求大神帮看看这行代码啥意思？

2014-12-27 03:30:16 96 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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gdal--矢量求交前言最近在帮同学写几个小程序，包括矢量数据求交（Intersection）。网上相关文章很少，所以我参考GDAL官网写了一个完整的程序（裁剪、合并、擦除、更新等功能只要修改代码的求交函数部分，下面会有说明）。代码 #include "gdal_priv.h" #include "ogrsf_frmts.h" //for ogr bool VectorIntersection(... 阅读详情

这代码有点看不懂，
VAR_DECLSPEC PayloadType payload_type_h264;
中的payload_type_h264代表啥数字？





#ifndef PAYLOADTYPE_H

#define PAYLOADTYPE_H

#include <ortp/port.h>



#ifdef __cplusplus

extern "C"{

#endif



/* flags for PayloadType::flags */



#define	PAYLOAD_TYPE_ALLOCATED (1)

	/* private flags for future use by ortp */

#define	PAYLOAD_TYPE_PRIV1 (1<<1)

#define	PAYLOAD_TYPE_PRIV2 (1<<2)

#define	PAYLOAD_TYPE_PRIV3 (1<<3)

	/* user flags, can be used by the application on top of oRTP */

#define	PAYLOAD_TYPE_USER_FLAG_0 (1<<4)

#define	PAYLOAD_TYPE_USER_FLAG_1 (1<<5)

#define	PAYLOAD_TYPE_USER_FLAG_2 (1<<6)

	/* ask for more if you need*/



#define PAYLOAD_AUDIO_CONTINUOUS 0

#define PAYLOAD_AUDIO_PACKETIZED 1

#define PAYLOAD_VIDEO 2

#define PAYLOAD_TEXT 4

#define PAYLOAD_OTHER 3  /* ?? */



struct _PayloadType

{

	int type; /**< one of PAYLOAD_* macros*/

	int clock_rate; /**< rtp clock rate*/

	char bits_per_sample;	/* in case of continuous audio data */

	char *zero_pattern;

	int pattern_length;

	/* other useful information for the application*/

	int normal_bitrate;	/*in bit/s */

	char *mime_type; /**<actually the submime, ex: pcm, pcma, gsm*/

	int channels; /**< number of channels of audio */

	char *recv_fmtp; /* various format parameters for the incoming stream */

	char *send_fmtp; /* various format parameters for the outgoing stream */

	int flags;

	void *user_data;

};



#ifndef PayloadType_defined

#define PayloadType_defined

typedef struct _PayloadType PayloadType;

#endif



#define payload_type_set_flag(pt,flag) (pt)->flags|=((int)flag)

#define payload_type_unset_flag(pt,flag) (pt)->flags&=(~(int)flag)

#define payload_type_get_flags(pt)	(pt)->flags





ORTP_PUBLIC PayloadType *payload_type_new(void);

ORTP_PUBLIC PayloadType *payload_type_clone(PayloadType *payload);

ORTP_PUBLIC char *payload_type_get_rtpmap(PayloadType *pt);

ORTP_PUBLIC void payload_type_destroy(PayloadType *pt);

ORTP_PUBLIC void payload_type_set_recv_fmtp(PayloadType *pt, const char *fmtp);

ORTP_PUBLIC void payload_type_set_send_fmtp(PayloadType *pt, const char *fmtp);

ORTP_PUBLIC void payload_type_append_recv_fmtp(PayloadType *pt, const char *fmtp);

ORTP_PUBLIC void payload_type_append_send_fmtp(PayloadType *pt, const char *fmtp);



#define payload_type_get_bitrate(pt)	((pt)->normal_bitrate)

#define payload_type_get_rate(pt)		((pt)->clock_rate)

#define payload_type_get_mime(pt)		((pt)->mime_type)



ORTP_PUBLIC bool_t fmtp_get_value(const char *fmtp, const char *param_name, char *result, size_t result_len);



#define payload_type_set_user_data(pt,p)	(pt)->user_data=(p)

#define payload_type_get_user_data(pt)		((pt)->user_data)





/* some payload types */

/* audio */

VAR_DECLSPEC PayloadType payload_type_pcmu8000;

VAR_DECLSPEC PayloadType payload_type_pcma8000;

VAR_DECLSPEC PayloadType payload_type_pcm8000;

VAR_DECLSPEC PayloadType payload_type_l16_mono;

VAR_DECLSPEC PayloadType payload_type_l16_stereo;

VAR_DECLSPEC PayloadType payload_type_lpc1016;

VAR_DECLSPEC PayloadType payload_type_g729;

VAR_DECLSPEC PayloadType payload_type_g7231;

VAR_DECLSPEC PayloadType payload_type_g7221;

VAR_DECLSPEC PayloadType payload_type_g726_40;

VAR_DECLSPEC PayloadType payload_type_g726_32;

VAR_DECLSPEC PayloadType payload_type_g726_24;

VAR_DECLSPEC PayloadType payload_type_g726_16;

VAR_DECLSPEC PayloadType payload_type_aal2_g726_40;

VAR_DECLSPEC PayloadType payload_type_aal2_g726_32;

VAR_DECLSPEC PayloadType payload_type_aal2_g726_24;

VAR_DECLSPEC PayloadType payload_type_aal2_g726_16;

VAR_DECLSPEC PayloadType payload_type_gsm;

VAR_DECLSPEC PayloadType payload_type_lpc;

VAR_DECLSPEC PayloadType payload_type_lpc1015;

VAR_DECLSPEC PayloadType payload_type_speex_nb;

VAR_DECLSPEC PayloadType payload_type_speex_wb;

VAR_DECLSPEC PayloadType payload_type_speex_uwb;

VAR_DECLSPEC PayloadType payload_type_ilbc;

VAR_DECLSPEC PayloadType payload_type_amr;

VAR_DECLSPEC PayloadType payload_type_amrwb;

VAR_DECLSPEC PayloadType payload_type_truespeech;

VAR_DECLSPEC PayloadType payload_type_evrc0;

VAR_DECLSPEC PayloadType payload_type_evrcb0;

VAR_DECLSPEC PayloadType payload_type_silk_nb;	

VAR_DECLSPEC PayloadType payload_type_silk_mb;

VAR_DECLSPEC PayloadType payload_type_silk_wb;

VAR_DECLSPEC PayloadType payload_type_silk_swb;



	/* video */

VAR_DECLSPEC PayloadType payload_type_mpv;

VAR_DECLSPEC PayloadType payload_type_h261;

VAR_DECLSPEC PayloadType payload_type_h263;

VAR_DECLSPEC PayloadType payload_type_h263_1998;

VAR_DECLSPEC PayloadType payload_type_h263_2000;

VAR_DECLSPEC PayloadType payload_type_mp4v;

VAR_DECLSPEC PayloadType payload_type_theora;

VAR_DECLSPEC PayloadType payload_type_h264;

VAR_DECLSPEC PayloadType payload_type_x_snow;

VAR_DECLSPEC PayloadType payload_type_jpeg;

VAR_DECLSPEC PayloadType payload_type_vp8;



VAR_DECLSPEC PayloadType payload_type_g722;



/* text */

VAR_DECLSPEC PayloadType payload_type_t140;

VAR_DECLSPEC PayloadType payload_type_t140_red;



/* non standard file transfer over UDP */

VAR_DECLSPEC PayloadType payload_type_x_udpftp;



/* telephone-event */

VAR_DECLSPEC PayloadType payload_type_telephone_event;



#ifdef __cplusplus

}

#endif



#endif