[Ffmpeg-devel-irc] ffmpeg.log.20180821

burek burek021 at gmail.com
Wed Aug 22 03:05:01 EEST 2018

[00:13:18 CEST] <hackpoetic> I am messing around with the chromakey filter and I have my settings working in ffplay, but when I write to a video with settings I read preserve transparency ("-c:v png out.mov") it's back to being blue!
[00:13:50 CEST] <hackpoetic> ffmpeg -i   ~/Downloads/Black\ Cat\ isolated\ on\ blue\ screen-AeYp3S0v0N8.mp4 -vf "chromakey=0x0000ff:0.4:0.1" -c:v png out.mov
[00:14:11 CEST] <hackpoetic> ffplay   ~/Downloads/Black\ Cat\ isolated\ on\ blue\ screen-AeYp3S0v0N8.mp4 -vf "chromakey=0x0000ff:0.4:0.1"
[00:15:01 CEST] <BtbN> Can you even put png into mov?
[00:15:13 CEST] <BtbN> You will need to overlay the now transparent image on top of something.
[00:16:18 CEST] <hackpoetic> oh, figured mplayer would show it as black and not the original color.
[00:16:23 CEST] <hackpoetic> I'll try overlaying
[00:16:45 CEST] <hackpoetic> Ha, I should have try with ffplay
[00:22:14 CEST] <hackpoetic> hmm... overlaying doesn't seem to work. The blue is right back
[00:22:23 CEST] <hackpoetic> Do you have suggested output encoding options?
[00:23:10 CEST] <BtbN> The encoding options don't really matter if you are overlaying it on top of a black or whatever kind of background
[00:24:16 CEST] <hackpoetic> I'm not. I'm doing the overlraying live in other software
[00:24:22 CEST] <hackpoetic> so I need to retain the alpha channel
[00:25:35 CEST] <BtbN> Video doesn't really support alpha
[00:25:52 CEST] <BtbN> VP9 has some hack to support it, and one of the various prores encoders in ffmpeg supports it as well
[00:43:50 CEST] <Cracki> qtrle does alpha. it's a lossless codec, of course.
[00:49:24 CEST] <hackpoetic> I keep typing aplay instead of ffplay and breaking my ears
[00:51:22 CEST] <hackpoetic> I'm having so many problems with this I'm wondering if I should just build chroma keying into my app and not have that a pre-processing step
[00:53:21 CEST] <hackpoetic> Now I just need to lookup how to implement chroma keying. More reason for me to rewrite my app to use libffmpeg
[00:53:51 CEST] <BtbN> There's no libffmpeg though
[00:54:11 CEST] <hackpoetic> What the heck am I thinking of
[00:54:24 CEST] <BtbN> libavfilter probably, for chromakey
[00:55:38 CEST] <hackpoetic> I see mention of a libffmpeg online that's for handling AV stuff... What are they referring to?
[00:56:35 CEST] <hackpoetic> http://ffmpeg.org/doxygen/trunk/
[00:56:47 CEST] <hackpoetic> Oh I see, I just called it the wrong thing
[00:56:51 CEST] <rjeli> >i keep typing aplay instead of ffplay
[00:56:53 CEST] <rjeli> l m a o
[00:57:27 CEST] <hackpoetic> ;-)
[00:57:38 CEST] <hackpoetic> It's the worst
[00:58:48 CEST] <hackpoetic> How would I find out finding where the chromakey source lives for libavfilter?
[00:59:01 CEST] <hackpoetic> Found it
[00:59:01 CEST] <hackpoetic> https://www.ffmpeg.org/doxygen/3.0/vf__chromakey_8c_source.html
[00:59:10 CEST] <BtbN> you're looking at ancient docs
[00:59:16 CEST] <mixfix41> hmm firefox youtube video runs better than ffplay for me now with some additional libraries,  libEGL libgles libdrm exynos libmali, going to need to optimize this to get full screen o nthis laptop
[00:59:38 CEST] <hackpoetic> Damn google
[01:00:25 CEST] <hackpoetic> Okay, I'll poke at this later
[01:00:29 CEST] <hackpoetic> Thank you all for the help!
[02:17:24 CEST] <ahoo> good day fine sirs!
[02:17:33 CEST] <ahoo> what is your preferred nopaste thing?
[02:25:38 CEST] <DHE> one that works without javascript and preferably no ads
[02:26:00 CEST] <DHE> often your distro's support site may have one and you can use that
[02:28:27 CEST] <Cracki> github gists are an option
[02:42:51 CEST] <DHE> a bit overkill, and require a github account, but quite viable
[02:56:40 CEST] <ahoo> https://www.irccloud.com/pastebin/nznU3jDP/
[02:56:52 CEST] <mijofa_> ix.io is good
[02:57:19 CEST] <ahoo> recording works fine but there are errors all the time
[02:57:24 CEST] <ahoo> see snippet
[02:58:31 CEST] <DHE> https://www.irccloud.com/pastebin/raw/nznU3jDP  because I said no javascript. :)
[02:59:02 CEST] <ahoo> oh, sorry. i confused that.
[02:59:36 CEST] <ahoo> my camera can only supply 33FPS - is that something i have to tell ffmpeg?
[03:00:26 CEST] <ahoo> never mind, just saw that i do.
[03:03:51 CEST] <ahoo> any idea what could be wrong?
[03:04:30 CEST] <DHE> if the output video is fine, I wouldn't worry about it...
[03:09:04 CEST] <ahoo> alright
[03:09:05 CEST] <ahoo> thanks
[03:09:28 CEST] <DHE> sounds like some kind of format error on the input, but a known error easily dealt with...
[03:28:23 CEST] <Hello71> why is it 33 anyways
[03:31:36 CEST] <ahoo> idk
[03:52:12 CEST] <opticron> hi, I've been provided a file as a sample for how one I create should be produced and I want the A/V codec setup to match exactly. is there an easy way to do that without spending a few days trying to get options right? I've already tried a concat filter with a sample of the original, but the wrong codecs are chosen regardless of the order specified
[03:59:56 CEST] <Cracki> a file is not a proper specification of codec parameters
[04:00:00 CEST] <Cracki> ask what they want
[04:22:47 CEST] <Hello71> that's not even specific to media
[04:32:12 CEST] <opticron> yeah, the video file wasn't encoded by the person that handed it to me, they don't have that information :/
[04:32:28 CEST] <opticron> I guess I'll just have to get it close
[04:32:37 CEST] <Hello71> here's this csv, please export in this format
[05:40:42 CEST] <teganburns> Building ffmpeg for Android with libopenh264 has proven to be quite a challenge. Does anyone here have and recommended resources? The ones listed on the site seem pretty dated. Thanks
[06:04:03 CEST] <leif> What is the best way to display an image for, say, 5 seconds, with the filter_complex flag?
[06:04:08 CEST] <leif> (If that's possible)
[06:04:34 CEST] <leif> Right now about all I've got is to generate 5 seconds of black with the `color` filter, and overlay the image on top of it. But that seems silly to me.
[06:07:03 CEST] <leif> (Also using the trim filter understandably has no effect.)
[06:25:30 CEST] <teganburns> leif: https://video.stackexchange.com/questions/12105/add-an-image-overlay-in-front-of-video-using-ffmpeg
[06:31:33 CEST] <leif> teganburns Interesting. I guess overlay really is the way to do it, thanks.
[06:49:21 CEST] <furq> leif: is this a transparent image
[06:50:03 CEST] <furq> if you just want to use an image as a bumper then use the loop filter and concat
[10:28:40 CEST] <ahoo> how to make ffmpeg creating more keyframes when recording?
[10:28:57 CEST] <ahoo> per default it's like every 1 minute or so
[10:29:10 CEST] <ahoo> i'd like to have  it every 1 or 2 seconds
[10:29:23 CEST] <ahoo> oh, and aac or mp3?
[10:29:36 CEST] <Mavrik> -g sets GOP size
[10:29:46 CEST] <Mavrik> and aac or mp3 depends on your target format and target players.
[10:31:48 CEST] <furq> i don't know of any codec that defaults to a gop size of one minute
[10:31:53 CEST] <furq> unless you're capturing at 4 fps
[10:32:33 CEST] <Nacht> Yeah that's a GOP of 1500 ~ 1800
[10:34:28 CEST] <ahoo> Mavrik: yeah but which of the two is the better choice? in terms of modernity, effectiveness, maintainedness
[10:34:39 CEST] <furq> aac
[10:35:42 CEST] <ahoo> thx
[11:16:50 CEST] <Nacht> Anyone know any formats/codecs who support alpha ? I got a MOV with QTRLE but it's a tad big
[11:19:33 CEST] <X-Kent> Hello, I have an HLS stream that has some misconfiguration that I cannot figure out. It seems that video is somehow getting it frames dropped while audio is OK. Is there any tool I can use to check what is it ?
[11:23:48 CEST] <Nacht> Apple themselves have a HLS validator. But it only works on Macs
[11:36:20 CEST] <durandal_1707> Nacht: utvideo? magicyuv?
[11:36:47 CEST] <Nacht> durandal_1707: Cheers, I'
[11:36:49 CEST] <Nacht> ve
[11:37:03 CEST] <Nacht> I've tried with VP9 but I dont seem to keep the alpha
[11:37:45 CEST] <furq> Nacht: the ffmpeg vp9 decoder doesn't support alpha
[11:37:56 CEST] <furq> you'd have to force using libvpx to decode
[11:38:58 CEST] <furq> if you want it to be lossless then i guess ffv1 is your best option
[11:39:42 CEST] <Nacht> furq: It doesn't have to be lossless. I just need it to not be 800mb at the moment.
[11:40:19 CEST] <Nacht> What I had was "-c:v libvpx -pix_fmt yuva420p -auto-alt-ref 0"
[11:40:40 CEST] <furq> that should work iirc
[11:41:08 CEST] <furq> but if you want to process it again with ffmpeg then you need -c:v libvpx -i ...
[11:41:11 CEST] <Nacht> Yeah that's the weird thing. But once I use that video and overlay it on top of another, i dont get the alpha
[11:41:13 CEST] <furq> or libvpx-vp9
[11:41:22 CEST] <Nacht> Ah
[11:41:29 CEST] <Nacht> That might be it then
[11:41:41 CEST] <furq> transparency in webm is a weird hack, it stores a separate alpha plane
[11:42:48 CEST] <furq> or a separate alpha stream, rather
[11:43:27 CEST] <ritsuka> prores 4444 supports alpha, but it still takes a lot of space, and I don't know if ffmpeg supports it
[11:45:03 CEST] <Nacht> The decoder trick worked, thanks furq
[11:45:04 CEST] <furq> you'd be better off just using ffv1 at that point
[11:45:17 CEST] <furq> it'll be better than qtrle but probably still pretty big
[14:06:28 CEST] <X-Kent> Nacht, it may be that the problem is not in the HLS itself but in the segments. Some players handle the stream well, others lose some frames, some just get stuck completely. HLS playlist itself looks legit in it's structure.
[14:07:29 CEST] <X-Kent> tried ffplay with debug options, don't see anything other than that it complains about CRLF at the end of headers.
[14:20:07 CEST] <Nacht> X-Kent: You would need to inspect the TS files then.
[14:24:49 CEST] <Nacht> X-Kent: I'm quite fond of this tool to check the TS files: http://www.pjdaniel.org.uk/mpeg/
[14:25:05 CEST] <Nacht> But it requires some knowledge regarding TS to know when something isn't valid
[14:25:12 CEST] <X-Kent> Nacht, ow, will check it out
[14:27:34 CEST] <X-Kent> crashes on linux under wine, will try it on my windows box
[14:28:44 CEST] <JEEB> for MPEG-TS I generally recommend DVBInspector
[14:28:53 CEST] <JEEB> it's java but seems pretty gut for stuff like checking PTS/DTS/PCR etc
[14:29:44 CEST] <JEEB> for examle it let me see how nicely Apple was muxing MPEG-TS https://kuroko.fushizen.eu/screenshots/apple_mpegts/nice_timestamps_there.png
[14:34:00 CEST] <Nacht> True, DVBinspector is quite nice as well. Nice visual representation of the PTS/DTS as well
[14:42:34 CEST] <JEEB> also generally if you're generating the HLS MPEG-TS yourself I recommend sticking at least two segments together and checking them like that
[14:42:48 CEST] <JEEB> that should also show if anything doesn't nicely flow from one segment to another
[15:17:11 CEST] <termos> av_opt_set(format->priv_data, "hls_flags", "program_date_time", 0); is it incorrect for me to set it like this? It does not work at least, wonder what the proper way to set it is
[18:43:56 CEST] <Mista_D> Why not extracting thumbnail at 0 seconds?  ./ffmpeg -i file.ts -vf fps=0.1:near=0 images/%04d.jpg
[18:44:44 CEST] <Mista_D> Why not extracting thumbnail at 0 seconds?  ./ffmpeg -i file.ts -vf fps=0.1:round=0 images/%04d.jpg
[18:44:59 CEST] <Mista_D> fixed the fps round...
[19:09:49 CEST] <kepstin> Mista_D: I believe you want to use round=inf to achieve that.
[19:56:24 CEST] Action: CoreX slaps tomaw around a bit with a large trout
[19:56:56 CEST] <tomaw> CoreX: hey, you got some warning :p
[19:57:57 CEST] <CoreX> surely you would rather give the advice via a global announce
[20:01:07 CEST] <tomaw> I might, when I've decided how many things I'm restarting :)
[22:12:26 CEST] <leif> Is there any way to set the time base with the ffmpeg filter graph?
[22:13:49 CEST] <ChocolateArmpits> leif, there's settb/asettb filter pair
[22:14:33 CEST] <ChocolateArmpits> but there's also -enc_time_base parameter for encoder
[22:15:19 CEST] <leif> ChocolateArmpits: Ah cool, thanks.
[22:15:41 CEST] <leif> (Also its for a programatic use, so using the filtergraph is much easier for this use case.)
[22:15:43 CEST] <leif> Anyway, thanks.
[22:16:16 CEST] <ChocolateArmpits> np
[22:16:17 CEST] <furq> dedicated muxers can do it without reencoding, if you happen to need that
[22:42:46 CEST] <dlb76> dlb76 #ffmpeg Cannot change nickname while banned on channel
[22:42:46 CEST] <dlb76> why you do this
[22:42:51 CEST] <dlb76> very uncomfortable
[22:51:40 CEST] <BtbN> Just register.
[22:52:15 CEST] <BtbN> The alternative is a bunch of spambots.
[22:55:53 CEST] <dlb76> i always identify
[22:56:19 CEST] <dlb76> https://pastebin.com/38mr3Uxq
[22:59:53 CEST] <furq> dlb76: auth with sasl instead
[23:00:08 CEST] <furq> i was going to say "it's less hassle" but i didn't want it to rhyme
[23:01:32 CEST] <dlb76> will see about it
[00:00:00 CEST] --- Wed Aug 22 2018

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