text: /*
   * RTMP packet utilities
   * Copyright (c) 2009 Konstantin Shishkov
   *
   * 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_RTMPPKT_H
  #define AVFORMAT_RTMPPKT_H
  
  #include "libavcodec/bytestream.h"
  #include "avformat.h"
  #include "url.h"
  
  /** maximum possible number of different RTMP channels */
  #define RTMP_CHANNELS 65599
  
  /**
   * channels used to for RTMP packets with different purposes (i.e. data, network
   * control, remote procedure calls, etc.)
   */
  enum RTMPChannel {
      RTMP_NETWORK_CHANNEL = 2,   ///< channel for network-related messages (bandwidth report, ping, etc)
      RTMP_SYSTEM_CHANNEL,        ///< channel for sending server control messages
      RTMP_SOURCE_CHANNEL,        ///< channel for sending a/v to server
      RTMP_VIDEO_CHANNEL = 8,     ///< channel for video data
      RTMP_AUDIO_CHANNEL,         ///< channel for audio data
  };
  
  /**
   * known RTMP packet types
   */
  typedef enum RTMPPacketType {
      RTMP_PT_CHUNK_SIZE   =  1,  ///< chunk size change
      RTMP_PT_BYTES_READ   =  3,  ///< number of bytes read
      RTMP_PT_PING,               ///< ping
      RTMP_PT_SERVER_BW,          ///< server bandwidth
      RTMP_PT_CLIENT_BW,          ///< client bandwidth
      RTMP_PT_AUDIO        =  8,  ///< audio packet
      RTMP_PT_VIDEO,              ///< video packet
      RTMP_PT_FLEX_STREAM  = 15,  ///< Flex shared stream
      RTMP_PT_FLEX_OBJECT,        ///< Flex shared object
      RTMP_PT_FLEX_MESSAGE,       ///< Flex shared message
      RTMP_PT_NOTIFY,             ///< some notification
      RTMP_PT_SHARED_OBJ,         ///< shared object
      RTMP_PT_INVOKE,             ///< invoke some stream action
      RTMP_PT_METADATA     = 22,  ///< FLV metadata
  } RTMPPacketType;
  
  /**
   * possible RTMP packet header sizes
   */
  enum RTMPPacketSize {
      RTMP_PS_TWELVEBYTES = 0, ///< packet has 12-byte header
      RTMP_PS_EIGHTBYTES,      ///< packet has 8-byte header
      RTMP_PS_FOURBYTES,       ///< packet has 4-byte header
      RTMP_PS_ONEBYTE          ///< packet is really a next chunk of a packet
  };
  
  /**
   * structure for holding RTMP packets
   */
  typedef struct RTMPPacket {
      int            channel_id; ///< RTMP channel ID (nothing to do with audio/video channels though)
      RTMPPacketType type;       ///< packet payload type
      uint32_t       timestamp;  ///< packet full timestamp
      uint32_t       ts_delta;   ///< timestamp increment to the previous one in milliseconds (latter only for media packets)
      uint32_t       extra;      ///< probably an additional channel ID used during streaming data
      uint8_t        *data;      ///< packet payload
      int            data_size;  ///< packet payload size
  } RTMPPacket;
  
  /**
   * Create new RTMP packet with given attributes.
   *
   * @param pkt        packet
   * @param channel_id packet channel ID
   * @param type       packet type
   * @param timestamp  packet timestamp
   * @param size       packet size
   * @return zero on success, negative value otherwise
   */
  int ff_rtmp_packet_create(RTMPPacket *pkt, int channel_id, RTMPPacketType type,
                            int timestamp, int size);
  
  /**
   * Free RTMP packet.
   *
   * @param pkt packet
   */
  void ff_rtmp_packet_destroy(RTMPPacket *pkt);
  
  /**
   * Read RTMP packet sent by the server.
   *
   * @param h          reader context
   * @param p          packet
   * @param chunk_size current chunk size
   * @param prev_pkt   previously read packet headers for all channels
   *                   (may be needed for restoring incomplete packet header)
   * @return number of bytes read on success, negative value otherwise
   */
  int ff_rtmp_packet_read(URLContext *h, RTMPPacket *p,
                          int chunk_size, RTMPPacket *prev_pkt);
  /**
   * Read internal RTMP packet sent by the server.
   *
   * @param h          reader context
   * @param p          packet
   * @param chunk_size current chunk size
   * @param prev_pkt   previously read packet headers for all channels
   *                   (may be needed for restoring incomplete packet header)
   * @param c          the first byte already read
   * @return number of bytes read on success, negative value otherwise
   */
  int ff_rtmp_packet_read_internal(URLContext *h, RTMPPacket *p, int chunk_size,
                                   RTMPPacket *prev_pkt, uint8_t c);
  
  /**
   * Send RTMP packet to the server.
   *
   * @param h          reader context
   * @param p          packet to send
   * @param chunk_size current chunk size
   * @param prev_pkt   previously sent packet headers for all channels
   *                   (may be used for packet header compressing)
   * @return number of bytes written on success, negative value otherwise
   */
  int ff_rtmp_packet_write(URLContext *h, RTMPPacket *p,
                           int chunk_size, RTMPPacket *prev_pkt);
  
  /**
   * Print information and contents of RTMP packet.
   *
   * @param ctx        output context
   * @param p          packet to dump
   */
  void ff_rtmp_packet_dump(void *ctx, RTMPPacket *p);
  
  /**
   * @name Functions used to work with the AMF format (which is also used in .flv)
   * @see amf_* funcs in libavformat/flvdec.c
   * @{
   */
  
  /**
   * Calculate number of bytes taken by first AMF entry in data.
   *
   * @param data input data
   * @param data_end input buffer end
   * @return number of bytes used by first AMF entry
   */
  int ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end);
  
  /**
   * Retrieve value of given AMF object field in string form.
   *
   * @param data     AMF object data
   * @param data_end input buffer end
   * @param name     name of field to retrieve
   * @param dst      buffer for storing result
   * @param dst_size output buffer size
   * @return 0 if search and retrieval succeeded, negative value otherwise
   */
  int ff_amf_get_field_value(const uint8_t *data, const uint8_t *data_end,
                             const uint8_t *name, uint8_t *dst, int dst_size);
  
  /**
   * Write boolean value in AMF format to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   * @param val value to write
   */
  void ff_amf_write_bool(uint8_t **dst, int val);
  
  /**
   * Write number in AMF format to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   * @param num value to write
   */
  void ff_amf_write_number(uint8_t **dst, double num);
  
  /**
   * Write string in AMF format to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   * @param str string to write
   */
  void ff_amf_write_string(uint8_t **dst, const char *str);
  
  /**
   * Write a string consisting of two parts in AMF format to a buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   * @param str1 first string to write, may be null
   * @param str2 second string to write, may be null
   */
  void ff_amf_write_string2(uint8_t **dst, const char *str1, const char *str2);
  
  /**
   * Write AMF NULL value to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   */
  void ff_amf_write_null(uint8_t **dst);
  
  /**
   * Write marker for AMF object to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   */
  void ff_amf_write_object_start(uint8_t **dst);
  
  /**
   * Write string used as field name in AMF object to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   * @param str string to write
   */
  void ff_amf_write_field_name(uint8_t **dst, const char *str);
  
  /**
   * Write marker for end of AMF object to buffer.
   *
   * @param dst pointer to the input buffer (will be modified)
   */
  void ff_amf_write_object_end(uint8_t **dst);
  
  /**
   * Read AMF boolean value.
   *
   *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
   *@param[out]    val 0 or 1
   *@return 0 on success or an AVERROR code on failure
  */
  int ff_amf_read_bool(GetByteContext *gbc, int *val);
  
  /**
   * Read AMF number value.
   *
   *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
   *@param[out]    val read value
   *@return 0 on success or an AVERROR code on failure
  */
  int ff_amf_read_number(GetByteContext *gbc, double *val);
  
  /**
   * Read AMF string value.
   *
   * Appends a trailing null byte to output string in order to
   * ease later parsing.
   *
   *@param[in,out] gbc     GetByteContext initialized with AMF-formatted data
   *@param[out]    str     read string
   *@param[in]     strsize buffer size available to store the read string
   *@param[out]    length  read string length
   *@return 0 on success or an AVERROR code on failure
  */
  int ff_amf_read_string(GetByteContext *gbc, uint8_t *str,
                         int strsize, int *length);
  
  /**
   * Read AMF NULL value.
   *
   *@param[in,out] gbc GetByteContext initialized with AMF-formatted data
   *@return 0 on success or an AVERROR code on failure
  */
  int ff_amf_read_null(GetByteContext *gbc);
  
  
  /** @} */ // AMF funcs
  
  #endif /* AVFORMAT_RTMPPKT_H */
  