摄像头输出是mjpeg格式的，需要实现在线预览功能，然后实现拍照功能
1.可以设置采集图像的分辨率，预览分辨率为640*480，可以自定义
2.ctrl+\ 拍照，ctrl+c 退出
void test() {
if (signal(SIGQUIT, sigHandle) == SIG_ERR) {
perror("set signal err");
}
if (signal(SIGINT, sigHandle) == SIG_ERR) {
perror("set signal err");
}
AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVCodecContext *ifcodec_ctx, *ofcodec_ctx;
AVCodec *icodec, *ocodec;
AVStream *out_stream;
AVFrame *pFrame, *pFrameYUV420, *pFrameBGR;
struct SwsContext *in_conCtx, *out_conCtx;
unsigned char *in_buffer, *out_buffer;
AVPacket inpkg, outpkg;
const char *in_filename;
int ret, i;
int got_picture;
IplImage *image;
int videoindex = -;
int frame_index = ;
int64_t start_time = , end_time = ;
// in_filename = "test.mp4";
in_filename = "/dev/video1";
// in_filename = "rtmp://219.216.87.170/live/test3";
// out_filename = "rtmp://219.216.87.170/live/test2";
av_register_all();
avdevice_register_all();
avformat_network_init();
ifmt_ctx = avformat_alloc_context();
ifmt_ctx->probesize = ;
ifmt_ctx->max_analyze_duration = ;
AVDictionary* options = NULL;
av_dict_set(&options, "fflags", "nobuffer", );
av_dict_set(&options, "max_delay", "", );
av_dict_set(&options, "framerate", "", );
av_dict_set(&options, "input_format", "mjpeg", );
av_dict_set(&options, "video_size", "1920x1080", );
// av_dict_set(&options, "video_size", "1280x720", 0);
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, , &options)) < ) {
printf("open input file err\n");
goto end;
}
av_dict_free(&options);
if ((ret = avformat_find_stream_info(ifmt_ctx, )) < ) {
printf("failed to retrieve input stream information\n");
goto end;
}
for (i = ; i < ifmt_ctx->nb_streams; i++) {
if (ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
videoindex = i;
break;
}
printf("codec %d:%d %d\n", i, ifmt_ctx->streams[i]->codec->codec_type,
ifmt_ctx->streams[i]->codec->codec_id);
}
// exit(1);
ifcodec_ctx = ifmt_ctx->streams[videoindex]->codec;
icodec = avcodec_find_decoder(ifcodec_ctx->codec_id);
if (icodec == NULL) {
printf("icodec not find\n");
goto end;
}
if (avcodec_open2(ifcodec_ctx, icodec, NULL) < ) {
printf("open icodec err\n");
goto end;
}
printf("**************** input file info ******************\n");
av_dump_format(ifmt_ctx, , in_filename, );
// avformat_alloc_output_context2(&ofmt_ctx, NULL, "flv", out_filename);
ofmt_ctx = avformat_alloc_context();
if (!ofmt_ctx) {
printf("could not create output context\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = av_guess_format("mjpeg", NULL, NULL);
ofmt_ctx->oformat = ofmt;
out_stream = avformat_new_stream(ofmt_ctx, NULL);
if (!out_stream) {
printf("failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofcodec_ctx = out_stream->codec;
ofcodec_ctx->codec_id = ofmt->video_codec;
ofcodec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
ofcodec_ctx->pix_fmt = AV_PIX_FMT_YUVJ420P;
ofcodec_ctx->width = ifcodec_ctx->width;
ofcodec_ctx->height = ifcodec_ctx->height;
ofcodec_ctx->time_base.den = ;
ofcodec_ctx->time_base.num = ;
printf("timebase %d %d\n", ofcodec_ctx->time_base.den,
ofcodec_ctx->time_base.num);
// ofcodec_ctx->bit_rate = 1000000;
// ofcodec_ctx->gop_size = 5;
// ofcodec_ctx->me_range = 16;
// ofcodec_ctx->max_qdiff = 4;
// ofcodec_ctx->qmin = 10;
// ofcodec_ctx->qmax = 51;
// ofcodec_ctx->qcompress = 0.6;
// if (ofcodec_ctx->codec_id == AV_CODEC_ID_H264) {
// av_opt_set(ofcodec_ctx->priv_data, "preset", "slow", 0);
// ofcodec_ctx->max_b_frames = 1;
// }
out_stream->codec->codec_tag = ;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) {
out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
}
ocodec = avcodec_find_encoder(ofcodec_ctx->codec_id);
if (!ocodec) {
printf("find encoder err\n");
goto end;
}
if (avcodec_open2(ofcodec_ctx, ocodec, NULL) < ) {
printf("open encoder err\n");
goto end;
}
/*******************************************/
pFrame = av_frame_alloc();
pFrameYUV420 = av_frame_alloc();
pFrameBGR = av_frame_alloc();
in_buffer = (unsigned char *) av_malloc(
avpicture_get_size(AV_PIX_FMT_BGR24, , ));
avpicture_fill((AVPicture*) pFrameBGR, in_buffer, AV_PIX_FMT_BGR24, ,
);
// printf("fmt %d\twidth %d\theight %d\n", pFrameBGR->format, pFrameBGR->width,
// pFrameBGR->height);
out_buffer = (unsigned char *) av_malloc(
avpicture_get_size(AV_PIX_FMT_YUV420P, ofcodec_ctx->width,
ofcodec_ctx->height));
avpicture_fill((AVPicture*) pFrameYUV420, out_buffer, AV_PIX_FMT_YUV420P,
ofcodec_ctx->width, ofcodec_ctx->height);
// printf("fmt %d\twidth %d\theight %d\n", pFrameYUV420->format,
// pFrameYUV420->width, pFrameYUV420->height);
in_conCtx = sws_getContext(ifcodec_ctx->width, ifcodec_ctx->height,
ifcodec_ctx->pix_fmt, , ,
AV_PIX_FMT_BGR24, SWS_BICUBIC, NULL, NULL, NULL);
out_conCtx = sws_getContext(ifcodec_ctx->width, ifcodec_ctx->height,
ifcodec_ctx->pix_fmt, ofcodec_ctx->width, ofcodec_ctx->height,
ofcodec_ctx->pix_fmt, SWS_BICUBIC, NULL, NULL, NULL);
image = cvCreateImageHeader(cvSize(, ),
IPL_DEPTH_8U, );
cvSetData(image, in_buffer, * );
// inpkg = (AVPacket*) av_malloc(sizeof(AVPacket));
// outpkg = (AVPacket*) av_malloc(sizeof(AVPacket));
start_time = av_gettime();
pFrameYUV420->format = AV_PIX_FMT_YUV420P;
pFrameYUV420->width = ofcodec_ctx->width;
pFrameYUV420->height = ofcodec_ctx->height;
av_new_packet(&outpkg, ofcodec_ctx->width * ofcodec_ctx->height * );
while (av_read_frame(ifmt_ctx, &inpkg) >= && runFlag) {
inpkg.dts = av_rescale_q_rnd(inpkg.dts,
ifmt_ctx->streams[videoindex]->time_base,
ifmt_ctx->streams[videoindex]->codec->time_base,
(enum AVRounding) (AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
inpkg.pts = av_rescale_q_rnd(inpkg.pts,
ifmt_ctx->streams[videoindex]->time_base,
ifmt_ctx->streams[videoindex]->codec->time_base,
(enum AVRounding) (AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
//decode
if (inpkg.stream_index == videoindex) {
ret = avcodec_decode_video2(ifcodec_ctx, pFrame, &got_picture,
&inpkg);
if (ret < ) {
printf("decode err\n");
exit(-);
}
if (got_picture) {
pFrame->pts = av_frame_get_best_effort_timestamp(pFrame);
sws_scale(in_conCtx,
(const unsigned char * const *) pFrame->data,
pFrame->linesize, , ifcodec_ctx->height,
pFrameBGR->data, pFrameBGR->linesize);
// printf("bgr fmt %d\twidth %d\theight %d\n", pFrameBGR->format,
// pFrameBGR->width, pFrameBGR->height);
cvShowImage("camera", image);
cvWaitKey();
if (flag == ) {
char out_filename[];
memset(out_filename, , sizeof(out_filename));
sprintf(out_filename, "%d.jpg", frame_index);
printf("encode frame %d\n", frame_index++);
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename,
AVIO_FLAG_WRITE);
if (ret < ) {
printf("could not open output url '%s'\n",
out_filename);
goto end;
}
}
printf(
"**************** output file info ******************\n");
av_dump_format(ofmt_ctx, , out_filename, );
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < ) {
printf("error occurred when opening output URL\n");
goto end;
}
sws_scale(out_conCtx,
(const unsigned char * const *) pFrame->data,
pFrame->linesize, , ofcodec_ctx->height,
pFrameYUV420->data, pFrameYUV420->linesize);
// printf("yuv420 fmt %d\twidth %d\theight %d\n",
// pFrameYUV420->format, pFrameYUV420->width,
// pFrameYUV420->height);
got_picture = ;
pFrameYUV420->pts = pFrame->pts;
ret = avcodec_encode_video2(ofcodec_ctx, &outpkg,
pFrameYUV420, &got_picture);
if (ret < ) {
printf("encode err\n");
goto end;
}
if (got_picture == && flag == ) {
av_write_frame(ofmt_ctx, &outpkg);
av_free_packet(&outpkg);
av_write_trailer(ofmt_ctx);
}
flag = ;
}
}
}
//encode
av_free_packet(&inpkg);
end_time = av_gettime();
printf("fps:%2f\n", (float) / (end_time - start_time));
start_time = end_time;
}
end: sws_freeContext(in_conCtx);
sws_freeContext(out_conCtx);
free(in_buffer);
free(out_buffer);
av_free(pFrameYUV420);
av_free(pFrameBGR);
avcodec_close(ifcodec_ctx);
avcodec_close(ofcodec_ctx);
avformat_close_input(&ifmt_ctx);
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_close(ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < && ret != AVERROR_EOF) {
printf("Error occurred.\n");
exit(-);
}
exit();
}
代码是从标准的视频采集/转码程序改过来的，是测试程序，没有啥封装，看起来比较乱。