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5e1a50c7f0
Original commit message from CVS: Various changes to AC3->IEC958 framer. Mostly to make our IEC958 headers more accurate, and to check AC3 checksums (both of them in each frame), and dump the frame (as a probable sync failure) if they don't match. General code cleanup, improved comments. Changed to not construct the header backwards, and not byteswap everything else. If we end up needing to do little-endian output, we should swap in the element doing the output (AC3 is big-endian).
137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/* GStreamer
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* Copyright (C) 2003 Martin Soto <martinsoto@users.sourceforge.net>
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*
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* ac3_padder.h: Pad AC3 frames for use with an SPDIF interface.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#ifndef AC3_PADDER_INC
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#define AC3_PADDER_INC
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#include <glib.h>
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/* Size of an IEC958 padded AC3 frame. */
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#define AC3P_IEC_FRAME_SIZE 6144
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/* Size of the IEC958 header. */
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#define AC3P_IEC_HEADER_SIZE 8
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/* Size of the AC3 header. */
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#define AC3P_AC3_HEADER_SIZE 7
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/* An IEC958 padded AC3 frame. */
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typedef struct {
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/* IEC header. */
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guchar header[AC3P_IEC_HEADER_SIZE];
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/* Begin of AC3 header. */
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guchar sync_byte1;
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guchar sync_byte2;
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guchar crc1[2];
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guchar code;
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guchar bsidmod;
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guchar acmod;
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/* End of AC3 header. */
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unsigned char data[AC3P_IEC_FRAME_SIZE - AC3P_IEC_HEADER_SIZE
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- AC3P_AC3_HEADER_SIZE];
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} ac3p_iec958_burst_frame;
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/* Possible states for the reading automaton: */
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/* Searching for sync byte 1. */
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#define AC3P_STATE_SYNC1 1
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/* Searching for sync byte 2. */
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#define AC3P_STATE_SYNC2 2
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/* Reading AC3 header. */
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#define AC3P_STATE_HEADER 3
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/* Reading packet contents.*/
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#define AC3P_STATE_CONTENT 4
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/* Events generated by the parse function: */
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/* The parser needs new data to be pushed. */
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#define AC3P_EVENT_PUSH 1
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/* There is a new padded frame ready to read from the padder structure. */
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#define AC3P_EVENT_FRAME 2
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/* The internal state for the padder. */
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typedef struct {
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guint state; /* State of the reading automaton. */
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guchar *buffer; /* Input buffer */
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gint buffer_end; /* End offset, in bytes, of currently valid data in
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buffer */
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gint buffer_size; /* Allocated size of buffer */
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gint buffer_cur; /* Current position in buffer */
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guchar *out_ptr; /* Output pointer, marking the current
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position in the output frame. */
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gint bytes_to_copy;
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/* Number of bytes that still must be copied
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to the output frame *during this reading
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stage*. */
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gint ac3_frame_size;
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/* The size in 16-bit units of the pure AC3 portion
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of the current frame. */
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gint skipped; /* Number of bytes skipped while trying to find sync */
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ac3p_iec958_burst_frame frame;
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/* The current output frame. */
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} ac3_padder;
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extern void
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ac3p_init(ac3_padder *padder);
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extern void
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ac3p_clear(ac3_padder *padder);
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extern void
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ac3p_push_data(ac3_padder *padder, guchar *data, guint size);
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extern int
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ac3p_parse(ac3_padder *padder);
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/**
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* ac3p_frame
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* @padder: The padder structure.
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*
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* Returns a pointer to the padded frame contained in the padder.
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*/
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#define ac3p_frame(padder) ((guint8 *) &((padder)->frame))
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/**
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* ac3p_frame_size
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* @padder: The padder structure.
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*
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* Returns the length in bytes of the last read raw AC3 frame.
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*/
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#define ac3p_frame_size(padder) ((padder)->ac3_frame_size * 2)
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#endif
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