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：
![最简单的基于FFmpeg的AVUtil样例 (AVLog, AVOption等)-LMLPHP]( "最简单的基于FFmpeg的AVUtil样例 (AVLog, AVOption等)-LMLPHP")
![最简单的基于FFmpeg的AVUtil样例 (AVLog, AVOption等)-LMLPHP]( "最简单的基于FFmpeg的AVUtil样例 (AVLog, AVOption等)-LMLPHP")
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("====================================\n");
av_log(obj,AV_LOG_PANIC,"Panic: Something went really wrong and we will crash now.\n");
av_log(obj,AV_LOG_FATAL,"Fatal: Something went wrong and recovery is not possible.\n");
av_log(obj,AV_LOG_ERROR,"Error: Something went wrong and cannot losslessly be recovered.\n");
av_log(obj,AV_LOG_WARNING,"Warning: This may or may not lead to problems.\n");
av_log(obj,AV_LOG_INFO,"Info: Standard information.\n");
av_log(obj,AV_LOG_VERBOSE,"Verbose: Detailed information.\n");
av_log(obj,AV_LOG_DEBUG,"Debug: Stuff which is only useful for libav* developers.\n");
printf("====================================\n");
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\n",val_str);
av_opt_get(pCodecCtx->priv_data,"tune",0,(uint8_t **)&val_str);
printf("tune val: %s\n",val_str);
av_opt_get(pCodecCtx->priv_data,"profile",0,(uint8_t **)&val_str);
printf("profile val: %s\n",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("====================================\n");
printf("Option Information:\n");
printf("[name]%s\n",opt_test->name);
printf("[help]%s\n",opt_test->help);
printf("[offset]%d\n",opt_test->offset);
switch(opt_test->type){
case AV_OPT_TYPE_INT:{
printf("[type]int\n[default]%d\n",opt_test->default_val.i64);
break;
}
case AV_OPT_TYPE_INT64:{
printf("[type]int64\n[default]%lld\n",opt_test->default_val.i64);
break;
}
case AV_OPT_TYPE_FLOAT:{
printf("[type]float\n[default]%f\n",opt_test->default_val.dbl);
break;
}
case AV_OPT_TYPE_STRING:{
printf("[type]string\n[default]%s\n",opt_test->default_val.str);
break;
}
case AV_OPT_TYPE_RATIONAL:{
printf("[type]rational\n[default]%d/%d\n",opt_test->default_val.q.num,opt_test->default_val.q.den);
break;
}
default:{
printf("[type]others\n");
break;
}
}
printf("[max val]%f\n",opt_test->max);
printf("[min val]%f\n",opt_test->min);
if(opt_test->flags&AV_OPT_FLAG_ENCODING_PARAM){
printf("Encoding param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_DECODING_PARAM){
printf("Decoding param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_AUDIO_PARAM){
printf("Audio param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_VIDEO_PARAM){
printf("Video param.\n");
}
if(opt_test->unit!=NULL)
printf("Unit belong to:%s\n",opt_test->unit);
printf("====================================\n");
}
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:\n");
printf("Object name:%s\n",(*(AVClass **) obj)->class_name);
printf("=====================================\n");
printf("Video param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_VIDEO_PARAM,NULL);
printf("Audio param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_AUDIO_PARAM,NULL);
printf("Decoding param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_DECODING_PARAM,NULL);
printf("Encoding param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_ENCODING_PARAM,NULL);
printf("====================================\n");
}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", "[email protected]", 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("====================================\n");
int dict_cnt= av_dict_count(d);
printf("dict_count:%d\n",dict_cnt);
printf("dict_element:\n");
while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
printf("key:%10s | value:%s\n",t->key,t->value);
}
t = av_dict_get(d, "email", t, AV_DICT_IGNORE_SUFFIX);
printf("email is %s\n",t->value);
printf("====================================\n");
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 =========\n");
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\n",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\n",output_w,output_h);
printf("========= Parse Frame Rate =========\n");
AVRational output_rational={0,0};
strcpy(input_str,"15/1");
av_parse_video_rate(&output_rational,input_str);
printf("framerate:%d/%d\n",output_rational.num,output_rational.den);
strcpy(input_str,"pal");
av_parse_video_rate(&output_rational,input_str);
printf("framerate:%d/%d\n",output_rational.num,output_rational.den);
printf("=========== Parse Time =============\n");
int64_t output_timeval;
strcpy(input_str,"00:01:01");
av_parse_time(&output_timeval,input_str,1);
printf("microseconds:%lld\n",output_timeval);
printf("====================================\n");
}
源码
/**
* 最简单的FFmpeg的AVUtil演示样例
* Simplest FFmpeg AVUtil
*
* 雷霄骅 Lei Xiaohua
* [email protected]
* 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:\n");
printf("Object name:%s\n",(*(AVClass **) obj)->class_name);
printf("=====================================\n");
printf("Video param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_VIDEO_PARAM,NULL);
printf("Audio param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_AUDIO_PARAM,NULL);
printf("Decoding param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_DECODING_PARAM,NULL);
printf("Encoding param:\n");
av_opt_show2(obj,stderr,AV_OPT_FLAG_ENCODING_PARAM,NULL);
printf("====================================\n");
} 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("====================================\n");
av_log(obj,AV_LOG_PANIC,"Panic: Something went really wrong and we will crash now.\n");
av_log(obj,AV_LOG_FATAL,"Fatal: Something went wrong and recovery is not possible.\n");
av_log(obj,AV_LOG_ERROR,"Error: Something went wrong and cannot losslessly be recovered.\n");
av_log(obj,AV_LOG_WARNING,"Warning: This may or may not lead to problems.\n");
av_log(obj,AV_LOG_INFO,"Info: Standard information.\n");
av_log(obj,AV_LOG_VERBOSE,"Verbose: Detailed information.\n");
av_log(obj,AV_LOG_DEBUG,"Debug: Stuff which is only useful for libav* developers.\n");
printf("====================================\n");
avformat_free_context(obj);
} void print_opt(const AVOption *opt_test){ printf("====================================\n");
printf("Option Information:\n");
printf("[name]%s\n",opt_test->name);
printf("[help]%s\n",opt_test->help);
printf("[offset]%d\n",opt_test->offset); switch(opt_test->type){
case AV_OPT_TYPE_INT:{
printf("[type]int\n[default]%d\n",opt_test->default_val.i64);
break;
}
case AV_OPT_TYPE_INT64:{
printf("[type]int64\n[default]%lld\n",opt_test->default_val.i64);
break;
}
case AV_OPT_TYPE_FLOAT:{
printf("[type]float\n[default]%f\n",opt_test->default_val.dbl);
break;
}
case AV_OPT_TYPE_STRING:{
printf("[type]string\n[default]%s\n",opt_test->default_val.str);
break;
}
case AV_OPT_TYPE_RATIONAL:{
printf("[type]rational\n[default]%d/%d\n",opt_test->default_val.q.num,opt_test->default_val.q.den);
break;
}
default:{
printf("[type]others\n");
break;
}
} printf("[max val]%f\n",opt_test->max);
printf("[min val]%f\n",opt_test->min); if(opt_test->flags&AV_OPT_FLAG_ENCODING_PARAM){
printf("Encoding param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_DECODING_PARAM){
printf("Decoding param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_AUDIO_PARAM){
printf("Audio param.\n");
}
if(opt_test->flags&AV_OPT_FLAG_VIDEO_PARAM){
printf("Video param.\n");
}
if(opt_test->unit!=NULL)
printf("Unit belong to:%s\n",opt_test->unit); printf("====================================\n");
} 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\n", 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!\n");
/* 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!\n");
return -1;
} pCodec = avcodec_find_encoder(pFormatCtx->oformat->video_codec);
if (!pCodec) {
fprintf(stderr, "Codec not found.\n");
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\n",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\n",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\n",val_str);
av_opt_get(pCodecCtx->priv_data,"tune",0,(uint8_t **)&val_str);
printf("tune val: %s\n",val_str);
av_opt_get(pCodecCtx->priv_data,"profile",0,(uint8_t **)&val_str);
printf("profile val: %s\n",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!\n");
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!\n");
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!\n");
return -1;
}
if (got_picture==1){
//printf("Succeed to encode 1 frame!\n");
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\n");
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 =========\n");
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\n",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\n",output_w,output_h);
printf("========= Parse Frame Rate =========\n");
AVRational output_rational={0,0};
strcpy(input_str,"15/1");
av_parse_video_rate(&output_rational,input_str);
printf("framerate:%d/%d\n",output_rational.num,output_rational.den);
strcpy(input_str,"pal");
av_parse_video_rate(&output_rational,input_str);
printf("framerate:%d/%d\n",output_rational.num,output_rational.den);
printf("=========== Parse Time =============\n");
int64_t output_timeval;
strcpy(input_str,"00:01:01");
av_parse_time(&output_timeval,input_str,1);
printf("microseconds:%lld\n",output_timeval);
printf("====================================\n");
} void test_avdictionary(){ AVDictionary *d = NULL;
AVDictionaryEntry *t = NULL; av_dict_set(&d, "name", "lei xiaohua", 0);
av_dict_set(&d, "email", "[email protected]", 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("====================================\n");
int dict_cnt= av_dict_count(d);
printf("dict_count:%d\n",dict_cnt);
printf("dict_element:\n");
while (t = av_dict_get(d, "", t, AV_DICT_IGNORE_SUFFIX)) {
printf("key:%10s | value:%s\n",t->key,t->value);
} t = av_dict_get(d, "email", t, AV_DICT_IGNORE_SUFFIX);
printf("email is %s\n",t->value);
printf("====================================\n");
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：
watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />
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：
watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />
编码的时候设置回调函数后输出到文本中的日志：
watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />
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：