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Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.
In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.
There are multiple important problems with this approach:
- the fields in AVCodecContext are in general one of
* stream parameters
* codec options
* codec state
However, it's not clear which ones are which. It is consequently
unclear which fields are a demuxer allowed to set or a muxer allowed to
read. This leads to erratic behaviour depending on whether decoding or
encoding is being performed or not (and whether it uses the AVStream
embedded codec context).
- various synchronization issues arising from the fact that the same
context is used by several different APIs (muxers/demuxers,
parsers, bitstream filters and encoders/decoders) simultaneously, with
there being no clear rules for who can modify what and the different
processes being typically delayed with respect to each other.
- avformat_find_stream_info() making it necessary to support opening
and closing a single codec context multiple times, thus
complicating the semantics of freeing various allocated objects in the
codec context.
Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
98 lines
2.4 KiB
C
98 lines
2.4 KiB
C
/*
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* Flash Compatible Streaming Format common header.
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* Copyright (c) 2000 Fabrice Bellard
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* Copyright (c) 2003 Tinic Uro
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVFORMAT_SWF_H
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#define AVFORMAT_SWF_H
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#include "config.h"
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#if CONFIG_ZLIB
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#include <zlib.h>
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#endif
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#include "libavutil/fifo.h"
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#include "avformat.h"
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#include "avio.h"
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#include "internal.h"
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/* should have a generic way to indicate probable size */
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#define DUMMY_FILE_SIZE (100 * 1024 * 1024)
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#define DUMMY_DURATION 600 /* in seconds */
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#define TAG_END 0
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#define TAG_SHOWFRAME 1
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#define TAG_DEFINESHAPE 2
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#define TAG_FREECHARACTER 3
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#define TAG_PLACEOBJECT 4
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#define TAG_REMOVEOBJECT 5
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#define TAG_STREAMHEAD 18
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#define TAG_STREAMBLOCK 19
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#define TAG_JPEG2 21
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#define TAG_PLACEOBJECT2 26
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#define TAG_STREAMHEAD2 45
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#define TAG_VIDEOSTREAM 60
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#define TAG_VIDEOFRAME 61
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#define TAG_FILEATTRIBUTES 69
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#define TAG_LONG 0x100
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/* flags for shape definition */
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#define FLAG_MOVETO 0x01
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#define FLAG_SETFILL0 0x02
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#define FLAG_SETFILL1 0x04
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#define AUDIO_FIFO_SIZE 65536
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/* character id used */
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#define BITMAP_ID 0
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#define VIDEO_ID 0
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#define SHAPE_ID 1
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#undef NDEBUG
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#include <assert.h>
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typedef struct SWFContext {
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int64_t duration_pos;
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int64_t tag_pos;
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int64_t vframes_pos;
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int samples_per_frame;
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int sound_samples;
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int swf_frame_number;
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int video_frame_number;
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int frame_rate;
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int tag;
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AVFifoBuffer *audio_fifo;
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AVCodecParameters *audio_par, *video_par;
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AVStream *video_st;
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#if CONFIG_ZLIB
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#define ZBUF_SIZE 4096
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AVIOContext *zpb;
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uint8_t *zbuf_in;
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uint8_t *zbuf_out;
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z_stream zstream;
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#endif
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} SWFContext;
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extern const AVCodecTag ff_swf_codec_tags[];
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#endif /* AVFORMAT_SWF_H */
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