duckstation

bsf.h (11540B)

---

 /*
  * Bitstream filters public API
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVCODEC_BSF_H
 #define AVCODEC_BSF_H
 
 #include "libavutil/dict.h"
 #include "libavutil/log.h"
 #include "libavutil/rational.h"
 
 #include "codec_id.h"
 #include "codec_par.h"
 #include "packet.h"
 
 /**
  * @defgroup lavc_bsf Bitstream filters
  * @ingroup libavc
  *
  * Bitstream filters transform encoded media data without decoding it. This
  * allows e.g. manipulating various header values. Bitstream filters operate on
  * @ref AVPacket "AVPackets".
  *
  * The bitstream filtering API is centered around two structures:
  * AVBitStreamFilter and AVBSFContext. The former represents a bitstream filter
  * in abstract, the latter a specific filtering process. Obtain an
  * AVBitStreamFilter using av_bsf_get_by_name() or av_bsf_iterate(), then pass
  * it to av_bsf_alloc() to create an AVBSFContext. Fill in the user-settable
  * AVBSFContext fields, as described in its documentation, then call
  * av_bsf_init() to prepare the filter context for use.
  *
  * Submit packets for filtering using av_bsf_send_packet(), obtain filtered
  * results with av_bsf_receive_packet(). When no more input packets will be
  * sent, submit a NULL AVPacket to signal the end of the stream to the filter.
  * av_bsf_receive_packet() will then return trailing packets, if any are
  * produced by the filter.
  *
  * Finally, free the filter context with av_bsf_free().
  * @{
  */
 
 /**
  * The bitstream filter state.
  *
  * This struct must be allocated with av_bsf_alloc() and freed with
  * av_bsf_free().
  *
  * The fields in the struct will only be changed (by the caller or by the
  * filter) as described in their documentation, and are to be considered
  * immutable otherwise.
  */
 typedef struct AVBSFContext {
     /**
      * A class for logging and AVOptions
      */
     const AVClass *av_class;
 
     /**
      * The bitstream filter this context is an instance of.
      */
     const struct AVBitStreamFilter *filter;
 
     /**
      * Opaque filter-specific private data. If filter->priv_class is non-NULL,
      * this is an AVOptions-enabled struct.
      */
     void *priv_data;
 
     /**
      * Parameters of the input stream. This field is allocated in
      * av_bsf_alloc(), it needs to be filled by the caller before
      * av_bsf_init().
      */
     AVCodecParameters *par_in;
 
     /**
      * Parameters of the output stream. This field is allocated in
      * av_bsf_alloc(), it is set by the filter in av_bsf_init().
      */
     AVCodecParameters *par_out;
 
     /**
      * The timebase used for the timestamps of the input packets. Set by the
      * caller before av_bsf_init().
      */
     AVRational time_base_in;
 
     /**
      * The timebase used for the timestamps of the output packets. Set by the
      * filter in av_bsf_init().
      */
     AVRational time_base_out;
 } AVBSFContext;
 
 typedef struct AVBitStreamFilter {
     const char *name;
 
     /**
      * A list of codec ids supported by the filter, terminated by
      * AV_CODEC_ID_NONE.
      * May be NULL, in that case the bitstream filter works with any codec id.
      */
     const enum AVCodecID *codec_ids;
 
     /**
      * A class for the private data, used to declare bitstream filter private
      * AVOptions. This field is NULL for bitstream filters that do not declare
      * any options.
      *
      * If this field is non-NULL, the first member of the filter private data
      * must be a pointer to AVClass, which will be set by libavcodec generic
      * code to this class.
      */
     const AVClass *priv_class;
 } AVBitStreamFilter;
 
 /**
  * @return a bitstream filter with the specified name or NULL if no such
  *         bitstream filter exists.
  */
 const AVBitStreamFilter *av_bsf_get_by_name(const char *name);
 
 /**
  * Iterate over all registered bitstream filters.
  *
  * @param opaque a pointer where libavcodec will store the iteration state. Must
  *               point to NULL to start the iteration.
  *
  * @return the next registered bitstream filter or NULL when the iteration is
  *         finished
  */
 const AVBitStreamFilter *av_bsf_iterate(void **opaque);
 
 /**
  * Allocate a context for a given bitstream filter. The caller must fill in the
  * context parameters as described in the documentation and then call
  * av_bsf_init() before sending any data to the filter.
  *
  * @param filter the filter for which to allocate an instance.
  * @param[out] ctx a pointer into which the pointer to the newly-allocated context
  *                 will be written. It must be freed with av_bsf_free() after the
  *                 filtering is done.
  *
  * @return 0 on success, a negative AVERROR code on failure
  */
 int av_bsf_alloc(const AVBitStreamFilter *filter, AVBSFContext **ctx);
 
 /**
  * Prepare the filter for use, after all the parameters and options have been
  * set.
  *
  * @param ctx a AVBSFContext previously allocated with av_bsf_alloc()
  */
 int av_bsf_init(AVBSFContext *ctx);
 
 /**
  * Submit a packet for filtering.
  *
  * After sending each packet, the filter must be completely drained by calling
  * av_bsf_receive_packet() repeatedly until it returns AVERROR(EAGAIN) or
  * AVERROR_EOF.
  *
  * @param ctx an initialized AVBSFContext
  * @param pkt the packet to filter. The bitstream filter will take ownership of
  * the packet and reset the contents of pkt. pkt is not touched if an error occurs.
  * If pkt is empty (i.e. NULL, or pkt->data is NULL and pkt->side_data_elems zero),
  * it signals the end of the stream (i.e. no more non-empty packets will be sent;
  * sending more empty packets does nothing) and will cause the filter to output
  * any packets it may have buffered internally.
  *
  * @return
  *  - 0 on success.
  *  - AVERROR(EAGAIN) if packets need to be retrieved from the filter (using
  *    av_bsf_receive_packet()) before new input can be consumed.
  *  - Another negative AVERROR value if an error occurs.
  */
 int av_bsf_send_packet(AVBSFContext *ctx, AVPacket *pkt);
 
 /**
  * Retrieve a filtered packet.
  *
  * @param ctx an initialized AVBSFContext
  * @param[out] pkt this struct will be filled with the contents of the filtered
  *                 packet. It is owned by the caller and must be freed using
  *                 av_packet_unref() when it is no longer needed.
  *                 This parameter should be "clean" (i.e. freshly allocated
  *                 with av_packet_alloc() or unreffed with av_packet_unref())
  *                 when this function is called. If this function returns
  *                 successfully, the contents of pkt will be completely
  *                 overwritten by the returned data. On failure, pkt is not
  *                 touched.
  *
  * @return
  *  - 0 on success.
  *  - AVERROR(EAGAIN) if more packets need to be sent to the filter (using
  *    av_bsf_send_packet()) to get more output.
  *  - AVERROR_EOF if there will be no further output from the filter.
  *  - Another negative AVERROR value if an error occurs.
  *
  * @note one input packet may result in several output packets, so after sending
  * a packet with av_bsf_send_packet(), this function needs to be called
  * repeatedly until it stops returning 0. It is also possible for a filter to
  * output fewer packets than were sent to it, so this function may return
  * AVERROR(EAGAIN) immediately after a successful av_bsf_send_packet() call.
  */
 int av_bsf_receive_packet(AVBSFContext *ctx, AVPacket *pkt);
 
 /**
  * Reset the internal bitstream filter state. Should be called e.g. when seeking.
  */
 void av_bsf_flush(AVBSFContext *ctx);
 
 /**
  * Free a bitstream filter context and everything associated with it; write NULL
  * into the supplied pointer.
  */
 void av_bsf_free(AVBSFContext **ctx);
 
 /**
  * Get the AVClass for AVBSFContext. It can be used in combination with
  * AV_OPT_SEARCH_FAKE_OBJ for examining options.
  *
  * @see av_opt_find().
  */
 const AVClass *av_bsf_get_class(void);
 
 /**
  * Structure for chain/list of bitstream filters.
  * Empty list can be allocated by av_bsf_list_alloc().
  */
 typedef struct AVBSFList AVBSFList;
 
 /**
  * Allocate empty list of bitstream filters.
  * The list must be later freed by av_bsf_list_free()
  * or finalized by av_bsf_list_finalize().
  *
  * @return Pointer to @ref AVBSFList on success, NULL in case of failure
  */
 AVBSFList *av_bsf_list_alloc(void);
 
 /**
  * Free list of bitstream filters.
  *
  * @param lst Pointer to pointer returned by av_bsf_list_alloc()
  */
 void av_bsf_list_free(AVBSFList **lst);
 
 /**
  * Append bitstream filter to the list of bitstream filters.
  *
  * @param lst List to append to
  * @param bsf Filter context to be appended
  *
  * @return >=0 on success, negative AVERROR in case of failure
  */
 int av_bsf_list_append(AVBSFList *lst, AVBSFContext *bsf);
 
 /**
  * Construct new bitstream filter context given it's name and options
  * and append it to the list of bitstream filters.
  *
  * @param lst      List to append to
  * @param bsf_name Name of the bitstream filter
  * @param options  Options for the bitstream filter, can be set to NULL
  *
  * @return >=0 on success, negative AVERROR in case of failure
  */
 int av_bsf_list_append2(AVBSFList *lst, const char * bsf_name, AVDictionary **options);
 /**
  * Finalize list of bitstream filters.
  *
  * This function will transform @ref AVBSFList to single @ref AVBSFContext,
  * so the whole chain of bitstream filters can be treated as single filter
  * freshly allocated by av_bsf_alloc().
  * If the call is successful, @ref AVBSFList structure is freed and lst
  * will be set to NULL. In case of failure, caller is responsible for
  * freeing the structure by av_bsf_list_free()
  *
  * @param      lst Filter list structure to be transformed
  * @param[out] bsf Pointer to be set to newly created @ref AVBSFContext structure
  *                 representing the chain of bitstream filters
  *
  * @return >=0 on success, negative AVERROR in case of failure
  */
 int av_bsf_list_finalize(AVBSFList **lst, AVBSFContext **bsf);
 
 /**
  * Parse string describing list of bitstream filters and create single
  * @ref AVBSFContext describing the whole chain of bitstream filters.
  * Resulting @ref AVBSFContext can be treated as any other @ref AVBSFContext freshly
  * allocated by av_bsf_alloc().
  *
  * @param      str String describing chain of bitstream filters in format
  *                 `bsf1[=opt1=val1:opt2=val2][,bsf2]`
  * @param[out] bsf Pointer to be set to newly created @ref AVBSFContext structure
  *                 representing the chain of bitstream filters
  *
  * @return >=0 on success, negative AVERROR in case of failure
  */
 int av_bsf_list_parse_str(const char *str, AVBSFContext **bsf);
 
 /**
  * Get null/pass-through bitstream filter.
  *
  * @param[out] bsf Pointer to be set to new instance of pass-through bitstream filter
  *
  * @return
  */
 int av_bsf_get_null_filter(AVBSFContext **bsf);
 
 /**
  * @}
  */
 
 #endif // AVCODEC_BSF_H