[Ffmpeg-devel-irc] ffmpeg.log.20161113

[burek]

[01:59:28 CET] <llamapixel> Can ffmpeg link a file from the web before performing an action like saving it as another format. refernce links appreciated if possible. wget / curl has to be added to the mix?
[02:00:49 CET] <DHE> ffmpeg can accept http URLs, though it may be best to save to disk with wget/curl anyway
[02:01:33 CET] <llamapixel> thanks
[02:07:47 CET] Action: llamapixel discovered youtube-dl instead of wget or curl , thanks again DHE. Now I can save tutorials to my local drives.
[02:09:15 CET] <DHE> oh, should have mentioned you were using youtube. I would have mentioned that
[02:10:10 CET] <llamapixel> np, just needed a nudge mate
[05:50:35 CET] <t4nk866> I use this command to stream a single image
[05:50:37 CET] <t4nk866> ffmpeg -loop 1 -i hell.png -r 10 -vcodec mpeg4 -f mpegts udp://127.0.0.1:1234
[05:50:50 CET] <t4nk866> but if I make changes to the image, it doesnt appear in stream
[05:51:01 CET] <t4nk866> Is there a way to force a reload?
[06:12:02 CET] <klaxa> <klaxa>	does something like this work? (while true; cat image.gif; done) | ffmpeg -f image2pipe -i - <stuff> ?
[06:12:13 CET] <klaxa> t4nk866: ^
[09:09:12 CET] <Nati323> hey someone here?
[09:09:27 CET] <Nati323> Which input formats ffmpeg support?
[09:13:18 CET] <durandal_1707> pixel or file data?
[09:34:08 CET] <Nati323> @durandal_1707 I send you private
[14:35:09 CET] <Bombo> hi
[14:50:44 CET] <Bombo> i got a feature request: m3u8 as input ;) this would be cool: ffmpeg -i https://zdfvodnone-vh.akamaihd.net/i/meta-files/zdf/smil/m3u8/300/16/11/161103_grabusbythepussy_nmg/1/161103_grabusbythepussy_nmg.smil/master.m3u8 -c copy grab.mp4
[14:55:41 CET] <kerio> ...doesn't that work
[14:55:45 CET] <JEEB> HLS as input should work
[14:55:50 CET] <furq> yeah that's worked for ages
[14:55:57 CET] <JEEB> the only issue there might be if you don't have a TLS library linked in
[14:56:05 CET] <JEEB> in which case nothing through HTTPS works
[14:56:16 CET] <JEEB> also depending on your version you might have to insert BSFs manually
[15:21:59 CET] <Bombo> oh it really works, i didn't even try https:// sorry ;) i just tried -i master.m3u8
[15:22:11 CET] <JEEB> lol
[15:22:46 CET] <Bombo> what does aac_adtstoasc do actually?
[15:24:02 CET] <furq> https://www.ffmpeg.org/ffmpeg-bitstream-filters.html#aac_005fadtstoasc
[15:25:01 CET] <Bombo> ok thx
[16:14:23 CET] <Threads> Bombo that video is on youtube if you want something higher https://www.youtube.com/watch?v=GZc8tBtIDhI
[16:18:10 CET] <bens218> hello
[16:18:41 CET] <Bombo> Threads: yes i know
[16:18:45 CET] <Bombo> thx
[16:22:17 CET] <bens218> i'm trying to come up with a way to transcode my FLAC music to either mp3 or aac but my sources all have different sample rates
[16:22:43 CET] <bens218> i know aac can handle higher sample rates than mp3 can, but not the player that i'm using
[16:23:24 CET] <bens218> is there a way to resample with ffmpeg to use half of the existing sample rate?
[16:23:45 CET] <bens218> for example 96000 > 48000 and 88200 > 44100
[16:32:46 CET] <Threads> -ar is your friend
[16:32:59 CET] <Threads> -ar 48000
[16:33:01 CET] <bens218> yea, but that sets a specific rate
[16:33:18 CET] <bens218> which would do 88.2 > 48000 which will work but isn't ideal
[16:41:34 CET] <Bombo> you want maths like -vf scale for video? like e.g. oar=iar/2, i don't think that exists, so you would need to get the inputrate before, with a script
[16:42:06 CET] <bens218> that's what i was thinking, thanks Bombo
[16:42:53 CET] <Bombo> i had a bash script that encodes audio stream just if mp2 br >192k (for dvb recordings)
[16:42:59 CET] <bens218> so in theory i could use ffprobe to get the sample rate and based on that info have the script choose the correct rate
[16:43:08 CET] <Bombo> right
[16:43:44 CET] <Bombo> or you could hack the maths into the source somehow ;)
[16:44:05 CET] <bens218> ha, seeing that i'm not good at maths for coding i think i'll pass lol
[16:44:22 CET] <bens218> coming up with a script is doable for me, but will take me time
[16:46:12 CET] <bens218> *or not for
[16:50:42 CET] <furq> bens218: ffprobe -v error -select_streams a:0 -show_entries stream=sample_rate:stream_tags=0:stream_disposition=0 -of default=nokey=1:noprint_wrappers=1 foo.flac
[16:54:27 CET] <bens218> thanks furq , always helping me out
[17:28:01 CET] <t4nk007> I am building ffmpeg libraries to use in a desktop application. I want to include some 3rd party libraries as well like openjpeg.  When I build the ffmpeg libraries, will all the 3rd party libs be included also?  Or will I need to include both the ffmpeg libraries and the openjpeg libraries in my application?
[17:28:59 CET] <furq> they'll be included if you have static openjpeg libraries and you build ffmpeg with --extra-ldflags=-static
[17:35:07 CET] <t4nk007> great, thanks for your help
[21:54:51 CET] <Filarius> hm, how to make video show me what is going on pixel format yuv420p ?
[21:55:19 CET] <Filarius> like convert to yuv420p but use as rgb
[21:55:31 CET] <Filarius> or gray
[22:26:51 CET] <Dylan> Hi! I'm running Ubuntu 14.04 and I'm trying to figure out how to use ffmpeg to convert an .ogv file to something that I can drop into a video editing program. Can anyone help me walk through how to set up and use FFmpeg?
[22:39:43 CET] <kepstin> what video editing program? I wouldn't be surprised if most on linux can open ogv files natively, since they usually just use ffmpeg to read the input files...
[22:41:19 CET] <Dylan> Well, what I want to be able to do first is edit the audio in audacity.
[22:41:38 CET] <Dylan> and I'm trying to figure out how to split the video and audio.
[22:41:57 CET] <kepstin> well, that's not a video editing program, that's a completely different question.
[22:42:20 CET] <Dylan> I'm recording my desktop with RecordMyDesktop, which is creating .ogv files, which audacity can't figure out how to use. I've been going through different video editing programs to see if I can demux the video.
[22:42:23 CET] <kepstin> probably easiest to just use ffmpeg to pull the audio out as a wav file, like 'ffmpeg -i video.ovg audio.wav'
[22:42:45 CET] <Dylan> That's the sort of thing I want to hear!
[22:42:59 CET] <Dylan> I knew I was making this too complicated.
[22:43:28 CET] <Dylan> Now... the next issue I'm having, is that I thought I had FFmpeg installed, but when I use the command in the Terminal, I'm told the command isn't found.
[22:44:04 CET] <kepstin> hmm, ubuntu 14.04 doesn't have an ffmpeg package (they have libav instead), how did you install it?
[22:44:49 CET] <Dylan> That might be my problem right there. I've been attempted to download it from the Terminal (sudo apt-get) and I think I'm getting told I already have it.
[22:44:58 CET] <Dylan> Might be time for me to upgrade to 16.10?
[22:45:51 CET] <kepstin> or 16.04 if you want to stick with an lts release. (16.04 has ffmpeg 2.8, 16.10 has ffmpeg 3.0)
[22:46:32 CET] <Dylan> Got it.
[22:46:36 CET] <Dylan> I'll start with doing that.
[22:46:54 CET] <kepstin> you could also build ffmpeg yourself or use one of the static builds that are available.
[22:47:28 CET] <Dylan> I'll just go with the update. I've been putting it off and now I have a reason to do it.
[22:48:29 CET] <Dylan> Thanks for the help. I'll be back in if I can't figure it out after this.
[22:48:49 CET] <kerio> audacity uses ffmpeg to extract audio, anyway
[22:49:10 CET] <Dylan> I thought so. I was wondering why I couldn't get it to work.
[22:49:49 CET] <kepstin> hmm, depends how it's built... iirc depending on the options it will sometimes only open wav, or have a limited number of native decoders?
[22:50:09 CET] <kepstin> ... for some reason the audacity on my box doesn't have ffmpeg support enabled.
[22:50:43 CET] <Dylan> Let's see if I can keep it simple and start by updating my Ubuntu version.
[22:51:44 CET] <kepstin> the audacity in ubuntu 14.04 does not have ffmpeg support enabled, the version in 16.04 and 16.10 does have ffmpeg enabled
[22:51:54 CET] <Dylan> Sweet.
[22:51:54 CET] <kepstin> so after you upgrade, you can probably just open the ogv right in audacity
[22:52:03 CET] <Dylan> Thanks for your help.
[22:52:24 CET] <Dylan> Now if I can figure out why the Software Updater isn't opening up...
[22:52:40 CET] <kepstin> oh, wait, the version of audacity in 14.04 updates does have ffmpeg (well, libav...) support enabled
[22:52:47 CET] <kepstin> weird that it's not working for you
[22:53:25 CET] <Dylan> Tell me about it.
[22:53:37 CET] <Dylan> It drives me nuts when something I know should be really simply ends up taking me hours to figure out.
[22:56:12 CET] <furq> i'm pretty sure the ffmpeg package on 14.04 is a virtual package that points to libav-tools
[22:59:04 CET] <kerio> the libav situation is silly
[23:01:01 CET] <Filarius> Hello. Any tip how to convert video to yuv420p pixel format AND use it like gray color space ?
[23:01:54 CET] <furq> huh
[23:03:12 CET] <Filarius> i want to see how yuv420p looks like )
[23:04:02 CET] <Filarius> for kind of research
[23:12:46 CET] <thebombzen> Filarius: well yuv420p is a frame of Y, a frame of U, and a frame of V
[23:13:13 CET] <thebombzen> most likely you'd want to output it as -pix_fmt yuv420p -c rawvideo -f rawvideo output.raw
[23:13:41 CET] <thebombzen> then input it with -f rawvideo -pixel_format gray8 -i output.raw
[23:14:28 CET] <thebombzen> however, since yuv420p is progressive (i.e. a frame of Y, then U, then V) you'd probably want to use a -vf select filter before previewing it
[23:15:01 CET] <thebombzen> or it'll be very hard to figure out what's going on
[23:18:13 CET] <furq> u and v are one quarter the size of y, so i can't imagine that will work
[23:18:46 CET] <furq> i'm sure there's a filter which splits colour channels but i can't remember the name
[23:20:51 CET] <furq> Filarius: https://ffmpeg.org/ffmpeg-filters.html#extractplanes
[23:22:20 CET] <thebombzen> I forgot about chroma sampling
[23:22:34 CET] <thebombzen> well if you want to see how yuv works you could use yuv444p and that fixes the problem of chroma subsampling
[23:23:06 CET] <thebombzen> yuv420p is the same as yuv444p but the U and V are half the vertical and half the horizontal resolution
[23:23:32 CET] <furq> i assume he wants to see how the subsampling works
[23:23:45 CET] <furq> extractplanes should do what he wants anyway
[00:00:00 CET] --- Mon Nov 14 2016