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/* 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;
}
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