kopia lustrzana https://github.com/F5OEO/tstools
140 wiersze
5.3 KiB
C
140 wiersze
5.3 KiB
C
/*
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* Datastructures for reading AVS 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 _avs_defns
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#define _avs_defns
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#include <stdio.h>
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#include "compat.h"
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#include "es_defns.h"
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#include "ts_defns.h"
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// Since reverse_data refers to avs and acces_unit datastructures, and
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// *they* refer to reverse_data, we need to break the circular referencing
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// at some point
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typedef struct avs_context *avs_context_p;
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#include "reverse_defns.h"
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// ------------------------------------------------------------
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// An AVS frame. This might be a picture or a sequence header (and
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// its associated ES units).
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struct _avs_frame
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{
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// The main thing we need is a list of the units that make up this picture
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ES_unit_list_p list;
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// An AVS "picture" might be a "proper" picture, a sequence header,
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// or (just) a sequence end item. It's useful to be able to identify
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// the two more common cases easily
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int is_frame;
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int is_sequence_header;
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// It's also useful to remember what the first ES unit is
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int start_code;
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// Data defined for a frame.
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byte picture_coding_type; // I, P or B (0, 1, 2)
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byte picture_distance; // presentation order of P/B frames
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// Data defined for a sequence header
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byte aspect_ratio; // 1=SAR/1.0 2=4/3, 3=16/9, 4=2.21/1 (?)
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byte frame_rate_code; // see Table 7-6
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};
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typedef struct _avs_frame *avs_frame_p;
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#define SIZEOF_AVS_FRAME sizeof(struct _avs_frame)
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// ------------------------------------------------------------
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#define is_avs_slice_item(unit) ((unit)->start_code<0xB0)
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#define is_avs_frame_item(unit) ((unit)->start_code==0xB3 || \
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(unit)->start_code==0xB6)
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#define is_avs_user_data_item(unit) ((unit)->start_code==0xB2)
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#define is_avs_seq_header_item(unit) ((unit)->start_code==0xB0)
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#define is_avs_seq_end_item(unit) ((unit)->start_code==0xB1)
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#define is_avs_extension_start_item(unit) ((unit)->start_code==0xB5)
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#define is_avs_video_edit_item(unit) ((unit)->start_code==0xB7)
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#define avs_frame_rate(code) ((code)==1?24000.0/1001: /* 23.967... */\
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(code)==2?24: \
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(code)==3?25: \
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(code)==4?30000.0/1001: /* 29.97... */ \
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(code)==5?30: \
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(code)==6?50: \
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(code)==7?60000.0/1001: /* 59.94... */ \
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(code)==8?60: \
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25) /* Hmm-really an error */
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#define AVS_I_PICTURE_CODING 0 // our invention, but reasonable in context
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#define AVS_P_PICTURE_CODING 1
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#define AVS_B_PICTURE_CODING 2
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// Note that "I" is made up by us (there is no picture coding on I frames)
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#define AVS_PICTURE_CODING_STR(s) \
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((s)==AVS_I_PICTURE_CODING?"I": \
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(s)==AVS_P_PICTURE_CODING?"P": \
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(s)==AVS_B_PICTURE_CODING?"B": \
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"Reserved")
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// ------------------------------------------------------------
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// Context for looping over the AVS items and pictures in an elementary
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// stream
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struct avs_context
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{
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ES_p es;
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// We count all of the frames as we read them (this is useful
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// when we are building up reverse_data arrays). If functions
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// move around in the data stream, we assume that they will
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// (re)set this to a sensible value.
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// The index of the first frame read is 1, and this value is
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// incremented by each call of `get_next_avs_frame` (note that
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// for this purpose, sequence headers are *not* considered frames)
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uint32_t frame_index; // The index of the last frame read
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// We detect the end of an AVS frame (or sequence header) by
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// reading the first item that cannot be part of it. We then need
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// to remember that item for *next* time we try to read a frame.
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ES_unit_p last_item;
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// If we are collecting reversing information, then we keep a reference
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// to the reverse data here
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reverse_data_p reverse_data;
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// In the same context, we need to remember how long it is since the
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// last sequence header
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byte count_since_seq_hdr;
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};
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#define SIZEOF_AVS_CONTEXT sizeof(struct avs_context)
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#endif // _avs_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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