[Ffmpeg-devel-irc] ffmpeg.log.20111228

burek burek021 at gmail.com
Thu Dec 29 02:05:02 CET 2011

[00:08] <JodaZ> wtf, why would ffprobe and ffmpeg be exclusive debian packages
[00:09] <JodaZ> -_- nvm one is debian default, one is multimedia
[03:29] <pythonirc1011> I've a file which is either an mp4 file or a flv file. But I dont know what type it is. Can ffmpeg help me rip out the audio from it -- in mp3 please?
[03:35] <JodaZ> pythonirc1011, maybe ffmpeg -i FILE -vn -acodec libmp3lame mp3 OUTFILE.mp3
[03:38] <pythonirc1011> I'm getting ERROR: audio conversion failed: Unknown encoder 'libmp3lame'
[03:38] <pythonirc1011> how do i fix this
[03:38] <pythonirc1011> JodaZ: I installed  ffmpeg using "apt-get install" on ubuntu
[03:39] <JodaZ> try without -acodec libmp3lame
[03:41] <JodaZ> pythonirc1011, alternatively add this repository to get a less broken ffmpeg http://medibuntu.org/repository.php
[03:41] <JodaZ> or follow compilation guide in topic
[03:41] <pythonirc1011> JodaZ: http://pbin.compgeom.com/show/2/ 
[03:42] <pythonirc1011> it seems its recognizing the filetype
[03:42] <JodaZ> your ffmpeg is shit
[03:42] <pythonirc1011> ffmpeg -i inpfile -vn -acodec libmp3lame mp3 OUTFILE.mp3
[03:43] <JodaZ> yes
[03:43] <JodaZ> now get a proper ffmpeg using the comilation guide in topic or the repo i showed you
[03:43] <pythonirc1011> JodaZ: I've a program that can use it to do what i want...so there is some trivial way that my crap ffmpeg should be able to do this
[03:44] <JodaZ> does that work ?
[03:44] <JodaZ> just check ps aux for the way ffmpeg is called and do it like that
[03:44] <relaxed> ffmpeg -i input -vn -acodec libmp3lame -aq 0 output.mp3
[03:44] <pythonirc1011> relaxed: Thanks ! 
[03:45] <pythonirc1011> relaxed: also, how do i get good quality mp3 with VBR?
[03:45] <relaxed> -aq 0
[03:45] <pythonirc1011> is this the best quality i can get?
[03:45] <relaxed> yes
[03:46] <relaxed> use flac if you want lossless
[03:47] <pythonirc1011> whats flac and how can i use it? libmp3flac?
[03:49] <relaxed> it's a lossless audio codec. ffmpeg -i input -vn -acodec flac output.flac
[03:50] <pythonirc1011> ah ok...thanks
[05:16] <kcm1700> can ffmpeg decode h.264 video encoded with forced intra refresh technology?
[05:42] <pythonirc1011> how can i make ffmpeg not output anything except in case there is an error?
[05:42] <pythonirc1011> I tried -loglevel quiet -- doesnt help
[06:06] <patrakov> Hi. I have a mov file with mjpeg codec and 29.97 fps. How to extract a frame with a known number to a regular jpeg file?
[06:58] <Aiwass> hi there, there a ffmpeg parameter that will turn off the configuration information when ffmpeg is used?
[08:03] <defaultro> hey folks, can ffmpeg split odd and even frames then save each file as jpeg?
[08:10] <defaultro> i got it
[09:15] <shifter1> anyone know how to set input buffering in ffmpeg?
[09:29] <heisenmink> can I do something like "ffmpeg -i IMG_1138.MOV -r 15 -f image2 -q 0  -s 480xANYTHING sharp\img-%d.jpg"
[09:29] <heisenmink> to get dynamic scaling after the source video?
[09:33] <heisenmink> "480x*" doesn't work, "480x" doesn't work
[09:33] <heisenmink> and not 480xH
[09:35] <sacarasc> -1 should scale it.
[09:35] <Mavrik> heisenmink, try replacing -s with -vf scale=480:-1
[09:39] <heisenmink> thanks! works perfectly
[09:40] <defaultro> what param specifies the quality of jpeg output?
[09:41] <Mavrik> -qscale I think
[09:41] <defaultro> k
[09:41] <heisenmink> -q 0 gives max quality
[09:41] <heisenmink> in my script
[09:42] <defaultro> so -q 0 is similar to Photoshop's 12 when saving an image to the max as jpeg
[09:46] <heisenmink> defaultro, I think so
[09:46] <defaultro> cool
[09:55] <verde> Hello, how do i extract subtitles from a .mkv file and save them as .srt?
[12:54] <MindSpark> hello, sorry to ask this here, but does anyone work with red5?
[13:32] <kollapse> Hi. What's the best way of cutting about 10 seconds out of a video clip ?
[14:45] <Kartagis> hi
[14:45] <Kartagis> how to stick in a MUXER at command line?
[14:48] <Kartagis> basically I want to extract audio from a webm file to mp3
[14:50] <ubitux> the webm file has a mp3 track?
[14:50] <ubitux> (is it even ok to have such file?)
[14:50] <Kartagis> it's video
[14:50] <ubitux> yes of course, but is the audio mp3 already?
[14:51] <ubitux> or you need to re-encode the audio?
[14:51] <Kartagis> let me see
[14:51] <ubitux> run ffprobe on the file
[14:51] <Kartagis> hmm
[14:51] <Kartagis> audio is vorbis
[14:51] <JEEB> unsurprisingly
[14:51] <ubitux> you can do a ffmpeg -i in.webm -vn acodec copy out.ogg then
[14:52] <ubitux> ffmpeg -i in.webm -vn -acodec copy out.ogg
[14:52] <Kartagis> thanks
[14:53] <ubitux> if you really want a mp3 (then you will have a lossy’lossy transcode), ffmpeg -i in.webm -acodec libmp3lame -aq 1 out.mp3 should do the trick
[14:53] <Mavrik> ubitux, since webm is slightly changed matroska container it can carry MP3 without problems
[14:53] <Mavrik> Kartagis, webm is not video -_-
[14:53] <ubitux> Mavrik: yes, but is it permitted?
[14:54] <JEEB> in the webm specs no
[14:54] <JEEB> AFAIK
[14:54] <Mavrik> I think it's defined only for vorbis as well, but I'm gonna go check
[14:55] <Mavrik> spec claims "Video codec SHOULD be VP8, audio codec SHOULD be vorbis"
[14:56] <Kartagis> webm is a container, right?
[14:56] <JEEB> it's a mixture of limited specs
[14:57] <JEEB> matroska, with limited features specified with certain video and audio codecs
[14:58] <Kartagis> Unknown encoder 'libmp3lame'
[14:58] <JEEB> then you have built ffmpeg without it
[14:58] <Kartagis> I thought I could do mp3
[14:58] <JEEB> it's an external encoder
[14:59] <JEEB> ffmpeg can decode mp3 just fine, as well as copy the stream itself just fine
[14:59] <JEEB> for encoding you need LAME
[14:59] <Kartagis> hmm
[15:00] <Kartagis> the one I have another directory should have it
[15:00] <Kartagis> I remember building ffmpeg with libmp3lame
[15:01] <Kartagis> I don't :(
[15:46] <Leoneof> JEEB: i've used 'ultrafast`, but it didn't work on psp, that's why you didn't recommend it?
[16:00] <JEEB> Leoneof, I don't think ultrafast by itself makes it non-playable...
[16:11] <Leoneof> JEEB: ouch
[16:12] <Leoneof> i will try to convert some files later
[16:17] <JEEB> but I think that superfast in most cases should be lolfast already :V
[16:46] <Milos> I have a quad core. How do I make use of all the threads with this command:
[16:46] <Milos> ffmpeg -i video_origine.avi -target pal-svcd video_finale.mpg
[16:46] <Milos> When running that only uses 1 CPU core.
[16:46] <Milos> I have ffmpeg compiled in with threading and 'cpudetection' enabled.
[16:48] <Milos> Nvm, -threads worked.
[17:05] <Slony> Hey
[17:05] <Slony> I'm reading this, and I see they used "-bf 0", why? http://code.google.com/p/gource/wiki/Videos
[17:14] <Grafica> I'm a newbie at programming. Is there something I can download so I can convert flv files to ogv, mp4, and webm?
[17:19] <Slony> there are guis for ffmpeg if thats what youre asking
[17:26] <Grafica> Yes, a GUI would be nice. I don't understand how to get to it.
[17:27] <Slony> try google
[17:28] <Slony> "ffmpeg gui"
[17:29] <pom> Can I run FFMPEG without specifying an output-file AND have it return 0, as in no error occured, if I only want it's informational input?
[17:30] <sacarasc> pom: ffprobe does that.
[17:30] <Mavrik> pom, you should run ffprobe
[17:37] <pom> If I've previously used ffmpeg to parse stream data, is ffprobe an inplace replacement as far as it's output goes?
[17:38] <pom> I've only executed ffmpeg with ffmpeg -i [inputfile]
[17:38] <JEEB> more or less
[17:38] <JEEB> I haven't tested ffprobe myself yet tho :)
[17:38] <ubitux> pom: ffprobe will give you all you need
[17:39] <ubitux> it also has various output such as csv, json or xml
[17:39] <ubitux> so you can extract the information in a simpler way
[17:39] <ubitux> see the -show_streams, -show_format or -show_packets options
[17:41] <pom> ubitux: Interesting. Just deployed ffprobe and using it pretty extensively thruout this project. Seem in-place-replaceable enough so far. =) Very happy to have this. ^^ Since when has this been around?
[17:42] <ubitux> Date:   Sun Feb 21 11:43:01 2010 +0000
[17:42] <pom> Time flies.
[17:42] <ubitux> csv, json or xml outputs are pretty recent though
[17:43] <ubitux> json being the first one, added in september 2011
[17:45] <pom> Nice! My proper regexp-fest is soon to meet it's maker, then. :)
[17:46] <Slony> I'm recording a video from png frames, a guide recommends using -bf 0, now then way I do it is to first capture using -preset ultrafast and -crf 18, and then i do a two pass -preset slower recoding. At which stage(s) should I use -bf 0, the ultrafast one, the slower first or second, or all?
[17:46] <Milos> I type -b 2000
[17:46] <Milos> and it says "2kb/s"
[17:46] <Milos> wtf?
[17:47] <Mavrik> Milos, of course.
[17:47] <Mavrik> you told it to encode to 2000 b/s
[17:47] <Milos> so I add four zeros and it says it's too high?
[17:47] <Milos> I mean three zeros
[17:47] <Mavrik> -b 2000k ;)
[17:48] <Milos> oh.. I did 2000kb and it yelled at me
[17:48] <Milos> ok, thanks
[17:49] <Milos> Does it make any sense whatsoever if runnning ffmpeg to pal-dvd with -threads 8 gives a load average of 0.08?
[17:49] <Mavrik> can't say with that info. :)
[17:50] <Milos> it's like
[17:51] <Milos> either my xeon server is amazing, or this is barely doing anything
[17:51] <Mavrik> whats "pal-dvd"?
[17:51] <Mavrik> mpeg2? 2-pass?
[17:52] <Milos> mpeg2 apparently
[17:52] <Mavrik> where did you put the -threads?
[17:52] <Mavrik> etc etc :)
[17:52] <Milos> at the beginning
[17:52] <Milos> oh
[17:52] <Milos> here's the whole thing
[17:52] <Milos> ffmpeg -threads 8 -i derp.avi -target pal-dvd -b 2000k derp.mpg
[17:52] <Mavrik> huh
[17:53] <Mavrik> Milos, would you mind pasting the ffmpeg output for that somewhere? :)
[17:53] <relaxed>  you're trying to decode derp.avi using 8 threads
[17:53] <Milos> sure
[17:53] <relaxed> put it after the input
[17:53] <Mavrik> Milos, and yes, you just told ffmpeg to decode input with 8 threads
[17:53] <Milos> D:
[17:53] <Mavrik> put it after -i, preferrably after -target as well
[17:54] <Milos> hmm makes no difference to speed
[17:54] <Milos> oddly
[17:56] <relaxed> Milos: Works here. Use htop to see how many threads are used while it's encoding.
[17:56] <Milos> relaxed, yeah 8
[17:56] <Milos> but my load average is 9
[17:56] <Milos> -_-
[17:56] <Milos> I mean
[17:56] <Milos> 0.09
[17:56] <relaxed> ffmpeg version?
[17:56] <sacarasc> What is CPU usage?
[17:56] <Milos> well 0.06 now
[17:56] <Milos> all cores are on average 25%
[17:56] <Mavrik> Milos, look at CPU usage, not load average
[17:57] <Milos> still does the job in like 2 minutes
[17:57] <Milos> but wtf
[17:57] <Mavrik> there's also a possibility mpeg2 encode doesn't allocate more threads
[17:57] <Mavrik> if you're using mpeg-2 encoder at all
[17:57] <Milos> well, without -threads 8, only one thing is in use and that one's at 100% as far as I remember
[17:57] <Milos> Mavrik, do you still want output?
[17:58] <Milos> What is dup= btw?
[17:58] <Milos> Sounds like "duplicate"
[17:58] <sacarasc> It is.
[17:58] <Milos> but it goes up a lot
[17:58] <Milos> it's at 5,000 - that can't be good?
[17:58] <Mavrik> yeah, dup= means number of frame duplicated
[17:58] <Mavrik> nop
[17:59] <Milos> nop what?
[17:59] <Mavrik> 5000 duplicated frames isn't good :)
[17:59] <Mavrik> are you sure your input isn't broken?
[17:59] <Slony> anything I can do to get rid of what looks like posterization in gradient areas?
[17:59] <Milos> does that mean... the source has duplicate frames, or the destination, or ... ?
[17:59] <Mavrik> Milos, that means that encoder is duplicating frames to keep up with designated framerate
[18:00] <Milos> oh..
[18:00] <Mavrik> 5000 duplicated frames means either you're increasing framerate by a rather large margin or your video is broken and the decoder isn't producing output
[18:00] <Milos> I see.
[18:01] <Milos> And a quick question, is it possible to estimate output size before doing something?
[18:02] <Mavrik> (bitrate / 8) * (number_of_video_seconds)
[18:02] <Mavrik> + same for audio of course
[18:02] <Grafica> Thanks Slony.
[18:03] <Milos> Wow perfect thanks Mavrik.
[18:03] <Milos> Are there any flaws in that formula?
[18:04] <Mavrik> yeah, the encoder doesn't really encode to the exact bitrate you set so it's only an estimation
[18:04] <Milos> Ah, that's fine.
[18:04] <Mavrik> (video encoding is VBR)
[18:04] <Milos> Yeah.
[18:04] <Milos> What if I use -min -max to set it
[18:04] <Milos> (the bitrate) perfectly
[18:04] <Mavrik> you'll just ruin your video quality :)
[18:06] <Milos> I must do that then.
[18:06] <Milos> I've got size limitations.
[18:06] <Milos> It's going over my given bitrate.
[18:08] <Mavrik> it's very unlikely the mpeg2 encode will listen to your -max setting
[18:08] <Mavrik> use 2-pass encoding if you need to hit certain filesize instead
[18:08] <Milos> Yeah it's jumped to 2400 again.
[18:08] <Milos> I set it at 1945.
[18:08] <Milos> (k)
[18:08] <Milos> Well that's great.
[18:09] <Mavrik> Milos, that's completely normal.
[18:09] <Milos> Yeah I bet but just unfortunate for me, although I'm experimenting anyway.
[18:09] <Mavrik> no, you don't understand:
[18:09] <Mavrik> even if it jumps to 2400kbps at times, the encoder will most likely hit the rit filesize because it'll compensate with lower bitrate on other scenes
[18:10] <Mavrik> you can make it even more accurate (and gain quality) with 2-pass encoding
[18:10] <Milos> I see.
[18:10] <Mavrik> if you try to force upper limit you'll just destroy quality on high-movement scenes and waste alot of bytes for still scenes
[18:10] <Milos> That makes sense, actually.
[18:10] <Milos> I've seen those crappy artifacts when stuff moves.
[18:10] <Milos> I guess that's what that is.
[18:10] <Mavrik> question is just how good the MPEG-2 encoder is (libx264 does that quite well, I have no idea how good the ffmpegs MPEG-2 encoder is)
[18:11] <Mavrik> yeah, that's exactly what it is :)
[18:11] <Milos> I've got x264, should probably find out how to use it.
[18:11] <JEEB> well, when creating a DVD f.ex. there are some rules on how high you can go
[18:11] <JEEB> and in what kind of a buffer
[18:11] <Mavrik> JEEB, yeah, I hope -target pal-dvd sets those limits as well
[18:12] <Milos> Essentially what I'm trying to do is fit three AVIs on a PAL DVD. Ignoring quality issues, is there a more automated way to do this with ffmpeg?
[18:12] <Milos> Or do I have to do the research myself and just plug in the right params?
[18:13] <Milos> Then use some DVD authoring tool to burn it.
[18:13] <JEEB> Mavrik, yes it should
[18:14] <Bertl> greetings! I'm wondering if there is a good way to combine two video streams (e.g. from two cameras) into one file suitable for stereoscopic display (e.g. side by side or similar)?
[18:22] <relaxed> Bertl: use the pad filter to extend width*2, then use the overlay filter and place it over the padded area.
[18:22] <Bertl> ah, good idea, let me try that
[18:27] <Bertl> hmm, I see filter examples with -vf "..." but my ffmpeg says unknown option -vf ? is my ffmpeg outdated?
[18:27] <Mavrik> Bertl, version?
[18:27] <Bertl> FFmpeg version 0.6.3, Copyright (c) 2000-2010 the FFmpeg developers
[18:27] <Mavrik> yeah, that's ancient
[18:27] <Mavrik> current stable is 0.9
[18:28] <Bertl> ah, thought so, no problem, let's build our own then, thanks!
[18:29] <Bertl> any big advantages/changes/new features in the snapshot/trunk vs. 0.9?
[18:30] <Mavrik> bugs? :P
[18:30] <Mavrik> Bertl, ffmpeg releases are pretty quick lately so I doublt there's anything really significant from 0.9
[18:30] <Mavrik> 0.9 is only like 2 weeks old or so
[18:31] <Bertl> ah, great, so I stick with that then, tx!
[18:31] <JEEB> you can check the changelog
[19:03] <Bertl> okay, I'm using 'ffmpeg -i left.ts -vf "movie=right.ts [right_side]; [in] pad=3840:1080:0:0 [left_side]; [left_side][right_side] overlay=1920:0 [out]" output.mkv
[19:04] <Bertl> this works, but gives really bad quality, despite the fact that the input streams are high quality, I guess I'm missing some options for the bandwidth or so
[19:05] <Mavrik> Bertl, yeah, you're missing all the optioins :)
[19:05] <Mavrik> Bertl, add -vcodec libx264 -crf 23 at least
[19:05] <Bertl> thought so :)
[19:05] <Mavrik> Bertl, change crf up (worsequality/smaller file) or down (better quality/larger file)
[19:23] <Bertl> hmm, obviously I'm missing libx264, but I tried with mpeg4, but quality is still bad, will search for libx264 now
[19:31] <relaxed> Bertl: for mpeg4 set -qscale 3 for high quality (1=highest - 31=lowest)
[20:20] <defaultro> anyone around
[20:22] <defaultro> i have a video at 30fps, each frame(odd/even) was recorded at different iso. I extract them and use the files as inputs to enfuse command line tool to generate an hdr image. Finally, I use ffmpeg again to reencode the hdr image. However, the video is faster. I slowed it down but I didn't like the playback
[21:37] <mmarschall> Hi, I already transcoded some dv files to mov using the very same command on the very same box successfully. Now I encountered at least two file where ffmpeg simply hangs fully using one CPU without finishing the transcode. Please see http://pastebin.com/rz6tipT3 for details. Any help is highly appreciated! Thanks.
[23:05] <Shimmy> Anyone please help me: https://ffmpeg.org/trac/ffmpeg/ticket/747
[23:06] Last message repeated 1 time(s).
[23:23] <relaxed> Shimmy: maybe you should offer a bounty
[23:29] <Guest51148> Hi all , i am using the libav* in an application on my linux-ubuntu pc and everything is working fine, however when i port the same code on the android platform i get an "signal 11 (SIGSEGV), fault addr" on avformat_write_header() or av_write_frame()  call. Does anyone have an idea ? Or what exactly the 2 above calls do ? thanks
[23:30] <Mavrik> Guest51148, basically, first saves the file header and the other one actually saves encoded frames to file
[23:30] <Mavrik> there's something wrong with your file output... do you have permissions to write?
[23:31] <Guest51148> yes i have
[23:31] <Guest51148> basically  i am writting on rtp output
[23:31] <Guest51148> and i also have permission INTERNET
[23:32] <Guest51148> which gives me the network permissions afaik
[23:32] <Shimmy> @relaxed how do i offer a bounty
[23:34] <Guest51148> i am using the latest ffmpeg-source
[23:37] <Guest51148> i don't know how to debug it but i checked with some prints on logcat that these 2 functions are the problem.
[23:41] <relaxed> Shimmy: Offer some money for a developer to add the support you need.
[23:43] <JodaZ> so someone said that i need to output to - instead of a file to prevent ffmpeg from muxing to something if i use -fyuv4mpegpipe
[23:43] <JodaZ> is that true ?
[23:44] <JodaZ> because i'd really rather not use -
[23:45] <Shimmy> relaxed: what means money? i.e. what's considered an entry point?
[23:48] <relaxed> Shimmy: I have no idea how much work is required or what would be an entry point. Ask in #ffmpeg-devel if anyone would be interested and then go from there.
[23:54] <huglester> hey everyone 
[23:56] <Nitsuga> How do yo use the audio filters? -af does not seem to work
[00:00] --- Thu Dec 29 2011

More information about the Ffmpeg-devel-irc mailing list