通过v4l2，采集视频，FFmpeg编码压缩封装视频（三）

采集摄像头图像，模拟音频，通过FFmpeg进行编码压缩，封装成mp4视频文件。

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <time.h>
#include <libavutil/avassert.h>
#include <libavutil/channel_layout.h>
#include <libavutil/opt.h>
#include <libavutil/mathematics.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>#include <stdio.h>
#include <sys/ioctl.h>
#include <linux/videodev2.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <poll.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <pthread.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>#define STREAM_DURATION   10.0   /*录制10秒的视频，由于缓冲的原因，一般只有8秒*/
#define STREAM_FRAME_RATE 25     /* 25 images/s   avfilter_get_by_name */
#define STREAM_PIX_FMT    AV_PIX_FMT_YUV420P /* default pix_fmt */
#define SCALE_FLAGS SWS_BICUBIC//固定摄像头输出画面的尺寸
#define VIDEO_WIDTH  640
#define VIDEO_HEIGHT 480//存放从摄像头读出转换之后的数据
unsigned char YUV420P_Buffer[VIDEO_WIDTH*VIDEO_HEIGHT*3/2];
unsigned char YUV420P_Buffer_temp[VIDEO_WIDTH*VIDEO_HEIGHT*3/2];/*一些摄像头需要使用的全局变量*/
unsigned char *image_buffer[4];
int video_fd;
pthread_mutex_t mutex;
pthread_cond_t cond;// 单个输出AVStream的包装器
typedef struct OutputStream {AVStream *st;AVCodecContext *enc;/* 下一帧的点数*/int64_t next_pts;int samples_count;AVFrame *frame;AVFrame *tmp_frame;float t, tincr, tincr2;struct SwsContext *sws_ctx;struct SwrContext *swr_ctx;
} OutputStream;static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)
{/*将输出数据包时间戳值从编解码器重新调整为流时基 */av_packet_rescale_ts(pkt, *time_base, st->time_base);pkt->stream_index = st->index;/*将压缩的帧写入媒体文件*/return av_interleaved_write_frame(fmt_ctx, pkt);
}/* 添加输出流。 */
static void add_stream(OutputStream *ost, AVFormatContext *oc,AVCodec **codec,enum AVCodecID codec_id)
{AVCodecContext *c;int i;/* find the encoder */*codec = avcodec_find_encoder(codec_id);if (!(*codec)) {fprintf(stderr, "Could not find encoder for '%s'\n",avcodec_get_name(codec_id));exit(1);}ost->st = avformat_new_stream(oc, NULL);if (!ost->st) {fprintf(stderr, "Could not allocate stream\n");exit(1);}ost->st->id = oc->nb_streams-1;c = avcodec_alloc_context3(*codec);if (!c) {fprintf(stderr, "Could not alloc an encoding context\n");exit(1);}ost->enc = c;switch ((*codec)->type) {case AVMEDIA_TYPE_AUDIO:c->sample_fmt  = (*codec)->sample_fmts ? (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;c->bit_rate    = 64000;  //设置码率c->sample_rate = 44100;  //音频采样率c->channels= av_get_channel_layout_nb_channels(c->channel_layout);c->channel_layout = AV_CH_LAYOUT_MONO; AV_CH_LAYOUT_MONO 单声道   AV_CH_LAYOUT_STEREO 立体声c->channels        = av_get_channel_layout_nb_channels(c->channel_layout);ost->st->time_base = (AVRational){ 1, c->sample_rate };break;case AVMEDIA_TYPE_VIDEO:c->codec_id = codec_id;//码率：影响体积，与体积成正比：码率越大，体积越大；码率越小，体积越小。c->bit_rate = 400000; //设置码率 400kps/*分辨率必须是2的倍数。 */c->width    =VIDEO_WIDTH;c->height   = VIDEO_HEIGHT;/*时基：这是基本的时间单位（以秒为单位）*表示其中的帧时间戳。 对于固定fps内容，*时基应为1 / framerate，时间戳增量应为*等于1。*/ost->st->time_base = (AVRational){1,STREAM_FRAME_RATE};c->time_base       = ost->st->time_base;c->gop_size      = 12; /* 最多每十二帧发射一帧内帧 */c->pix_fmt       = STREAM_PIX_FMT;c->max_b_frames = 0;  //不要B帧if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {c->mb_decision = 2;}break;default:break;}/* 某些格式希望流头分开。 */if (oc->oformat->flags & AVFMT_GLOBALHEADER)c->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}/**************************************************************/
/* audio output */static AVFrame *alloc_audio_frame(enum AVSampleFormat sample_fmt,uint64_t channel_layout,int sample_rate, int nb_samples)
{AVFrame *frame = av_frame_alloc();frame->format = sample_fmt;frame->channel_layout = channel_layout;frame->sample_rate = sample_rate;frame->nb_samples = nb_samples;if(nb_samples){av_frame_get_buffer(frame, 0);}return frame;
}static void open_audio(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
{AVCodecContext *c;int nb_samples;int ret;AVDictionary *opt = NULL;c = ost->enc;av_dict_copy(&opt, opt_arg, 0);ret = avcodec_open2(c, codec, &opt);av_dict_free(&opt);/*下面3行代码是为了生成虚拟的声音设置的频率参数*/ost->t     = 0;ost->tincr = 2 * M_PI * 110.0 / c->sample_rate;ost->tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;//AAC编码这里就固定为1024nb_samples = c->frame_size;ost->frame     = alloc_audio_frame(c->sample_fmt, c->channel_layout,c->sample_rate, nb_samples);ost->tmp_frame = alloc_audio_frame(AV_SAMPLE_FMT_S16, c->channel_layout,c->sample_rate, nb_samples);/* copy the stream parameters to the muxer */avcodec_parameters_from_context(ost->st->codecpar, c);/* create resampler context */ost->swr_ctx = swr_alloc();/* set options */av_opt_set_int       (ost->swr_ctx, "in_channel_count",   c->channels,       0);av_opt_set_int       (ost->swr_ctx, "in_sample_rate",     c->sample_rate,    0);av_opt_set_sample_fmt(ost->swr_ctx, "in_sample_fmt",      AV_SAMPLE_FMT_S16, 0);av_opt_set_int       (ost->swr_ctx, "out_channel_count",  c->channels,       0);av_opt_set_int       (ost->swr_ctx, "out_sample_rate",    c->sample_rate,    0);av_opt_set_sample_fmt(ost->swr_ctx, "out_sample_fmt",     c->sample_fmt,     0);/* initialize the resampling context */swr_init(ost->swr_ctx);
}/*
准备虚拟音频帧
这里可以替换成从声卡读取的PCM数据
*/
static AVFrame *get_audio_frame(OutputStream *ost)
{AVFrame *frame = ost->tmp_frame;int j, i, v;int16_t *q = (int16_t*)frame->data[0];/* 检查我们是否要生成更多帧，用于判断是否结束*/if (av_compare_ts(ost->next_pts, ost->enc->time_base,STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)return NULL;for(j = 0; j<frame->nb_samples; j++)  //nb_samples: 此帧描述的音频样本数（每个通道）{v=(int)(sin(ost->t) * 1000);for(i=0;i<ost->enc->channels;i++)  //channels:音频通道数{*q++ = v;  //音频数据} ost->t     += ost->tincr;ost->tincr += ost->tincr2;}frame->pts = ost->next_pts;ost->next_pts  += frame->nb_samples;return frame;
}/**编码一个音频帧并将其发送到多路复用器*编码完成后返回1，否则返回0*/
static int write_audio_frame(AVFormatContext *oc, OutputStream *ost)
{AVCodecContext *c;AVPacket pkt = { 0 };AVFrame *frame;int ret;int got_packet;int dst_nb_samples;av_init_packet(&pkt);c = ost->enc;frame = get_audio_frame(ost);if(frame){/*使用重采样器将样本从本机格式转换为目标编解码器格式*//*计算样本的目标数量*/dst_nb_samples = av_rescale_rnd(swr_get_delay(ost->swr_ctx, c->sample_rate) + frame->nb_samples,c->sample_rate, c->sample_rate, AV_ROUND_UP);av_assert0(dst_nb_samples == frame->nb_samples);av_frame_make_writable(ost->frame);/*转换为目标格式 */swr_convert(ost->swr_ctx,ost->frame->data, dst_nb_samples,(const uint8_t **)frame->data, frame->nb_samples);frame = ost->frame;frame->pts = av_rescale_q(ost->samples_count, (AVRational){1, c->sample_rate}, c->time_base);ost->samples_count += dst_nb_samples;}avcodec_encode_audio2(c, &pkt, frame, &got_packet);if (got_packet) {write_frame(oc, &c->time_base, ost->st, &pkt);}return (frame || got_packet) ? 0 : 1;
}static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
{AVFrame *picture;int ret;picture = av_frame_alloc();picture->format = pix_fmt;picture->width  = width;picture->height = height;/* allocate the buffers for the frame data */av_frame_get_buffer(picture, 32);return picture;
}static void open_video(AVFormatContext *oc, AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
{AVCodecContext *c = ost->enc;AVDictionary *opt = NULL;av_dict_copy(&opt, opt_arg, 0);/* open the codec */avcodec_open2(c, codec, &opt);av_dict_free(&opt);/* allocate and init a re-usable frame */ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);ost->tmp_frame = NULL;/* 将流参数复制到多路复用器 */avcodec_parameters_from_context(ost->st->codecpar, c);
}/*
准备图像数据
YUV422占用内存空间 = w * h * 2
YUV420占用内存空间 = width*height*3/2
*/
static void fill_yuv_image(AVFrame *pict, int frame_index,int width, int height)
{int y_size=width*height;/*等待条件成立*/pthread_cond_wait(&cond,&mutex);memcpy(YUV420P_Buffer_temp,YUV420P_Buffer,sizeof(YUV420P_Buffer));/*互斥锁解锁*/pthread_mutex_unlock(&mutex);//将YUV数据拷贝到缓冲区  y_size=wXhmemcpy(pict->data[0],YUV420P_Buffer_temp,y_size);memcpy(pict->data[1],YUV420P_Buffer_temp+y_size,y_size/4);memcpy(pict->data[2],YUV420P_Buffer_temp+y_size+y_size/4,y_size/4);
}static AVFrame *get_video_frame(OutputStream *ost)
{AVCodecContext *c = ost->enc;/* 检查我们是否要生成更多帧---判断是否结束录制 */if(av_compare_ts(ost->next_pts, c->time_base,STREAM_DURATION, (AVRational){ 1, 1 }) >= 0)return NULL;/*当我们将帧传递给编码器时，它可能会保留对它的引用*内部； 确保我们在这里不覆盖它*/if (av_frame_make_writable(ost->frame) < 0)exit(1);//制作虚拟图像//DTS（解码时间戳）和PTS（显示时间戳）fill_yuv_image(ost->frame, ost->next_pts, c->width, c->height);ost->frame->pts = ost->next_pts++;return ost->frame;
}/*
*编码一个视频帧并将其发送到多路复用器
*编码完成后返回1，否则返回0
*/
static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
{int ret;AVCodecContext *c;AVFrame *frame;int got_packet = 0;AVPacket pkt = { 0 };c=ost->enc;//获取一帧数据frame = get_video_frame(ost);av_init_packet(&pkt);/* 编码图像 */ret=avcodec_encode_video2(c, &pkt, frame, &got_packet);if(got_packet) {ret=write_frame(oc, &c->time_base, ost->st, &pkt);}else{ret = 0;}return (frame || got_packet) ? 0 : 1;
}static void close_stream(AVFormatContext *oc, OutputStream *ost)
{avcodec_free_context(&ost->enc);av_frame_free(&ost->frame);av_frame_free(&ost->tmp_frame);sws_freeContext(ost->sws_ctx);swr_free(&ost->swr_ctx);
}//编码视频和音频
int video_audio_encode(char *filename)
{OutputStream video_st = { 0 }, audio_st = { 0 };AVOutputFormat *fmt;AVFormatContext *oc;AVCodec *audio_codec, *video_codec;int ret;int have_video = 0, have_audio = 0;int encode_video = 0, encode_audio = 0;AVDictionary *opt = NULL;int i;/* 分配输出环境 */avformat_alloc_output_context2(&oc,NULL,NULL,filename);fmt=oc->oformat;/*使用默认格式的编解码器添加音频和视频流，初始化编解码器。 */if(fmt->video_codec != AV_CODEC_ID_NONE){add_stream(&video_st,oc,&video_codec,fmt->video_codec);have_video = 1;encode_video = 1;}if(fmt->audio_codec != AV_CODEC_ID_NONE){add_stream(&audio_st, oc, &audio_codec, fmt->audio_codec);have_audio = 1;encode_audio = 1;}/*现在已经设置了所有参数，可以打开音频视频编解码器，并分配必要的编码缓冲区。 */if (have_video)open_video(oc, video_codec, &video_st, opt);if (have_audio)open_audio(oc, audio_codec, &audio_st, opt);av_dump_format(oc, 0, filename, 1);/* 打开输出文件（如果需要） */if(!(fmt->flags & AVFMT_NOFILE)) {ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);if (ret < 0){fprintf(stderr, "无法打开输出文件: '%s': %s\n", filename,av_err2str(ret));return 1;}}/* 编写流头（如果有）*/avformat_write_header(oc,&opt);while(encode_video || encode_audio){/* 选择要编码的流*/if(encode_video &&(!encode_audio || av_compare_ts(video_st.next_pts, video_st.enc->time_base,audio_st.next_pts, audio_st.enc->time_base) <= 0)){encode_video = !write_video_frame(oc,&video_st);}else {encode_audio = !write_audio_frame(oc,&audio_st);}}av_write_trailer(oc);if (have_video)close_stream(oc, &video_st);if (have_audio)close_stream(oc, &audio_st);if (!(fmt->flags & AVFMT_NOFILE))avio_closep(&oc->pb);avformat_free_context(oc);return 0;
}/*
函数功能: 摄像头设备初始化
*/
int VideoDeviceInit(char *DEVICE_NAME)
{/*1. 打开摄像头设备*/video_fd=open(DEVICE_NAME,O_RDWR);if(video_fd<0)return -1;/*2. 设置摄像头支持的颜色格式和输出的图像尺寸*/struct v4l2_format video_formt;memset(&video_formt,0,sizeof(struct v4l2_format));	video_formt.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/video_formt.fmt.pix.height=VIDEO_HEIGHT; //480 video_formt.fmt.pix.width=VIDEO_WIDTH; //640video_formt.fmt.pix.pixelformat=V4L2_PIX_FMT_YUYV;if(ioctl(video_fd,VIDIOC_S_FMT,&video_formt))return -2;printf("当前摄像头尺寸:width*height=%d*%d\n",video_formt.fmt.pix.width,video_formt.fmt.pix.height);/*3.请求申请缓冲区的数量*/struct v4l2_requestbuffers video_requestbuffers;memset(&video_requestbuffers,0,sizeof(struct v4l2_requestbuffers));	video_requestbuffers.count=4;video_requestbuffers.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/video_requestbuffers.memory=V4L2_MEMORY_MMAP;if(ioctl(video_fd,VIDIOC_REQBUFS,&video_requestbuffers))return -3;printf("video_requestbuffers.count=%d\n",video_requestbuffers.count);/*4. 获取缓冲区的首地址*/struct v4l2_buffer video_buffer;memset(&video_buffer,0,sizeof(struct v4l2_buffer));int i;for(i=0;i<video_requestbuffers.count;i++){video_buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/video_buffer.memory=V4L2_MEMORY_MMAP;video_buffer.index=i;/*缓冲区的编号*/if(ioctl(video_fd,VIDIOC_QUERYBUF,&video_buffer))return -4;/*映射地址*/image_buffer[i]=mmap(NULL,video_buffer.length,PROT_READ|PROT_WRITE,MAP_SHARED,video_fd,video_buffer.m.offset);printf("image_buffer[%d]=0x%X\n",i,image_buffer[i]);}/*5. 将缓冲区加入到采集队列*/memset(&video_buffer,0,sizeof(struct v4l2_buffer));for(i=0;i<video_requestbuffers.count;i++){video_buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/video_buffer.memory=V4L2_MEMORY_MMAP;video_buffer.index=i;/*缓冲区的编号*/if(ioctl(video_fd,VIDIOC_QBUF,&video_buffer))return -5;}/*6. 启动采集队列*/int opt=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/if(ioctl(video_fd,VIDIOC_STREAMON,&opt))return -6;return 0;
}//YUYV==YUV422
int yuyv_to_yuv420p(const unsigned char *in, unsigned char *out, unsigned int width, unsigned int height)
{unsigned char *y = out;unsigned char *u = out + width*height;unsigned char *v = out + width*height + width*height/4;unsigned int i,j;unsigned int base_h;unsigned int  is_u = 1;unsigned int y_index = 0, u_index = 0, v_index = 0;unsigned long yuv422_length = 2 * width * height;//序列为YU YV YU YV，一个yuv422帧的长度 width * height * 2 个字节//丢弃偶数行 u vfor(i=0; i<yuv422_length; i+=2){*(y+y_index) = *(in+i);y_index++;}for(i=0; i<height; i+=2){base_h = i*width*2;for(j=base_h+1; j<base_h+width*2; j+=2){if(is_u){*(u+u_index) = *(in+j);u_index++;is_u = 0;}else{*(v+v_index) = *(in+j);v_index++;is_u = 1;}}}return 1;
}/*
子线程函数: 采集摄像头的数据
*/
void *pthread_read_video_data(void *arg)
{/*1. 循环读取摄像头采集的数据*/struct pollfd fds;fds.fd=video_fd;fds.events=POLLIN;/*2. 申请存放JPG的数据空间*/struct v4l2_buffer video_buffer;while(1){/*(1)等待摄像头采集数据*/poll(&fds,1,-1);/*(2)取出队列里采集完毕的缓冲区*/video_buffer.type=V4L2_BUF_TYPE_VIDEO_CAPTURE; /*视频捕获设备*/video_buffer.memory=V4L2_MEMORY_MMAP;ioctl(video_fd,VIDIOC_DQBUF,&video_buffer);/*(3)处理图像数据*//*YUYV数据转YUV420P*/pthread_mutex_lock(&mutex);   /*互斥锁上锁*/yuyv_to_yuv420p(image_buffer[video_buffer.index],YUV420P_Buffer,VIDEO_WIDTH,VIDEO_HEIGHT);pthread_mutex_unlock(&mutex); /*互斥锁解锁*/pthread_cond_broadcast(&cond);/*广播方式唤醒休眠的线程*//*(4)将缓冲区再放入队列*/ioctl(video_fd,VIDIOC_QBUF,&video_buffer);}	
}//运行示例:  ./a.out /dev/video0
int main(int argc,char **argv)
{if(argc!=2){printf("./app </dev/videoX>\n");return 0;}int err;pthread_t thread_id;/*初始化互斥锁*/pthread_mutex_init(&mutex,NULL);/*初始化条件变量*/pthread_cond_init(&cond,NULL);/*初始化摄像头设备*/err=VideoDeviceInit(argv[1]);printf("VideoDeviceInit=%d\n",err);if(err!=0)return err;/*创建子线程: 采集摄像头的数据*/pthread_create(&thread_id,NULL,pthread_read_video_data,NULL);/*设置线程的分离属性: 采集摄像头的数据*/pthread_detach(thread_id);char filename[100];time_t t;struct tm *tme;//开始音频、视频编码while(1){//获取本地时间t=time(NULL);t=t+8*60*60; //+上8个小时tme=gmtime(&t);sprintf(filename,"%d-%d-%d-%d-%d-%d.mp4",tme->tm_year+1900,tme->tm_mon+1,tme->tm_mday,tme->tm_hour,tme->tm_min,tme->tm_sec);printf("视频名称:%s\n",filename);//开始视频编码video_audio_encode(filename);}return 0;
}