[Ffmpeg-devel-irc] ffmpeg.log.20140429

[burek]

[01:59] <kode54> ah
[01:59] <kode54> I was using ffmpeg 2.2.1 built against libvpx 1.3.0
[10:50] <djdduty> hallo! I probably have a peculiar problem.... I am trying to use ffmpeg on windowns to compile images into a timelapse, but the images are name things like screen_11398474789.43.png and they don't increment in any way, how can I just add all images?
[10:50] <djdduty> *.png type of thing doesn't work.
[10:56] <djdduty> so I group renamed them and now they are img (n).png
[10:56] <djdduty> still cannot add it with img (%05d).png
[11:07] <brontosaurusrex> djdduty, hold on
[11:08] <brontosaurusrex> %05d.png < should work
[11:09] <brontosaurusrex> ffmpeg -f image2 -i img%05d.png ... < example
[11:10] <brontosaurusrex> (looking at my script, which is doing temporary soft-links before feeding those to ffmpeg (counter=$(printf %05d $x); ln -s "$i" /tmp/img"$counter"."$ext"; x=$(($x+1));))
[11:11] <djdduty> I am running ffmpeg -i "%05d.png" timelapse.mp4 now, and I did rename the pictures so they are all 1.png, 2.png etc now
[11:12] <brontosaurusrex> that would be %1d.png i imagine
[11:12] <djdduty> brontosaurusrex: it goes up to 16664.png
[11:13] <brontosaurusrex> djdduty, let me google on the %d formating ....
[11:14] <brontosaurusrex> try %5d
[11:14] <djdduty> did already
[11:14] <brontosaurusrex> http://www.promotic.eu/en/pmdoc/Appendix/FormatStringSpec.htm < reading this
[11:16] <brontosaurusrex> how about only %d ?
[11:16] <djdduty> brontosaurusrex: did that as well :(
[11:17] <djdduty> wait, even typing in 1.png it doesn't find it
[11:17] <djdduty> dir reveals I am in the right path etc
[11:17] <djdduty> gah
[11:17] <brontosaurusrex> ffmpeg -f image2 -i 1.png ... ?
[11:19] <djdduty> brontosaurusrex: wait I got it
[11:19] <djdduty> moved all the images to ffmpeg bin directory :DDD
[11:20] <djdduty> the prompt bat script ffmpeg comes with must be botching it
[11:20] <brontosaurusrex> djdduty, what os are you on?
[11:20] <djdduty> windows
[11:20] <brontosaurusrex> oh
[11:20] <brontosaurusrex> so what was the correct option? %d only?
[11:23] <djdduty> that's what I did yeah, but I didn't really try the others here
[11:23] <djdduty> it is only working now because I just put all the images in the bin dir and ran it there
[11:24] <djdduty> it's on image 4600 now.
[12:45] <termos> when using yadif I get half the framerate, so my video is playing in slow motion! I see from http://avisynth.org.ru/yadif/yadif.html that there's a double framerate option but this does not exist in ffmpeg.
[12:45] <termos> Do I need to do setpts=0.5*PTS as my next filter?
[12:48] <termos> it's not really an ffmpeg command as I'm linking against libffmpeg and using the API, but the filtering command is: yadif=0:-1:0
[12:51] <c_14> Are you sure the source is interlaced? you might also want to try yadif=1:-1:0
[13:39] <lkiesow> Question about the ffmpeg parameters: Is there a difference between -ab X and -b:a X? And which expression is preferred nowadays? My feeling is that -b:a is more consitent to the other options like -c:[av]
[13:40] <JEEBsv> lkiesow: yeah the x:y settings are newer and more consistent/preferred right now
[13:40] <lkiesow> thought so, thanks
[15:52] <Lumbendil> hey
[16:09] <superc2_> ffmpeg: Server error: call to function _checkbw failed
[16:13] <Lumbendil> if I tell ffmpeg to encode a 200k source to 600k, it'll yeild a file 3 times bigger, even if that doesn't increase image quality. Is there any way to prevent such behaviour?
[16:13] <klaxa> superc2_: provide more information please
[16:13] <klaxa> Lumbendil: not really since you specify the bitrate in a hard way
[16:13] <klaxa> it is also pretty much the expected behavior
[16:14] <klaxa> you can use different quality control methods
[16:14] <superc2_> What I'm doing is " ffmpeg -i rtmp://localhost/live/mp4:webCam.f4v  rtmp://localhost/live/test"
[16:14] <Lumbendil> for instance? Quite newby to this
[16:14] <klaxa> that depends on the codec you are using
[16:14] <Lumbendil> h264
[16:15] <Lumbendil> with libx264
[16:15] <klaxa> see: https://trac.ffmpeg.org/wiki/x264EncodingGuide
[16:15] <Lumbendil> ty
[16:15] <superc2_> so I'm trying to restream this mp4:webcam.f4v stream to 'test' stream on same host
[16:15] <superc2_> and then I get this error message
[16:15] <klaxa> phew no idea, what's your server setup?
[16:16] <superc2_> in the meanwhile I installed crtmpserver because I didn't get ffserver running
[16:17] <superc2_> so basically I'm able to stream from a flash app to the server and from there back to the flash app an see the video
[16:17] <superc2_> now I need to connect the stream and restream it to another
[16:18] <superc2_> and as I understand I need ffmpeg for this
[16:18] <Lumbendil> klaxa: from what I'm reading, if I want a certain max bitrate, but to give up to a certain quality, I'd use -crf X -maxrate Y, right? :)
[16:19] <klaxa> pretty much
[16:19] <klaxa> if the desired quality would require more bitrate than Y, quality should be degraded in order to stay below the maxrate limit
[16:21] <klaxa> ehh... documentation for crtmpserver is pretty sparse
[16:24] <superc2_> jep... actually there is no documentation
[16:24] <superc2_> but it works
[16:36] <Lumbendil> klaxa: do you know if with ffprobe there is any way to get the crf?
[16:36] <klaxa> unless it is written in the metadata there is no way to obtain crf value
[16:36] <klaxa> i don't know whether ffprobe prints it, mediainfo prints it if it exists
[17:45] <Lumbendil> klaxa: I'm checking the mediainfo output, if it existed, it'd be shown somewhere like "crf", right?
[17:46] <Lumbendil> I guess on "Encoding settings"
[21:35] <nineteenninetyni> Hi.
[21:36] <nineteenninetyni> How can I know the usage of each enconder in Ffmpeg? I know the supported codecs by putting -encoders.
[21:36] <c_14> ffmpeg -h encoder=$encoder ?
[21:38] <nineteenninetyni> Thanks!
[23:21] <Lokie> hello, i got 2 questions that a quick search in the site & google didn't solve. Is it possible to rip the font from a video and use it for the encode to avoid having ffmpeg fall back to Arial?
[23:22] <Lokie> also is there a way to encode without specifying target bitrate? like letting ffmpeg choose it?
[23:22] <c_14> For the second question, you can use -crf.
[23:22] <sacarasc> Assuming Matroska, you can use mkvextract to take out the font.
[23:23] <Lokie> it's in a cli linux box
[23:23] <Lokie> c_14 as far as i see in the encoding guide it still specifies target bitrate
[23:23] <sacarasc> That changes neither of our answers.
[23:25] <c_14> Lokie: you can also use: ffmpeg -dump_attachment:t "" -i INPUT
[23:25] <c_14> assuming the fonts are attached to the video
[23:25] <sacarasc> I did not know you could do that. :O
[23:25] <sacarasc> c_14 educates us all.
[23:26] <c_14> Lokie: you have to define a bitrate _somewhere_, you can't have a video file without one.
[23:27] <sacarasc> You need one form of rate control, yeah, but it doesn't have to be a target bitrate.
[23:27] <Lokie> i was thinking something along the lines ffmpeg looks at the size of the source and creates the new file  with a bitrate that should make the target file similar
[23:28] <Lokie> something like megui can do
[23:28] <Lokie> not really important since i am sure a bit of googling will show me some tool that can tell me what bitrate the source is using
[23:29] <c_14> ffprobe will give you the total bitrate and you can subtract the bitrate of the audio from that
[23:29] <sacarasc> -crf between 19 and 22 will usually give you a ~transparent file.
[23:30] <Lokie> i am not sure i follow you sacarasc. Wouldn't i still need to specify the bitrate? what do you mean with transparent?
[23:31] <Lokie> thx c_14. for the dump_attachment there seems to be limited documentation
[23:31] <sacarasc> Looking pretty much like the original.
[23:31] <sacarasc> And no, you'd not have to specify a bit rate.
[23:31] <Lokie> so ffmpeg -i input.mp4 -c:v libvpx -crf 10 -b:v -c:a libvorbis output.webm
[23:31] <Lokie> copying the example command from the guide and removing the bitrate value
[23:31] <sacarasc> Oh, you're using vp8.
[23:32] <Lokie> yes i failed to mention that
[23:33] <c_14> With vp8 it really depends, I usually set the crf to 4 and also set a bitrate to get it to look decent. But to your specific command: If you don't want to explicitly set a bitrate, don't type the -b:v or else ffmpeg will error
[23:34] <Lokie> and it should be around the same with the values sacarasc said
[23:34] <Lokie> will try it out
[23:34] <Lokie> same size*
[23:34] <sacarasc> I don't know the range that VPX uses, mine was for x264.
[23:34] <Lokie> By default the CRF value can be from 463, and 10 is a good starting point. Low
[23:35] <Lokie> lower  = better
[23:35] <Lokie> i will have to try a few values
[23:35] <Lokie> still good to know
[23:36] <Lokie> ffmpeg -dump_attachment:t "" -i out.mkv <-- out.mkv is what it should check for the attachments
[23:36] <Lokie> and it dumps them in the current dir?
[23:37] <c_14> ye, if your input is called out.mkv that is
[23:38] <Lokie> i get hit with "At least one output file must be specified"
[23:38] <c_14> It still works though...
[23:38] <c_14> Check your cwd.
[23:39] <c_14> That confused me for a while as well.
[23:39] <Lokie> both the dir i used the command from and the dir that the file resides in
[23:39] <Lokie> don't contain anything new
[23:39] <Lokie> wait
[23:41] <Lokie> i don't see anything but might be that the source is not the best choice being an avi (ignoring the fact that the subs there are hardsubs it should spit out the video and audio streams?)
[23:41] <Lokie> will try tomorrow, thank you both for your help!
[23:42] <c_14> Nah, it'll only spit out things specifically labeled as attachments or "codec extradata".
[23:42] <c_14> Also, not every format supports them.
[23:43] <c_14> Check with ffprobe to see if there are attachments before trying to extract them.
[23:44] <Lokie> Stream #0:0: Video: msmpeg4v3 (DIV3 / 0x33564944), yuv420p, 640x352, 1569 kb/s, 23.98 tbr, 23.98 tbn, 23.98 tbc
[23:44] <Lokie> Stream #0:1: Audio: ac3 ([0] [0][0] / 0x2000), 48000 Hz, 5.1(side), fltp, 448 kb/s
[23:44] <Lokie> so i am guessing nothing to be extracted
[23:44] <Lokie> will try with a proper mkv tomorrow
[23:45] <c_14> It should look something like this: http://ix.io/c0t
[23:46] <Lokie> cheers
[23:47] <c_14> \o
[00:00] --- Wed Apr 30 2014