/* GStreamer * Copyright (C) 2003 Martin Soto * * 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. */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include "ac3_padder.h" #define IEC61937_DATA_TYPE_AC3 1 struct frmsize_s { unsigned short bit_rate; unsigned short frm_size[3]; }; static const struct frmsize_s frmsizecod_tbl[64] = { {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}} }; /* Go one byte forward in the input buffer. */ #define ac3p_in_fw(padder) ((padder)->in_ptr++, (padder)->remaining--) /* Go one byte forward in the output buffer. */ #define ac3p_out_fw(padder) ((padder)->out_ptr++, (padder)->bytes_to_copy--) /** * 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. */ extern void ac3p_init (ac3_padder * padder) { const char sync[4] = { 0x72, 0xF8, 0x1F, 0x4E }; padder->state = AC3P_STATE_SYNC1; /* No material to read yet. */ padder->remaining = 0; /* Initialize the sync bytes in the frame. */ memcpy (padder->frame.header, sync, 4); } /** * 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) { padder->in_ptr = data; padder->remaining = 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. */ extern int ac3p_parse (ac3_padder * padder) { while (padder->remaining > 0) { switch (padder->state) { case AC3P_STATE_SYNC1: if (*(padder->in_ptr) == 0x0b) { /* The first sync byte was found. Go to the next state. */ padder->frame.sync_byte1 = 0x0b; padder->state = AC3P_STATE_SYNC2; } ac3p_in_fw (padder); break; case AC3P_STATE_SYNC2: if (*(padder->in_ptr) == 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; /* Skip one byte. */ ac3p_in_fw (padder); /* 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. */ padder->state = AC3P_STATE_SYNC1; } break; case AC3P_STATE_HEADER: if (padder->bytes_to_copy > 0) { /* Copy one byte. */ *(padder->out_ptr) = *(padder->in_ptr); ac3p_in_fw (padder); ac3p_out_fw (padder); } else { int fscod; /* The header is ready: */ fscod = (padder->frame.code >> 6) & 0x03; /* Calculate the frame size. */ padder->ac3_frame_size = 2 * frmsizecod_tbl[padder->frame.code & 0x3f].frm_size[fscod]; /* Set up the IEC header. */ if (padder->ac3_frame_size > 0) { padder->frame.header[4] = IEC61937_DATA_TYPE_AC3; } else { /* Don't know what it is, better be careful. */ padder->state = AC3P_STATE_SYNC1; break; } padder->frame.header[5] = 0x00; padder->frame.header[6] = (padder->ac3_frame_size * 8) & 0xFF; padder->frame.header[7] = ((padder->ac3_frame_size * 8) >> 8) & 0xFF; /* Prepare for reading the body. */ padder->bytes_to_copy = padder->ac3_frame_size - 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->in_ptr); ac3p_in_fw (padder); ac3p_out_fw (padder); } else { guint16 *ptr, i; /* Frame ready. Prepare for output: */ /* Zero the non AC3 portion of the padded frame. */ memset (&(padder->frame.sync_byte1) + padder->ac3_frame_size, 0, AC3P_IEC_FRAME_SIZE - AC3P_IEC_HEADER_SIZE - padder->ac3_frame_size); /* Fix the byte order in the AC3 portion: */ ptr = (guint16 *) & (padder->frame.sync_byte1); i = padder->ac3_frame_size / 2; while (i > 0) { *ptr = GUINT16_TO_BE (*ptr); ptr++; i--; } /* Start over again. */ padder->state = AC3P_STATE_SYNC1; return AC3P_EVENT_FRAME; } break; } } return AC3P_EVENT_PUSH; }