[Ffmpeg-devel-irc] ffmpeg.log.20190904

[burek]

[00:29:20 CEST] <classsic48> hi, how can discard N seconds on live input stream? I try with ffmpeg -ss 5 -i ....
[00:29:30 CEST] <classsic48> but doesn´t work
[00:30:00 CEST] <another> seek after -i ?
[00:30:57 CEST] <classsic48> I will try
[00:42:06 CEST] <classsic48> don`t work
[00:42:18 CEST] <classsic48> *doesn`t work
[10:11:54 CEST] <oid> I am using ffmpeg to give a text file of the silences in some audio files using this command;
[10:11:59 CEST] <oid> ffmpeg -i audio.mp3 -af silencedetect=n=-50dB:d=1,ametadata=print:file=log.txt -f null
[10:13:19 CEST] <oid> which gives me the info needed but these are large files with many silence, so it is slow I get huge amount of data, I know the general time of the silences that interest me, is there a way to specify that start and duration of this filter?
[10:56:32 CEST] <gamelaster> Hi, does anyone know about any libav up-to-date example application, except ffplay.c a ffmpeg.c ?
[10:57:27 CEST] <durandal_1707> mpv
[11:00:52 CEST] <gamelaster> durandal_1707 nice, thanks, I will take a look. I'm implementing libav into my project, and I have problems with syncing read and decoding thread without getting deadlocked or having huge latencies
[11:34:19 CEST] <thnee1> Trying to transcode an h265 file to either h264, or h265. Why does h265 take 5x longer time? https://dpaste.de/yr88
[11:35:17 CEST] <thnee> I have been trying to follow this article https://slhck.info/video/2017/03/01/rate-control.html
[11:37:23 CEST] <Mavrik> thnee: because h265 encoder is newer and slower.
[11:37:26 CEST] <Mavrik> It's expected.
[11:40:29 CEST] <BtbN> Why even transcode HEVC to HEVC?
[11:41:58 CEST] <bencoh> downscale maybe? or bitrate reduction
[11:45:06 CEST] <thnee> Yeah it's actually going to be an HLS with multiple renditions, but this was just an example
[11:45:41 CEST] <thnee> Mavrik: Ok thanks a lot, I thought I was maybe doing something wrong, but this kind of difference is actually expected, thats interesting!
[11:47:25 CEST] <bencoh> I personally wouldn't bother much with h265 for hls, but ... :)
[11:48:02 CEST] <thnee> Okay
[11:48:56 CEST] <thnee> Yeah looks like I should be encoding my HLS streams using h264 regardless of if the uploaded video from the smart phone is h264 or h265
[11:49:59 CEST] <BtbN> What phone even outputs HEVC? That seems quite wasteful to encode on a mobile device, even with a hwenc.
[11:50:22 CEST] <Mavrik> Most new ones
[11:50:35 CEST] <JEEB> iOS at least seems to have started moving towards HEVC
[11:50:36 CEST] <Mavrik> iPhones, Galxy S series, Galaxy Note series, new Pixels, etc.
[11:50:43 CEST] <Mavrik> On a lot of them it's optional
[11:50:54 CEST] <Mavrik> But people turn it on so those 4K videos don't munch through the storage
[11:50:54 CEST] <JEEB> my oneplus 6T it doesn't even offer the option
[11:51:05 CEST] <JEEB> 2160p60 is just 120mbps H.264
[11:51:12 CEST] <JEEB> which is OK for me
[11:51:15 CEST] <Mavrik> Yeah, my S9 and pixel have the option
[11:51:23 CEST] <thnee> All iphones from 7 and up with iOS 11 produces hevc
[11:51:29 CEST] <BtbN> Seems also a bit troublesome regarding licensing
[11:51:50 CEST] <JEEB> yea most likely everyone has the stuff on the SoC but whether or not they expose/use it is different
[11:51:59 CEST] <BtbN> But I guess it's exactly those Phone-Manufacturers using it that are in one of the stupid HEVC patent pools
[11:52:07 CEST] <Mavrik> If the device has the HEVC encoder, they expose it
[11:52:20 CEST] <Mavrik> And most of the new ones do (depending on SoC)
[11:52:29 CEST] <BtbN> I wouldn't bet on that. Plenty of them won't want to deal with the license mess that HEVC is.
[11:52:42 CEST] <JEEB> I'd be pretty sure my phone has one (aforementioned 6T), but it isn't exposed
[11:53:56 CEST] <Mavrik> Also Android 10 now has official support
[11:54:26 CEST] <Mavrik> Although, decoder only it seems :'
[11:54:46 CEST] <JEEB> HEVC decoder has been part of AOSP or so for pretty long time.
[11:55:02 CEST] <JEEB> they've required a decoder for new devices since 5 or so
[11:55:05 CEST] <Mavrik> Yeah, looking at history now, it was mandated in API 21 / 5.0
[11:55:17 CEST] <JEEB> and there was a swdec available
[11:55:28 CEST] <JEEB> my oneplus one deffo has no hwdec in the SoC but it started using that one ARM library
[11:55:34 CEST] <JEEB> which was exposed through mediacodec
[11:55:39 CEST] <Mavrik> I misremembered, Android 10 added HEIC support
[11:55:58 CEST] <JEEB> I wish HEIC was without all the mp4-forking shenanigans
[11:56:10 CEST] <Mavrik> Which is optional IIRC
[14:09:56 CEST] <gamelaster> again here (connection drop), mpv is too complex, I'm just looking for some app which have simple video playback with correct made reading and decoding threads + sync by external timer
[14:12:30 CEST] <BtbN> "sync by external timer" sound like something you'll have to build yourself
[14:14:17 CEST] <gamelaster> BtbN I meant classical "-sync ext" by system time
[14:14:39 CEST] <gamelaster> but generally, any examples or apps will be highly appreciated, since I have really hard times to get all of this working correctly
[14:15:21 CEST] <pink_mist> why not just use mpv or link to libmpv?
[14:24:14 CEST] <gamelaster> pink_mist well, I double checked the libmpv, it looks like it supports what I want, but I will need to rework some things. Thanks for the tip
[14:39:54 CEST] <pk08> hi, i want to add a global variable which can access in libavformat/mpegts.c and libavfilter/vf_drawtext.c
[14:39:55 CEST] <pk08> so for that, i created a header file called "test.h" and defined a variable with extern int anyError and then included test.h file in both above .c files
[14:39:55 CEST] <pk08> (and redifined in mpegts.c)
[14:39:55 CEST] <pk08> now when i try to compile ffmpeg i am getting libavfilter/libavfilter.so: undefined reference to `anyError'
[14:40:10 CEST] <pk08> can any one help me to solve this error?
[14:41:56 CEST] <DHE> declaring it extern means that it exists somewhere, but it still has to be actually declared somewhere
[14:42:07 CEST] <DHE> in some file you have to put "int anyError;" or whatever
[14:42:35 CEST] <DHE> also do note that this is a race condition waiting to happen because it's completely legitimate to have several mpegts decoders running at once
[14:42:56 CEST] <pk08> i have declared in mpegts.c
[14:43:37 CEST] <pk08> and thats why i am getting error in libavfilter
[14:44:14 CEST] <pk08> and if i redefine in vf_drawtext.c then i get error in libavformat
[14:44:33 CEST] <pk08> so i am not sure, where i can redefine that variable
[15:04:29 CEST] <pk08> hello! anyone please?
[15:06:34 CEST] <DHE> not having the time to look at this in more detail, have you considered a static build rather than shared build?
[15:16:02 CEST] <pk08> DHE: just tried to compile static build but getting same error
[15:50:01 CEST] <Freneticks> Any idea why some player for a m3u8 playlist cannot seek backward or forward but only seek full ts segment ? Is my playlist is not good ?
[15:54:08 CEST] <Xogium> JEEB, durandal_1707: hah looks like someone went way faster than me to report https://trac.ffmpeg.org/ticket/7011
[15:55:37 CEST] <Xogium> and yep chained opus really exists :p especially for webradio
[16:51:19 CEST] <pk08> did any one gave any replay for my issue?
[16:51:34 CEST] <pk08> i was offline for last hour
[17:26:07 CEST] <b0bby|> hello
[17:26:45 CEST] <b0bby|> This is going to sound weird, but I would like to remote decode a video file for playback on a lan computer
[17:27:36 CEST] <BtbN> so you want to decode on one PC, and play on the other?
[17:27:48 CEST] <b0bby|> Im trying "ffmpeg -i file.mkv -vcodec rawvideo -f mpegts udp://127.0.0.1:1234" but mpv wont play the stream
[17:28:14 CEST] <BtbN> Keep in mind that you need at least a 10G Network for that to be even remotely realistic
[17:29:11 CEST] <pink_mist> eh, not if it's tiny resolution :P
[17:30:06 CEST] <b0bby|> fair point, my main problem is I have something that can decode the video fast enough, but not encode it fast enough
[17:30:07 CEST] <kepstin> hey, you should be able to do 24fps 1080p yuv420p on 1gbit
[17:31:20 CEST] <BtbN> Isn't 720p60 raw video yuv420p already 200MB/s?
[17:31:30 CEST] <BtbN> so, 1.5GBit/s
[17:31:47 CEST] <b0bby|> ok, so then raw is probably out of the question, is there any form of quick compression that can encode fast with the sacrifice of file size
[17:31:58 CEST] <BtbN> ah, no. It's 6 byte per 4 pixel, nvm, math is wrong
[17:32:22 CEST] <kepstin> 1080p24 4:2:0 is about 600mbit/s
[17:32:24 CEST] <BtbN> b0bby|, nothing will be as efficient as just not transcoding at all and letting the playing side do it.
[17:33:11 CEST] <BtbN> 720p60 is ~80MB/s
[17:33:11 CEST] <kepstin> b0bby|: it's pretty rare to find a system that can't do realtime decoding of typical video formats nowadays, even on cpu only :/
[17:33:15 CEST] <BtbN> yuv420p
[17:35:24 CEST] <b0bby|> so what is the fastest method of encoding, with a possible to stream file size?
[17:35:44 CEST] <kepstin> b0bby|: fastest method is to use -c copy, and then your file is probably already small enough to stream
[17:36:08 CEST] <kepstin> or just play it off an nfs or samba server if this is a lan setting, tbh.
[17:37:20 CEST] <kepstin> or buy a long hdmi cable (or one of those hdmi extensions over cat6 things) and just play the video on the remote box with a long cable
[17:37:44 CEST] <b0bby|> kepstin: that might be good enough
[17:37:57 CEST] <b0bby|> thank you guys for all the help
[19:27:42 CEST] <TheRock> before trying around ... do you guys have any favorite settings for dark videos to brighten them up?
[19:27:55 CEST] <TheRock> shot in low light surrounding
[19:29:36 CEST] <HumanSheeple> Hi I'm on a dedicated linux server remotely via SSH, the computer has no on board sound, it's running ubuntu, can you tell me how I set up a dummy audio output that is ffmpeg-able ?
[19:29:45 CEST] <HumanSheeple> pulseaudio won't book
[19:29:47 CEST] <HumanSheeple> boot
[19:29:56 CEST] <HumanSheeple> daemon refuses to start
[19:30:45 CEST] <kepstin> why do you need an audio output at all? ffmpeg can discard stuff or send it to a null output.
[19:43:37 CEST] <HumanSheeple> OK I'm trying to set up gstreamer on my dedicated linux machine so it can get audio from discord and mix it with the video of one of us playing minecraft then upload it to ty, twitch, bitchute etc
[19:47:04 CEST] <DHE> that still shouldn't require pulseaudio on the host
[19:47:13 CEST] <kepstin> oh, so it's not that you need the audio output for ffmpeg, it's that you want to capture the audio from some other application and record it with ffmpeg
[19:47:51 CEST] <DHE> I guess there's no direct way to capture audio from discord...
[19:48:01 CEST] <kepstin> your options are to use pulseaudio (which can be configured with a virtual soundcard, newer versions do this automatically if no hardware is detected), or to use the 'aloop' alsa driver to make a virtual soundcard in the kernel.
[19:50:30 CEST] <HumanSheeple> I think there's a way with the bot
[19:51:07 CEST] <HumanSheeple> So if I can get the bot to produce a stream can I get gstreamer to capture the video and mix the two together and output to yt, twitch, bitchute
[00:00:00 CEST] --- Thu Sep  5 2019