[Ffmpeg-devel-irc] ffmpeg.log.20190402

[burek]

[00:08:51 CEST] <dipole> Hi! I'm trying to record 3 seconds of webcam with audio, but the following command just hangs after encoding the resulting video. If I interrupt it, I get my 3 second video
[00:08:53 CEST] <dipole> ffmpeg -y -f alsa -ac 2 -i default -f video4linux2 -s vga -i /dev/video0 -c:v libx264 -t 3 /tmp/tmp19y9jqar.mp4
[00:09:10 CEST] <dipole> Any ideas how can I make this command not hang after it generated result?
[00:11:26 CEST] <dipole> well, the problem is in this arguments: -f alsa -ac 2 -t 3 -i default
[00:11:32 CEST] <dipole> if I remove it, the script works seamlessly
[00:19:48 CEST] <dipole> what is pb? :)
[00:21:24 CEST] <another> hmm.. seems to be broken. anyway, post your command output to some pastebin site
[00:23:06 CEST] <dipole> ahh, https://pastebin.com/90Tk3GdX sure!
[00:23:45 CEST] <dipole> (accidentally sent two commandline outputs, double Ctrl-C stops hanging ffmpeg
[00:24:20 CEST] <dipole> also, while it hangs, it maxes the CPU
[00:26:11 CEST] <another> hmm.. your alsa device looks wrong. have you looked at https://trac.ffmpeg.org/wiki/Capture/ALSA ?
[00:27:31 CEST] <dipole> I have pulseaudio btw
[00:28:51 CEST] <another> then maybe you should use -f pulse
[00:30:04 CEST] <dipole> you are my hero!!!
[00:31:17 CEST] <another> :)
[03:16:43 CEST] <bray90820> The premium Tv service that was canceled was that the stuff that was on the OTA Tuners
[08:53:31 CEST] <pk08> hi
[08:53:49 CEST] <pk08> i want to output stream to udp multicast
[08:54:19 CEST] <pk08> so by default what is the ttl of that multicast and how can i change in c program?
[09:03:53 CEST] <JEEB> see the AVOptions of the UDP protocol
[09:07:49 CEST] <pk08> thanks JEEB
[09:08:09 CEST] <pk08> will this type of url work? url syntax: udp://host:port[?option=val...]
[09:08:33 CEST] <JEEB> just use AVOptions
[09:08:40 CEST] <pk08> ok, thank you
[09:08:41 CEST] <JEEB> see the examples using av_dict
[09:08:49 CEST] <JEEB> you set a key and a value :P
[09:09:21 CEST] <JEEB> the UDP protocol does abuse URL options, but I don't recommend them unless required
[09:12:31 CEST] <pk08> i will use av_dict option
[09:13:11 CEST] <pk08> and i have to pass that option to avformat_init_output or avformat_write_header?
[09:17:16 CEST] <JEEB> there's some examples under doc/examples
[09:21:08 CEST] <pk08> thank you JEEB
[13:27:24 CEST] <ehsanv> hi guys. i have a problem! i want to overlay my webcam on top of my desktop(making a screencapture with my video on it) and it works with ffmpeg. the problem is, i want to transparent it, and flip the camera verticaly, but when i use this code, it not works at all!
[13:27:29 CEST] <ehsanv> ffmpeg -f dshow -i video="USB2.0 HD UVC WebCam":audio="Microphone (Realtek High Definition Audio)" -f gdigrab -i desktop -filter_complex "[0]geq='p(X,Y)'[a];[1][a]overlay=10:main_h-overlay_h-10" output.mp4
[13:29:01 CEST] <ehsanv> the [a] output is not show anything! but when use [0] instead of [a] on overlay input it works!
[13:30:31 CEST] <ehsanv> P.S: sorry for posting command line here, pastebin is filtered for me, i'm from a sanctioned country, IRAN!
[13:33:26 CEST] <durandal_1707> geq is extremly slow, why you use it at all?
[13:34:26 CEST] <ehsanv> i'm newbie, any alternatives to suggest?!
[13:34:38 CEST] <durandal_1707> vflip/hflip
[13:34:47 CEST] <ehsanv> and for transparency?
[13:35:02 CEST] <durandal_1707> what about it?
[13:35:22 CEST] <thebombzen> overlay is fine if you're actually using it to overlay, which is what it appears you're doing
[13:35:25 CEST] <ehsanv> i want to make whole picture semi transparent
[13:35:48 CEST] <ehsanv> thanks durandal_1707
[13:35:59 CEST] <thebombzen> oh that, you want to set the alpha value to 0.5
[13:36:12 CEST] <ehsanv> yep
[13:37:19 CEST] <thebombzen> try something like alphamerge. like: color=gray[alpha]; [input][alpha] alphamerge [output]
[13:40:17 CEST] <ehsanv> thanks thebombzen,
[13:40:25 CEST] <ehsanv> this command worked!
[13:40:25 CEST] <ehsanv> ffmpeg -thread_queue_size 16 -f dshow -i video="USB2.0 HD UVC WebCam":audio="Microphone (Realtek High Definition Audio)" -f gdigrab -i desktop -filter_complex "color=gray:640x480[alpha];[0]hflip[a];[a][alpha]alphamerge[ao];[1][ao]overlay=10:main_h-overlay_h-10" output.mp4
[13:42:42 CEST] <ehsanv> i get the point! geq not worked because as durandal_1707 said, its slow and my webcam is a video stream and maybe the geq result isn't fast enough to sync with other inputs, so thats the problem. thank you both
[14:37:25 CEST] <kubast2> Any of you know which audio codecs and containers does twitch.tv support?
[14:39:43 CEST] <TheAMM> Isn't that better asked from Twitch?
[14:40:05 CEST] <BtbN> h264 and aac
[14:40:13 CEST] <BtbN> You stream to them via rtmp. That's it.
[14:42:36 CEST] <kubast2> flv, h264 and aac
[14:43:15 CEST] <BtbN> They will remux it though. The player never gets flv, it's all mpeg-ts
[15:50:34 CEST] <MyStartx> Hello
[15:53:25 CEST] <MyStartx> Guys how can i record just a terminal session in linux with ffmpeg? what input should i have in command line? thank you
[15:53:57 CEST] <BtbN> script
[15:58:08 CEST] <DHE> I assume he wants an x11grab that's single-window aware...
[15:58:29 CEST] <MyStartx> yes..but i dont want all screen
[15:58:44 CEST] <MyStartx> just onecterminal session
[15:58:48 CEST] <pink_mist> that's what DHE meant by "single-window aware"
[15:59:27 CEST] <DHE> ffmpeg -x $TOPLEFT_X -y $TOPLEFT_Y -s ${WIDTH}x${HEIGHT} -framerate 30 -f x11grab -i :0.0 [...]
[15:59:40 CEST] <BtbN> I think the best you can do is query the region beforehand, so it won't track the window when you move it around
[15:59:50 CEST] <DHE> realistically I would run a private X11 window (Xvnc is great for this) and record the whole screen anyway
[16:00:20 CEST] <DHE> this would protect you against pop-ups, etc.
[16:00:32 CEST] <BtbN> Don't you usually use Xephyr or something for thaT?
[16:01:08 CEST] <DHE> umm.. not me. I thought xephyr was for hotseating
[16:01:21 CEST] <BtbN> Xephyr is modern Xnest
[16:01:29 CEST] <BtbN> Literally an X-Server in an X-Window
[16:01:32 CEST] <DHE> oh... Xnest could work
[16:01:37 CEST] <BtbN> Xnest is old and slow
[16:01:39 CEST] <BtbN> use Xephyr
[16:02:39 CEST] <DHE> that makes sense...
[16:04:08 CEST] <mozzarella> please help me
[16:04:11 CEST] <MyStartx> thank you guys
[16:13:31 CEST] <Hello71> or just use script
[19:54:41 CEST] <TheWild> hello
[19:56:53 CEST] <TheWild> well, never mind. Tried concatenating two files losslessly, but just now I found out they use different codecs :/
[19:57:00 CEST] <Matttttt> Can anyone help me with an error, "dimensions not set" when trying to copy an HLS stream?
[19:57:09 CEST] <Matttttt> https://pastebin.com/kNfMhfRq
[21:31:07 CEST] <dawgly> Hello, does anyone know where I could learn the differences between huffyuv  and v210 and which is better for capturing video using v4l2?
[22:16:57 CEST] <rlot> Hi everyone. I'm streaming combined audio + video stream to youtube rtmp livestream. Is it possible to switch the input stream without killing the ffmpeg process?
[22:17:25 CEST] <rlot> Do I need to use libav manually to achieve it?
[22:18:45 CEST] <BtbN> No, ffmpeg can't do that.
[22:18:56 CEST] <BtbN> You probably want to use OBS for dynamic live streams.
[22:19:47 CEST] <rlot> Can't really use OBS because its supposed to be streamed from vps
[22:19:54 CEST] <rlot> so no gpu
[22:20:22 CEST] <BtbN> Probably have to roll your own software then, I'm not aware of anything headless that does that kind of stuff
[22:21:46 CEST] <rlot> Hmm
[22:22:34 CEST] <rlot> Or can I concat multiple of these streams before starting the transmission and use -stream_loop -1?
[22:39:41 CEST] <bugre> Hi, i'm searching for a 'duration' limiter on `ffprobe`, to limit the probing of the stream to a specific time. Something similar as '-t' on the ffmpeg input, that limits the amount of time that is read from the input. I've searched the man and internet, but wasn't able to find an equivalent for ffprobe, but i'm probably looking at it from the wrong perspective. Would appreciate some itp/help if someone knows it.
[22:40:51 CEST] <furq> bugre: analyzeduration/probesize
[22:40:54 CEST] <faLUCE> bugre: did you try probesize?
[22:41:06 CEST] <furq> although those are set by default unless you do something like -count_frames that requires decoding the whole stream
[22:43:08 CEST] <bugre> thanks @furq and @faLUCE. I've not tried those options. Right now i've a script around the ffprobe that kills the command when desired time is reached. (it's something like: `fprobe -show_entries frame -select_streams V -print_format xml...`)
[22:43:26 CEST] <bugre> I'll look into analyzeduration/probesize.
[22:58:06 CEST] <bugre> @furq and @faLUCE, apparently the analyzeduration/probesize only affect the amount used to get the 'stream identified' and don't make the stream read operation stop, in my case, where i'm checking information on the frames itself. I've also tried the fpsprobesize, but not the expected result neither.
[23:10:11 CEST] <faLUCE> bugre: do you want to stop ffprobe after getting these infos?
[00:00:00 CEST] --- Wed Apr  3 2019