[Ffmpeg-devel-irc] ffmpeg.log.20150221

burek burek021 at gmail.com
Sun Feb 22 02:05:01 CET 2015

[00:57] <olivierrr> Hello. how can i tell ffmpeg to only use x frames as input
[01:05] <klaxa> olivierrr: see -vframes
[01:06] <olivierrr> thanks klaxa
[01:27] Action: Guest96197 is away: auto-away
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[03:00] <c_14> Guest96197: please turn off your public away message
[03:18] <Donald_ET3> How do you encode JPEG 2000? I can't get ffmpeg to recognize libopenjpeg nor j2k. :(
[03:31] <relaxed> Donald_ET3: use -v:c libopenjpeg
[03:32] <relaxed> er, -c:v
[03:32] <relaxed> or -c:v jpeg2000
[03:32] <Donald_ET3> Oops, the ffmpeg internal encoder is jpeg2000 instead of j2k.
[03:33] <Donald_ET3> relaxed: I can't get ffmpeg to recompile with libopenjpeg.
[03:33] <relaxed> my builds have it, http://johnvansickle.com/ffmpeg/
[03:34] <Donald_ET3> Awesome! :D
[03:39] <Donald_ET3> relaxed: That works! Thank you! :)
[15:01] <joakimkilby> Hi, question about usage of ffmpeg on OSX: I've got a c++ application running on windows platform that grabs video and audio from webcam/mic. I am now trying to port that application to OS X, i've got video working but cant seem to find how to activate audio as well. (Im using avfoundation as input). I've also not been able to figure out how to query a specific device for options (such as available video resoultions fr
[15:01] <joakimkilby> om camera etc.). Much googling has led me to where i am now but i seem to be stuck at the moment. does anyone know of a resource where i could find tips an tricks? Thanks in advance
[15:03] <BtbN> You want to capture your audio output?
[15:03] <BtbN> or some microphone?
[15:03] <joakimkilby> microphone
[15:05] <BtbN> Some posts from Sep 2014 suggest that the avfoundation capture doesn't support audio.
[15:05] <BtbN> No idea about the current state of this.
[15:05] <joakimkilby> yeah i saw those, also saw something about an experimental version which may have had audio support. cant seem to find it thou
[15:06] <BtbN> experimental patches
[15:06] <BtbN> doesn't sound like those were merged
[15:06] <joakimkilby> ah, that'd be why then
[15:07] <BtbN> "lavd/avfoundation: Add basic PCM audio support." is the only audio related commit i can find
[15:08] <joakimkilby> okidok. thanks man! i'll have to see if i can find another solution
[15:09] <BtbN> No idea about OSX, it's not entirely impossible there are other ways to capture audio.
[15:14] <joakimkilby> looks like using AVFoundation directly in my code could give me audio and video, i was just hoping i could stick with ffmpeg for the capture as im streaming the audio/video onwards to other machines using ffmpeg.
[17:12] <Meomari> hello anyone can help to begginer how to use ffmpeg? :)
[17:12] <klaxa> only if you tell us what you want to do
[17:14] <Meomari> i have ffmpeg on ubuntu 0.6.5 version
[17:14] <klaxa> that is a) pretty old and b) probably not even ffmpeg but avconv
[17:14] <Meomari> can i convert videos to h264 and scaling it to 360.480.720 and other formats?
[17:15] <Meomari> yes i know but i already buy hosting with ffmpeg and my hosting shared plan don't gives me access to upgrade ffmpeg
[17:15] <klaxa> as you can see from the topic, ffmpeg's current version is 2.5.4, i strongly suggest you update ffmpeg
[17:15] <klaxa> you should be able to run binaries without having to install them system-wide
[17:16] <Meomari> i know but i just beggining learn ffmpeg and i don't want pay 100$/monthly for vps server for testing period
[17:16] <c_14> Download the static build?
[17:16] <klaxa> you can test on your local system, also 100$/mo is pretty exaggerated
[17:17] <Meomari> i have windows on my desktop pc and i don't know how to setup ffmpeg
[17:18] <Meomari> with SSH without sudo access i can't update ffmpeg sure?
[17:18] <c_14> Just download the static build.
[17:18] <c_14> http://johnvansickle.com/ffmpeg/
[17:36] <Meomari> now i have code, for 2 pass he convert and rescaling video
[17:36] <Meomari> can i update that code for 1 pass?
[17:36] <c_14> yes
[17:37] <Meomari> http://wall.ge/ffmpeg/show.php
[17:37] <Meomari> here is code
[17:37] <Meomari> for showing
[17:37] <Meomari> check code from $options
[17:38] <Meomari> first pass makes video without audio, second recomple video with sound
[17:41] <klaxa> do you know what these options do? do you have to match a certain encoding?
[17:42] <klaxa> otherwise for most people using a crf value (somewhere around 20 and 25 depending on what quality/filesize you want) should be sufficient
[17:43] <Meomari> when i call that file?file=php he makes me thumbs and videos in mp4 format with scaling
[17:43] <Meomari> but very slow
[17:44] <c_14> Get rid of the '-pass 2' in the second command and get rid of the first command, then you'll have a one-pass encode
[17:44] <c_14> But like klaxa said, you most likely won't need most of what's in $options
[17:44] <c_14> Also, if it's too slow you can use -vpre ultrafast
[17:45] <c_14> Though with cbr encoding (which is what you're doing) a faster preset will lead to lower quality video, if you use crf the video quality will be the same, it'll just be bigger.
[17:46] <Meomari> it's no problem
[17:46] <Meomari> i have space
[17:46] <Meomari> how to use crf?
[17:47] <klaxa> ffmpeg -i input.mp4 -c:v libx264 -crf 20 output.mp4
[17:49] <c_14> Get rid of everything in $options, replace with -c:v libx264 -preset:v ultrafast -crf 20
[17:49] <klaxa> ^
[17:50] <c_14> Oh, you'll still need the -s $size though
[17:58] <Meomari> if i use that code? /usr/local/bin/ffmpeg -i input -aspect 16:9 -vcodec libx264 -vpre ultrafast -crf 25 -ar $rate -ab 128k -acodec libfaac -ac 2 -r 20 -f mp4 -sameq -s $scale output.mp4
[17:58] <Meomari> but that code makes from 4:3 videos to 16:9 and 16:9 to 4:3
[17:59] <c_14> Get rid of -sameq, and get rid of -aspect 16:9
[17:59] <Meomari> $rate is audiosimplarerate
[18:00] <Meomari> without -sameq how to scale video from 1280x720 to 640x360 ?
[18:00] <c_14> sameq has nothing to do with scaling video
[18:00] <c_14> that's what -s does
[18:01] <klaxa> isn't usage of -sameq discouraged even?
[18:01] <c_14> yes
[18:01] <Meomari> Oh...
[18:01] <Meomari> that code it's better ?
[18:01] <c_14> hmm?
[18:02] <Meomari> than old what i showed before
[18:02] <c_14> yes
[18:02] <c_14> cleaner, simpler, less likely to do weird things
[18:02] <Meomari> ok im go to test
[18:03] <Meomari> thanks you very much
[18:03] <Meomari> and last question
[18:03] <Meomari> can i terminate current command for ffmpeg if that command calls from php?
[18:04] <klaxa> `pkill ffmpeg` will probably work
[18:04] <c_14> You can always kill ffmpeg, or if stdin is a terminal press q
[18:04] <klaxa> if you want to do test encodes, you can add -t 10 to your options, it will encode only 10 seconds of video
[18:06] <Meomari> pkill: 356 - Operation not permitted
[18:06] <Meomari> pkill: 5340 - Operation not permitted
[18:06] <Meomari> pkill: 9482 - Operation not permitted
[18:06] <Meomari> pkill: 16586 - Operation not permitted
[18:06] <Meomari> pkill: 22425 - Operation not permitted
[18:06] <c_14> You have to execute kill as the user who has ffmpeg runnning, or root
[18:20] <Meomari> how can i check from php % of progress?
[20:02] <c_14> Either parse the output of ffmpeg or play around with the -progress option.
[23:50] <Kris> hi, can someone tell me why this python script for ffplay wont work? http://paste.i6.io/iqomudidug.py
[23:55] <Kris> nevermind, found the error
[00:00] --- Sun Feb 22 2015

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