[Ffmpeg-devel-irc] ffmpeg.log.20131214

burek burek021 at gmail.com
Sun Dec 15 02:05:01 CET 2013

[00:38] <slorbast> oh derp, an easy solution would be to convert the video into images, then use imagemagick to add the text, then ffmpeg the images back to a video at same FPS
[00:44] <relaxed> slorbast: there's ffmpeg filters for that
[00:46] <relaxed> slorbast: man ffmpeg-all|less +/^'   drawtext'
[00:47] <slorbast> relaxed, thanks I'll check it out
[03:20] <SirCmpwn> given an mkv file with some font attachments in it
[03:20] <SirCmpwn> can I extract them to a second file with ffmpeg?
[03:22] <SirCmpwn> yes, I can
[03:22] <SirCmpwn> -dump_attachment, if anyone was wondering
[04:26] <SLAYBoz> what is best container out of these 3?  flv/mpfour/mkv
[04:28] <chiller-> ...best for what?
[04:30] <zap0> gif is teh bestest!!!1111eleventy11!!11
[04:32] <SirCmpwn> gif is not a container :(
[04:37] <zap0> stop being sensible.
[05:26] <liam-kelly> Hello, I am having some issues running a command in ffmpeg, http://pastebin.com/vftYQ54v
[05:32] <SirCmpwn> liam-kelly: build ffmpeg from source and include libx264
[05:35] <liam-kelly> Thanks.
[05:40] <SLAYBoz> does ffmpeg support h265 encoding
[06:16] <relaxed> SLAYBoz: decoding only right now
[06:16] <SLAYBoz> why no encoding
[06:17] <relaxed> because it's too new
[06:22] <SLAYBoz> i cannot even playback
[06:23] <relaxed> what does this return: ffmpeg -codecs 2>&1| grep hevc
[06:23] <SLAYBoz> nothing
[06:23] <relaxed> then you need to update ffmpeg to a more recent version. git head would be best
[06:26] <SLAYBoz> okay fixed
[06:26] <SLAYBoz> does vlc use ffmpeg to play
[06:26] <SLAYBoz> it won't work with vlc
[07:00] <SLAYBoz> what is the difference between aac  and he-aac
[07:11] <SirCmpwn> are there any containers that will take a font file as an actual stream, and not as an attachment?
[07:24] <LithosLaptop> SLAYBoz: When you encode to HE-AAC from 44.1Khz input the output file will be 22.05Khz LC-AAC with additional SBR info to replicate the missing high frequencies
[07:24] <LithosLaptop> just basically some tricks to make the audio sound semi-acceptable <= 80Kbps
[07:24] <SLAYBoz> what if you encode original 22 khz file
[07:25] <LithosLaptop> hmm not sure what it will do then
[07:26] <LithosLaptop> but only use HE-AAC <= 80Kbps, because it will only worsen the audio once you go above 80Kbps
[07:26] <LithosLaptop> in that case use LC-AAC
[07:26] <SLAYBoz> what is the difference between aac-fdk  aac-avcodec
[07:27] <LithosLaptop> aac-fdk is a high quality AAC encoder that supports lots of different AAC profiles such as LD-AAC, HE-AAC, LC-AAC
[07:29] <LithosLaptop> aac-avcodec only supports LC-AAC and you need about >=240Kbps for it to sound acceptable
[07:30] <SLAYBoz> what are lib name for aac-fdk and aac-avcodec
[07:30] <LithosLaptop> libfdk_aac
[07:31] <LithosLaptop> and aac
[07:31] <SLAYBoz> okay what about "aac-avcodec"
[07:32] <LithosLaptop> Quality from high to low: libfdk_aac > libfaac > aac > libvo_aacenc
[07:32] <LithosLaptop> aac-avcodec is aac
[07:32] <SLAYBoz> i see
[07:32] <SLAYBoz> libvo is worst?
[07:32] <LithosLaptop> yes
[07:32] <LithosLaptop> terrible encoder
[07:32] <SLAYBoz> somebody told me that was best
[07:32] <SLAYBoz> libvo is the google one
[07:32] <LithosLaptop> noooooo
[07:32] <LithosLaptop> yes
[07:33] <SLAYBoz> what about "ffmpeg-aac" one
[07:34] <LithosLaptop> I would think aac-avcodec and ffmpeg-aac is the same thing
[07:34] <LithosLaptop> where do you see these names?
[07:34] <SLAYBoz> handbrake
[07:35] <LithosLaptop> aac-avcodec and ffmpeg-aac two seperate options?
[07:35] <SLAYBoz> old versions had  aac(faac)  and aac(ffmpeg)   new version has   aac(avcodec)  aac(fdk)
[07:36] <LithosLaptop> yes aac(ffmpeg)  and aac(avcodec) is the same thing
[07:36] <SLAYBoz> are you sure?
[07:36] <LithosLaptop> aac(fdk) will give you the best quality
[07:37] <SLAYBoz> okay thanks
[07:37] <LithosLaptop> yes because ffmpeg uses avcodec
[07:37] <SLAYBoz> where does nero and apple  stand compared to this list:  libfdk_aac > libfaac > aac > libvo_aacenc
[07:38] <LithosLaptop> in my opinion: apple > libfdk_aac > nero > libfaac > aac > libvo_aacenc
[07:38] <SLAYBoz> i see
[07:39] <SLAYBoz> it's not possible to add apple on  ffmpeg?
[07:40] <LithosLaptop> there is no source code / library available for ffmpeg to use as far as I know
[07:41] <SLAYBoz> i don't know if you use handbrake but  handbrake for mac  comes with   aac(apple) but rest doesn't
[07:41] <LithosLaptop> aple would ned to relese souce code for the apple encoder
[07:41] <LithosLaptop> *aple
[07:41] <LithosLaptop> *apple
[07:42] <LithosLaptop> mac probably allready comes with an apple aac encoder. I am not sure
[07:42] <SLAYBoz> is libfdk_aac  pretty recent?
[07:43] <LithosLaptop> yes
[07:43] <SLAYBoz> i never seen it before
[07:43] <SLAYBoz> i see
[07:44] <SLAYBoz> is it new encoder or is it just new to ffmpeg?
[07:44] <LithosLaptop> usually only faac was available, you will see lots of guides online still mentioning faac / libfaac
[07:44] <LithosLaptop> new encoder
[07:44] <SLAYBoz> i see
[07:45] <LithosLaptop> released last year by Fraunhofer for Android
[07:45] <SirCmpwn> -threads 0
[07:45] <SirCmpwn> this will use as many cores as it can, right?
[07:45] <LithosLaptop> anyway I need to go
[07:45] <SirCmpwn> relevant codecs: h264, theora, vp8
[07:45] <LithosLaptop> cheers
[08:03] <SirCmpwn> the answer is that you can't encode theora with several cores ;_;
[08:40] <SLAYBoz> is .ts a container?
[10:45] <iamtakingiteasy> hello, when i am trying to record a monitor source of pulseaudio with ffmpeg, as in 'ffmpeg -f alsa -i pulse out.wav' ; i am getting pretty pitched down sound. but when i try to do 'arecord -f cd > out.wav'; with the same monitor source all is recorded just fine. where to look for the problem and how to fix it?
[11:21] <SirCmpwn> say I want to extract a short clip from a mkv file
[11:21] <SirCmpwn> this file has subtitles, though, advanced substation
[11:21] <SirCmpwn> I want to extract the softsubbed clip, so I need to be able to modify the subtitles so that the timing isn't off
[11:21] <SirCmpwn> suggestions?
[12:32] <SirCmpwn> so here's a weird thing
[12:33] <SirCmpwn> ffmpeg -dump_attachment:t:<index>
[12:33] <SirCmpwn> always dumps t:0
[12:33] <SirCmpwn> and ignore the index specified
[12:59] <Compn> use mkvextract :P
[13:05] <SirCmpwn> nah, I got it working
[13:05] <SirCmpwn> it was just behaving strangely
[15:26] <luc4> Hello! Any way to dump the popularimeter frame of id3v2 tags in mp3s?
[15:29] <jure> ffmpeg -i input.mp3 -mod:id3v2 popularimeter -dump -o out.mp3 (j/k)
[15:33] <luc4> jure: Unrecognized option 'mod:id3v2'
[15:34] <jure> j/k = just kidding
[15:37] <luc4> jure: that didn't make me laugh...
[15:40] <jure> :)
[15:42] <luc4> jure: maybe I'd get it if I was good with ffmpeg :-)
[17:44] <pj_double_u> does anyone have experience with ffmpeg API / libx264 and low latency streaming?
[17:45] <Compn> pj_double_u : gaikow uses x264 in low latency streaming
[17:45] <pj_double_u> i've read some guides and have come a long way
[17:45] <Compn> but thats a gaming website
[17:45] <Compn> heh
[17:45] <Compn> ask in #x264 mayyybe ?
[17:46] <Compn> i dont know low latency stuff so good luck
[17:46] <pj_double_u> actually i think i've hit a barrier concerning mpegts, rather than x264
[17:46] <Compn> ah
[17:46] <Compn> you going to write a howto for us ?
[17:46] <Compn> whats your setup and which part is lagging ?
[17:46] <Compn> command lines, etc
[17:47] <pj_double_u> basically the trick is: -tune zerolatency,fastdecode -preset ultrafast :)
[17:47] <pj_double_u> i'm programming in C, not using cli
[17:47] <Compn> ah
[17:47] <pj_double_u> but should offcourse also work on cli
[17:48] <Compn> running into 5mb mpegts probe slowdown ?
[17:48] <pj_double_u> the weird thing is that the latency is on the client side.
[17:48] <pj_double_u> ffmpeg always seems to hold one frame (video) back
[17:48] <pj_double_u> as in av_read_frame () returns one frame  in the past.
[17:49] <Compn> http://stackoverflow.com/questions/16690898/what-are-the-correct-x264-settings-to-achieve-the-lowest-latency-possible
[17:49] <Compn> you saw that i asssume
[17:49] <pj_double_u> yes. thanx :)
[17:49] <pj_double_u> that fixed latency on server side.
[17:49] <pj_double_u> the server-side is now latency free -> an encoded frame gets transported immediately
[17:50] <Compn> ah
[17:50] <Compn> what ffmpeg ver you using ?
[17:50] <pj_double_u> 2.1.1
[17:50] <Compn> its possible that av_read_frame thing was changed , if so, go back to old ffmpeg :)
[17:50] <pj_double_u> the problem has been in ffmpeg for ages i'm afraid
[17:51] <Compn> ah
[17:51] <pj_double_u> i've done a project some time ago with ffmpeg 0.5. same problem. always one frame latency introduced on the client side
[17:51] <Compn> so 1/30th of a second is too slow for you ? :)
[17:52] <pj_double_u> however now, i really need to get rid of this one frame latency.. :P
[17:52] <pj_double_u> it seems ridiculous, but yes :)
[17:52] <Compn> eheh
[17:52] <pj_double_u> 1/50th even! :P
[17:53] <pj_double_u> i'm trying to get the video of a camera on the screen of a client application as fast as possible. every frame counts! :)
[17:53] <Compn> well the only person i know who uses x264 low latency is jason (x264 dev)
[17:53] <Compn> there maybe others here, if you stick around
[17:54] <pj_double_u> i will thank u
[17:54] <Compn> np
[17:55] <Compn> michaelni might know about the av_read_frame ... or you might be using ffmpeg incorrectly. i dont know
[17:55] <pj_double_u> could be, that's what i'm trying to find out :)
[17:55] <pj_double_u> or i might be hitting a limt
[17:56] <pj_double_u> does anyone know if the mpegts demuxer always introduces one frame latency (for video atleast)?
[17:56] <pj_double_u> because it's OK for a private data stream (KLV)
[17:56] <Compn> pj_double_u : http://comments.gmane.org/gmane.comp.video.ffmpeg.libav.user/6654
[17:58] <pj_double_u> aha! exactly my 'problem'.
[17:58] <pj_double_u> i'm reading  it further now.
[17:58] <Compn> sounds like there was 2 frame delay 2 years ago
[17:58] <Compn> nice to hear its down to 1 frame :D
[17:59] <pj_double_u> haha. there _is_ progress yes :)
[17:59] <Compn> btw i found that by google for >>> av_read_frame one frame delay
[17:59] <Compn> so you can findd other posts
[17:59] <Compn> now i go kinda afk , feel free to ask me other q
[18:00] <pj_double_u> thanx!
[18:01] <Compn> btw when you get it working, please write a small example C file if you can showing how to get perfect zero latency for other users :)
[18:01] <pj_double_u> i will.
[18:01] <pj_double_u> maybe on the wiki (streaming guide)?
[18:11] <Compn> yes
[18:50] <pj_double_u> Some more info: if i pass AVSTREAM_PARSE_NONE to the video AVStream, then the delay is gone.
[18:51] <pj_double_u> However! now av_read_frame() is basecally 'broken' because it does not promise to return exactly one frame..
[18:53] <jure> aresample vs ar
[20:03] <maujhsn> llogan...U "Nut" how the hell are you?
[00:00] --- Sun Dec 15 2013

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