text: /*
   * copyright (c) 2001 Fabrice Bellard
   *
   * 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 AVFORMAT_INTERNAL_H
  #define AVFORMAT_INTERNAL_H
  
  #include <stdint.h>
  
  #include "libavutil/bprint.h"
  #include "avformat.h"
  #include "os_support.h"
  
  #define MAX_URL_SIZE 4096
  
  /** size of probe buffer, for guessing file type from file contents */
  #define PROBE_BUF_MIN 2048
  #define PROBE_BUF_MAX (1 << 20)
  
  #define MAX_PROBE_PACKETS 2500
  
  #ifdef DEBUG
  #    define hex_dump_debug(class, buf, size) av_hex_dump_log(class, AV_LOG_DEBUG, buf, size)
  #else
  #    define hex_dump_debug(class, buf, size) do { if (0) av_hex_dump_log(class, AV_LOG_DEBUG, buf, size); } while(0)
  #endif
  
  typedef struct AVCodecTag {
      enum AVCodecID id;
      unsigned int tag;
  } AVCodecTag;
  
  typedef struct CodecMime{
      char str[32];
      enum AVCodecID id;
  } CodecMime;
  
  /*************************************************/
  /* fractional numbers for exact pts handling */
  
  /**
   * The exact value of the fractional number is: 'val + num / den'.
   * num is assumed to be 0 <= num < den.
   */
  typedef struct FFFrac {
      int64_t val, num, den;
  } FFFrac;
  
  
  struct AVFormatInternal {
      /**
       * Number of streams relevant for interleaving.
       * Muxing only.
       */
      int nb_interleaved_streams;
  
      /**
       * This buffer is only needed when packets were already buffered but
       * not decoded, for example to get the codec parameters in MPEG
       * streams.
       */
      struct AVPacketList *packet_buffer;
      struct AVPacketList *packet_buffer_end;
  
      /* av_seek_frame() support */
      int64_t data_offset; /**< offset of the first packet */
  
      /**
       * Raw packets from the demuxer, prior to parsing and decoding.
       * This buffer is used for buffering packets until the codec can
       * be identified, as parsing cannot be done without knowing the
       * codec.
       */
      struct AVPacketList *raw_packet_buffer;
      struct AVPacketList *raw_packet_buffer_end;
      /**
       * Packets split by the parser get queued here.
       */
      struct AVPacketList *parse_queue;
      struct AVPacketList *parse_queue_end;
      /**
       * Remaining size available for raw_packet_buffer, in bytes.
       */
  #define RAW_PACKET_BUFFER_SIZE 2500000
      int raw_packet_buffer_remaining_size;
  
      /**
       * Offset to remap timestamps to be non-negative.
       * Expressed in timebase units.
       * @see AVStream.mux_ts_offset
       */
      int64_t offset;
  
      /**
       * Timebase for the timestamp offset.
       */
      AVRational offset_timebase;
  
  #if FF_API_COMPUTE_PKT_FIELDS2
      int missing_ts_warning;
  #endif
  
      int inject_global_side_data;
  
      int avoid_negative_ts_use_pts;
  
      /**
       * Timestamp of the end of the shortest stream.
       */
      int64_t shortest_end;
  
      /**
       * Whether or not avformat_init_output has already been called
       */
      int initialized;
  
      /**
       * Whether or not avformat_init_output fully initialized streams
       */
      int streams_initialized;
  
      /**
       * ID3v2 tag useful for MP3 demuxing
       */
      AVDictionary *id3v2_meta;
  
      /*
       * Prefer the codec framerate for avg_frame_rate computation.
       */
      int prefer_codec_framerate;
  };
  
  struct AVStreamInternal {
      /**
       * Set to 1 if the codec allows reordering, so pts can be different
       * from dts.
       */
      int reorder;
  
      /**
       * bitstream filters to run on stream
       * - encoding: Set by muxer using ff_stream_add_bitstream_filter
       * - decoding: unused
       */
      AVBSFContext **bsfcs;
      int nb_bsfcs;
  
      /**
       * Whether or not check_bitstream should still be run on each packet
       */
      int bitstream_checked;
  
      /**
       * The codec context used by avformat_find_stream_info, the parser, etc.
       */
      AVCodecContext *avctx;
      /**
       * 1 if avctx has been initialized with the values from the codec parameters
       */
      int avctx_inited;
  
      enum AVCodecID orig_codec_id;
  
      /* the context for extracting extradata in find_stream_info()
       * inited=1/bsf=NULL signals that extracting is not possible (codec not
       * supported) */
      struct {
          AVBSFContext *bsf;
          AVPacket     *pkt;
          int inited;
      } extract_extradata;
  
      /**
       * Whether the internal avctx needs to be updated from codecpar (after a late change to codecpar)
       */
      int need_context_update;
  
      FFFrac *priv_pts;
  };
  
  #ifdef __GNUC__
  #define dynarray_add(tab, nb_ptr, elem)\
  do {\
      __typeof__(tab) _tab = (tab);\
      __typeof__(elem) _elem = (elem);\
      (void)sizeof(**_tab == _elem); /* check that types are compatible */\
      av_dynarray_add(_tab, nb_ptr, _elem);\
  } while(0)
  #else
  #define dynarray_add(tab, nb_ptr, elem)\
  do {\
      av_dynarray_add((tab), nb_ptr, (elem));\
  } while(0)
  #endif
  
  struct tm *ff_brktimegm(time_t secs, struct tm *tm);
  
  char *ff_data_to_hex(char *buf, const uint8_t *src, int size, int lowercase);
  
  /**
   * Parse a string of hexadecimal strings. Any space between the hexadecimal
   * digits is ignored.
   *
   * @param data if non-null, the parsed data is written to this pointer
   * @param p the string to parse
   * @return the number of bytes written (or to be written, if data is null)
   */
  int ff_hex_to_data(uint8_t *data, const char *p);
  
  /**
   * Add packet to AVFormatContext->packet_buffer list, determining its
   * interleaved position using compare() function argument.
   * @return 0, or < 0 on error
   */
  int ff_interleave_add_packet(AVFormatContext *s, AVPacket *pkt,
                               int (*compare)(AVFormatContext *, AVPacket *, AVPacket *));
  
  void ff_read_frame_flush(AVFormatContext *s);
  
  #define NTP_OFFSET 2208988800ULL
  #define NTP_OFFSET_US (NTP_OFFSET * 1000000ULL)
  
  /** Get the current time since NTP epoch in microseconds. */
  uint64_t ff_ntp_time(void);
  
  /**
   * Append the media-specific SDP fragment for the media stream c
   * to the buffer buff.
   *
   * Note, the buffer needs to be initialized, since it is appended to
   * existing content.
   *
   * @param buff the buffer to append the SDP fragment to
   * @param size the size of the buff buffer
   * @param st the AVStream of the media to describe
   * @param idx the global stream index
   * @param dest_addr the destination address of the media stream, may be NULL
   * @param dest_type the destination address type, may be NULL
   * @param port the destination port of the media stream, 0 if unknown
   * @param ttl the time to live of the stream, 0 if not multicast
   * @param fmt the AVFormatContext, which might contain options modifying
   *            the generated SDP
   */
  void ff_sdp_write_media(char *buff, int size, AVStream *st, int idx,
                          const char *dest_addr, const char *dest_type,
                          int port, int ttl, AVFormatContext *fmt);
  
  /**
   * Write a packet to another muxer than the one the user originally
   * intended. Useful when chaining muxers, where one muxer internally
   * writes a received packet to another muxer.
   *
   * @param dst the muxer to write the packet to
   * @param dst_stream the stream index within dst to write the packet to
   * @param pkt the packet to be written
   * @param src the muxer the packet originally was intended for
   * @param interleave 0->use av_write_frame, 1->av_interleaved_write_frame
   * @return the value av_write_frame returned
   */
  int ff_write_chained(AVFormatContext *dst, int dst_stream, AVPacket *pkt,
                       AVFormatContext *src, int interleave);
  
  /**
   * Get the length in bytes which is needed to store val as v.
   */
  int ff_get_v_length(uint64_t val);
  
  /**
   * Put val using a variable number of bytes.
   */
  void ff_put_v(AVIOContext *bc, uint64_t val);
  
  /**
   * Read a whole line of text from AVIOContext. Stop reading after reaching
   * either a \\n, a \\0 or EOF. The returned string is always \\0-terminated,
   * and may be truncated if the buffer is too small.
   *
   * @param s the read-only AVIOContext
   * @param buf buffer to store the read line
   * @param maxlen size of the buffer
   * @return the length of the string written in the buffer, not including the
   *         final \\0
   */
  int ff_get_line(AVIOContext *s, char *buf, int maxlen);
  
  /**
   * Same as ff_get_line but strip the white-space characters in the text tail
   *
   * @param s the read-only AVIOContext
   * @param buf buffer to store the read line
   * @param maxlen size of the buffer
   * @return the length of the string written in the buffer
   */
  int ff_get_chomp_line(AVIOContext *s, char *buf, int maxlen);
  
  /**
   * Read a whole line of text from AVIOContext to an AVBPrint buffer. Stop
   * reading after reaching a \\r, a \\n, a \\r\\n, a \\0 or EOF.  The line
   * ending characters are NOT included in the buffer, but they are skipped on
   * the input.
   *
   * @param s the read-only AVIOContext
   * @param bp the AVBPrint buffer
   * @return the length of the read line, not including the line endings,
   *         negative on error.
   */
  int64_t ff_read_line_to_bprint(AVIOContext *s, AVBPrint *bp);
  
  /**
   * Read a whole line of text from AVIOContext to an AVBPrint buffer overwriting
   * its contents. Stop reading after reaching a \\r, a \\n, a \\r\\n, a \\0 or
   * EOF. The line ending characters are NOT included in the buffer, but they
   * are skipped on the input.
   *
   * @param s the read-only AVIOContext
   * @param bp the AVBPrint buffer
   * @return the length of the read line not including the line endings,
   *         negative on error, or if the buffer becomes truncated.
   */
  int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp);
  
  #define SPACE_CHARS " \t\r\n"
  
  /**
   * Callback function type for ff_parse_key_value.
   *
   * @param key a pointer to the key
   * @param key_len the number of bytes that belong to the key, including the '='
   *                char
   * @param dest return the destination pointer for the value in *dest, may
   *             be null to ignore the value
   * @param dest_len the length of the *dest buffer
   */
  typedef void (*ff_parse_key_val_cb)(void *context, const char *key,
                                      int key_len, char **dest, int *dest_len);
  /**
   * Parse a string with comma-separated key=value pairs. The value strings
   * may be quoted and may contain escaped characters within quoted strings.
   *
   * @param str the string to parse
   * @param callback_get_buf function that returns where to store the
   *                         unescaped value string.
   * @param context the opaque context pointer to pass to callback_get_buf
   */
  void ff_parse_key_value(const char *str, ff_parse_key_val_cb callback_get_buf,
                          void *context);
  
  /**
   * Find stream index based on format-specific stream ID
   * @return stream index, or < 0 on error
   */
  int ff_find_stream_index(AVFormatContext *s, int id);
  
  /**
   * Internal version of av_index_search_timestamp
   */
  int ff_index_search_timestamp(const AVIndexEntry *entries, int nb_entries,
                                int64_t wanted_timestamp, int flags);
  
  /**
   * Internal version of av_add_index_entry
   */
  int ff_add_index_entry(AVIndexEntry **index_entries,
                         int *nb_index_entries,
                         unsigned int *index_entries_allocated_size,
                         int64_t pos, int64_t timestamp, int size, int distance, int flags);
  
  void ff_configure_buffers_for_index(AVFormatContext *s, int64_t time_tolerance);
  
  /**
   * Add a new chapter.
   *
   * @param s media file handle
   * @param id unique ID for this chapter
   * @param start chapter start time in time_base units
   * @param end chapter end time in time_base units
   * @param title chapter title
   *
   * @return AVChapter or NULL on error
   */
  AVChapter *avpriv_new_chapter(AVFormatContext *s, int id, AVRational time_base,
                                int64_t start, int64_t end, const char *title);
  
  /**
   * Ensure the index uses less memory than the maximum specified in
   * AVFormatContext.max_index_size by discarding entries if it grows
   * too large.
   */
  void ff_reduce_index(AVFormatContext *s, int stream_index);
  
  enum AVCodecID ff_guess_image2_codec(const char *filename);
  
  /**
   * Perform a binary search using av_index_search_timestamp() and
   * AVInputFormat.read_timestamp().
   *
   * @param target_ts target timestamp in the time base of the given stream
   * @param stream_index stream number
   */
  int ff_seek_frame_binary(AVFormatContext *s, int stream_index,
                           int64_t target_ts, int flags);
  
  /**
   * Update cur_dts of all streams based on the given timestamp and AVStream.
   *
   * Stream ref_st unchanged, others set cur_dts in their native time base.
   * Only needed for timestamp wrapping or if (dts not set and pts!=dts).
   * @param timestamp new dts expressed in time_base of param ref_st
   * @param ref_st reference stream giving time_base of param timestamp
   */
  void ff_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp);
  
  int ff_find_last_ts(AVFormatContext *s, int stream_index, int64_t *ts, int64_t *pos,
                      int64_t (*read_timestamp)(struct AVFormatContext *, int , int64_t *, int64_t ));
  
  /**
   * Perform a binary search using read_timestamp().
   *
   * @param target_ts target timestamp in the time base of the given stream
   * @param stream_index stream number
   */
  int64_t ff_gen_search(AVFormatContext *s, int stream_index,
                        int64_t target_ts, int64_t pos_min,
                        int64_t pos_max, int64_t pos_limit,
                        int64_t ts_min, int64_t ts_max,
                        int flags, int64_t *ts_ret,
                        int64_t (*read_timestamp)(struct AVFormatContext *, int , int64_t *, int64_t ));
  
  /**
   * Set the time base and wrapping info for a given stream. This will be used
   * to interpret the stream's timestamps. If the new time base is invalid
   * (numerator or denominator are non-positive), it leaves the stream
   * unchanged.
   *
   * @param s stream
   * @param pts_wrap_bits number of bits effectively used by the pts
   *        (used for wrap control)
   * @param pts_num time base numerator
   * @param pts_den time base denominator
   */
  void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits,
                           unsigned int pts_num, unsigned int pts_den);
  
  /**
   * Add side data to a packet for changing parameters to the given values.
   * Parameters set to 0 aren't included in the change.
   */
  int ff_add_param_change(AVPacket *pkt, int32_t channels,
                          uint64_t channel_layout, int32_t sample_rate,
                          int32_t width, int32_t height);
  
  /**
   * Set the timebase for each stream from the corresponding codec timebase and
   * print it.
   */
  int ff_framehash_write_header(AVFormatContext *s);
  
  /**
   * Read a transport packet from a media file.
   *
   * @param s media file handle
   * @param pkt is filled
   * @return 0 if OK, AVERROR_xxx on error
   */
  int ff_read_packet(AVFormatContext *s, AVPacket *pkt);
  
  /**
   * Interleave a packet per dts in an output media file.
   *
   * Packets with pkt->destruct == av_destruct_packet will be freed inside this
   * function, so they cannot be used after it. Note that calling av_packet_unref()
   * on them is still safe.
   *
   * @param s media file handle
   * @param out the interleaved packet will be output here
   * @param pkt the input packet
   * @param flush 1 if no further packets are available as input and all
   *              remaining packets should be output
   * @return 1 if a packet was output, 0 if no packet could be output,
   *         < 0 if an error occurred
   */
  int ff_interleave_packet_per_dts(AVFormatContext *s, AVPacket *out,
                                   AVPacket *pkt, int flush);
  
  void ff_free_stream(AVFormatContext *s, AVStream *st);
  
  /**
   * Return the frame duration in seconds. Return 0 if not available.
   */
  void ff_compute_frame_duration(AVFormatContext *s, int *pnum, int *pden, AVStream *st,
                                 AVCodecParserContext *pc, AVPacket *pkt);
  
  unsigned int ff_codec_get_tag(const AVCodecTag *tags, enum AVCodecID id);
  
  enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag);
  
  /**
   * Select a PCM codec based on the given parameters.
   *
   * @param bps     bits-per-sample
   * @param flt     floating-point
   * @param be      big-endian
   * @param sflags  signed flags. each bit corresponds to one byte of bit depth.
   *                e.g. the 1st bit indicates if 8-bit should be signed or
   *                unsigned, the 2nd bit indicates if 16-bit should be signed or
   *                unsigned, etc... This is useful for formats such as WAVE where
   *                only 8-bit is unsigned and all other bit depths are signed.
   * @return        a PCM codec id or AV_CODEC_ID_NONE
   */
  enum AVCodecID ff_get_pcm_codec_id(int bps, int flt, int be, int sflags);
  
  /**
   * Chooses a timebase for muxing the specified stream.
   *
   * The chosen timebase allows sample accurate timestamps based
   * on the framerate or sample rate for audio streams. It also is
   * at least as precise as 1/min_precision would be.
   */
  AVRational ff_choose_timebase(AVFormatContext *s, AVStream *st, int min_precision);
  
  /**
   * Chooses a timebase for muxing the specified stream.
   */
  enum AVChromaLocation ff_choose_chroma_location(AVFormatContext *s, AVStream *st);
  
  /**
   * Generate standard extradata for AVC-Intra based on width/height and field
   * order.
   */
  int ff_generate_avci_extradata(AVStream *st);
  
  /**
   * Add a bitstream filter to a stream.
   *
   * @param st output stream to add a filter to
   * @param name the name of the filter to add
   * @param args filter-specific argument string
   * @return  >0 on success;
   *          AVERROR code on failure
   */
  int ff_stream_add_bitstream_filter(AVStream *st, const char *name, const char *args);
  
  /**
   * Copy encoding parameters from source to destination stream
   *
   * @param dst pointer to destination AVStream
   * @param src pointer to source AVStream
   * @return >=0 on success, AVERROR code on error
   */
  int ff_stream_encode_params_copy(AVStream *dst, const AVStream *src);
  
  /**
   * Wrap errno on rename() error.
   *
   * @param oldpath source path
   * @param newpath destination path
   * @return        0 or AVERROR on failure
   */
  static inline int ff_rename(const char *oldpath, const char *newpath, void *logctx)
  {
      int ret = 0;
      if (rename(oldpath, newpath) == -1) {
          ret = AVERROR(errno);
          if (logctx) {
              char err[AV_ERROR_MAX_STRING_SIZE] = {0};
              av_make_error_string(err, AV_ERROR_MAX_STRING_SIZE, ret);
              av_log(logctx, AV_LOG_ERROR, "failed to rename file %s to %s: %s\n", oldpath, newpath, err);
          }
      }
      return ret;
  }
  
  /**
   * Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end
   * which is always set to 0.
   *
   * Previously allocated extradata in par will be freed.
   *
   * @param size size of extradata
   * @return 0 if OK, AVERROR_xxx on error
   */
  int ff_alloc_extradata(AVCodecParameters *par, int size);
  
  /**
   * Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end
   * which is always set to 0 and fill it from pb.
   *
   * @param size size of extradata
   * @return >= 0 if OK, AVERROR_xxx on error
   */
  int ff_get_extradata(AVFormatContext *s, AVCodecParameters *par, AVIOContext *pb, int size);
  
  /**
   * add frame for rfps calculation.
   *
   * @param dts timestamp of the i-th frame
   * @return 0 if OK, AVERROR_xxx on error
   */
  int ff_rfps_add_frame(AVFormatContext *ic, AVStream *st, int64_t dts);
  
  void ff_rfps_calculate(AVFormatContext *ic);
  
  /**
   * Flags for AVFormatContext.write_uncoded_frame()
   */
  enum AVWriteUncodedFrameFlags {
  
      /**
       * Query whether the feature is possible on this stream.
       * The frame argument is ignored.
       */
      AV_WRITE_UNCODED_FRAME_QUERY           = 0x0001,
  
  };
  
  /**
   * Copies the whilelists from one context to the other
   */
  int ff_copy_whiteblacklists(AVFormatContext *dst, const AVFormatContext *src);
  
  int ffio_open2_wrapper(struct AVFormatContext *s, AVIOContext **pb, const char *url, int flags,
                         const AVIOInterruptCB *int_cb, AVDictionary **options);
  
  /**
   * Returned by demuxers to indicate that data was consumed but discarded
   * (ignored streams or junk data). The framework will re-call the demuxer.
   */
  #define FFERROR_REDO FFERRTAG('R','E','D','O')
  
  /**
   * Utility function to open IO stream of output format.
   *
   * @param s AVFormatContext
   * @param url URL or file name to open for writing
   * @options optional options which will be passed to io_open callback
   * @return >=0 on success, negative AVERROR in case of failure
   */
  int ff_format_output_open(AVFormatContext *s, const char *url, AVDictionary **options);
  
  /*
   * A wrapper around AVFormatContext.io_close that should be used
   * instead of calling the pointer directly.
   */
  void ff_format_io_close(AVFormatContext *s, AVIOContext **pb);
  
  /**
   * Utility function to check if the file uses http or https protocol
   *
   * @param s AVFormatContext
   * @param filename URL or file name to open for writing
   */
  int ff_is_http_proto(char *filename);
  
  /**
   * Parse creation_time in AVFormatContext metadata if exists and warn if the
   * parsing fails.
   *
   * @param s AVFormatContext
   * @param timestamp parsed timestamp in microseconds, only set on successful parsing
   * @param return_seconds set this to get the number of seconds in timestamp instead of microseconds
   * @return 1 if OK, 0 if the metadata was not present, AVERROR(EINVAL) on parse error
   */
  int ff_parse_creation_time_metadata(AVFormatContext *s, int64_t *timestamp, int return_seconds);
  
  /**
   * Standardize creation_time metadata in AVFormatContext to an ISO-8601
   * timestamp string.
   *
   * @param s AVFormatContext
   * @return <0 on error
   */
  int ff_standardize_creation_time(AVFormatContext *s);
  
  #define CONTAINS_PAL 2
  /**
   * Reshuffles the lines to use the user specified stride.
   *
   * @param ppkt input and output packet
   * @return negative error code or
   *         0 if no new packet was allocated
   *         non-zero if a new packet was allocated and ppkt has to be freed
   *         CONTAINS_PAL if in addition to a new packet the old contained a palette
   */
  int ff_reshuffle_raw_rgb(AVFormatContext *s, AVPacket **ppkt, AVCodecParameters *par, int expected_stride);
  
  /**
   * Retrieves the palette from a packet, either from side data, or
   * appended to the video data in the packet itself (raw video only).
   * It is commonly used after a call to ff_reshuffle_raw_rgb().
   *
   * Use 0 for the ret parameter to check for side data only.
   *
   * @param pkt pointer to packet before calling ff_reshuffle_raw_rgb()
   * @param ret return value from ff_reshuffle_raw_rgb(), or 0
   * @param palette pointer to palette buffer
   * @return negative error code or
   *         1 if the packet has a palette, else 0
   */
  int ff_get_packet_palette(AVFormatContext *s, AVPacket *pkt, int ret, uint32_t *palette);
  
  /**
   * Finalize buf into extradata and set its size appropriately.
   */
  int ff_bprint_to_codecpar_extradata(AVCodecParameters *par, struct AVBPrint *buf);
  
  /**
   * Find the next packet in the interleaving queue for the given stream.
   * The pkt parameter is filled in with the queued packet, including
   * references to the data (which the caller is not allowed to keep or
   * modify).
   *
   * @return 0 if a packet was found, a negative value if no packet was found
   */
  int ff_interleaved_peek(AVFormatContext *s, int stream,
                          AVPacket *pkt, int add_offset);
  
  
  int ff_lock_avformat(void);
  int ff_unlock_avformat(void);
  
  /**
   * Set AVFormatContext url field to the provided pointer. The pointer must
   * point to a valid string. The existing url field is freed if necessary. Also
   * set the legacy filename field to the same string which was provided in url.
   */
  void ff_format_set_url(AVFormatContext *s, char *url);
  
  #define FF_PACKETLIST_FLAG_REF_PACKET (1 << 0) /**< Create a new reference for the packet instead of
                                                      transferring the ownership of the existing one to the
                                                      list. */
  
  /**
   * Append an AVPacket to the list.
   *
   * @param head  List head element
   * @param tail  List tail element
   * @param pkt   The packet being appended
   * @param flags Any combination of FF_PACKETLIST_FLAG_* flags
   * @return 0 on success, negative AVERROR value on failure. On failure,
             the list is unchanged
   */
  int ff_packet_list_put(AVPacketList **head, AVPacketList **tail,
                         AVPacket *pkt, int flags);
  
  /**
   * Remove the oldest AVPacket in the list and return it.
   *
   * @note The pkt will be overwritten completely. The caller owns the
   *       packet and must unref it by itself.
   *
   * @param head List head element
   * @param tail List tail element
   * @param pkt  Pointer to an initialized AVPacket struct
   */
  int ff_packet_list_get(AVPacketList **head, AVPacketList **tail,
                         AVPacket *pkt);
  
  /**
   * Wipe the list and unref all the packets in it.
   *
   * @param head List head element
   * @param tail List tail element
   */
  void ff_packet_list_free(AVPacketList **head, AVPacketList **tail);
  
  void avpriv_register_devices(const AVOutputFormat * const o[], const AVInputFormat * const i[]);
  
  #endif /* AVFORMAT_INTERNAL_H */
  