[Ffmpeg-devel-irc] ffmpeg.log.20191020

[burek]

[01:33:49 CEST] <DHE> fred1807: yes, so long as your system can handle the transcode work. which it probably can
[08:52:32 CEST] <MoziM> stupid question... but can someone explain to me what the point of upscaling? doesn't it just make the file size bigger? is it just to make a video applicable to a larger screen/monitor?
[08:53:38 CEST] <furq> if you mean why are there upscaled commercial releases then yes
[08:53:53 CEST] <furq> and also to make money from people buying the same master twice
[08:54:10 CEST] <MoziM> master?
[08:59:00 CEST] <MoziM> furq: the original video series?
[08:59:17 CEST] <furq> the original copy of the film
[08:59:49 CEST] <furq> unless it was shot on film and they remastered it then the 4k bluray will literally just be the 2k bluray source run through an upscaler
[09:00:08 CEST] <furq> rescanned and/or remastered
[09:00:26 CEST] <MoziM> but it will be the same information?
[09:00:31 CEST] <MoziM> but larger size?
[09:00:37 CEST] <MoziM> ....
[09:00:42 CEST] <furq> yeah
[09:00:48 CEST] <furq> normally if it's an upscale then the film was shot in 2k
[09:01:05 CEST] <furq> the justification is they have fancier upscalers than your tv has
[09:01:10 CEST] <furq> which is often not true
[09:14:25 CEST] <MoziM> furq: so if i have a video that's 640x480 and upscale it to 1280x960 in what situation would this look better than the former in a tv?
[09:14:49 CEST] <furq> it depends on how good the upscaler in the tv is
[09:15:17 CEST] <furq> you'd probably want to go to 1440x1080 so it's native res
[09:15:39 CEST] <phobosoph> hi
[09:15:48 CEST] <phobosoph> so I use ffmpeg to stream to YouTube Live
[09:16:04 CEST] <phobosoph> it works nicely - but suddenly, after some hours, the stream is terminated
[09:16:20 CEST] <phobosoph> ffmpeg still runs and tells (logs) me that it still is streaming
[09:16:30 CEST] <phobosoph> but YouTube tells me "No data" and eventually the stream is ended
[09:16:32 CEST] <MoziM> furq: tv or monitor?
[09:16:44 CEST] <furq> well your monitor doesn't have an upscaler
[09:16:52 CEST] <phobosoph> so ffmpeg should end itself if the connection doesn#t work
[09:16:58 CEST] <phobosoph> but it doesn't, it think it still works
[09:17:02 CEST] <furq> if you're playing it in mpv or something then it'll make zero difference if you upscale it
[09:17:10 CEST] <furq> since you can just use the same upscaler in that
[09:17:27 CEST] <furq> the original will probably look better since you didn't reencode it
[09:21:10 CEST] <MoziM> oh... wow i honestly never thought of it like that
[09:21:31 CEST] <MoziM> a tv needs an upscaler because video "resolution" has an objective size
[09:22:37 CEST] <MoziM> err... i guess a tv as in something that's 3ft in width right?
[09:23:06 CEST] <MoziM> furq: so an upscaler reencodes the video as it's playing it?
[09:23:15 CEST] <furq> no
[09:23:20 CEST] <furq> it upscales the decoded video
[09:23:40 CEST] <MoziM> is upscaling a form of encoding?
[09:23:46 CEST] <furq> no
[09:23:49 CEST] <MoziM> err it would be decoding
[09:23:51 CEST] <MoziM> right?
[09:23:54 CEST] <furq> neither
[09:24:03 CEST] <furq> it's already decoded when it's scaled
[09:24:09 CEST] <MoziM> what is scaling then?
[09:24:13 CEST] <MoziM> just it's own thing?
[09:24:14 CEST] <furq> filternig
[09:24:16 CEST] <furq> ing
[09:24:19 CEST] <MoziM> wat
[09:31:18 CEST] <MoziM> furq: is filtering anything that doesn't modify the original information?
[09:31:24 CEST] <MoziM> furq: i.e. modifying it for viewing?
[18:59:51 CEST] <Polochon_street> Hi! I have an audio cable plugged to a (playing) physical player and my laptop's mic audio IN, and I'm wondering why this command that I use to display the associated spectrogram has a 1-2s lag from the real input? `ffmpeg -f pulse -i alsa_input.pci-0000_00_1f.3.analog-stereo -c:v rawvideo -filter_complex "showcqt" -f nut - | ffplay -fflags nobuffer -`
[19:00:00 CEST] <Polochon_street> am I doing something obviously wrong here?
[19:00:24 CEST] <BtbN> just overall buffering
[19:00:54 CEST] <BtbN> Just use ffplay directly, that cuts out two whole buffered steps
[19:02:12 CEST] <Polochon_street> I've tried to, but I couldn't figure out the equivalent ffplay command :/
[19:02:25 CEST] <BtbN> It's pretty much identical
[19:02:29 CEST] <Polochon_street> it took me quite some time for this one to work tbh :D
[19:06:47 CEST] <Polochon_street> like, since `filter_complex` doesn't exist in ffplay I have to use `-f lavfi` but then I don't really know how to specify my mic as input
[19:06:54 CEST] <Polochon_street> (cf https://video.stackexchange.com/questions/9644/how-do-i-turn-audio-into-video-that-is-show-the-waveforms-in-a-video)
[19:13:03 CEST] <BtbN> Why would you use -f lavfi?
[19:13:19 CEST] <BtbN> Just use normal -vf, there is no point to -filter-complex for a single filter with no arguments anyway.
[19:17:39 CEST] <Polochon_street> indeed, it works. My bad
[19:18:28 CEST] <Polochon_street> there's still 2 seconds lag though :/. I can't cut it down to less, right?
[19:22:11 CEST] <Polochon_street> hm, it actually doesn't work, it just shows the default visualization :D
[19:23:39 CEST] <Polochon_street> I've tried something like ` ffplay -f pulse -i alsa_input.pci-0000_00_1f.3.analog-stereo -vf showcq`
[19:25:46 CEST] <Lynne> ffmpeg -f pulse -fragment_size 512 -sample_rate 48000 -channels 2 -wallclock 0 -i default
[19:26:00 CEST] <Lynne> I get less than 20 ms with that
[19:27:06 CEST] <Lynne> high cpu usage though, so if you don't care about a few more ms of latency set the fragment_size to 2048 or so
[19:27:16 CEST] <Polochon_street> indeed
[19:27:33 CEST] <Polochon_street> that works great, thanks :)
[19:27:40 CEST] <Polochon_street> could I achieve the same result using ffplay?
[19:28:24 CEST] <Lynne> no
[19:28:33 CEST] <Lynne> use -c:v rawvideo -f sdl2 /dev/null if you want video output
[19:29:30 CEST] <Polochon_street> thanks a lot!
[19:35:54 CEST] <HickHoward> okay, so uhhhh
[19:40:42 CEST] <HickHoward> does ffmpeg cover mp1 encoding?
[19:41:36 CEST] <JEEB> what do you mean with mp1?
[19:41:54 CEST] <JEEB> video, audio, or container from MPEG-1?
[19:42:17 CEST] <HickHoward> MPEG-1 Audio Layer I
[19:42:26 CEST] <HickHoward> yeah i sould've said that instead
[19:42:49 CEST] <JEEB> seems like we don't
[19:42:58 CEST] <HickHoward> right
[19:43:03 CEST] <JEEB> D.A.L. mp1                  MP1 (MPEG audio layer 1) (decoders: mp1 mp1float )
[19:43:06 CEST] <HickHoward> another question
[19:43:23 CEST] <JEEB> we do have one for mpeg-1 layer 2, though. and mpeg-1 layer 3 can be generated through LAME
[19:54:56 CEST] <HickHoward> cool
[19:56:44 CEST] <HickHoward> actually what i meant to ask is if ffmpeg handles MPEG Multichannel, which is an extension of MPEG-1 Audio Layer I/II(or just Layer II according to wikipedia)
[19:57:00 CEST] <HickHoward> either as an decoder or encoder
[20:12:14 CEST] <jemius> Does by chance one of you have a command line example of denoising videos with ffmpeg?
[20:12:40 CEST] <JEEB> HickHoward: simplest is to just test if you have sample
[20:12:45 CEST] <JEEB> *have a sample
[20:12:46 CEST] <HickHoward> right
[20:13:37 CEST] <HickHoward> i do have a bunch of files encoded using MPEG Multichannel and i got them from a site that covers multi-channel audio codecs
[20:13:44 CEST] <HickHoward> just hold on
[20:16:26 CEST] <HickHoward> yeah it's this site
[20:16:27 CEST] <HickHoward> http://www.mpegmultichannel.free.fr/
[20:25:52 CEST] <phobosoph> hi
[20:26:00 CEST] <HickHoward> hi
[20:26:25 CEST] <phobosoph> This channel is awesome and helped me a lot !
[20:26:48 CEST] <phobosoph> So I got a sucessful youtube live stream running - but after some hours, e.g. 12 hours Youtube just says the stream is terminated.
[20:27:08 CEST] <phobosoph> when I look closer it seems YouTube got no Data - and when there is no data for a too long time it will end the stream
[20:27:23 CEST] <phobosoph> when I check ffmpeg, it still happily sends the stream data to YouTube
[20:27:53 CEST] <phobosoph> so ffmpeg somehow doesn't notice the stream to youtube failed
[22:07:02 CEST] <jemius> Is de-noising audio (mathematically) harder than de-noising video? I'm asking because I noticed that my installation only contains video de-noisers
[22:08:54 CEST] <durandal_1707> jemius: your installation is what ffmpeg version?
[22:09:58 CEST] <jemius> 3.2.14.1
[22:12:26 CEST] <durandal_1707> jemius: pra historic and unsupported
[22:13:44 CEST] <jemius> I am not asking for support. I'm curious about the tech. The only way of de-noising audio I know of is compressing the amplitudes so you don't hear the noise anymore
[22:14:20 CEST] <durandal_1707> afftdn, anlmdn, arnndn, anlms are audio denoising filter in FFmpeg
[22:15:15 CEST] <durandal_1707> none of them are in 3.2.X
[22:17:36 CEST] <durandal_1707> those are native filters, there are also ladspa and lv2 ffmpeg filters that can be used with plugins
[00:00:00 CEST] --- Mon Oct 21 2019