| /* GStreamer |
| * Copyright (C) 2003 Martin Soto <martinsoto@users.sourceforge.net> |
| * |
| * 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., 51 Franklin St, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| */ |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include <stdio.h> |
| #include <string.h> |
| |
| #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; |
| } |
