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 #include #include #include #include #include #include #include #include #include #include #include #include  #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include  #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1024 nb_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 * 2YUV420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==YUV422int 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 v for(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/video0int main(int argc,char **argv){if(argc!=2){printf(\"./app \\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;}