我能够在自己的代码中流式传输用h264编码的静态mp4文件。
但是当我在程序中使用Linux视频设备/dev/video0
作为输入时,它会出现此错误:
failed to open file `udp://xxx.xxx.xxx.xxx:28000` or configure filtergraph.
我尚未在程序中使用编码器。我不明白为什么我不能直接从摄像机流式传输。
静态mp4文件以h264编码。我的代码流保持原样,但是当我尝试以video4linux2
格式流传输相机时,它无法播放。
我需要使用任何格式对摄像机的输出进行编码吗?
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
static void log_packet(const AVFormatContext *fmt_ctx,const AVPacket *pkt,const char *tag)
{
AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;
printf("%s: pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",tag,av_ts2str(pkt->pts),av_ts2timestr(pkt->pts,time_base),av_ts2str(pkt->dts),av_ts2timestr(pkt->dts,av_ts2str(pkt->duration),av_ts2timestr(pkt->duration,pkt->stream_index);
}
int main(int argc,char **argv)
{
AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL,*ofmt_ctx = NULL;
AVPacket pkt;
const char *in_filename,*out_filename;
AVInputFormat *inputFormat =av_find_input_format("video4linux2");
int ret,i;
/*if (argc < 3) {
printf("usage: %s input output\n"
"API example program to remux a media file with libavformat and libavcodec.\n"
"The output format is guessed according to the file extension.\n"
"\n",argv[0]);
return 1;
}
//in_filename = argv[1];
// out_filename = argv[2];*/
in_filename = "/dev/video0";
out_filename = "udp://xxx.xxx.xxx.xxx:28000";
avdevice_register_all();
avcodec_register_all();
av_register_all();
//Networkq
avformat_network_init();
if ((ret = avformat_open_input(&ifmt_ctx,in_filename,inputFormat,0)) < 0) {
fprintf(stderr,"Could not open input file '%s'",in_filename);
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx,"Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx,0);
avformat_alloc_output_context2(&ofmt_ctx,NULL,"mpegts",out_filename);
if (!ofmt_ctx) {
fprintf(stderr,"Could not create output context\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = ofmt_ctx->oformat;
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
AVStream *in_stream = ifmt_ctx->streams[i];
AVStream *out_stream = avformat_new_stream(ofmt_ctx,in_stream->codec->codec);
if (!out_stream) {
fprintf(stderr,"Failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ret = avcodec_copy_context(out_stream->codec,in_stream->codec);
if (ret < 0) {
fprintf(stderr,"Failed to copy context from input to output stream codec context\n");
goto end;
}
out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= AV_CODEC_flaG_GLOBAL_HEADER;
}
av_dump_format(ofmt_ctx,out_filename,1);
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb,AVIO_flaG_WRITE);
if (ret < 0) {
fprintf(stderr,"Could not open output file '%s'",out_filename);
goto end;
}
}
ret = avformat_write_header(ofmt_ctx,NULL);
if (ret < 0) {
fprintf(stderr,"Error occurred when opening output file\n");
goto end;
}
while (1) {
AVStream *in_stream,*out_stream;
ret = av_read_frame(ifmt_ctx,&pkt);
if (ret < 0)
break;
in_stream = ifmt_ctx->streams[pkt.stream_index];
out_stream = ofmt_ctx->streams[pkt.stream_index];
log_packet(ifmt_ctx,&pkt,"in");
/* copy packet */
pkt.pts = av_rescale_q_rnd(pkt.pts,in_stream->time_base,out_stream->time_base,AV_ROUND_NEAR_INF|AV_ROUND_PASS_MInmAX);
pkt.dts = av_rescale_q_rnd(pkt.dts,AV_ROUND_NEAR_INF|AV_ROUND_PASS_MInmAX);
pkt.duration = av_rescale_q(pkt.duration,out_stream->time_base);
pkt.pos = -1;
log_packet(ofmt_ctx,"out");
ret = av_interleaved_write_frame(ofmt_ctx,&pkt);
if (ret < 0) {
fprintf(stderr,"Error muxing packet\n");
break;
}
av_free_packet(&pkt);
}
av_write_trailer(ofmt_ctx);
end:
avformat_close_input(&ifmt_ctx);
/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_closep(&ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < 0 && ret != AVERROR_EOF) {
fprintf(stderr,"Error occurred: %s\n",av_err2str(ret));
return 1;
}
return 0;
}
输出为
pi@raspberrypi:~/source_code $ ./deneme_4
Input #0,video4linux2,v4l2,from '/dev/video0':
Duration: N/A,start: 74626.180310,bitrate: 235929 kb/s
Stream #0:0: Video: rawvideo (I420 / 0x30323449),yuv420p,1024x768,235929 kb/s,25 fps,25 tbr,1000k tbn,1000k tbc
Output #0,mpegts,to 'udp://xxx.xxx.xxx.xxx:28000':
Stream #0:0: Unknown: none
[mpegts @ 0x1d6a5c0] Using AVStream.codec to pass codec parameters to muxers is deprecated,use AVStream.codecpar instead.
in: pts:74626180310 pts_time:74626.2 dts:74626180310 dts_time:74626.2 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716356228 pts_time:74626.2 dts:6716356228 dts_time:74626.2 duration:3600 duration_time:0.04 stream_index:0
in: pts:74626408490 pts_time:74626.4 dts:74626408490 dts_time:74626.4 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716376764 pts_time:74626.4 dts:6716376764 dts_time:74626.4 duration:3600 duration_time:0.04 stream_index:0
in: pts:74626665690 pts_time:74626.7 dts:74626665690 dts_time:74626.7 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716399912 pts_time:74626.7 dts:6716399912 dts_time:74626.7 duration:3600 duration_time:0.04 stream_index:0
in: pts:74626923514 pts_time:74626.9 dts:74626923514 dts_time:74626.9 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716423116 pts_time:74626.9 dts:6716423116 dts_time:74626.9 duration:3600 duration_time:0.04 stream_index:0
in: pts:74627180935 pts_time:74627.2 dts:74627180935 dts_time:74627.2 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716446284 pts_time:74627.2 dts:6716446284 dts_time:74627.2 duration:3600 duration_time:0.04 stream_index:0
in: pts:74627439174 pts_time:74627.4 dts:74627439174 dts_time:74627.4 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716469526 pts_time:74627.4 dts:6716469526 dts_time:74627.4 duration:3600 duration_time:0.04 stream_index:0
in: pts:74627695789 pts_time:74627.7 dts:74627695789 dts_time:74627.7 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716492621 pts_time:74627.7 dts:6716492621 dts_time:74627.7 duration:3600 duration_time:0.04 stream_index:0
in: pts:74627951834 pts_time:74628 dts:74627951834 dts_time:74628 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716515665 pts_time:74628 dts:6716515665 dts_time:74628 duration:3600 duration_time:0.04 stream_index:0
in: pts:74628208064 pts_time:74628.2 dts:74628208064 dts_time:74628.2 duration:40000 duration_time:0.04 stream_index:0
out: pts:6716538726 pts_time:74628.2 dts:6716538726 dts_time:74628.2 duration:3600 duration_time:0.04 stream_index:0
^C