/* GStreamer * Copyright (C) 2003, 2004 Martin Soto * 2005 Michael Smith * * ac3_padder.c: Pad AC3 frames for use with an SPDIF interface. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library 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 * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ #include #include #include "ac3_padder.h" struct frmsize_s { unsigned short bit_rate; unsigned short frm_size[3]; }; static const struct frmsize_s frmsizecod_tbl[] = { {32, {64, 69, 96}}, {32, {64, 70, 96}}, {40, {80, 87, 120}}, {40, {80, 88, 120}}, {48, {96, 104, 144}}, {48, {96, 105, 144}}, {56, {112, 121, 168}}, {56, {112, 122, 168}}, {64, {128, 139, 192}}, {64, {128, 140, 192}}, {80, {160, 174, 240}}, {80, {160, 175, 240}}, {96, {192, 208, 288}}, {96, {192, 209, 288}}, {112, {224, 243, 336}}, {112, {224, 244, 336}}, {128, {256, 278, 384}}, {128, {256, 279, 384}}, {160, {320, 348, 480}}, {160, {320, 349, 480}}, {192, {384, 417, 576}}, {192, {384, 418, 576}}, {224, {448, 487, 672}}, {224, {448, 488, 672}}, {256, {512, 557, 768}}, {256, {512, 558, 768}}, {320, {640, 696, 960}}, {320, {640, 697, 960}}, {384, {768, 835, 1152}}, {384, {768, 836, 1152}}, {448, {896, 975, 1344}}, {448, {896, 976, 1344}}, {512, {1024, 1114, 1536}}, {512, {1024, 1115, 1536}}, {576, {1152, 1253, 1728}}, {576, {1152, 1254, 1728}}, {640, {1280, 1393, 1920}}, {640, {1280, 1394, 1920}} }; static const guint16 ac3_crc_lut[256] = { 0x0000, 0x8005, 0x800f, 0x000a, 0x801b, 0x001e, 0x0014, 0x8011, 0x8033, 0x0036, 0x003c, 0x8039, 0x0028, 0x802d, 0x8027, 0x0022, 0x8063, 0x0066, 0x006c, 0x8069, 0x0078, 0x807d, 0x8077, 0x0072, 0x0050, 0x8055, 0x805f, 0x005a, 0x804b, 0x004e, 0x0044, 0x8041, 0x80c3, 0x00c6, 0x00cc, 0x80c9, 0x00d8, 0x80dd, 0x80d7, 0x00d2, 0x00f0, 0x80f5, 0x80ff, 0x00fa, 0x80eb, 0x00ee, 0x00e4, 0x80e1, 0x00a0, 0x80a5, 0x80af, 0x00aa, 0x80bb, 0x00be, 0x00b4, 0x80b1, 0x8093, 0x0096, 0x009c, 0x8099, 0x0088, 0x808d, 0x8087, 0x0082, 0x8183, 0x0186, 0x018c, 0x8189, 0x0198, 0x819d, 0x8197, 0x0192, 0x01b0, 0x81b5, 0x81bf, 0x01ba, 0x81ab, 0x01ae, 0x01a4, 0x81a1, 0x01e0, 0x81e5, 0x81ef, 0x01ea, 0x81fb, 0x01fe, 0x01f4, 0x81f1, 0x81d3, 0x01d6, 0x01dc, 0x81d9, 0x01c8, 0x81cd, 0x81c7, 0x01c2, 0x0140, 0x8145, 0x814f, 0x014a, 0x815b, 0x015e, 0x0154, 0x8151, 0x8173, 0x0176, 0x017c, 0x8179, 0x0168, 0x816d, 0x8167, 0x0162, 0x8123, 0x0126, 0x012c, 0x8129, 0x0138, 0x813d, 0x8137, 0x0132, 0x0110, 0x8115, 0x811f, 0x011a, 0x810b, 0x010e, 0x0104, 0x8101, 0x8303, 0x0306, 0x030c, 0x8309, 0x0318, 0x831d, 0x8317, 0x0312, 0x0330, 0x8335, 0x833f, 0x033a, 0x832b, 0x032e, 0x0324, 0x8321, 0x0360, 0x8365, 0x836f, 0x036a, 0x837b, 0x037e, 0x0374, 0x8371, 0x8353, 0x0356, 0x035c, 0x8359, 0x0348, 0x834d, 0x8347, 0x0342, 0x03c0, 0x83c5, 0x83cf, 0x03ca, 0x83db, 0x03de, 0x03d4, 0x83d1, 0x83f3, 0x03f6, 0x03fc, 0x83f9, 0x03e8, 0x83ed, 0x83e7, 0x03e2, 0x83a3, 0x03a6, 0x03ac, 0x83a9, 0x03b8, 0x83bd, 0x83b7, 0x03b2, 0x0390, 0x8395, 0x839f, 0x039a, 0x838b, 0x038e, 0x0384, 0x8381, 0x0280, 0x8285, 0x828f, 0x028a, 0x829b, 0x029e, 0x0294, 0x8291, 0x82b3, 0x02b6, 0x02bc, 0x82b9, 0x02a8, 0x82ad, 0x82a7, 0x02a2, 0x82e3, 0x02e6, 0x02ec, 0x82e9, 0x02f8, 0x82fd, 0x82f7, 0x02f2, 0x02d0, 0x82d5, 0x82df, 0x02da, 0x82cb, 0x02ce, 0x02c4, 0x82c1, 0x8243, 0x0246, 0x024c, 0x8249, 0x0258, 0x825d, 0x8257, 0x0252, 0x0270, 0x8275, 0x827f, 0x027a, 0x826b, 0x026e, 0x0264, 0x8261, 0x0220, 0x8225, 0x822f, 0x022a, 0x823b, 0x023e, 0x0234, 0x8231, 0x8213, 0x0216, 0x021c, 0x8219, 0x0208, 0x820d, 0x8207, 0x0202 }; typedef guint16 ac3_crc_state; static void ac3_crc_init (ac3_crc_state * state) { *state = 0; } static void ac3_crc_update (ac3_crc_state * state, guint8 * data, guint32 num_bytes) { int i; for (i = 0; i < num_bytes; i++) *state = ac3_crc_lut[data[i] ^ (*state >> 8)] ^ (*state << 8); } static int ac3_crc_validate (ac3_crc_state * state) { return (*state == 0); } /** * ac3p_init * @padder: The padder structure to initialize. * * Initializes an AC3 stream padder. This structure can be * subsequently used to parse an AC3 stream and convert it to IEC958 * (S/PDIF) padded packets. */ void ac3p_init (ac3_padder * padder) { const char sync[4] = { 0xF8, 0x72, 0x4E, 0x1F }; padder->state = AC3P_STATE_SYNC1; padder->skipped = 0; /* No material to read yet. */ padder->buffer = NULL; padder->buffer_end = 0; padder->buffer_cur = 0; padder->buffer_size = 0; /* Initialize the sync bytes in the frame. */ memcpy (padder->frame.header, sync, 4); } void ac3p_clear (ac3_padder * padder) { g_free (padder->buffer); } static void resync (ac3_padder * padder, int offset, int skipped) { padder->buffer_cur -= offset; padder->state = AC3P_STATE_SYNC1; padder->skipped += skipped; /* We don't want our buffer to grow unboundedly if we fail to find sync, but * nor do we want to do this every time we call resync() */ if (padder->buffer_cur > 4096) { memmove (padder->buffer, padder->buffer + padder->buffer_cur, padder->buffer_end - padder->buffer_cur); padder->buffer_end -= padder->buffer_cur; padder->buffer_cur = 0; } } /** * ac3_push_data * @padder: The padder structure. * @data: A pointer to a buffer with new data to parse. This should * correspond to a new piece of a stream containing raw AC3 data. * @size: The number of available bytes in the buffer. * * Pushes a new buffer of data to be parsed by the ac3 padder. The * ac3_parse() function will actually parse the data and report when * new frames are found. This funcion should only be called once at * the beginning of the parsing process, or when the ac3_parse() * function returns the %AC3P_EVENT_PUSH event. */ extern void ac3p_push_data (ac3_padder * padder, guchar * data, guint size) { if (padder->buffer_end + size > padder->buffer_size) { padder->buffer_size = padder->buffer_end + size; padder->buffer = g_realloc (padder->buffer, padder->buffer_size); } memcpy (padder->buffer + padder->buffer_end, data, size); padder->buffer_end += size; } /** * ac3p_parse * @padder: The padder structure. * * Parses the bytes already pushed into the padder structure (see * ac3p_push_data()) and returns an event value depending on the * results of the parsing. * * Returns: %AC3P_EVENT_FRAME to indicate that a new AC3 was found and * padded for IEC958 transmission. This frame can be read inmediatly * with ac3p_frame(). %AC3P_EVENT_PUSH to indicate that new data from * the input stream must be pushed into the padder using * ac3p_push_data(). This function should be called again after * pushing the data. * * Note that the returned data (which naturally comes in 16 bit sub-frames) is * big-endian, and may need to be byte-swapped for little-endian output. */ extern int ac3p_parse (ac3_padder * padder) { while (padder->buffer_cur < padder->buffer_end) { switch (padder->state) { case AC3P_STATE_SYNC1: if (padder->buffer[padder->buffer_cur++] == 0x0b) { /* The first sync byte was found. Go to the next state. */ padder->frame.sync_byte1 = 0x0b; padder->state = AC3P_STATE_SYNC2; } else resync (padder, 0, 1); break; case AC3P_STATE_SYNC2: if (padder->buffer[padder->buffer_cur++] == 0x77) { /* The second sync byte was seen right after the first. Go to the next state. */ padder->frame.sync_byte2 = 0x77; padder->state = AC3P_STATE_HEADER; /* Prepare for reading the header. */ padder->out_ptr = (guchar *) & (padder->frame.crc1); /* Discount the 2 sync bytes from the header size. */ padder->bytes_to_copy = AC3P_AC3_HEADER_SIZE - 2; } else { /* The second sync byte was not seen. Go back to the first state. */ resync (padder, 0, 2); } break; case AC3P_STATE_HEADER: if (padder->bytes_to_copy > 0) { /* Copy one byte. */ *(padder->out_ptr++) = padder->buffer[padder->buffer_cur++]; padder->bytes_to_copy--; } else { int fscod; /* The header is ready: */ fscod = (padder->frame.code >> 6) & 0x03; /* fscod == 3 is a reserved code, we're not meant to do playback in * this case. frmsizecod being out-of-range (there are 38 entries) * doesn't appear to be well-defined, but treat the same. * The likely cause of both of these is false sync, so skip back to * just in front of the previous sync word and start looking again. */ if (fscod == 3 || (padder->frame.code & 0x3f) >= 38) { resync (padder, AC3P_AC3_HEADER_SIZE - 2, 2); continue; } /* Calculate the frame size (in 16 bit units). */ padder->ac3_frame_size = frmsizecod_tbl[padder->frame.code & 0x3f].frm_size[fscod]; /* Prepare for reading the body. */ padder->bytes_to_copy = padder->ac3_frame_size * 2 - AC3P_AC3_HEADER_SIZE; padder->state = AC3P_STATE_CONTENT; } break; case AC3P_STATE_CONTENT: if (padder->bytes_to_copy > 0) { /* Copy one byte. */ *(padder->out_ptr++) = padder->buffer[padder->buffer_cur++]; padder->bytes_to_copy--; } else { int framesize; int crclen1, crclen2; guint8 *tmp; ac3_crc_state state; /* Frame ready. Prepare for output: */ /* Zero the non AC3 portion of the padded frame. */ memset (&(padder->frame.sync_byte1) + padder->ac3_frame_size * 2, 0, AC3P_IEC_FRAME_SIZE - AC3P_IEC_HEADER_SIZE - padder->ac3_frame_size * 2); /* Now checking the two CRCs. If either fails, then we re-feed all * the data starting immediately after the 16-bit syncword (which we * can now assume was a false sync) */ /* Length of CRC1 is defined as truncate(framesize/2) + truncate(framesize/8) units (each of which is 16 bit, as is 'framesize'), but this includes the syncword, which is NOT calculated as part of the CRC. */ framesize = padder->ac3_frame_size; crclen1 = (framesize / 2 + framesize / 8) * 2 - 2; tmp = (guint8 *) (&(padder->frame.crc1)); ac3_crc_init (&state); ac3_crc_update (&state, tmp, crclen1); if (!ac3_crc_validate (&state)) { /* Rewind current stream pointer to immediately following the last * attempted sync point, then continue parsing in initial state */ resync (padder, padder->ac3_frame_size - 2, 2); continue; } /* Now check CRC2, which covers the entire frame other than the * 16-bit syncword */ crclen2 = padder->ac3_frame_size * 2 - 2; ac3_crc_init (&state); ac3_crc_update (&state, tmp, crclen2); if (!ac3_crc_validate (&state)) { /* Rewind current stream pointer to immediately following the last * attempted sync point, then continue parsing in initial state */ resync (padder, padder->ac3_frame_size - 2, 2); continue; } /* Now set up the rest of the IEC header (we already filled in the 32 bit sync word. */ /* Byte 5 has: bits 0-4: data type dependent. For AC3, the bottom 3 of these bits are copied from the AC3 frame (bsmod value), the top 2 bits are reserved, and set to zero. bits 5-7: data stream number. We only do one data stream, so it's zero. */ padder->frame.header[4] = padder->frame.bsidmod & 0x07; /* Byte 6: bits 0-4: data type. 1 for AC3. bits 5-6: reserved, zero. bit 7: error_flag. Zero if frame contains no errors */ padder->frame.header[5] = 1; /* AC3 is defined as datatype 1 */ /* Now, 16 bit frame size, in bits. */ padder->frame.header[6] = ((padder->ac3_frame_size * 16) >> 8) & 0xFF; padder->frame.header[7] = (padder->ac3_frame_size * 16) & 0xFF; /* We're done, reset state and signal that we have a frame */ padder->skipped = 0; padder->state = AC3P_STATE_SYNC1; memmove (padder->buffer, padder->buffer + padder->buffer_cur, padder->buffer_end - padder->buffer_cur); padder->buffer_end -= padder->buffer_cur; padder->buffer_cur = 0; return AC3P_EVENT_FRAME; } break; } } return AC3P_EVENT_PUSH; }