/* 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. */ #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; }