48000, 56000, 64000, 80000, 96000, 112000, /* Layer II */ + 128000, 160000, 192000, 224000, 256000, 320000, 384000 + }, + { + 0, 32000, 40000, 48000, 56000, 64000, 80000, 96000, /* Layer III */ + 112000, 128000, 160000, 192000, 224000, 256000, 320000 + }, + + /* MPEG-2 LSF */ + { + 0, 32000, 48000, 56000, 64000, 80000, 96000, 112000, /* Layer I */ + 128000, 144000, 160000, 176000, 192000, 224000, 256000 + }, + { + 0, 8000, 16000, 24000, 32000, 40000, 48000, 56000, /* Layers */ + 64000, 80000, 96000, 112000, 128000, 144000, 160000 + } /* II & III */ +}; + +static +unsigned int const samplerate_table[3] = { 44100, 48000, 32000 }; + +static +int (*const decoder_table[3])(struct mad_stream *, struct mad_frame *) = { + mad_layer_I, + mad_layer_II, + mad_layer_III +}; + +/* + * NAME: header->init() + * DESCRIPTION: initialize header struct + */ +void mad_header_init(struct mad_header *header) +{ + header->layer = 0; + header->mode = 0; + header->mode_extension = 0; + header->emphasis = 0; + + header->bitrate = 0; + header->samplerate = 0; + + header->crc_check = 0; + header->crc_target = 0; + + header->flags = 0; + header->private_bits = 0; + + header->duration = mad_timer_zero; +} + +/* + * NAME: frame->init() + * DESCRIPTION: initialize frame struct + */ +void mad_frame_init(struct mad_frame *frame) +{ + mad_header_init(&frame->header); + + frame->options = 0; + + frame->overlap = 0; + mad_frame_mute(frame); +} + +/* + * NAME: frame->finish() + * DESCRIPTION: deallocate any dynamic memory associated with frame + */ +void mad_frame_finish(struct mad_frame *frame) +{ + mad_header_finish(&frame->header); + + if (frame->overlap) { + free(frame->overlap); + frame->overlap = 0; + } +} + +/* + * NAME: decode_header() + * DESCRIPTION: read header data and following CRC word + */ +static +int decode_header(struct mad_header *header, struct mad_stream *stream) +{ + unsigned int index; + + header->flags = 0; + header->private_bits = 0; + + /* header() */ + + /* syncword */ + mad_bit_skip(&stream->ptr, 11); + + /* MPEG 2.5 indicator (really part of syncword) */ + if (mad_bit_read(&stream->ptr, 1) == 0) { + header->flags |= MAD_FLAG_MPEG_2_5_EXT; + } + + /* ID */ + if (mad_bit_read(&stream->ptr, 1) == 0) { + header->flags |= MAD_FLAG_LSF_EXT; + } else if (header->flags & MAD_FLAG_MPEG_2_5_EXT) { + stream->error = MAD_ERROR_LOSTSYNC; + return -1; + } + + /* layer */ + header->layer = 4 - mad_bit_read(&stream->ptr, 2); + + if (header->layer == 4) { + stream->error = MAD_ERROR_BADLAYER; + return -1; + } + + /* protection_bit */ + if (mad_bit_read(&stream->ptr, 1) == 0) { + header->flags |= MAD_FLAG_PROTECTION; + header->crc_check = mad_bit_crc(stream->ptr, 16, 0xffff); + } + + /* bitrate_index */ + index = mad_bit_read(&stream->ptr, 4); + + if (index == 15) { + stream->error = MAD_ERROR_BADBITRATE; + return -1; + } + + if (header->flags & MAD_FLAG_LSF_EXT) { + header->bitrate = bitrate_table[3 + (header->layer >> 1)][index]; + } else { + header->bitrate = bitrate_table[header->layer - 1][index]; + } + + /* sampling_frequency */ + index = mad_bit_read(&stream->ptr, 2); + + if (index == 3) { + stream->error = MAD_ERROR_BADSAMPLERATE; + return -1; + } + + header->samplerate = samplerate_table[index]; + + if (header->flags & MAD_FLAG_LSF_EXT) { + header->samplerate /= 2; + + if (header->flags & MAD_FLAG_MPEG_2_5_EXT) { + header->samplerate /= 2; + } + } + + /* padding_bit */ + if (mad_bit_read(&stream->ptr, 1)) { + header->flags |= MAD_FLAG_PADDING; + } + + /* private_bit */ + if (mad_bit_read(&stream->ptr, 1)) { + header->private_bits |= MAD_PRIVATE_HEADER; + } + + /* mode */ + header->mode = 3 - mad_bit_read(&stream->ptr, 2); + + /* mode_extension */ + header->mode_extension = mad_bit_read(&stream->ptr, 2); + + /* copyright */ + if (mad_bit_read(&stream->ptr, 1)) { + header->flags |= MAD_FLAG_COPYRIGHT; + } + + /* original/copy */ + if (mad_bit_read(&stream->ptr, 1)) { + header->flags |= MAD_FLAG_ORIGINAL; + } + + /* emphasis */ + header->emphasis = mad_bit_read(&stream->ptr, 2); + +# if defined(OPT_STRICT) + /* + * ISO/IEC 11172-3 says this is a reserved emphasis value, but + * streams exist which use it anyway. Since the value is not important + * to the decoder proper, we allow it unless OPT_STRICT is defined. + */ + if (header->emphasis == MAD_EMPHASIS_RESERVED) { + stream->error = MAD_ERROR_BADEMPHASIS; + return -1; + } +# endif + + /* error_check() */ + + /* crc_check */ + if (header->flags & MAD_FLAG_PROTECTION) { + header->crc_target = mad_bit_read(&stream->ptr, 16); + } + + return 0; +} + +/* + * NAME: free_bitrate() + * DESCRIPTION: attempt to discover the bitstream's free bitrate + */ +static +int free_bitrate(struct mad_stream *stream, struct mad_header const *header) +{ + struct mad_bitptr keep_ptr; + unsigned long rate = 0; + unsigned int pad_slot, slots_per_frame; + unsigned char const *ptr = 0; + + keep_ptr = stream->ptr; + + pad_slot = (header->flags & MAD_FLAG_PADDING) ? 1 : 0; + slots_per_frame = (header->layer == MAD_LAYER_III && + (header->flags & MAD_FLAG_LSF_EXT)) ? 72 : 144; + + while (mad_stream_sync(stream) == 0) { + struct mad_stream peek_stream; + struct mad_header peek_header; + + peek_stream = *stream; + peek_header = *header; + + if (decode_header(&peek_header, &peek_stream) == 0 && + peek_header.layer == header->layer && + peek_header.samplerate == header->samplerate) { + unsigned int N; + + ptr = mad_bit_nextbyte(&stream->ptr); + + N = ptr - stream->this_frame; + + if (header->layer == MAD_LAYER_I) { + rate = (unsigned long) header->samplerate * + (N - 4 * pad_slot + 4) / 48 / 1000; + } else { + rate = (unsigned long) header->samplerate * + (N - pad_slot + 1) / slots_per_frame / 1000; + } + + if (rate >= 8) { + break; + } + } + + mad_bit_skip(&stream->ptr, 8); + } + + stream->ptr = keep_ptr; + + if (rate < 8 || (header->layer == MAD_LAYER_III && rate > 640)) { + stream->error = MAD_ERROR_LOSTSYNC; + return -1; + } + + stream->freerate = rate * 1000; + + return 0; +} + +/* + * NAME: header->decode() + * DESCRIPTION: read the next frame header from the stream + */ +int mad_header_decode(struct mad_header *header, struct mad_stream *stream) +{ + register unsigned char const *ptr, *end; + unsigned int pad_slot, N; + + ptr = stream->next_frame; + end = stream->bufend; + + if (ptr == 0) { + stream->error = MAD_ERROR_BUFPTR; + goto fail; + } + + /* stream skip */ + if (stream->skiplen) { + if (!stream->sync) { + ptr = stream->this_frame; + } + + if (end - ptr < stream->skiplen) { + stream->skiplen -= end - ptr; + stream->next_frame = end; + + stream->error = MAD_ERROR_BUFLEN; + goto fail; + } + + ptr += stream->skiplen; + stream->skiplen = 0; + + stream->sync = 1; + } + +sync: + /* synchronize */ + if (stream->sync) { + if (end - ptr < MAD_BUFFER_GUARD) { + stream->next_frame = ptr; + + stream->error = MAD_ERROR_BUFLEN; + goto fail; + } else if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { + /* mark point where frame sync word was expected */ + stream->this_frame = ptr; + stream->next_frame = ptr + 1; + + stream->error = MAD_ERROR_LOSTSYNC; + goto fail; + } + } else { + mad_bit_init(&stream->ptr, ptr); + + if (mad_stream_sync(stream) == -1) { + if (end - stream->next_frame >= MAD_BUFFER_GUARD) { + stream->next_frame = end - MAD_BUFFER_GUARD; + } + + stream->error = MAD_ERROR_BUFLEN; + goto fail; + } + + ptr = mad_bit_nextbyte(&stream->ptr); + } + + /* begin processing */ + stream->this_frame = ptr; + stream->next_frame = ptr + 1; /* possibly bogus sync word */ + + mad_bit_init(&stream->ptr, stream->this_frame); + + if (decode_header(header, stream) == -1) { + goto fail; + } + + /* calculate frame duration */ + mad_timer_set(&header->duration, 0, + 32 * MAD_NSBSAMPLES(header), header->samplerate); + + /* calculate free bit rate */ + if (header->bitrate == 0) { + if ((stream->freerate == 0 || !stream->sync || + (header->layer == MAD_LAYER_III && stream->freerate > 640000)) && + free_bitrate(stream, header) == -1) { + goto fail; + } + + header->bitrate = stream->freerate; + header->flags |= MAD_FLAG_FREEFORMAT; + } + + /* calculate beginning of next frame */ + pad_slot = (header->flags & MAD_FLAG_PADDING) ? 1 : 0; + + if (header->layer == MAD_LAYER_I) { + N = ((12 * header->bitrate / header->samplerate) + pad_slot) * 4; + } else { + unsigned int slots_per_frame; + + slots_per_frame = (header->layer == MAD_LAYER_III && + (header->flags & MAD_FLAG_LSF_EXT)) ? 72 : 144; + + N = (slots_per_frame * header->bitrate / header->samplerate) + pad_slot; + } + + /* verify there is enough data left in buffer to decode this frame */ + if (N + MAD_BUFFER_GUARD > end - stream->this_frame) { + stream->next_frame = stream->this_frame; + + stream->error = MAD_ERROR_BUFLEN; + goto fail; + } + + stream->next_frame = stream->this_frame + N; + + if (!stream->sync) { + /* check that a valid frame header follows this frame */ + + ptr = stream->next_frame; + if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { + ptr = stream->next_frame = stream->this_frame + 1; + goto sync; + } + + stream->sync = 1; + } + + header->flags |= MAD_FLAG_INCOMPLETE; + + return 0; + +fail: + stream->sync = 0; + + return -1; +} + +/* + * NAME: frame->decode() + * DESCRIPTION: decode a single frame from a bitstream + */ +int mad_frame_decode(struct mad_frame *frame, struct mad_stream *stream) +{ + frame->options = stream->options; + + /* header() */ + /* error_check() */ + + if (!(frame->header.flags & MAD_FLAG_INCOMPLETE) && + mad_header_decode(&frame->header, stream) == -1) { + goto fail; + } + + /* audio_data() */ + + frame->header.flags &= ~MAD_FLAG_INCOMPLETE; + + if (decoder_table[frame->header.layer - 1](stream, frame) == -1) { + if (!MAD_RECOVERABLE(stream->error)) { + stream->next_frame = stream->this_frame; + } + + goto fail; + } + + /* ancillary_data() */ + + if (frame->header.layer != MAD_LAYER_III) { + struct mad_bitptr next_frame; + + mad_bit_init(&next_frame, stream->next_frame); + + stream->anc_ptr = stream->ptr; + stream->anc_bitlen = mad_bit_length(&stream->ptr, &next_frame); + + mad_bit_finish(&next_frame); + } + + return 0; + +fail: + stream->anc_bitlen = 0; + return -1; +} + +/* + * NAME: frame->mute() + * DESCRIPTION: zero all subband values so the frame becomes silent + */ +void mad_frame_mute(struct mad_frame *frame) +{ + unsigned int s, sb; + + for (s = 0; s < 36; ++s) { + for (sb = 0; sb < 32; ++sb) { + frame->sbsample[0][s][sb] = + frame->sbsample[1][s][sb] = 0; + } + } + + if (frame->overlap) { + for (s = 0; s < 18; ++s) { + for (sb = 0; sb < 32; ++sb) { + (*frame->overlap)[0][sb][s] = + (*frame->overlap)[1][sb][s] = 0; + } + } + } +} |