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-rw-r--r--src/libmad/frame.c502
1 files changed, 502 insertions, 0 deletions
diff --git a/src/libmad/frame.c b/src/libmad/frame.c
new file mode 100644
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--- /dev/null
+++ b/src/libmad/frame.c
@@ -0,0 +1,502 @@
+/*
+ * libmad - MPEG audio decoder library
+ * Copyright (C) 2000-2003 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 1.1 2003/08/14 03:57:13 shank 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) &&
+ 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;
+ }
+ }
+ }
+}
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