最简单的基于FFmpeg的AVUtil样例 (AVLog, AVOption等)

本文的演示样例程序记录了FFmpeg的libavutil中几种工具函数的用法：

AVLog：日志输出
AVOption (AVClass)：选项设置
AVDictionary：键值对存储
ParseUtil：字符串解析

几个libavutil的工具

AVLog

AVLog是FFmpeg的日志输出工具。在FFmpeg中全部的日志输出不是通过printf()函数而是通过av_log()函数。av_log()会终于调用fprintf(stderr,…)函数将日志内容输出到命令行界面上。可是在一些非命令行程序（MFC程序，Android程序等）中。av_log()调用的fprintf(stderr,…)就无法将日志内容显示出来了。

对于这样的情况，FFmpeg提供了日志回调函数av_log_set_callback()。

该函数能够指定一个自己定义的日志输出函数，将日志输出到指定的位置。

以下的自己定义函数custom_output()将日志输出到了“simplest_ffmpeg_log.txt”文本中。

void custom_output(void* ptr, int level, const char* fmt,va_list vl){
	FILE *fp = fopen("simplest_ffmpeg_log.txt","a+");   
	if(fp){   
		vfprintf(fp,fmt,vl);
		fflush(fp);
		fclose(fp);
	}   
}

在主函数中调用av_log_set_callback()设置一下该函数就能够了，例如以下所看到的。

int main(int argc, char* argv[])
{
	av_log_set_callback(custom_output);
	return 0;
}

此外。日志信息从重到轻分为Panic、Fatal、Error、Warning、Info、Verbose、Debug几个级别。以下的函数输出了几种不同级别的日志。

void test_log(){
	av_register_all();
	AVFormatContext *obj=NULL;
	obj=avformat_alloc_context();
	printf("====================================
");
	av_log(obj,AV_LOG_PANIC,"Panic: Something went really wrong and we will crash now.
");
	av_log(obj,AV_LOG_FATAL,"Fatal: Something went wrong and recovery is not possible.
");
	av_log(obj,AV_LOG_ERROR,"Error: Something went wrong and cannot losslessly be recovered.
");
	av_log(obj,AV_LOG_WARNING,"Warning: This may or may not lead to problems.
");
	av_log(obj,AV_LOG_INFO,"Info: Standard information.
");
	av_log(obj,AV_LOG_VERBOSE,"Verbose: Detailed information.
");
	av_log(obj,AV_LOG_DEBUG,"Debug: Stuff which is only useful for libav* developers.
");
	printf("====================================
");
	avformat_free_context(obj);
}

PS：该部分源码的解析能够參考文章《FFmpeg源码简单分析：日志输出系统（av_log()等）》

AVOption (AVClass)

AVOption是FFmpeg的选项设置工具。与AVOption最相关的选项设置函数就是av_opt_set()了。AVOption的核心概念就是“依据字符串操作结构体的属性值”。比如以下代码中“#if”和“#else”之间代码的作用和“#else”和“#endif”之间代码的作用是一样的。

#if TEST_OPT
	av_opt_set(pCodecCtx,"b","400000",0);		//bitrate
	//Another method
	//av_opt_set_int(pCodecCtx,"b",400000,0);	//bitrate

	av_opt_set(pCodecCtx,"time_base","1/25",0);	//time_base
	av_opt_set(pCodecCtx,"bf","5",0);			//max b frame
	av_opt_set(pCodecCtx,"g","25",0);			//gop
	av_opt_set(pCodecCtx,"qmin","10",0);		//qmin/qmax
	av_opt_set(pCodecCtx,"qmax","51",0);
#else
	pCodecCtx->time_base.num = 1;  
	pCodecCtx->time_base.den = 25;  
	pCodecCtx->max_b_frames=5;
	pCodecCtx->bit_rate = 400000;  
	pCodecCtx->gop_size=25;
	pCodecCtx->qmin = 10;
	pCodecCtx->qmax = 51;
#endif

同理。av_opt_get()能够将结构体的属性值以字符串的形式返回回来。

比如以下这段代码就验证了av_opt_get()的作用：

		char *val_str=(char *)av_malloc(50);

		//preset: ultrafast, superfast, veryfast, faster, fast, 
		//medium, slow, slower, veryslow, placebo
		av_opt_set(pCodecCtx->priv_data,"preset","slow",0);
		//tune: film, animation, grain, stillimage, psnr, 
		//ssim, fastdecode, zerolatency
		av_opt_set(pCodecCtx->priv_data,"tune","zerolatency",0);
		//profile: baseline, main, high, high10, high422, high444
		av_opt_set(pCodecCtx->priv_data,"profile","main",0);

		//print
		av_opt_get(pCodecCtx->priv_data,"preset",0,(uint8_t **)&val_str);
		printf("preset val: %s
",val_str);
		av_opt_get(pCodecCtx->priv_data,"tune",0,(uint8_t **)&val_str);
		printf("tune val: %s
",val_str);
		av_opt_get(pCodecCtx->priv_data,"profile",0,(uint8_t **)&val_str);
		printf("profile val: %s
",val_str);
		av_free(val_str);

能够通过av_opt_find()获取结构体中随意选项的AVOption结构体。

写了一个简单的函数读取该结构体中一些字段的值。

void print_opt(const AVOption *opt_test){

	printf("====================================
");
	printf("Option Information:
");
	printf("[name]%s
",opt_test->name);
	printf("[help]%s
",opt_test->help);
	printf("[offset]%d
",opt_test->offset);

	switch(opt_test->type){
	case AV_OPT_TYPE_INT:{
		printf("[type]int
[default]%d
",opt_test->default_val.i64);
		break;
						 }
	case AV_OPT_TYPE_INT64:{
		printf("[type]int64
[default]%lld
",opt_test->default_val.i64);
		break;
						   }
	case AV_OPT_TYPE_FLOAT:{
		printf("[type]float
[default]%f
",opt_test->default_val.dbl);
		break;
						   }
	case AV_OPT_TYPE_STRING:{
		printf("[type]string
[default]%s
",opt_test->default_val.str);
		break;
							}
	case AV_OPT_TYPE_RATIONAL:{
		printf("[type]rational
[default]%d/%d
",opt_test->default_val.q.num,opt_test->default_val.q.den);
		break;
							  }
	default:{
		printf("[type]others
");
		break;
			}
	}

	printf("[max val]%f
",opt_test->max);
	printf("[min val]%f
",opt_test->min);

	if(opt_test->flags&AV_OPT_FLAG_ENCODING_PARAM){
		printf("Encoding param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_DECODING_PARAM){
		printf("Decoding param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_AUDIO_PARAM){
		printf("Audio param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_VIDEO_PARAM){
		printf("Video param.
");
	}
	if(opt_test->unit!=NULL)
		printf("Unit belong to:%s
",opt_test->unit);

	printf("====================================
");
}

使用下列代码调用上面的函数就能够打印出AVOption结构体每一个字段的值。

	const AVOption *opt=NULL;
	opt=av_opt_find(pCodecCtx, "b", NULL, 0, 0);
	print_opt(opt);
	opt=av_opt_find(pCodecCtx, "g", NULL, 0, 0);
	print_opt(opt);
	opt=av_opt_find(pCodecCtx, "time_base", NULL, 0, 0);
	print_opt(opt);

以下代码能够打印出支持AVOption（即包括AVClass）的结构体的全部选项：

void list_obj_opt(void *obj){
	printf("Output some option info about object:
");
	printf("Object name:%s
",(*(AVClass **) obj)->class_name);
	printf("=====================================
");
	printf("Video param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_VIDEO_PARAM,NULL);
	printf("Audio param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_AUDIO_PARAM,NULL);
	printf("Decoding param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_DECODING_PARAM,NULL);
	printf("Encoding param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_ENCODING_PARAM,NULL);
	printf("====================================
");
}

以下代码调用上面的函数就能够打印出AVFormatContext中的全部选项。

void test_opt(){
	av_register_all();
	AVFormatContext *obj=NULL;
	obj=avformat_alloc_context();
	list_obj_opt(obj);
	avformat_free_context(obj);
}

PS：该部分源码的解析能够參考文章《FFmpeg源码简单分析：结构体成员管理系统-AVClass》、《FFmpeg源码简单分析：结构体成员管理系统-AVOption》。

AVDictionary

AVDictionary是FFmpeg的键值对存储工具，FFmpeg常常使用AVDictionary设置/读取内部參数。以下这段代码记录了AVDictionary的用法。

void test_avdictionary(){

	AVDictionary *d = NULL;
	AVDictionaryEntry *t = NULL;

	av_dict_set(&d, "name", "lei xiaohua", 0);
	av_dict_set(&d, "email", "leixiaohua1020@126.com", 0);
	av_dict_set(&d, "school", "cuc", 0);
	av_dict_set(&d, "gender", "man", 0);
	av_dict_set(&d, "website", "http://blog.csdn.net/leixiaohua1020", 0);
	//av_strdup()
	char *k = av_strdup("location");
	char *v = av_strdup("Beijing-China");
	av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
	printf("====================================
");
	int dict_cnt= av_dict_count(d);
	printf("dict_count:%d
",dict_cnt);
	printf("dict_element:
");
	while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
		printf("key:%10s  |  value:%s
",t->key,t->value);
	}

	t = av_dict_get(d, "email", t, AV_DICT_IGNORE_SUFFIX);
	printf("email is %s
",t->value);
	printf("====================================
");
	av_dict_free(&d);
}

ParseUtil

ParseUtil是FFmpeg的字符串解析工具。

它的分辨率解析函数av_parse_video_size()能够从形如“1920x1080”的字符串中解析出图像宽为1920，高为1080；它的帧率函数av_parse_video_rate()能够解析出帧率信息。它的时间解析函数则能够从形如“00:01:01”的字符串解析出时间的毫秒数。以下这段代码记录了ParseUtil的用法。

void test_parseutil(){
	char input_str[100]={0};
	printf("========= Parse Video Size =========
");
	int output_w=0;
	int output_h=0;
	strcpy(input_str,"1920x1080");
	av_parse_video_size(&output_w,&output_h,input_str);
	printf("w:%4d | h:%4d
",output_w,output_h);
	strcpy(input_str,"vga");
	//strcpy(input_str,"hd1080");
	//strcpy(input_str,"ntsc");
	av_parse_video_size(&output_w,&output_h,input_str);
	printf("w:%4d | h:%4d
",output_w,output_h);
	printf("========= Parse Frame Rate =========
");
	AVRational output_rational={0,0};
	strcpy(input_str,"15/1");
	av_parse_video_rate(&output_rational,input_str);
	printf("framerate:%d/%d
",output_rational.num,output_rational.den);
	strcpy(input_str,"pal");
	av_parse_video_rate(&output_rational,input_str);
	printf("framerate:%d/%d
",output_rational.num,output_rational.den);
	printf("=========== Parse Time =============
");
	int64_t output_timeval;
	strcpy(input_str,"00:01:01");
	av_parse_time(&output_timeval,input_str,1);
	printf("microseconds:%lld
",output_timeval);
	printf("====================================
");
}

源码

/**
 * 最简单的FFmpeg的AVUtil演示样例
 * Simplest FFmpeg AVUtil
 *
 * 雷霄骅 Lei Xiaohua
 * leixiaohua1020@126.com
 * 中国传媒大学/数字电视技术
 * Communication University of China / Digital TV Technology
 * http://blog.csdn.net/leixiaohua1020
 *
 * 本程序是FFmpeg中的libavutil的演示样例。眼下包括：
 * AVLog
 * AVOption (AVClass)
 * AVDictionary
 * ParseUtil
 *
 * This software is the example about FFmpeg's libavutil.
 * It contains:
 * AVLog
 * AVOption (AVClass)
 * AVDictionary
 * ParseUtil 
 *
 */

#include <stdio.h>

#define __STDC_CONSTANT_MACROS

#ifdef _WIN32
//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libavutil/opt.h"
#include "libavutil/parseutils.h"
#include "libavutil/avutil.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/opt.h>
#include <libavutil/parseutils.h>
#include <libavutil/avutil.h>
#ifdef __cplusplus
};
#endif
#endif


#define TEST_OPT	1
#define TEST_LOG	1
#define TEST_DIC	0


void list_obj_opt(void *obj){
	printf("Output some option info about object:
");
	printf("Object name:%s
",(*(AVClass **) obj)->class_name);
	printf("=====================================
");
	printf("Video param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_VIDEO_PARAM,NULL);
	printf("Audio param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_AUDIO_PARAM,NULL);
	printf("Decoding param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_DECODING_PARAM,NULL);
	printf("Encoding param:
");
	av_opt_show2(obj,stderr,AV_OPT_FLAG_ENCODING_PARAM,NULL);
	printf("====================================
");
}

void test_opt(){
	av_register_all();
	AVFormatContext *obj=NULL;
	obj=avformat_alloc_context();
	list_obj_opt(obj);
	avformat_free_context(obj);
}


void test_log(){
	av_register_all();
	AVFormatContext *obj=NULL;
	obj=avformat_alloc_context();
	printf("====================================
");
	av_log(obj,AV_LOG_PANIC,"Panic: Something went really wrong and we will crash now.
");
	av_log(obj,AV_LOG_FATAL,"Fatal: Something went wrong and recovery is not possible.
");
	av_log(obj,AV_LOG_ERROR,"Error: Something went wrong and cannot losslessly be recovered.
");
	av_log(obj,AV_LOG_WARNING,"Warning: This may or may not lead to problems.
");
	av_log(obj,AV_LOG_INFO,"Info: Standard information.
");
	av_log(obj,AV_LOG_VERBOSE,"Verbose: Detailed information.
");
	av_log(obj,AV_LOG_DEBUG,"Debug: Stuff which is only useful for libav* developers.
");
	printf("====================================
");
	avformat_free_context(obj);
}

void print_opt(const AVOption *opt_test){

	printf("====================================
");
	printf("Option Information:
");
	printf("[name]%s
",opt_test->name);
	printf("[help]%s
",opt_test->help);
	printf("[offset]%d
",opt_test->offset);

	switch(opt_test->type){
	case AV_OPT_TYPE_INT:{
		printf("[type]int
[default]%d
",opt_test->default_val.i64);
		break;
						 }
	case AV_OPT_TYPE_INT64:{
		printf("[type]int64
[default]%lld
",opt_test->default_val.i64);
		break;
						   }
	case AV_OPT_TYPE_FLOAT:{
		printf("[type]float
[default]%f
",opt_test->default_val.dbl);
		break;
						   }
	case AV_OPT_TYPE_STRING:{
		printf("[type]string
[default]%s
",opt_test->default_val.str);
		break;
							}
	case AV_OPT_TYPE_RATIONAL:{
		printf("[type]rational
[default]%d/%d
",opt_test->default_val.q.num,opt_test->default_val.q.den);
		break;
							  }
	default:{
		printf("[type]others
");
		break;
			}
	}

	printf("[max val]%f
",opt_test->max);
	printf("[min val]%f
",opt_test->min);

	if(opt_test->flags&AV_OPT_FLAG_ENCODING_PARAM){
		printf("Encoding param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_DECODING_PARAM){
		printf("Decoding param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_AUDIO_PARAM){
		printf("Audio param.
");
	}
	if(opt_test->flags&AV_OPT_FLAG_VIDEO_PARAM){
		printf("Video param.
");
	}
	if(opt_test->unit!=NULL)
		printf("Unit belong to:%s
",opt_test->unit);

	printf("====================================
");
}

int flush_encoder(AVFormatContext *fmt_ctx,unsigned int stream_index)
{
	int ret;
	int got_frame;
	AVPacket enc_pkt;
	if (!(fmt_ctx->streams[stream_index]->codec->codec->capabilities &
		CODEC_CAP_DELAY))
		return 0;
	while (1) {
		printf("Flushing stream #%u encoder
", stream_index);
		enc_pkt.data = NULL;
		enc_pkt.size = 0;
		av_init_packet(&enc_pkt);
		ret = avcodec_encode_video2 (fmt_ctx->streams[stream_index]->codec, &enc_pkt,
			NULL, &got_frame);
		av_frame_free(NULL);
		if (ret < 0)
			break;
		if (!got_frame){
			ret=0;
			break;
		}
		printf("Succeed to encode 1 frame!
");
		/* mux encoded frame */
		ret = av_write_frame(fmt_ctx, &enc_pkt);
		if (ret < 0)
			break;
	}
	return ret;
}

int encoder(){
	AVFormatContext* pFormatCtx;
	AVStream* video_st;
	AVCodecContext* pCodecCtx;
	AVCodec* pCodec;

	uint8_t* picture_buf;
	AVFrame* picture;
	int size;
	int ret;
	AVPacket pkt;
	int y_size;

	FILE *in_file = fopen("ds_480x272.yuv", "rb");	//Input YUV data
	int in_w=480,in_h=272;                          //Input width and height
	//Frames to encode
	int framenum=100;
	const char* out_file = "ds.h264";	            //Output Filepath
	//const char* out_file = "ds.ts";
	//const char* out_file = "ds.hevc";
	char temp_str[250]={0};

	av_register_all();
	
	avformat_alloc_output_context2(&pFormatCtx, NULL, NULL, out_file);

	if (avio_open(&pFormatCtx->pb,out_file, AVIO_FLAG_READ_WRITE) < 0){
		printf("Failed to open output file!
");
		return -1;
	}

	pCodec = avcodec_find_encoder(pFormatCtx->oformat->video_codec);
	if (!pCodec) {
		fprintf(stderr, "Codec not found.
");
		return -1;
	}
	video_st = avformat_new_stream(pFormatCtx, pCodec);
	video_st->time_base.num = 1; 
	video_st->time_base.den = 25;  

	if (video_st==NULL){
		return -1;
	}
	//Param that must set
	pCodecCtx = video_st->codec;
	pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
	pCodecCtx->pix_fmt = PIX_FMT_YUV420P;
	pCodecCtx->width = in_w;  
	pCodecCtx->height = in_h;

#if TEST_OPT
	av_opt_set(pCodecCtx,"b","400000",0);		//bitrate
	//Another method
	//av_opt_set_int(pCodecCtx,"b",400000,0);	//bitrate

	av_opt_set(pCodecCtx,"time_base","1/25",0);	//time_base
	av_opt_set(pCodecCtx,"bf","5",0);			//max b frame
	av_opt_set(pCodecCtx,"g","25",0);			//gop
	av_opt_set(pCodecCtx,"qmin","10",0);		//qmin/qmax
	av_opt_set(pCodecCtx,"qmax","51",0);
#else
	pCodecCtx->time_base.num = 1;  
	pCodecCtx->time_base.den = 25;  
	pCodecCtx->max_b_frames=5;
	pCodecCtx->bit_rate = 400000;  
	pCodecCtx->gop_size=25;
	pCodecCtx->qmin = 10;
	pCodecCtx->qmax = 51;
#endif

#if TEST_OPT
	//list_obj_opt(pFormatCtx);
	//list_obj_opt(pCodecCtx);
	const AVOption *opt=NULL;
	opt=av_opt_find(pCodecCtx, "b", NULL, 0, 0);
	print_opt(opt);
	opt=av_opt_find(pCodecCtx, "g", NULL, 0, 0);
	print_opt(opt);
	opt=av_opt_find(pCodecCtx, "time_base", NULL, 0, 0);
	print_opt(opt);
	//Get Option
	//Get String
	int64_t *val_str=(int64_t *)av_malloc(1*sizeof(int64_t));
	av_opt_get(pCodecCtx,"b",0,(uint8_t **)&val_str);
	printf("get bitrate(str):%s
",val_str);
	av_free(val_str);
	//Get int
	int64_t val_int=0;
	av_opt_get_int(pCodecCtx,"b",0,&val_int);
	printf("get bitrate(int):%lld
",val_int);
#endif

	AVDictionary *param = 0;

	//H.264
	if(pCodecCtx->codec_id == AV_CODEC_ID_H264) {
		char *val_str=(char *)av_malloc(50);
		//List it
		//list_obj_opt(pCodecCtx->priv_data);

		//preset: ultrafast, superfast, veryfast, faster, fast, 
		//medium, slow, slower, veryslow, placebo
		av_opt_set(pCodecCtx->priv_data,"preset","slow",0);
		//tune: film, animation, grain, stillimage, psnr, 
		//ssim, fastdecode, zerolatency
		av_opt_set(pCodecCtx->priv_data,"tune","zerolatency",0);
		//profile: baseline, main, high, high10, high422, high444
		av_opt_set(pCodecCtx->priv_data,"profile","main",0);

		//print
		av_opt_get(pCodecCtx->priv_data,"preset",0,(uint8_t **)&val_str);
		printf("preset val: %s
",val_str);
		av_opt_get(pCodecCtx->priv_data,"tune",0,(uint8_t **)&val_str);
		printf("tune val: %s
",val_str);
		av_opt_get(pCodecCtx->priv_data,"profile",0,(uint8_t **)&val_str);
		printf("profile val: %s
",val_str);
		av_free(val_str);

#if TEST_DIC
		av_dict_set(¶m, "preset", "slow", 0);  
		av_dict_set(¶m, "tune", "zerolatency", 0);  
		//av_dict_set(¶m, "profile", "main", 0);  
#endif
	}
	//H.265
	if(pCodecCtx->codec_id == AV_CODEC_ID_H265){
		//list_obj_opt(pCodecCtx->priv_data);

		//preset: ultrafast, superfast, veryfast, faster, fast, 
		//medium, slow, slower, veryslow, placebo
		av_opt_set(pCodecCtx->priv_data, "preset", "ultrafast", 0);
		//tune: psnr, ssim, zerolatency, fastdecode
		av_opt_set(pCodecCtx->priv_data, "tune", "zero-latency", 0);
		//profile: main, main10, mainstillpicture
		av_opt_set(pCodecCtx->priv_data,"profile","main",0);
	}

	if (avcodec_open2(pCodecCtx, pCodec,¶m) < 0){
		printf("Failed to open encoder!
");
		return -1;
	}

	picture = avcodec_alloc_frame();
	size = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);
	picture_buf = (uint8_t *)av_malloc(size);
	avpicture_fill((AVPicture *)picture, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);

	//Write File Header
	avformat_write_header(pFormatCtx,NULL);

	y_size = pCodecCtx->width * pCodecCtx->height;
	av_new_packet(&pkt,y_size*3);

	for (int i=0; i<framenum; i++){
		//Read YUV
		if (fread(picture_buf, 1, y_size*3/2, in_file) < 0){
			printf("Failed to read YUV data!
");
			return -1;
		}else if(feof(in_file)){
			break;
		}
		picture->data[0] = picture_buf;              // Y
		picture->data[1] = picture_buf+ y_size;      // U 
		picture->data[2] = picture_buf+ y_size*5/4;  // V
		//PTS
		picture->pts=i;
		int got_picture=0;
		//Encode
		ret = avcodec_encode_video2(pCodecCtx, &pkt,picture, &got_picture);
		if(ret < 0){
			printf("Failed to encode!
");
			return -1;
		}
		if (got_picture==1){
			//printf("Succeed to encode 1 frame!
");
			pkt.stream_index = video_st->index;
			ret = av_write_frame(pFormatCtx, &pkt);
			av_free_packet(&pkt);
		}
	}
	//Flush Encoder
	ret = flush_encoder(pFormatCtx,0);
	if (ret < 0) {
		printf("Flushing encoder failed
");
		return -1;
	}

	//Write file trailer
	av_write_trailer(pFormatCtx);

	//Clean
	if (video_st){
		avcodec_close(video_st->codec);
		av_free(picture);
		av_free(picture_buf);
	}
	avio_close(pFormatCtx->pb);
	avformat_free_context(pFormatCtx);

	fclose(in_file);
	return 0;
}

void custom_output(void* ptr, int level, const char* fmt,va_list vl){
	FILE *fp = fopen("simplest_ffmpeg_log.txt","a+");   
	if(fp){   
		vfprintf(fp,fmt,vl);
		fflush(fp);
		fclose(fp);
	}   
}

void test_parseutil(){
	char input_str[100]={0};
	printf("========= Parse Video Size =========
");
	int output_w=0;
	int output_h=0;
	strcpy(input_str,"1920x1080");
	av_parse_video_size(&output_w,&output_h,input_str);
	printf("w:%4d | h:%4d
",output_w,output_h);
	strcpy(input_str,"vga");
	//strcpy(input_str,"hd1080");
	//strcpy(input_str,"ntsc");
	av_parse_video_size(&output_w,&output_h,input_str);
	printf("w:%4d | h:%4d
",output_w,output_h);
	printf("========= Parse Frame Rate =========
");
	AVRational output_rational={0,0};
	strcpy(input_str,"15/1");
	av_parse_video_rate(&output_rational,input_str);
	printf("framerate:%d/%d
",output_rational.num,output_rational.den);
	strcpy(input_str,"pal");
	av_parse_video_rate(&output_rational,input_str);
	printf("framerate:%d/%d
",output_rational.num,output_rational.den);
	printf("=========== Parse Time =============
");
	int64_t output_timeval;
	strcpy(input_str,"00:01:01");
	av_parse_time(&output_timeval,input_str,1);
	printf("microseconds:%lld
",output_timeval);
	printf("====================================
");
}

void test_avdictionary(){

	AVDictionary *d = NULL;
	AVDictionaryEntry *t = NULL;

	av_dict_set(&d, "name", "lei xiaohua", 0);
	av_dict_set(&d, "email", "leixiaohua1020@126.com", 0);
	av_dict_set(&d, "school", "cuc", 0);
	av_dict_set(&d, "gender", "man", 0);
	av_dict_set(&d, "website", "http://blog.csdn.net/leixiaohua1020", 0);
	//av_strdup()
	char *k = av_strdup("location");
	char *v = av_strdup("Beijing-China");
	av_dict_set(&d, k, v, AV_DICT_DONT_STRDUP_KEY | AV_DICT_DONT_STRDUP_VAL);
	printf("====================================
");
	int dict_cnt= av_dict_count(d);
	printf("dict_count:%d
",dict_cnt);
	printf("dict_element:
");
	while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
		printf("key:%10s  |  value:%s
",t->key,t->value);
	}

	t = av_dict_get(d, "email", t, AV_DICT_IGNORE_SUFFIX);
	printf("email is %s
",t->value);
	printf("====================================
");
	av_dict_free(&d);
}

int main(int argc, char* argv[])
{
	int loglevel=av_log_get_level();
	av_log_set_level(AV_LOG_DEBUG);
	//av_log_set_flags(AV_LOG_PRINT_LEVEL);
	//av_log_set_callback(custom_output);
	test_log();

	test_avdictionary();
	test_parseutil();

	//test_opt();

	encoder();

	return 0;
}

执行结果

不同级别的AVLog日志输出后的结果：

 

结构体中全部AVOption信息输出后的结果：

 

AVDictionary演示样例输出的结果：

 

ParseUtil演示样例输出的结果：

 

编码的时候设置回调函数后输出到文本中的日志：

 

下载

Simplest FFmpeg AVUtil

项目主页
SourceForge：https://sourceforge.net/projects/simplestffmpegavutil/
Github：https://github.com/leixiaohua1020/simplest_ffmpeg_avutil
开源中国：http://git.oschina.net/leixiaohua1020/simplest_ffmpeg_avutil

CSDN下载地址：http://download.csdn.net/detail/leixiaohua1020/8924311

本程序是FFmpeg中的libavutil的演示样例，眼下包括：

AVLog
AVOption (AVClass)
AVDictionary
ParseUtil