[Ffmpeg-devel-irc] ffmpeg.log.20121230

[burek]

[00:36] <taylanub> ./configure is giving me internal error: too many args.
[00:36] <taylanub> s/args/vars/
[00:37] <taylanub> Well let me just paste:  http://sprunge.us/JOEc
[00:37] <taylanub> (Ignore the second line.  Emacs shell-mode stuff.)
[02:54] <chadmaynard> Does anyone know why I get this error after a few moments? http://pastebin.com/tMLL4mbQ
[03:47] <taylanub> OK, the "too many vars" error doesn't happen with bash, but only OpenBSD's ksh (which /bin/sh symlinks to).  I'm currently trying to figure out whether the script breaches any values defined in http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/limits.h.html .
[03:59] <taylanub> ksh seems to handle 65536 arguments just fine .. weird.
[04:22] <taylanub> Looking at sh -x output, the error seems to happen when check_deps is called with 1437 arguments.  ksh surely handles more than that just fine, also when called as /bin/sh.  Ideas welcome, I've also asked #openbsd.
[09:11] <tlp> hello. I have a TrueHD track extracted from Blu-ray with MakeMKV. When ffmpeg reads it, I get all kinds of "Lossless check failed" errors. does this mean the source file is damaged?
[09:12] <tlp> (it plays, however)
[09:21] <JRT> hi. i am wondering if there is a simple, elegant way to get a screen capture of a video using the command line. specifically, i want one every 29 minutes, with the same dimensions as the video.
[09:22] <JRT> also, i would like them in png format.
[09:22] <JRT> after about two hours of intense googling i have not found an answer, so i decided to come here.
[09:23] <klaxa> JRT: http://ffmpeg.org/trac/ffmpeg/wiki/Create%20a%20thumbnail%20image%20every%20X%20seconds%20of%20the%20video
[09:23] <tlp> mplayer can output to png
[09:23] <tlp> er, or that
[09:23] <JRT> ah, thank you
[09:52] <buhman> I was just yesterday successfully compiling libavformat
[09:52] <buhman> with today's commits, it's being mean to me
[09:52] <buhman> ffmpeg/libavformat/libavformat.a(movenchint.o): In function `ff_mov_init_hinting':
[09:52] <buhman> movenchint.c:(.text+0x7e): undefined reference to `ff_rtp_chain_mux_open'
[10:02] <ubitux> can you share your ./configure line?
[10:03] <ubitux> erm i guess that's because of 5ad2f0bfb23c757bcd02875c6664ff383630790d
[10:05] <ubitux> buhman ^
[10:13] <buhman> ubitux: oh
[12:52] <mpfundstein_home> if you were building some transcoding workstations to use ffmpeg, what are important factors? cpu, gpu, ram, cores? note that every workstation is actually a VM.
[12:53] <mpfundstein_home> my guess what be that 2 gig ram are enough and cpu's + cores (4 per ffmpeg) are the "keys" to fast encoding
[12:58] <Mavrik> mpfundstein_home: 1.) CPU Frequency 2.) Number of cores 3.) storage/network
[12:58] <Mavrik> everything else is secondary
[12:58] <mpfundstein_home> Mavrik: thanks
[12:58] <Mavrik> ffmpeg uses max. cca 200MB per transcode
[12:58] <Mavrik> of ram
[12:59] <Mavrik> mpfundstein_home: CPU frequency is the most deciding factor, cores as well
[12:59] <mpfundstein_home> Mavrik: Thanks. How much instances would you run per machine?
[12:59] <Mavrik> more than 4 cores doesn't significantly improve transcode speed (for a single transcode) thouzgh
[12:59] <mpfundstein_home> Mavrik: Lets say i have 16 cores available. 4 processes than?
[12:59] <Mavrik> mpfundstein_home: I usually run 1 ffmpeg per about 4 CPU threads
[12:59] <mpfundstein_home> Mavrik: K, i thought so
[12:59] <Mavrik> mpfundstein_home: depends on the encoder really
[13:00] <Mavrik> theora or example doesn't really do multicore well
[13:00] <Mavrik> so that's 1 ffmpeg per core
[13:00] <Mavrik> you'll have to tweak it depending on your CPU utilization
[13:00] <mpfundstein_home> Mavrik: Thanks for clearing that out. can NFS access speed be ignored?
[13:00] <mpfundstein_home> Mavrik: I use libx264 and libfaac(sry)
[13:00] <mpfundstein_home> Mavrik: I read and write from a NFS shard
[13:01] <Mavrik> mpfundstein_home: um, CPU is usually the bottleneck
[13:01] <mpfundstein_home> Mavrik: k, i think so too. just wasnt sure. thanks
[13:01] <mpfundstein_home> Mavrik: is there any advantage by using more -threads than cores ?
[13:01] <Mavrik> mpfundstein_home: if you have a 15Mbit/s source video that's transcoding at 60fps, that means you're burning 30Mbit/s + 2x output bitrate network I/O
[13:01] <Mavrik> mpfundstein_home: not really a problem on modern Gbit links
[13:02] <Mavrik> mpfundstein_home: nope, it'll lower the perfromance probably due to context switch overhead
[13:02] <mpfundstein_home> i have 15 Mbit/s input videos. I transcode with lousy 9 fps
[13:02] <mpfundstein_home> on second pass
[13:03] <Mavrik> well, I/O isn't really an issue then :)
[13:03] <mpfundstein_home> yes :-)
[13:03] <mpfundstein_home> i think 9 is quite slow
[13:03] <mpfundstein_home> -.-
[13:03] <mpfundstein_home> but i do some stuff like resizing, letterboxing etc..
[13:03] <mpfundstein_home> and i use the medium profile
[13:03] <Mavrik> 1080p?
[13:04] <mpfundstein_home> no 720p
[13:04] <Mavrik> mpfundstein_home: resizing, letterboxing, etc is quite cheap comparing to the actual x264 encode
[13:04] <mpfundstein_home> source material can be whatever.
[13:04] <Mavrik> 9fps is kinda slow... medium profile usually goes at around 25-30fps on a modern quad-core CPU
[13:04] <mpfundstein_home> thats brings another question. i read that if i use a crf of 23 and i dont want to go resize a lot, that one pass is enough and i dont need 2 passes. is that right?
[13:05] <mpfundstein_home> than* one pass .. sry for the types
[13:05] <mpfundstein_home> Mavrik: 32bit debian on virtual box :-)
[13:05] <mpfundstein_home> 4 virtual boxes at the same time transcoding -> 9fps
[13:05] <mpfundstein_home> per box
[13:06] <Mavrik> mpfundstein_home: if you're using "-crf" for quality, the 2-pass encode it totally pointless
[13:06] <Mavrik> I think ffmpeg won't even allow you to do it
[13:09] <mpfundstein_home> i dont use it yet
[13:11] <mpfundstein_home> right now i use only 2pass. but i've read that a crf of 23 would be sufficient so i am thinking of switching. would reduce my transcoding time by 25 % or s.th.
[13:12] <Mavrik> yeah, it's also better for quality
[13:12] <Mavrik> you won't have a predictable output bitrate though
[13:12] <mpfundstein_home> that doesnt matter in my case
[13:12] <mpfundstein_home> the playout software doesnt mind that :-)
[13:13] <mpfundstein_home> cool, thanks for the info
[13:33] <leoj3n> Building chromium w/ ninja, and my MBPr is 92 celcius w/ full fans... is that normal? Why so hot?
[13:33] <sacarasc> Did you mean to ask in #ffmpeg?
[13:33] <leoj3n> oops
[13:33] <leoj3n> thought i was in #chromium-developers !
[13:37] <Mavrik> leoj3n: because it's using your cpu.
[13:37] <Mavrik> cpus get hot when they're working.
[14:13] <asturel> anyone using ffmpeg to convert movies to lumia?
[17:33] <Nolaan> hi all!
[17:33] <Nolaan> How to compile ffmpeg with alsa support?
[17:35] <burek> Nolaan, install libasound-dev
[17:35] <burek> prior to ./configure
[17:48] <Nolaan> ok thanks
[18:23] <gagan662> Hello, I have some_file.mp4, this file is not seekable, i get this line during seek in mplayer -> seek_frame_generic failed as this stream seems to contain no keyframes after the target timestamp, 1002 non keyframes found
[18:24] <gagan662> Is there any fix for thid
[18:24] <gagan662> ?
[23:30] <Mentos> Hey if I'm interested in taking 4 ffmpeg streams and composing them into 1 stream thats a 2x2 grid, can i easily do this with ffmpeg?
[23:32] <Mentos> or can i achieve it at all
[23:44] <saste> Mentos, overlay filter, there is an example for that
[23:45] <Mentos> saste: Completely new to this, trying to stream my 4 room mates laptops to 1 projector so i was going to make a server with ffmpeg that composed them
[23:45] <Mentos> think you could link me?
[23:46] <Mentos> pretty please
[23:46] <saste> !doc Mentos
[23:46] <saste> filters -> overlay -> examples
[23:48] <Mentos> searching thanks so much
[23:56] <mickkie> Hi All, I'm struggling with adding padding to get the right ratio, because I fail to understand how it works when used with -target pal-dvd.
[23:59] <mickkie> My command is: "ffmpeg -i test.avi -target pal-dvd -vf pad=720:576:0:135 ..." when I try to convert a 640x272 avi to a 720x576 video.
[23:59] <mickkie> but I'm getting: "Input area 0:134:720:710 not within the padded area 0:0:720:576 or zero-sized"
[00:00] --- Mon Dec 31 2012