[Ffmpeg-devel-irc] ffmpeg.log.20150321

[burek]

[02:06:52 CET] <dsl420> hey, i want to make a screenshot on DAR of frame 2000 http://pastebin.com/q7zPQq8A but it makes a screenshot in SAR
[02:07:18 CET] <dsl420> ffmpeg -ss 00:00:05 -i input.mkv -y  -vframes 1 -vf "scale='max(sar,1)*iw':'max(1/sar,1)*ih'" output.png this command works
[02:07:38 CET] <dsl420> in DAR*
[02:58:29 CET] <lawltoad> Hi all, I'm using -ss and -to to try and cut a file into three pieces and join them again ... but the results are far from seemless
[02:58:33 CET] <lawltoad> am i doing this wrong?
[02:59:03 CET] <c_14> -codec copy ?
[03:00:18 CET] <lawltoad> yea
[03:00:35 CET] <c_14> Then you'll only cut to the nearest keyframe.
[03:00:55 CET] <lawltoad> oh? how does one do that?
[03:01:29 CET] <c_14> It's automatic. If you want to cut frame-perfect, you have to reencode.
[03:03:26 CET] <lawltoad> so instead of -c copy i sue -c fg
[03:03:41 CET] <lawltoad> **libx264
[03:04:08 CET] <c_14> -c:v libx264 for example, you just have to remember that every time you do a lossy conversion you'll lose quality
[03:04:25 CET] <c_14> The :v is important if the stream has audio/subtitle streams or else you'll get an error.
[03:08:09 CET] <lawltoad> theres a pretty intense hickup at the seams when I try to recombind it
[03:14:25 CET] <smo_> hi :)
[03:15:51 CET] <smo_> i use ffmpeg to transcode live http streams some users have a strange behavior, the video start normally then ffmpeg freeze... process is still alive but nothing happen, they just backward seek one second then everything works normally after that
[03:15:55 CET] <smo_> what can do that ?
[03:16:02 CET] <smo_> (we use -re)
[03:16:34 CET] <smo_> (they have fibre connexion so not a downloading problem)
[03:17:13 CET] <c_14> lawltoad: can you pastebin all your commands and the output?
[03:17:27 CET] <c_14> smo_: the ffmpeg process producing output stops producing output, or the video on the client side freezes?
[03:17:59 CET] <smo_> the 2 it s live piping thru nodejs
[03:18:07 CET] <smo_>  ht5server.js:466 grep stderr: frame=  263 fps= 24 q=17.0 size=    1001kB time=00:00:11.15 bitrate= 734.8kbits/s
[03:18:18 CET] <smo_> log freeze on this
[03:18:24 CET] <smo_> and video is freezed too
[03:19:13 CET] <smo_> very strange
[03:19:41 CET] <c_14> What could be happening is that their client progresses further in the stream than the source, then freezes/pauses
[03:20:14 CET] <smo_> but why it do not restart alone ?
[03:20:22 CET] <smo_> downloading too fast ?
[03:20:47 CET] <lawltoad> c_14, http://pastebin.com/di6NLs5q
[03:21:34 CET] <beaver> c_14: http://pastebin.com/xNRunvpn
[03:21:44 CET] <c_14> Why it doesn't restart by itself depends on the player, as for why it happens, could be that the source was a bit slow preparing some frames and then the player hiccups because of it
[03:22:34 CET] <smo_> humm i see no way for ffmpeg to limit this ?
[03:23:08 CET] <c_14> lawltoad: when you use -to as an output option and -ss as an input option -to is equivalent to -t
[03:23:43 CET] <c_14> smo_: if the problem is what I think it is, the usual way of dealing with it is to buffer in the client
[03:24:13 CET] <smo_> ffmpeg or the player ? (don t have control on the player since it s basic html5 player finally...)
[03:24:25 CET] <smo_> (medialement.js)
[03:24:35 CET] <smo_> mediaelement.js*
[03:24:36 CET] <c_14> the player would be best
[03:25:06 CET] <smo_> don t think  can :/, something i could try in ffmpg ?
[03:25:50 CET] <lawltoad> oh, thats weird, haha
[03:26:01 CET] <lawltoad> theres still a subtle hiccup, but not replaying
[03:26:49 CET] <c_14> smo_: what's your current ffmpeg command?
[03:27:02 CET] <smo_> wait
[03:28:10 CET] <smo_> http://pastebin.com/y61Fefx9 c_14
[03:28:30 CET] <smo_> (joined array commands...)
[03:30:16 CET] <c_14> Does the source stream provide content at faster than realtime?
[03:30:35 CET] <smo_> for myuser yes i think so he hs a veryyy fastconnexion
[03:30:51 CET] <smo_> i have a really slower connexion and don t have this problem
[03:31:27 CET] <c_14> Where does the pipe output to?
[03:31:30 CET] <smo_> never freeze for me ...
[03:32:24 CET] <smo_> player make a request -> go thru ffmpeg -> return to the player directly
[03:33:01 CET] <c_14> could you somehow add a small cache in between the ffmpeg pipe output and before where it's going?
[03:33:02 CET] <smo_> it a torrent downloading live in a temp file (the http link you have in my pastebin)
[03:33:27 CET] <smo_> i could add a timeout before it start play yes
[03:34:01 CET] <c_14> Adding something like that should get rid of hiccups.
[03:34:02 CET] <smo_> can choose the amout of data before player start or anything i want...
[03:34:08 CET] <smo_> ok will try
[03:55:11 CET] <smo_> seems to fix the problem c_14 thanks :)
[08:54:58 CET] <Chillance> so, I'm using ffmpeg -f x11grab to record part of my screen, but the video has some 20px in height bars flickering across the screen sometimes... why and how to fix this?
[13:51:45 CET] <gcl5cp> i have 2 videos, i want swap audio/video, i mean file1(video)+file2.avi(audio) and file2(video)+file1(audio), how i do that=
[14:00:31 CET] <klaxa> ffmpeg -i input1.mp4 -i input2.mp4 -c copy -map 0:v -map 1:a output1.mp4 -map 0:a -map 1:v output2.mp4
[14:00:34 CET] <klaxa> that should work
[14:00:37 CET] <klaxa> gcl5cp: ^
[14:21:28 CET] <gcl5cp> thank klaxa, i was a mess with 0:0..0:3
[23:28:26 CET] <hexagon5un> howdy all.  i've been creating videos by slicing them up using -ss and -d, operating on chunks individually, and then concatenating them back together.  problem is the soundtrack is missing a few milliseconds here and there, and so glitches.  any ideas how to make it right?
[00:00:00 CET] --- Sun Mar 22 2015