Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
Thanks Nicolas. Please remember to follow the mailing list's netiquette, in particular not hijacking threads (too late for that this time) but all of it. Apologies for hijacking the thread (though I'm not clear as to what in particular I did in that regard--I started the thread). You did not bother to tell what kind of capture you are doing, so it is not possible to point you to the exact place in the documentation. The capture I'm doing is v4l2 to nvenc to matroska. Here's the command line I've been using: ffmpeg -f v4l2 -framerate 60 -video_size 1920x1080 -i /dev/video0 -r 2997/100 -f matroska -c:v nvenc -b:v 25000k -minrate 25000k -maxrate 25000k -g 1 -profile:v high -preset hq my_video.mkv Thanks again for any tips you can provide. ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
Le nonidi 29 floréal, an CCXXIII, Arthur Wait a écrit : Apologies for hijacking the thread (though I'm not clear as to what in particular I did in that regard--I started the thread). No real harm done, ans sorry for the harsh tone. Your initial message has this: In-Reply-To: cae6_u_rtud6z-kd1fidfaz6_zo6fhlfvrv_nw7vqb2a0pum...@mail.gmail.com That means you wrote it by replying to this message. The capture I'm doing is v4l2 to nvenc to matroska. Then frames have timestamps provided by the kernel: ffprobe -i /dev/video0 -of compact -show_packets [...] packet|codec_type=video|stream_index=0|pts=1392045174616|pts_time=1392045.174616|... As you can see, this is the monotonic clock (and my uptime here is 16 days), but lavd can convert for you: http://ffmpeg.org/ffmpeg-devices.html#video4linux2_002c-v4l2 With that, you just need to do whatever you want with the timestamps. By default, ffmpeg will normalize the timestamps before any filtering or encoding, but you can disable that with the -copyts option. Regards, -- Nicolas George signature.asc Description: Digital signature ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
Fantastic Nicolas, thanks so much! This is exactly what I needed. Arthur ffprobe -i /dev/video0 -of compact -show_packets [...] packet|codec_type=video|stream_index=0|pts=1392045174616|pts_time=1392045.174616|... As you can see, this is the monotonic clock (and my uptime here is 16 days), but lavd can convert for you: ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
On Mon, May 18, 2015 at 18:38:18 +0200, Nicolas George wrote: As you can see, this is the monotonic clock (and my uptime here is 16 days), but lavd can convert for you: http://ffmpeg.org/ffmpeg-devices.html#video4linux2_002c-v4l2 I tried that, because I wanted to answer the question as well. It was non-obvious to me that this, what you call normalize, would happen: With that, you just need to do whatever you want with the timestamps. By default, ffmpeg will normalize the timestamps before any filtering or encoding, but you can disable that with the -copyts option. I see the timestamp of the first frame reset to 0 - is that what you mean with normalize? From the description of the v4l2 device, I had expected the wallclock to be copied to the timestamps (PTS, right?), but they began with 0 for the first frame. I then tried to add -vf setpts=RTCSTART+PTS-STARTPTS but that was apparently a long shot - it didn't help. So I added -copyts, but again to no avail. The first frame always shows: pkt_pts=0 pkt_pts_time=0.00 pkt_dts=0 pkt_dts_time=0.00 best_effort_timestamp=0 best_effort_timestamp_time=0.00 I was hoping to be able to hint the original poster to grab the start time from the PTS of the first frame. So: How to get wallclock timestamps into the video? For reference, my attempt. (The input obviously has the correct wallclock time: 1431981242.712328.) $ ffmpeg -f v4l2 -input_format yuv420p -timestamps abs -i /dev/video1 -t 1 -c:v libx264 -copyts ~/tmp/video1.mkv -y ffmpeg version 2.6.git Copyright (c) 2000-2015 the FFmpeg developers built with icc (ICC) 14.0.3 20140422 configuration: --prefix=/usr/new/tools/video/install/ffmpeg/2015-05-11 --cc=icc --cxx=icpc --enable-gpl --enable-version3 --enable-nonfree --disable-shared --enable-gnutls --enable-libcdio -- enable-libfreetype --enable-libx264 --enable-libmp3lame --enable-openal --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libass --enable-libv 4l2 --enable-libvidstab --enable-libfdk-aac --enable-libsmbclient --enable-libquvi --enable-libzvbi --enable-libzmq --extra-ldflags=-L/usr/new/tools/video/install/fdk-aac/current/lib --extra-cf lags=-I/usr/new/tools/video/install/fdk-aac/current/include libavutil 54. 23.101 / 54. 23.101 libavcodec 56. 38.100 / 56. 38.100 libavformat56. 32.100 / 56. 32.100 libavdevice56. 4.100 / 56. 4.100 libavfilter 5. 16.101 / 5. 16.101 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 1.100 / 1. 1.100 libpostproc53. 3.100 / 53. 3.100 [video4linux2,v4l2 @ 0xa60bd00] Detected absolute timestamps Input #0, video4linux2,v4l2, from '/dev/video1': Duration: N/A, start: 1431981242.712328, bitrate: 124416 kb/s Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 720x576, 124416 kb/s, 25 fps, 25 tbr, 1000k tbn, 1000k tbc [libx264 @ 0xa60de20] using cpu capabilities: MMX2 SSE2 Cache64 [libx264 @ 0xa60de20] profile High, level 3.0 [libx264 @ 0xa60de20] 264 - core 142 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00 Output #0, matroska, to '/home/barsnick/tmp/video1.mkv': Metadata: encoder : Lavf56.32.100 Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 720x576, q=-1--1, 25 fps, 1k tbn, 25 tbc Metadata: encoder : Lavc56.38.100 libx264 Stream mapping: Stream #0:0 - #0:0 (rawvideo (native) - h264 (libx264)) Press [q] to stop, [?] for help [libx264 @ 0xa60de20] non-strictly-monotonic PTS Last message repeated 12 times [libx264 @ 0xa60de20] non-strictly-monotonic PTS0:00:00.00 bitrate=N/A Last message repeated 10 times frame= 24 fps=2.6 q=-1.0 Lsize=2129kB time=-23860:55:45.88 bitrate=N/A video:2128kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.039607% [libx264 @ 0xa60de20] frame I:1 Avg QP:38.00 size: 90932 [libx264 @ 0xa60de20] frame P:23Avg QP:38.00 size: 90753 [libx264 @ 0xa60de20] mb I I16..4: 0.0% 70.0% 30.0% [libx264 @ 0xa60de20] mb P I16..4: 0.9% 85.8% 13.1% P16..4: 0.0% 0.1% 0.1% 0.0% 0.0%skip: 0.0% [libx264 @ 0xa60de20] 8x8 transform intra:85.3% inter:65.0% [libx264 @ 0xa60de20] coded y,uvDC,uvAC intra: 100.0% 0.0% 0.0% inter: 100.0% 0.0% 0.0% [libx264 @ 0xa60de20] i16 v,h,dc,p: 0% 7% 81% 13% [libx264 @ 0xa60de20] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 1% 42% 29% 2% 3%
Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
I see the timestamp of the first frame reset to 0 - is that what you mean with normalize? Here's what seems to have worked for me: ffmpeg -f v4l2 -framerate 60 -video_size 1920x1080 -ts mono2abs -i /dev/video-static -r 2997/100 -f matroska -c:v nvenc -b:v 25000k -minrate 25000k -maxrate 25000k -g 1 -profile:v high -preset hq -copyts output.mkv It took me a few tries to get the -ts mono2abs and -copyts into the right location, but now I believe I'm getting good wall-clock time (at least, it looks logical to me). I'm still doing some testing, though... ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Getting precise start time from wall-clock for capture
Le nonidi 29 floréal, an CCXXIII, Arthur Wait a écrit : I'm using FFMPEG to record video from several cameras attached to several networked computers. The computers' clocks are all synced. I'd like to be able to get a precise date/time for the first captured frame All captured frames should have a timestamp attached, usually to the microsecond; an option may be needed to have it based on the wall clock. You did not bother to tell what kind of capture you are doing, so it is not possible to point you to the exact place in the documentation. Please remember to follow the mailing list's netiquette, in particular not hijacking threads (too late for that this time) but all of it. Regards, -- Nicolas George signature.asc Description: Digital signature ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
[FFmpeg-user] Getting precise start time from wall-clock for capture
Hi all, I'm using FFMPEG to record video from several cameras attached to several networked computers. The computers' clocks are all synced. I'd like to be able to get a precise date/time for the first captured frame; this will allow me to easily sync the recordings later on. I've found that just getting the date/time from the command line is not accurate enough--it reflects the time that the file is first written to disk, but not the time that the first frame is captured. I found a similar question posted to StackOverflow ( https://stackoverflow.com/questions/21262786/accurate-ffmpeg-capture-start-time), and he describes the requirement quite well, though no one seemed to have a workable solution (I tried the suggestions posted). Anyone else have ideas for this? Thanks very much! Art ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
