前段时间，公司的一个项目需要一个rtsp的播放库，原本打算直接用vlc播放的，但我觉得vlc太庞大了，很多功能没必要，还不如用ffmpeg+d3d简单的实现一个库，因此就有了今天讲的这个东西。一个解码库，分为三个部分：网络，解码，显示。网络和解码在ffmpeg里带了，直接用就好，显示，用d3d直接显示yuv是最佳方案了。整个库采用多线程模型，播放一路就创建一个播放线程。库的接口如下：
struct hvplayer;
typedef struct hvplayer hvplayer;
/**
*播放退出回调
*@param h 播放器指针
*@param state 退出状态
*/
typedef void (*playend_cb)(hvplayer *h); enum player_state
{
PLAYER_CONNECTING=,
PLAYER_PLAYING,
PLAYER_OFF
}; /**
*初始化一个播放器
*@param hwnd 一个表示画面显示区域的id,windows上为窗口句柄
*@param url rtsp地址
*@return NULL失败,>0为一个播放器指针
*/
HVEXP hvplayer *hvplayer_new(int32_t hwnd, const char *url); /**
*播放一个rtsp视频,该方法是一个非阻塞函数,内部会创建一个线程去执行播放
*任务，自动无限重连，直到调用hvplayer_close
*
*@param h 一个指向播放器的指针
*@return 成功为0,失败-1
*/
HVEXP int hvplayer_play(hvplayer *h); /**
*获取播放器的状态,成功会设置state
*
*@param h 一个指向播放器的指针
*@return player_state枚举的值
*/
HVEXP int hvplayer_getstate(hvplayer *h); /**
*停止播放,并结束播放线程,该方法会阻塞至播放线程结束,同时释放hvplayer句柄
*
*@param h 一个指向播放器的指针
*/
HVEXP void hvplayer_close(hvplayer *h); /**
*注册播放结束回调,hvplayer_close后回调会被调用
*
*@param h 一个指向播放器的指针
*@param cb 具体见回调定义
*@waring 多次注册会覆盖
*@waring 不要阻塞该调用线程
*/
HVEXP void hvplayer_set_endcb(hvplayer *h, playend_cb cb);
/************************************************************************/
/*SDK初始化,必须在使用SDK之前初始化
*@return 0成功
/************************************************************************/
HVEXP int hvdevicevideo_init(void);
使用起来很简单，一个hvplayer对象对应一路视频，先hvplayer_new(),在hvplayer_play(),最后hvplayer_close()就好了。库使用前要调用hvdevicevideo_init进行初始化.
hvplayer的定义如下：
struct hvplayer
{
playend_cb end;
int32_t hwnd;
int32_t flage;
char *url;
enum player_state ste;
HANDLE thread;
clock_t pretm;
int play;
};
flage是控制重连循环的，play是控制帧数据读取循环的,pretm是控制rtsp服务器连接超时的.
play_loop是播放线程的函数，外层是重连循环,_do是实际播放循环.
static int play_loop(void* p)
{
hvplayer *h=(hvplayer*)p;
while(h->flage)
{
h->ste=PLAYER_CONNECTING;
h->pretm=clock();
_do(h);
int s=TIMEOUT_S-(clock()-h->pretm)/CLOCKS_PER_SEC;
if(s>) Sleep(s*);
}
if(h->end) h->end(h);
free(h->url);
free(h);
return ;
}
static void _do(hvplayer*h)
{
AVCodec *codec=NULL;
AVCodecContext *cc=NULL;
AVPacket pk={};
AVFormatContext *afc=NULL;
int vindex=-;
afc=avformat_alloc_context();
if(afc==){
goto err;
}
afc->interrupt_callback.callback=timeoutcheck;
afc->interrupt_callback.opaque=h;
AVDictionary *dir=NULL;
char *k1="stimeout";
char *v1="";
char *k2="rtsp_transport";
char *v2="tcp";
char *k4="max_delay";
char *v4="";
int r=av_dict_set(&dir,k1,v1,);
r=av_dict_set(&dir,k2,v2,);
av_dict_set(&dir,k4,v4,);
if(avformat_open_input(&afc,h->url,NULL,&dir)) {
goto err;
}
if(avformat_find_stream_info(afc,NULL)<) {
goto err;
}
for(int i=;i<(int)afc->nb_streams;i++)
{
if(afc->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
vindex=i;
break;
}
}
if(vindex==-){
goto err;
}
cc=afc->streams[vindex]->codec;
codec=avcodec_find_decoder(cc->codec_id); if(codec==) goto end;
if(avcodec_open2(cc,codec,NULL)<) {
goto err;
}
int dr;
hvframe frame;
render *render=render_create(RENDER_TYPE_D3D,h->hwnd,cc->coded_width,cc->coded_height);
if(render==NULL)
{
render=render_create(RENDER_TYPE_GDI,h->hwnd,cc->coded_width,cc->coded_height);
if(render==NULL){
goto end;
}
}
AVFrame *yuv_buf=av_frame_alloc();
if(yuv_buf==) {
goto end;
}
h->ste=PLAYER_PLAYING;
DWORD a,b;
while (h->flage&&av_read_frame(afc,&pk)>=)
{ if(pk.stream_index==vindex)
{
avcodec_decode_video2(cc,yuv_buf,&dr,&pk);
if(dr>)
{
frame.h=cc->coded_height;
frame.y=yuv_buf->data[];
frame.u=yuv_buf->data[];
frame.v=yuv_buf->data[];
frame.ypitch=yuv_buf->linesize[];
frame.uvpitch=yuv_buf->linesize[];
render->draw(render,&frame);
}
}
av_free_packet(&pk);
}
end:
if(yuv_buf) av_frame_free(&yuv_buf);
if(render) render->destory(&render);
err:
if(cc) avcodec_close(cc);
if(afc){
avformat_close_input(&afc);
avformat_free_context(afc);
}
}
- avformat_alloc_context（）分配AVFormatContext对象。
- avformat_open_input（）打开一个流媒体源，可以是文件，rtsp,这是一个阻塞函数，知道解析成功或失败才返回.那如何设置超时时间呢？这个对象提供了两个中断回调，解析时ffmpeg会以一定频率调用这个回调，这个回调的返回值影响avformat_open_input（）是否立马返回.这个回调函数指针就是AVFormatContext->interrupt_callback.callback,同时可以用->interrupt_callback.opaque绑定一个用户数据.回调函数返回1时，avformat_open_input（）会失败返回,返回0则正常运行.
我是这样处理的(为了6秒超时判定):
#define TIMEOUT_S 6 int timeoutcheck(void *p)
{
hvplayer *h=(hvplayer*)p;
if(h->flage==) return ;
if(h->ste==PLAYER_CONNECTING)
{
clock_t ctm=clock();
int s=(ctm-h->pretm)/CLOCKS_PER_SEC;
if(s>=TIMEOUT_S)
return ;
}
return ;
}
3、avformat_find_stream_info()解析流的格式信息，再用以下代码获取AVCodecContext:
for(int i=;i<(int)afc->nb_streams;i++)
{
if(afc->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
vindex=i;
break;
}
}
if(vindex==-){
goto err;
}
cc=afc->streams[vindex]->codec;
4、avcodec_find_decoder(),利用AVCodecContext->codec_id创建AVCodec,再用avcodec_open2()打开解码器.
5、循环调用av_read_frame()获取一帧编码数据，再调用avcodec_decode_video2(AVCodec*,AVFrame*,int*,AVPacket*)解码为yuv,第三个参数标示是否解码成功(>0成功),最后调用显示模块显示即可.
显示上，我将其封装为render对象，分别实现了d3d,gdi.render的结构如下：
struct render{
int hwnd;
void (*draw)(struct render *self,hvframe *frame);
void (*destory)(struct render **self);
};
typedef struct render render;
d3d实现如下：
#include <stdlib.h>
#include "hvtype.h"
#include "irender.h"
#include "winapi.h"
struct render_d3d
{
render base;
IDirect3D9 *d3d;
IDirect3DDevice9 *d3d_dev;
IDirect3DSurface9 *surface;
RECT rec;
}; void d3d_draw(render *h,hvframe *frame);
void render_free(render **h); render *d3d_new(int hwnd,int pic_w,int pic_h)
{
struct render_d3d *result=(struct render_d3d *)malloc(sizeof(*result));
result->base.hwnd=hwnd;
result->d3d=Direct3DCreate9(D3D_SDK_VERSION);
if(result->d3d==NULL) return NULL;
D3DPRESENT_PARAMETERS d3dpp;
memset(&d3dpp,,sizeof(d3dpp));
d3dpp.Windowed=TRUE;
d3dpp.SwapEffect=D3DSWAPEFFECT_DISCARD;
d3dpp.BackBufferFormat=D3DFMT_UNKNOWN;
GetClientRect((HWND)result->base.hwnd,&result->rec);
HRESULT re=IDirect3D9_CreateDevice(result->d3d,D3DADAPTER_DEFAULT,D3DDEVTYPE_HAL,(HWND)result->base.hwnd,
D3DCREATE_SOFTWARE_VERTEXPROCESSING,&d3dpp,&result->d3d_dev);
if(FAILED(re)) return NULL;
re=IDirect3DDevice9_CreateOffscreenPlainSurface(result->d3d_dev,pic_w,pic_h,
(D3DFORMAT)MAKEFOURCC('Y','V','',''),
D3DPOOL_DEFAULT,&result->surface,NULL);
if(FAILED(re)) return NULL;
result->base.draw=d3d_draw;
result->base.destory=render_free;
return (render *)result;
} void d3d_draw(render *h,hvframe *frame)
{
struct render_d3d *self=(struct render_d3d*)h;
D3DLOCKED_RECT texture;
HRESULT re=IDirect3DSurface9_LockRect(self->surface,&texture,NULL,D3DLOCK_DONOTWAIT);
if(FAILED(re)) return;
int uvstep=texture.Pitch/;
char *dest=(char*)texture.pBits;
char *vdest=(char*)texture.pBits+frame->h*texture.Pitch;
char *udest=(char*)vdest+frame->h/*uvstep;
int uvn=;
for(int i=;i<frame->h;i++)
{
memcpy(dest,frame->y,frame->ypitch);
frame->y+=frame->ypitch;
dest+=texture.Pitch;
}
for(int i=;i<frame->h/;i++)
{
memcpy(vdest,frame->v,frame->uvpitch);
memcpy(udest,frame->u,frame->uvpitch);
vdest+=uvstep;
udest+=uvstep;
frame->v+=frame->uvpitch;
frame->u+=frame->uvpitch;
}
IDirect3DSurface9_UnlockRect(self->surface);
IDirect3DDevice9_BeginScene(self->d3d_dev);
IDirect3DSurface9 *back_surface;
IDirect3DDevice9_GetBackBuffer(self->d3d_dev,,,D3DBACKBUFFER_TYPE_MONO,&back_surface);
IDirect3DDevice9_StretchRect(self->d3d_dev,self->surface,NULL,back_surface,&self->rec,D3DTEXF_LINEAR);
IDirect3DDevice9_EndScene(self->d3d_dev);
IDirect3DDevice9_Present(self->d3d_dev,NULL,NULL,NULL,NULL);
}
void render_free(render **h)
{
if((*h)==)return;
struct render_d3d *self=(struct render_d3d*)(*h);
IDirect3DDevice9_Clear(self->d3d_dev,, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(,,), 1.0f, );
IDirect3DDevice9_Present(self->d3d_dev,NULL,NULL,NULL,NULL);
IDirect3DSurface9_Release(self->surface);
IDirect3DDevice9_Release(self->d3d_dev);
IDirect3D9_Release(self->d3d);
free(*h);
*h=;
}
都是标准的固定管线步骤，就不赘述了，唯一要注意的就是yuv数据填充到surface中时要注意行对齐.
gdi实现如下：
#include <stdlib.h>
#include <windows.h>
#include "hvpfconvert.h"
#include "irender.h"
#include "winapi.h" struct render_gdi
{
render base;
BITMAPINFO bmp;
HDC dc;
hvpfconvert *convert;
uint8_t *buf;
RECT rec;
}; void gdi_free(render **h)
{
if((*h)==)return;
struct render_gdi *self=(struct render_gdi*)(*h);
FillRect(self->dc,&self->rec,(HBRUSH)(pGetStockObject(BLACK_BRUSH)));
ReleaseDC((HWND)self->base.hwnd,self->dc);
hvpfconvert_free(&self->convert);
free(*h);
*h=;
} void gdi_draw(render *h,hvframe *frame)
{
struct render_gdi *self=(struct render_gdi*)h;
hvpfconvert_convert2(self->convert, frame, self->buf);
pSetStretchBltMode(self->dc, STRETCH_HALFTONE);
pStretchDIBits(self->dc, , , self->rec.right, self->rec.bottom, , ,
self->bmp.bmiHeader.biWidth, frame->h, self->buf, &self->bmp, DIB_RGB_COLORS, SRCCOPY);
} render *gdi_new(int32_t hwnd,int pic_w,int pic_h)
{
struct render_gdi *re = (struct render_gdi *)calloc(,sizeof(*re));
re->convert = hvpfconvert_new(pic_w, pic_h, pic_w, pic_h, PF_YUV420P, PF_BGR24);
re->dc = GetDC((HWND)hwnd);
re->base.hwnd = hwnd;
GetClientRect((HWND)re->base.hwnd, &re->rec);
re->buf = (uint8_t*)malloc(hvpfconvert_get_size(pic_w, pic_h, PF_RGB24));
re->bmp.bmiHeader.biBitCount = ;
re->bmp.bmiHeader.biClrImportant = BI_RGB;
re->bmp.bmiHeader.biClrUsed = ;
re->bmp.bmiHeader.biCompression = ;
re->bmp.bmiHeader.biHeight = -pic_h;
re->bmp.bmiHeader.biWidth = pic_w;
re->bmp.bmiHeader.biPlanes = ;
re->bmp.bmiHeader.biSize = sizeof(re->bmp.bmiHeader);
re->bmp.bmiHeader.biSizeImage = pic_w*pic_h * ;
re->bmp.bmiHeader.biXPelsPerMeter = ;
re->bmp.bmiHeader.biYPelsPerMeter = ;
re->base.destory=gdi_free;
re->base.draw=gdi_draw;
return (render *)re;
}
gdi是利用StretchDIBits函数显示位图，因此要将yuv转换为rgb数据，图像格式转换，ffmpeg也自带了高效的转换函数:sws_scale().
最后是sdk的初始化，hvdevicevideo_init()我调用了ffmpeg库和d3d所需的初始化函数：
int hvdevicevideo_init(void){
if(hv_winapi_init()) return -;
avcodec_register_all();
av_register_all();
avformat_network_init();
sdk_init=;
CoInitializeEx(NULL,COINIT_MULTITHREADED);
return ;
}
最后整个库，性能还不错，不必vlc差。在支持d3d的i5机器上解码一路1080p视频占3%-5%左右的cpu.不支持的将启用gdi显示，每路占13%的cpu.可优化点是rtsp，ffmpeg的rtsp效率
一般般，基本有400毫秒左右的延迟，而liv555可以做到200的延迟，不过我的需求400延迟可以接受，因此就没去折腾了。后来公司有一嵌入式的项目，我又做了一版linux的实现，用了英特尔的vaapi驱动进行硬解码(因为项目运行的机器是一款atom的cpu,主频只有1.2g,软解一路要占40%多的cpu),后续再写基于ffmpeg的vaapi硬解码播放吧.