kopia lustrzana https://github.com/F5OEO/tstools
114 wiersze
4.2 KiB
C
114 wiersze
4.2 KiB
C
/*
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* Datastructures for filtering ES data ("fast forward") and writing to ES or
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* TS.
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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 _filter_defns
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#define _filter_defns
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#include "compat.h"
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#include "es_defns.h"
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#include "h262_defns.h"
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#include "accessunit_defns.h"
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#include "reverse_defns.h"
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// Filtering comes in two varieties:
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// - "stripping" means retaining just reference pictures. For H.262 this
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// means the I pictures (and maybe the P pictures), for H.264 this means
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// the IDR and I pictures (or maybe all reference pictures). This is simple
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// to do, but the speedup resulting is very dependant on the data.
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// - "filtering" means attempting to keep frames as a particular frequency,
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// so, for instance, a frequency of 8 would mean trying to keep every 8th
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// frame, or a speedup of 8x. This is harder to do as it depends rather
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// crucially on the distribution of reference frames in the data.
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// ------------------------------------------------------------
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struct h262_filter_context
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{
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h262_context_p h262; // The H.262 stream we are reading from
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int filter; // TRUE if filtering, FALSE if stripping
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int freq; // Frequency of frames to try to keep if filtering
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int allref; // Keep all I and P pictures if stripping?
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// (the name `allref` is used for compatibility with the H.264 filter
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// context - it's a little easier to have one name for both filters)
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// For any operation on H.262, we want:
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int pending_EOF; // next time a function is called, say we had EOF
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// When filtering, we want:
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int count; // a rolling count to compare with the desired frequency
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int last_was_slice;
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int had_previous_picture;
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h262_picture_p last_seq_hdr;
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// When stripping, we want:
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int new_seq_hdr; // has the sequence header changed?
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int frames_seen; // number of pictures seen this filter run
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int frames_written; // number of pictures written (or, returned)
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};
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typedef struct h262_filter_context *h262_filter_context_p;
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#define SIZEOF_H262_FILTER_CONTEXT sizeof(struct h262_filter_context)
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// ------------------------------------------------------------
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struct h264_filter_context
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{
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access_unit_context_p access_unit_context; // our "reader" for access units
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int filter; // TRUE if filtering, FALSE if stripping
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int freq; // Frequency of frames to try to keep if filtering
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int allref; // Keep all reference pictures
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// When filtering, we want:
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// a rolling count to compare with the desired frequency
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int count;
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// `skipped_ref_pic` is TRUE if we've skipped any reference pictures
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// since our last IDR.
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int skipped_ref_pic;
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// `last_accepted_was_not_IDR` is TRUE if the last frame kept (output)
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// was not an IDR. We set it TRUE initially so that we will decide
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// to output the first IDR we *do* find, regardless of the count.
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int last_accepted_was_not_IDR;
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int had_previous_access_unit;
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// Have we had an IDR in this run of the filter?
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int not_had_IDR;
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int frames_seen; // number seen this filter run
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int frames_written; // number written (or, returned)
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};
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typedef struct h264_filter_context *h264_filter_context_p;
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#define SIZEOF_H264_FILTER_CONTEXT sizeof(struct h264_filter_context)
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#endif // _filter_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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