FFmpeg  5.0
bsf.h
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1 /*
2  * Bitstream filters public API
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVCODEC_BSF_H
22 #define AVCODEC_BSF_H
23 
24 #include "libavutil/dict.h"
25 #include "libavutil/log.h"
26 #include "libavutil/rational.h"
27 
28 #include "codec_id.h"
29 #include "codec_par.h"
30 #include "packet.h"
31 
32 /**
33  * @addtogroup lavc_core
34  * @{
35  */
36 
37 /**
38  * The bitstream filter state.
39  *
40  * This struct must be allocated with av_bsf_alloc() and freed with
41  * av_bsf_free().
42  *
43  * The fields in the struct will only be changed (by the caller or by the
44  * filter) as described in their documentation, and are to be considered
45  * immutable otherwise.
46  */
47 typedef struct AVBSFContext {
48  /**
49  * A class for logging and AVOptions
50  */
51  const AVClass *av_class;
52 
53  /**
54  * The bitstream filter this context is an instance of.
55  */
56  const struct AVBitStreamFilter *filter;
57 
58  /**
59  * Opaque filter-specific private data. If filter->priv_class is non-NULL,
60  * this is an AVOptions-enabled struct.
61  */
62  void *priv_data;
63 
64  /**
65  * Parameters of the input stream. This field is allocated in
66  * av_bsf_alloc(), it needs to be filled by the caller before
67  * av_bsf_init().
68  */
70 
71  /**
72  * Parameters of the output stream. This field is allocated in
73  * av_bsf_alloc(), it is set by the filter in av_bsf_init().
74  */
76 
77  /**
78  * The timebase used for the timestamps of the input packets. Set by the
79  * caller before av_bsf_init().
80  */
82 
83  /**
84  * The timebase used for the timestamps of the output packets. Set by the
85  * filter in av_bsf_init().
86  */
88 } AVBSFContext;
89 
90 typedef struct AVBitStreamFilter {
91  const char *name;
92 
93  /**
94  * A list of codec ids supported by the filter, terminated by
95  * AV_CODEC_ID_NONE.
96  * May be NULL, in that case the bitstream filter works with any codec id.
97  */
98  const enum AVCodecID *codec_ids;
99 
100  /**
101  * A class for the private data, used to declare bitstream filter private
102  * AVOptions. This field is NULL for bitstream filters that do not declare
103  * any options.
104  *
105  * If this field is non-NULL, the first member of the filter private data
106  * must be a pointer to AVClass, which will be set by libavcodec generic
107  * code to this class.
108  */
110 
111  /*****************************************************************
112  * No fields below this line are part of the public API. They
113  * may not be used outside of libavcodec and can be changed and
114  * removed at will.
115  * New public fields should be added right above.
116  *****************************************************************
117  */
118 
120  int (*init)(AVBSFContext *ctx);
121  int (*filter)(AVBSFContext *ctx, AVPacket *pkt);
122  void (*close)(AVBSFContext *ctx);
123  void (*flush)(AVBSFContext *ctx);
125 
126 /**
127  * @return a bitstream filter with the specified name or NULL if no such
128  * bitstream filter exists.
129  */
130 const AVBitStreamFilter *av_bsf_get_by_name(const char *name);
131 
132 /**
133  * Iterate over all registered bitstream filters.
134  *
135  * @param opaque a pointer where libavcodec will store the iteration state. Must
136  * point to NULL to start the iteration.
137  *
138  * @return the next registered bitstream filter or NULL when the iteration is
139  * finished
140  */
141 const AVBitStreamFilter *av_bsf_iterate(void **opaque);
142 
143 /**
144  * Allocate a context for a given bitstream filter. The caller must fill in the
145  * context parameters as described in the documentation and then call
146  * av_bsf_init() before sending any data to the filter.
147  *
148  * @param filter the filter for which to allocate an instance.
149  * @param ctx a pointer into which the pointer to the newly-allocated context
150  * will be written. It must be freed with av_bsf_free() after the
151  * filtering is done.
152  *
153  * @return 0 on success, a negative AVERROR code on failure
154  */
155 int av_bsf_alloc(const AVBitStreamFilter *filter, AVBSFContext **ctx);
156 
157 /**
158  * Prepare the filter for use, after all the parameters and options have been
159  * set.
160  */
162 
163 /**
164  * Submit a packet for filtering.
165  *
166  * After sending each packet, the filter must be completely drained by calling
167  * av_bsf_receive_packet() repeatedly until it returns AVERROR(EAGAIN) or
168  * AVERROR_EOF.
169  *
170  * @param pkt the packet to filter. The bitstream filter will take ownership of
171  * the packet and reset the contents of pkt. pkt is not touched if an error occurs.
172  * If pkt is empty (i.e. NULL, or pkt->data is NULL and pkt->side_data_elems zero),
173  * it signals the end of the stream (i.e. no more non-empty packets will be sent;
174  * sending more empty packets does nothing) and will cause the filter to output
175  * any packets it may have buffered internally.
176  *
177  * @return 0 on success. AVERROR(EAGAIN) if packets need to be retrieved from the
178  * filter (using av_bsf_receive_packet()) before new input can be consumed. Another
179  * negative AVERROR value if an error occurs.
180  */
182 
183 /**
184  * Retrieve a filtered packet.
185  *
186  * @param[out] pkt this struct will be filled with the contents of the filtered
187  * packet. It is owned by the caller and must be freed using
188  * av_packet_unref() when it is no longer needed.
189  * This parameter should be "clean" (i.e. freshly allocated
190  * with av_packet_alloc() or unreffed with av_packet_unref())
191  * when this function is called. If this function returns
192  * successfully, the contents of pkt will be completely
193  * overwritten by the returned data. On failure, pkt is not
194  * touched.
195  *
196  * @return 0 on success. AVERROR(EAGAIN) if more packets need to be sent to the
197  * filter (using av_bsf_send_packet()) to get more output. AVERROR_EOF if there
198  * will be no further output from the filter. Another negative AVERROR value if
199  * an error occurs.
200  *
201  * @note one input packet may result in several output packets, so after sending
202  * a packet with av_bsf_send_packet(), this function needs to be called
203  * repeatedly until it stops returning 0. It is also possible for a filter to
204  * output fewer packets than were sent to it, so this function may return
205  * AVERROR(EAGAIN) immediately after a successful av_bsf_send_packet() call.
206  */
208 
209 /**
210  * Reset the internal bitstream filter state. Should be called e.g. when seeking.
211  */
213 
214 /**
215  * Free a bitstream filter context and everything associated with it; write NULL
216  * into the supplied pointer.
217  */
219 
220 /**
221  * Get the AVClass for AVBSFContext. It can be used in combination with
222  * AV_OPT_SEARCH_FAKE_OBJ for examining options.
223  *
224  * @see av_opt_find().
225  */
227 
228 /**
229  * Structure for chain/list of bitstream filters.
230  * Empty list can be allocated by av_bsf_list_alloc().
231  */
232 typedef struct AVBSFList AVBSFList;
233 
234 /**
235  * Allocate empty list of bitstream filters.
236  * The list must be later freed by av_bsf_list_free()
237  * or finalized by av_bsf_list_finalize().
238  *
239  * @return Pointer to @ref AVBSFList on success, NULL in case of failure
240  */
242 
243 /**
244  * Free list of bitstream filters.
245  *
246  * @param lst Pointer to pointer returned by av_bsf_list_alloc()
247  */
249 
250 /**
251  * Append bitstream filter to the list of bitstream filters.
252  *
253  * @param lst List to append to
254  * @param bsf Filter context to be appended
255  *
256  * @return >=0 on success, negative AVERROR in case of failure
257  */
259 
260 /**
261  * Construct new bitstream filter context given it's name and options
262  * and append it to the list of bitstream filters.
263  *
264  * @param lst List to append to
265  * @param bsf_name Name of the bitstream filter
266  * @param options Options for the bitstream filter, can be set to NULL
267  *
268  * @return >=0 on success, negative AVERROR in case of failure
269  */
270 int av_bsf_list_append2(AVBSFList *lst, const char * bsf_name, AVDictionary **options);
271 /**
272  * Finalize list of bitstream filters.
273  *
274  * This function will transform @ref AVBSFList to single @ref AVBSFContext,
275  * so the whole chain of bitstream filters can be treated as single filter
276  * freshly allocated by av_bsf_alloc().
277  * If the call is successful, @ref AVBSFList structure is freed and lst
278  * will be set to NULL. In case of failure, caller is responsible for
279  * freeing the structure by av_bsf_list_free()
280  *
281  * @param lst Filter list structure to be transformed
282  * @param[out] bsf Pointer to be set to newly created @ref AVBSFContext structure
283  * representing the chain of bitstream filters
284  *
285  * @return >=0 on success, negative AVERROR in case of failure
286  */
288 
289 /**
290  * Parse string describing list of bitstream filters and create single
291  * @ref AVBSFContext describing the whole chain of bitstream filters.
292  * Resulting @ref AVBSFContext can be treated as any other @ref AVBSFContext freshly
293  * allocated by av_bsf_alloc().
294  *
295  * @param str String describing chain of bitstream filters in format
296  * `bsf1[=opt1=val1:opt2=val2][,bsf2]`
297  * @param[out] bsf Pointer to be set to newly created @ref AVBSFContext structure
298  * representing the chain of bitstream filters
299  *
300  * @return >=0 on success, negative AVERROR in case of failure
301  */
302 int av_bsf_list_parse_str(const char *str, AVBSFContext **bsf);
303 
304 /**
305  * Get null/pass-through bitstream filter.
306  *
307  * @param[out] bsf Pointer to be set to new instance of pass-through bitstream filter
308  *
309  * @return
310  */
312 
313 /**
314  * @}
315  */
316 
317 #endif // AVCODEC_BSF_H
static AVPacket * pkt
Public dictionary API.
AVBSFList * av_bsf_list_alloc(void)
Allocate empty list of bitstream filters.
void av_bsf_free(AVBSFContext **ctx)
Free a bitstream filter context and everything associated with it; write NULL into the supplied point...
void av_bsf_list_free(AVBSFList **lst)
Free list of bitstream filters.
int av_bsf_init(AVBSFContext *ctx)
Prepare the filter for use, after all the parameters and options have been set.
int av_bsf_list_append(AVBSFList *lst, AVBSFContext *bsf)
Append bitstream filter to the list of bitstream filters.
void av_bsf_flush(AVBSFContext *ctx)
Reset the internal bitstream filter state.
int av_bsf_alloc(const AVBitStreamFilter *filter, AVBSFContext **ctx)
Allocate a context for a given bitstream filter.
int av_bsf_receive_packet(AVBSFContext *ctx, AVPacket *pkt)
Retrieve a filtered packet.
const AVClass * av_bsf_get_class(void)
Get the AVClass for AVBSFContext.
int av_bsf_list_finalize(AVBSFList **lst, AVBSFContext **bsf)
Finalize list of bitstream filters.
int av_bsf_send_packet(AVBSFContext *ctx, AVPacket *pkt)
Submit a packet for filtering.
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: codec_id.h:47
int av_bsf_list_parse_str(const char *str, AVBSFContext **bsf)
Parse string describing list of bitstream filters and create single AVBSFContext describing the whole...
struct AVBSFList AVBSFList
Structure for chain/list of bitstream filters.
Definition: bsf.h:232
int av_bsf_get_null_filter(AVBSFContext **bsf)
Get null/pass-through bitstream filter.
const AVBitStreamFilter * av_bsf_get_by_name(const char *name)
int av_bsf_list_append2(AVBSFList *lst, const char *bsf_name, AVDictionary **options)
Construct new bitstream filter context given it's name and options and append it to the list of bitst...
const AVBitStreamFilter * av_bsf_iterate(void **opaque)
Iterate over all registered bitstream filters.
struct AVDictionary AVDictionary
Definition: dict.h:84
Utilties for rational number calculation.
The bitstream filter state.
Definition: bsf.h:47
AVRational time_base_out
The timebase used for the timestamps of the output packets.
Definition: bsf.h:87
void * priv_data
Opaque filter-specific private data.
Definition: bsf.h:62
AVCodecParameters * par_in
Parameters of the input stream.
Definition: bsf.h:69
const AVClass * av_class
A class for logging and AVOptions.
Definition: bsf.h:51
AVCodecParameters * par_out
Parameters of the output stream.
Definition: bsf.h:75
AVRational time_base_in
The timebase used for the timestamps of the input packets.
Definition: bsf.h:81
const struct AVBitStreamFilter * filter
The bitstream filter this context is an instance of.
Definition: bsf.h:56
void(* flush)(AVBSFContext *ctx)
Definition: bsf.h:123
int(* filter)(AVBSFContext *ctx, AVPacket *pkt)
Definition: bsf.h:121
const AVClass * priv_class
A class for the private data, used to declare bitstream filter private AVOptions.
Definition: bsf.h:109
const char * name
Definition: bsf.h:91
enum AVCodecID * codec_ids
A list of codec ids supported by the filter, terminated by AV_CODEC_ID_NONE.
Definition: bsf.h:98
int(* init)(AVBSFContext *ctx)
Definition: bsf.h:120
int priv_data_size
Definition: bsf.h:119
void(* close)(AVBSFContext *ctx)
Definition: bsf.h:122
Describe the class of an AVClass context structure.
Definition: log.h:66
This struct describes the properties of an encoded stream.
Definition: codec_par.h:52
This structure stores compressed data.
Definition: packet.h:350
Rational number (pair of numerator and denominator).
Definition: rational.h:58