--- /dev/null
+/*
+ This file borrowed from liboggz
+ */
+/*
+ Copyright (C) 2003 Commonwealth Scientific and Industrial Research
+ Organisation (CSIRO) Australia
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ - Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+ - Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ - Neither the name of CSIRO Australia nor the names of its
+ contributors may be used to endorse or promote products derived from
+ this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ORGANISATION OR
+ CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/*
+ * oggz_auto.c
+ *
+ * Conrad Parker <conrad@annodex.net>
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "gstoggstream.h"
+#include "vorbis_parse.h"
+
+/*
+ * Vorbis packets can be short or long, and each packet overlaps the previous
+ * and next packets. The granulepos of a packet is always the last sample
+ * that is completely decoded at the end of decoding that packet - i.e. the
+ * last packet before the first overlapping packet. If the sizes of packets
+ * are 's' and 'l', then the increment will depend on the previous and next
+ * packet types:
+ * v prev<<1 | next
+ * lll: l/2 3
+ * lls: 3l/4 - s/4 2
+ * lsl: s/2
+ * lss: s/2
+ * sll: l/4 + s/4 1
+ * sls: l/2 0
+ * ssl: s/2
+ * sss: s/2
+ *
+ * The previous and next packet types can be inferred from the current packet
+ * (additional information is not required)
+ *
+ * The two blocksizes can be determined from the first header packet, by reading
+ * byte 28. 1 << (packet[28] >> 4) == long_size.
+ * 1 << (packet[28] & 0xF) == short_size.
+ *
+ * (see http://xiph.org/vorbis/doc/Vorbis_I_spec.html for specification)
+ */
+
+
+void
+parse_vorbis_header_packet (GstOggStream * pad, ogg_packet * packet)
+{
+ /*
+ * on the first (b_o_s) packet, determine the long and short sizes,
+ * and then calculate l/2, l/4 - s/4, 3 * l/4 - s/4, l/2 - s/2 and s/2
+ */
+ int short_size;
+ int long_size;
+
+ long_size = 1 << (packet->packet[28] >> 4);
+ short_size = 1 << (packet->packet[28] & 0xF);
+
+ pad->nln_increments[3] = long_size >> 1;
+ pad->nln_increments[2] = 3 * (long_size >> 2) - (short_size >> 2);
+ pad->nln_increments[1] = (long_size >> 2) + (short_size >> 2);
+ pad->nln_increments[0] = pad->nln_increments[3];
+ pad->short_size = short_size;
+ pad->long_size = long_size;
+ pad->nsn_increment = short_size >> 1;
+}
+
+void
+parse_vorbis_setup_packet (GstOggStream * pad, ogg_packet * op)
+{
+ /*
+ * the code pages, a whole bunch of other fairly useless stuff, AND,
+ * RIGHT AT THE END (of a bunch of variable-length compressed rubbish that
+ * basically has only one actual set of values that everyone uses BUT YOU
+ * CAN'T BE SURE OF THAT, OH NO YOU CAN'T) is the only piece of data that's
+ * actually useful to us - the packet modes (because it's inconceivable to
+ * think people might want _just that_ and nothing else, you know, for
+ * seeking and stuff).
+ *
+ * Fortunately, because of the mandate that non-used bits must be zero
+ * at the end of the packet, we might be able to sneakily work backwards
+ * and find out the information we need (namely a mapping of modes to
+ * packet sizes)
+ */
+ unsigned char *current_pos = &op->packet[op->bytes - 1];
+ int offset;
+ int size;
+ int size_check;
+ int *mode_size_ptr;
+ int i;
+ int ii;
+
+ /*
+ * This is the format of the mode data at the end of the packet for all
+ * Vorbis Version 1 :
+ *
+ * [ 6:number_of_modes ]
+ * [ 1:size | 16:window_type(0) | 16:transform_type(0) | 8:mapping ]
+ * [ 1:size | 16:window_type(0) | 16:transform_type(0) | 8:mapping ]
+ * [ 1:size | 16:window_type(0) | 16:transform_type(0) | 8:mapping ]
+ * [ 1:framing(1) ]
+ *
+ * e.g.:
+ *
+ * <-
+ * 0 0 0 0 0 1 0 0
+ * 0 0 1 0 0 0 0 0
+ * 0 0 1 0 0 0 0 0
+ * 0 0 1|0 0 0 0 0
+ * 0 0 0 0|0|0 0 0
+ * 0 0 0 0 0 0 0 0
+ * 0 0 0 0|0 0 0 0
+ * 0 0 0 0 0 0 0 0
+ * 0 0 0 0|0 0 0 0
+ * 0 0 0|1|0 0 0 0 |
+ * 0 0 0 0 0 0 0 0 V
+ * 0 0 0|0 0 0 0 0
+ * 0 0 0 0 0 0 0 0
+ * 0 0 1|0 0 0 0 0
+ * 0 0|1|0 0 0 0 0
+ *
+ *
+ * i.e. each entry is an important bit, 32 bits of 0, 8 bits of blah, a
+ * bit of 1.
+ * Let's find our last 1 bit first.
+ *
+ */
+
+ size = 0;
+
+ offset = 8;
+ while (!((1 << --offset) & *current_pos)) {
+ if (offset == 0) {
+ offset = 8;
+ current_pos -= 1;
+ }
+ }
+
+ while (1) {
+
+ /*
+ * from current_pos-5:(offset+1) to current_pos-1:(offset+1) should
+ * be zero
+ */
+ offset = (offset + 7) % 8;
+ if (offset == 7)
+ current_pos -= 1;
+
+ if (((current_pos[-5] & ~((1 << (offset + 1)) - 1)) != 0)
+ ||
+ current_pos[-4] != 0
+ ||
+ current_pos[-3] != 0
+ ||
+ current_pos[-2] != 0
+ || ((current_pos[-1] & ((1 << (offset + 1)) - 1)) != 0)
+ ) {
+ break;
+ }
+
+ size += 1;
+
+ current_pos -= 5;
+
+ }
+
+ /* Give ourselves a chance to recover if we went back too far by using
+ * the size check. */
+ for (ii = 0; ii < 2; ii++) {
+ if (offset > 4) {
+ size_check = (current_pos[0] >> (offset - 5)) & 0x3F;
+ } else {
+ /* mask part of byte from current_pos */
+ size_check = (current_pos[0] & ((1 << (offset + 1)) - 1));
+ /* shift to appropriate position */
+ size_check <<= (5 - offset);
+ /* or in part of byte from current_pos - 1 */
+ size_check |= (current_pos[-1] & ~((1 << (offset + 3)) - 1)) >>
+ (offset + 3);
+ }
+
+ size_check += 1;
+ if (size_check == size) {
+ break;
+ }
+ offset = (offset + 1) % 8;
+ if (offset == 0)
+ current_pos += 1;
+ current_pos += 5;
+ size -= 1;
+ }
+
+ /* Store mode size information in our info struct */
+ i = -1;
+ while ((1 << (++i)) < size);
+ pad->vorbis_log2_num_modes = i;
+
+ mode_size_ptr = pad->vorbis_mode_sizes;
+
+ for (i = 0; i < size; i++) {
+ offset = (offset + 1) % 8;
+ if (offset == 0)
+ current_pos += 1;
+ *mode_size_ptr++ = (current_pos[0] >> offset) & 0x1;
+ current_pos += 5;
+ }
+
+}
projects / mafwsubrenderer / blobdiff