C++编程FFMpeg实时直播推流实战–提取码:nh21
1.libswscale实现YUV转RGB
libswscale里面实现了各种图像像素格式的转换。
libswscale使用起来很方便,最主要的函数只有3个:
(1) sws_getContext():使用参数初始化SwsContext结构体。
(2) sws_scale():转换一帧图像。
(3) sws_freeContext():释放SwsContext结构体。
其中sws_getContext()也可以用另一个接口函数sws_getCachedContext()取代。
初始化方法
初始化SwsContext除了调用sws_getContext()之外还有另一种方法,更加灵活,可以配置更多的参数。该方法调用的函数如下所示。
(1) sws_alloc_context():为SwsContext结构体分配内存。
(2) av_opt_set_XXX():通过av_opt_set_int(),av_opt_set()…等等一系列方法设置SwsContext结构体的值。在这里需要注意,SwsContext结构体的定义看不到,所以不能对其中的成员变量直接进行赋值,必须通过av_opt_set()这类的API才能对其进行赋值。
(3) sws_init_context():初始化SwsContext结构体。
这种复杂的方法可以配置一些sws_getContext()配置不了的参数。比如说设置图像的YUV像素的取值范围是JPEG标准(Y、U、V取值范围都是0-255)还是MPEG标准(Y取值范围是16-235,U、V的取值范围是16-240)。
通过av_pix_fmt_desc_get()可以获得指定像素格式的AVPixFmtDescriptor结构体。
通过AVPixFmtDescriptor结构体可以获得不同像素格式的一些信息。例如av_get_bits_per_pixel(),通过该函数可以获得指定像素格式每个像素占用的比特数(Bit Per Pixel)。
图像拉伸
SWS_BICUBIC性能比较好;SWS_FAST_BILINEAR在性能和速度之间有一个比好好的平衡。
源代码:
#include
#define __STDC_CONSTANT_MACROS
#ifdef _WIN32
//Windows
extern "C"
{
#include "libswscale/swscale.h"
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include
#include
#include
#ifdef __cplusplus
};
#endif
#endif
int main(int argc, char* argv[])
{
//Parameters
FILE *src_file =fopen("ws.yuv", "rb");
const int src_w=1920,src_h=1080;
AVPixelFormat src_pixfmt=AV_PIX_FMT_YUV420P;
//该函数可以获得指定像素格式每个像素占用的比特数(Bit Per Pixel),av_pix_fmt_desc_get()可以获得指定像素格式的AVPixFmtDescriptor结构体。
int src_bpp=av_get_bits_per_pixel(av_pix_fmt_desc_get(src_pixfmt));
FILE *dst_file = fopen("ws.rgb", "wb");
const int dst_w=1280,dst_h=720;
AVPixelFormat dst_pixfmt=AV_PIX_FMT_RGB24;
int dst_bpp=av_get_bits_per_pixel(av_pix_fmt_desc_get(dst_pixfmt));//av_pix_fmt_desc_get()可以获得指定像素格式的AVPixFmtDescriptor结构体。
//Structures
uint8_t *src_data[4];
int src_linesize[4];
uint8_t *dst_data[4];
int dst_linesize[4];
int rescale_method=SWS_BICUBIC;
struct SwsContext *img_convert_ctx;
uint8_t *temp_buffer=(uint8_t *)malloc(src_w*src_h*src_bpp/8);
int frame_idx=0;
int ret=0;
ret= av_image_alloc(src_data, src_linesize,src_w, src_h, src_pixfmt, 1);//分配资源控件
if (ret< 0) {
printf( "Could not allocate source image\n");
return -1;
}
ret = av_image_alloc(dst_data, dst_linesize,dst_w, dst_h, dst_pixfmt, 1);
if (ret< 0) {
printf( "Could not allocate destination image\n");
return -1;
}
//-----------------------------
img_convert_ctx =sws_alloc_context();//为SwsContext结构体分配内存。
//Show AVOption
av_opt_show2(img_convert_ctx,stdout,AV_OPT_FLAG_VIDEO_PARAM,0);
//Set Value
av_opt_set_int(img_convert_ctx,"sws_flags",SWS_BICUBIC|SWS_PRINT_INFO,0);
av_opt_set_int(img_convert_ctx,"srcw",src_w,0);
av_opt_set_int(img_convert_ctx,"srch",src_h,0);
av_opt_set_int(img_convert_ctx,"src_format",src_pixfmt,0);
//'0' for MPEG (Y:0-235);'1' for JPEG (Y:0-255)
av_opt_set_int(img_convert_ctx,"src_range",1,0);
av_opt_set_int(img_convert_ctx,"dstw",dst_w,0);
av_opt_set_int(img_convert_ctx,"dsth",dst_h,0);
av_opt_set_int(img_convert_ctx,"dst_format",dst_pixfmt,0);
av_opt_set_int(img_convert_ctx,"dst_range",1,0);
sws_init_context(img_convert_ctx,NULL,NULL);//对SwsContext中的各种变量进行赋值
while(1)
{
if (fread(temp_buffer, 1, src_w*src_h*src_bpp/8, src_file) != src_w*src_h*src_bpp/8){
break;
}
switch(src_pixfmt){
case AV_PIX_FMT_GRAY8:{
memcpy(src_data[0],temp_buffer,src_w*src_h);
break;
}
case AV_PIX_FMT_YUV420P:{
memcpy(src_data[0],temp_buffer,src_w*src_h); //Y
memcpy(src_data[1],temp_buffer+src_w*src_h,src_w*src_h/4); //U
memcpy(src_data[2],temp_buffer+src_w*src_h*5/4,src_w*src_h/4); //V
break;
}
case AV_PIX_FMT_YUV422P:{
memcpy(src_data[0],temp_buffer,src_w*src_h); //Y
memcpy(src_data[1],temp_buffer+src_w*src_h,src_w*src_h/2); //U
memcpy(src_data[2],temp_buffer+src_w*src_h*3/2,src_w*src_h/2); //V
break;
}
case AV_PIX_FMT_YUV444P:{
memcpy(src_data[0],temp_buffer,src_w*src_h); //Y
memcpy(src_data[1],temp_buffer+src_w*src_h,src_w*src_h); //U
memcpy(src_data[2],temp_buffer+src_w*src_h*2,src_w*src_h); //V
break;
}
case AV_PIX_FMT_YUYV422:{
memcpy(src_data[0],temp_buffer,src_w*src_h*2); //Packed
break;
}
case AV_PIX_FMT_RGB24:{
memcpy(src_data[0],temp_buffer,src_w*src_h*3); //Packed
break;
}
default:{
printf("Not Support Input Pixel Format.\n");
break;
}
}
sws_scale(img_convert_ctx, src_data, src_linesize, 0, src_h, dst_data, dst_linesize);//转换像素
printf("Finish process frame %5d\n",frame_idx);
frame_idx++;
switch(dst_pixfmt){
case AV_PIX_FMT_GRAY8:{
fwrite(dst_data[0],1,dst_w*dst_h,dst_file);
break;
}
case AV_PIX_FMT_YUV420P:{
fwrite(dst_data[0],1,dst_w*dst_h,dst_file); //Y
fwrite(dst_data[1],1,dst_w*dst_h/4,dst_file); //U
fwrite(dst_data[2],1,dst_w*dst_h/4,dst_file); //V
break;
}
case AV_PIX_FMT_YUV422P:{
fwrite(dst_data[0],1,dst_w*dst_h,dst_file); //Y
fwrite(dst_data[1],1,dst_w*dst_h/2,dst_file); //U
fwrite(dst_data[2],1,dst_w*dst_h/2,dst_file); //V
break;
}
case AV_PIX_FMT_YUV444P:{
fwrite(dst_data[0],1,dst_w*dst_h,dst_file); //Y
fwrite(dst_data[1],1,dst_w*dst_h,dst_file); //U
fwrite(dst_data[2],1,dst_w*dst_h,dst_file); //V
break;
}
case AV_PIX_FMT_YUYV422:{
fwrite(dst_data[0],1,dst_w*dst_h*2,dst_file); //Packed
break;
}
case AV_PIX_FMT_RGB24:{
fwrite(dst_data[0],1,dst_w*dst_h*3,dst_file); //Packed
break;
}
default:{
printf("Not Support Output Pixel Format.\n");
break;
}
}
}
sws_freeContext(img_convert_ctx);
free(temp_buffer);
fclose(dst_file);
av_freep(&src_data[0]);
av_freep(&dst_data[0]);
return 0;
}
2.使用libavfilter为视音频添加特效功能
关键函数如下所示:
avfilter_register_all():注册所有AVFilter。
avfilter_graph_alloc():为FilterGraph分配内存。
avfilter_graph_create_filter():创建并向FilterGraph中添加一个Filter。
avfilter_graph_parse_ptr():将一串通过字符串描述的Graph添加到FilterGraph中。
avfilter_graph_config():检查FilterGraph的配置。
av_buffersrc_add_frame():向FilterGraph中加入一个AVFrame。
av_buffersink_get_frame():从FilterGraph中取出一个AVFrame。
程序中提供了几种特效:
//const char *filter_descr = "lutyuv='u=128:v=128'";
//const char *filter_descr = "boxblur";
//const char *filter_descr = "hflip";
//const char *filter_descr = "hue='h=60:s=-3'";
//const char *filter_descr = "crop=2/3*in_w:2/3*in_h";
//const char *filter_descr = "drawbox=x=100:y=100:w=100:h=100:[email protected]";
const char *filter_descr = "drawtext=fontfile=arial.ttf:fontcolor=red:fontsize=50:text='Shuo.Wang'";
输入ws.yuv,输出ws_output.yuv
源代码如下:
#include
#define __STDC_CONSTANT_MACROS
#ifdef _WIN32
#define snprintf _snprintf
//Windows
extern "C"
{
#include "libavfilter/avfiltergraph.h"
#include "libavfilter/buffersink.h"
#include "libavfilter/buffersrc.h"
#include "libavutil/avutil.h"
#include "libavutil/imgutils.h"
};
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include
#include
#include
#include
#include
#ifdef __cplusplus
};
#endif
#endif
int main(int argc, char* argv[])
{
int ret;
AVFrame *frame_in;
AVFrame *frame_out;
unsigned char *frame_buffer_in;
unsigned char *frame_buffer_out;
AVFilterContext *buffersink_ctx;
AVFilterContext *buffersrc_ctx;
AVFilterGraph *filter_graph;
static int video_stream_index = -1;
//Input YUV
FILE *fp_in=fopen("ws.yuv","rb+");
if(fp_in==NULL){
printf("Error open input file.\n");
return -1;
}
int in_width=1920;
int in_height=1080;
//Output YUV
FILE *fp_out=fopen("ws_output.yuv","wb+");
if(fp_out==NULL){
printf("Error open output file.\n");
return -1;
}
//const char *filter_descr = "lutyuv='u=128:v=128'";
//const char *filter_descr = "boxblur";
//const char *filter_descr = "hflip";
//const char *filter_descr = "hue='h=60:s=-3'";
//const char *filter_descr = "crop=2/3*in_w:2/3*in_h";
//const char *filter_descr = "drawbox=x=100:y=100:w=100:h=100:[email protected]";
const char *filter_descr = "drawtext=fontfile=arial.ttf:fontcolor=red:fontsize=50:text='Shuo.Wang'";
avfilter_register_all();//注册所有AVFilter。
char args[512];
AVFilter *buffersrc = avfilter_get_by_name("buffer");
AVFilter *buffersink = avfilter_get_by_name("ffbuffersink");
AVFilterInOut *outputs = avfilter_inout_alloc();
AVFilterInOut *inputs = avfilter_inout_alloc();
enum PixelFormat pix_fmts[] = { PIX_FMT_YUV420P, PIX_FMT_NONE };
AVBufferSinkParams *buffersink_params;
filter_graph = avfilter_graph_alloc();//为FilterGraph分配内存。
/* buffer video source: the decoded frames from the decoder will be inserted here. */
snprintf(args, sizeof(args),
"video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
in_width,in_height,PIX_FMT_YUV420P,
1, 25,1,1);
//创建并向FilterGraph中添加一个Filter。
ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
args, NULL, filter_graph);
if (ret < 0) {
printf("Cannot create buffer source\n");
return ret;
}
/* buffer video sink: to terminate the filter chain. */
buffersink_params = av_buffersink_params_alloc();
buffersink_params->pixel_fmts = pix_fmts;
ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
NULL, buffersink_params, filter_graph);
av_free(buffersink_params);
if (ret < 0) {
printf("Cannot create buffer sink\n");
return ret;
}
/* Endpoints for the filter graph. */
outputs->name = av_strdup("in");
outputs->filter_ctx = buffersrc_ctx;
outputs->pad_idx = 0;
outputs->next = NULL;
inputs->name = av_strdup("out");
inputs->filter_ctx = buffersink_ctx;
inputs->pad_idx = 0;
inputs->next = NULL;
//将一串通过字符串描述的Graph添加到FilterGraph中。
if ((ret = avfilter_graph_parse_ptr(filter_graph, filter_descr,
&inputs, &outputs, NULL)) < 0)
return ret;
//检查FilterGraph的配置。
if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
return ret;
frame_in=av_frame_alloc();
frame_buffer_in=(unsigned char *)av_malloc(av_image_get_buffer_size(PIX_FMT_YUV420P, in_width,in_height,1));
av_image_fill_arrays(frame_in->data, frame_in->linesize,frame_buffer_in,
PIX_FMT_YUV420P,in_width, in_height,1);
frame_out=av_frame_alloc();
frame_buffer_out=(unsigned char *)av_malloc(av_image_get_buffer_size(PIX_FMT_YUV420P, in_width,in_height,1));
av_image_fill_arrays(frame_out->data, frame_out->linesize,frame_buffer_out,
PIX_FMT_YUV420P,in_width, in_height,1);
frame_in->width=in_width;
frame_in->height=in_height;
frame_in->format=PIX_FMT_YUV420P;
while (1) {
if(fread(frame_buffer_in, 1, in_width*in_height*3/2, fp_in)!= in_width*in_height*3/2){
break;
}
//input Y,U,V
frame_in->data[0]=frame_buffer_in;
frame_in->data[1]=frame_buffer_in+in_width*in_height;
frame_in->data[2]=frame_buffer_in+in_width*in_height*5/4;
//向FilterGraph中加入一个AVFrame。
if (av_buffersrc_add_frame(buffersrc_ctx, frame_in) < 0) {
printf( "Error while add frame.\n");
break;
}
/* pull filtered pictures from the filtergraph 从FilterGraph中取出一个AVFrame。*/
ret = av_buffersink_get_frame(buffersink_ctx, frame_out);
if (ret < 0)
break;
//output Y,U,V
if(frame_out->format==PIX_FMT_YUV420P){
for(int i=0;iheight;i++){
fwrite(frame_out->data[0]+frame_out->linesize[0]*i,1,frame_out->width,fp_out);
}
for(int i=0;iheight/2;i++){
fwrite(frame_out->data[1]+frame_out->linesize[1]*i,1,frame_out->width/2,fp_out);
}
for(int i=0;iheight/2;i++){
fwrite(frame_out->data[2]+frame_out->linesize[2]*i,1,frame_out->width/2,fp_out);
}
}
printf("Process 1 frame!\n");
}
fclose(fp_in);
fclose(fp_out);
av_frame_free(&frame_in);
av_frame_free(&frame_out);
avfilter_graph_free(&filter_graph);
return 0;
}
转自:https://blog.csdn.net/King1425/article/details/71160339