kopia lustrzana https://github.com/F5OEO/tstools
152 wiersze
5.7 KiB
C
152 wiersze
5.7 KiB
C
/*
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* Datastructures for handling H.264 elementary streams.
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*
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* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is the MPEG TS, PS and ES tools.
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*
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* The Initial Developer of the Original Code is Amino Communications Ltd.
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* Portions created by the Initial Developer are Copyright (C) 2008
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Amino Communications Ltd, Swavesey, Cambridge UK
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*
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* ***** END LICENSE BLOCK *****
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*/
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#ifndef _es_defns
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#define _es_defns
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#include <stdio.h>
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#include "compat.h"
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#include "pes_defns.h"
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// ------------------------------------------------------------
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// A "file" offset in an ES stream, suitable for seeking to
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// For an ES based on a "bare" file, the `infile` value is all that is needed
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// For an ES based on a PES, the file offset of the PES packet and the byte
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// offset within that packet's ES data are needed.
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struct _ES_offset
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{
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offset_t infile; // as used by lseek
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int32_t inpacket;
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};
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typedef struct _ES_offset ES_offset;
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typedef struct _ES_offset *ES_offset_p;
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#define SIZEOF_ES_OFFSET sizeof(struct _ES_offset)
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// The number of bytes to "read ahead" when reading directly from an
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// elementary stream
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#define ES_READ_AHEAD_SIZE 1000
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// ------------------------------------------------------------
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// A datastructure to represent our input elementary stream (ES)
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// (*output* elementary streams shouldn't need any particular housekeeping)
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struct elementary_stream
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{
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int reading_ES; // TRUE if we're reading ES data direct, FALSE if PES
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// If we're reading from an elementary data stream directly, then
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// we use the input directly
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int input;
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// And maintain a buffer of "read ahead" bytes
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byte read_ahead[ES_READ_AHEAD_SIZE];
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offset_t read_ahead_posn; // location of this data in the file
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int32_t read_ahead_len; // actual number of bytes in the buffer
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// And the next byte to be read is specified by its offset in said
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// data stream. For "bare" ES data, the `infile` value is used to
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// remember the next bytes actual position in the file, and for PES
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// based ES data, the `inpacket` value is used to remember the next
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// bytes offset in the current PES packet. In both cases, the "unused"
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// quantity in the ES_offset is undefined.
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// (this is, in fact, more used by tsserve than by anything else)
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ES_offset posn_of_next_byte;
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// If we're reading from PES packets (from either a PS or TS file),
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// then we need to remember our PES reader
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PES_reader_p reader;
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byte *data; // Where we're reading our bytes from
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byte *data_end; // How to tell we've read them all
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byte *data_ptr; // And which byte we're interested in
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offset_t last_packet_posn; // Where the last PES packet was in the file
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int32_t last_packet_es_data_len; // And its number of ES bytes
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// Regardless, our triple byte memory is the same
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byte cur_byte; // The current (last read) byte
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byte prev1_byte; // The previous byte
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byte prev2_byte; // The byte before *that*
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};
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typedef struct elementary_stream *ES_p;
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#define SIZEOF_ES sizeof(struct elementary_stream)
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// ------------------------------------------------------------
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// And a representation of a single unit from the elementary stream
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// (whether an MPEG-2 (H.262) item, or an MPEG-4/AVC (H.264) NAL unit)
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// - basically, the thing that starts with a 00 00 01 prefix, and continues
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// to end of file or before the next 00 00 01 prefix (so note that it
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// contains any "trailing" 00 bytes).
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//
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// The normal way to acquire such a datastructure is via `build_ES_unit()`,
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// or `find_and_build_next_ES_unit()`. If instead you want to use the
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// address of a `struct ES_unit`, it is imperative that it be set up
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// correctly with `setup_ES_unit()` before it is passed to any of the
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// functions that use it, otherwise the contents will not be valid (and,
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// particularly, the "data" pointer will reference random memory).
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struct ES_unit
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{
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ES_offset start_posn; // The start of the current data unit
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byte *data; // Its data, including the leading 00 00 01
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uint32_t data_len; // Its length
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uint32_t data_size; // The total buffer size
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byte start_code; // The byte after the 00 00 01 prefix
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// Something of a hack - if we were reading PES, did any of the PES packets
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// we read to make this ES unit contain a PTS?
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byte PES_had_PTS;
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};
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typedef struct ES_unit *ES_unit_p;
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#define SIZEOF_ES_UNIT sizeof(struct ES_unit)
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// Start and increment sizes for the es_unit/data array.
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#define ES_UNIT_DATA_START_SIZE 1000 // was 500
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#define ES_UNIT_DATA_INCREMENT 500 // was 100
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// ------------------------------------------------------------
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// An expandable list of ES units
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struct ES_unit_list
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{
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struct ES_unit *array; // The current array of ES units
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int length; // How many there are
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int size; // How big the array is
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};
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typedef struct ES_unit_list *ES_unit_list_p;
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#define SIZEOF_ES_UNIT_LIST sizeof(struct ES_unit_list)
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#define ES_UNIT_LIST_START_SIZE 20
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#define ES_UNIT_LIST_INCREMENT 20
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#endif // _es_defns
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// Local Variables:
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// tab-width: 8
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// indent-tabs-mode: nil
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// c-basic-offset: 2
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// End:
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// vim: set tabstop=8 shiftwidth=2 expandtab:
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