[Ffmpeg-devel-irc] ffmpeg.log.20181102

burek burek021 at gmail.com
Sat Nov 3 03:05:02 EET 2018

[04:43:35 CET] <grosso> hi
[04:44:44 CET] <grosso> any chance to get ffplay utility in android?
[07:08:00 CET] <grosso> ffplay for android?
[08:02:13 CET] <Mavrik> That would be pretty silly to have.
[10:43:09 CET] <friki> grosso: I have a Debian chroot with xorg+vnc server in my rooted Android (LineageOS). I've tested ffmpeg and ffplay, both work fine even to encode video. Probably it isn't what you are looking for ;-)
[11:50:30 CET] <kingmanor> is there a reason the static builds are compiled with gcc 6 vs gcc 8?
[12:13:51 CET] <relaxed> kingmanor: I encountered too many build issues with 8, if you're asking about https://www.johnvansickle.com/ffmpeg/
[12:23:17 CET] <kingmanor> yeah i guess i am as that is the main one linked on the download page.  yes ubuntu ffmpeg is built on gcc8 but it is 4.0.2 release i was looking for latest.
[12:24:01 CET] <kingmanor> its ok im gonna try to build it myself
[12:26:54 CET] <relaxed> kingmanor: if you haven't seen it, check out  https://trac.ffmpeg.org/wiki/CompilationGuide
[14:16:54 CET] <zivanovicb> we have to transcode one video which is 1080p to 1080p,720p,480p, all in mp4,webm & hls, which would be 9 different outputs i guess
[14:17:11 CET] <zivanovicb> is it better to do all this in one ffmpeg instance using multiple outputs or break it down in their own separate ffmpeg instances?
[14:18:18 CET] <zivanovicb> its also really important that original resolution(1080p) finishes as fast as possible
[15:37:16 CET] <Shibe> hi, what is wrong with this command? sudo ffmpeg -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -vcodec h264_vaapi -f pulse -ac 2 -i 1 -crf 0 -preset ultrafast -acodec pcm_s16le output.mkv
[15:37:22 CET] <Shibe> Option vf (set video filters) cannot be applied to input url 1 -- you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to.
[15:41:55 CET] <relaxed> try, ffmpeg -f kmsgrab -i - -f pulse -ac 2 -i 1 ...
[15:44:59 CET] <Shibe> relaxed: sudo ffmpeg -f kmsgrab -i - -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' -vcodec h264_vaapi -f pulse -ac 2  -preset ultrafast -acodec pcm_s16le -i 1 output.mkv
[15:45:04 CET] <Shibe> Option vf (set video filters) cannot be applied to input url 1 -- you are trying to apply an input option to an output file or vice versa. Move this option before the file it belongs to.
[15:45:55 CET] <durandal_1707> move -vf before output.mkv
[15:47:57 CET] <relaxed> Shibe: your inputs go first in the command
[15:50:59 CET] <Shibe> relaxed: 'sudo ffmpeg -f kmsgrab -vcodec h264_vaapi -f pulse -ac 2  -preset ultrafast -acodec pcm_s16le -vf 'hwmap=derive_device=vaapi,scale_vaapi=w=1920:h=1080:format=nv12' output.mkv' like this?
[15:58:30 CET] <relaxed> Shibe: ffmpeg <demuxer/format 1 options> -i <input 1> <demuxer/format 2 options> -i <input 2> <filters & encoding options> <output>
[15:59:20 CET] <relaxed> your last command has no inputs (-i)
[16:16:44 CET] <Shibe> relaxed: works perfect, thanks!
[20:22:29 CET] <teratorn> is there a way to select [*] (all) audio and video stream pairs from the input list in an ffmpeg filtergraph?
[20:24:33 CET] <durandal_1707> teratorn: huh, you can only pick them, there is no  * thing
[20:25:30 CET] <furq> teratorn: if it's the first filter in the list then maybe don't set an input label
[20:25:43 CET] <furq> that'll give you all the input streams in the order they were specified
[20:31:42 CET] <teratorn> furq: i was thinking that ^
[20:31:55 CET] <teratorn> would be nice to have some simple patterns in "label expansion" :)
[20:32:18 CET] <furq> you could also do [0][1]... if you know how many inputs you have
[20:42:49 CET] <grosso> hi
[20:44:18 CET] <grosso> can I receive a rtsp stream with ffmpeg and save to sequence of images realtime?
[20:46:18 CET] <edgy> Hi, In https://trac.ffmpeg.org/wiki/Encode/H.264 "It is not required if you are going to use a video service such as YouTube. YouTube recommends using faststart" Isn't there a contradiction here? I thought the phrase should say "It is required"
[20:50:48 CET] <edgy> Also the channel title says 4.0.1, shall I tell you that 4.0.2 is released? ;)
[20:52:53 CET] <HarveyPwca> An odd thing is happening when I am using ffmpeg. After ripping a film from a dvd and combining the vob files into a single file I use ffmpeg (cli) to select the video, audio and subtitles desired. ffmpeg starts out really well at 16x but then slooooowwwws down to <1x. Never used to do this. Anyone know how I can figure out how/why this is happening?
[20:55:45 CET] <HarveyPwca> Generally the command I'm using is:  ffmpeg -i [film name] -map 0:0 -c:v copy -map 0:1 -c:a copy -map 0:2 -c:s copy [new file]
[20:56:41 CET] <HarveyPwca> Depending on the film the 0:x for desired language/subtitles changes.
[20:57:09 CET] <HarveyPwca> So the above is just a general command.
[20:57:33 CET] <durandal_1707> you sure it doesnt start using swap?
[20:58:12 CET] <HarveyPwca> Never looked before. But looking just now it seems to be.
[21:18:17 CET] <HarveyPwca> It seems to be using very little of the system memory and none of the swap space.
[21:18:52 CET] <HarveyPwca> System memory fluctuates between 11% - 16%.
[21:19:56 CET] <HarveyPwca> Gawd it's slow. It's taken 45 minutes to process a lousy 10 minutes of film.
[21:20:13 CET] <durandal_1707> HarveyPwca: pastebin full uncut ffmpeg output
[21:22:10 CET] <edgy> any help?
[21:23:20 CET] <durandal_1707> edgy: no, i see no contradiction
[21:23:40 CET] <furq> edgy: it'll start processing faster if you use faststart, but it'll work fine either way
[21:24:08 CET] <furq> although i'd just use mkv in any case because that doesn't require a second pass
[21:24:33 CET] <edgy> furq: ah! thanks!
[21:24:52 CET] <edgy> furq: you mean mkv instead of mp4?
[21:24:55 CET] <furq> yeah
[21:25:07 CET] <furq> faststart mp4 with ffmpeg has to copy the entire file after writing it
[21:25:38 CET] <edgy> furq: but youtube recommends mp4 not mkv
[21:25:48 CET] <furq> yeah youtube recommends a lot of insane things that don't matter
[21:25:49 CET] <edgy> furq: I don't know why though
[21:25:57 CET] <edgy> furq: ;)
[21:26:17 CET] <furq> probably half of the things on that youtube recommendation page are either irrelevant or wrong
[21:27:04 CET] <edgy> furq: that's really strange! Can you please give me the command you recommend for youtube? I will trust you better than google ;)
[21:27:13 CET] <furq> what are you using now
[21:28:04 CET] <furq> i checked again and they fixed a lot of the stupider recommendations on there
[21:28:16 CET] <furq> 2 consecutive B frames
[21:28:16 CET] <furq> Closed GOP. GOP of half the frame rate.
[21:28:20 CET] <furq> these are the only bits i disagree with
[21:28:37 CET] <furq> just keep both of those at the x264 defaults
[21:29:06 CET] <edgy> furq: may be something like ffmpeg -i input -c:v libx264 -preset slow -profile:v high -crf 18 -coder 1 -pix_fmt yuv420p -movflags +faststart -g 30 -bf 2 -c:a aac -b:a 384k -profile:a aac_low output
[21:29:10 CET] <HarveyPwca> durandal_1707: Here is the pastebin link, I hope... https://pastebin.com/eYpch2Rs
[21:29:19 CET] <furq> yeah just get rid of -g 30 -bf 2
[21:29:24 CET] <furq> and also 384k aac is absolutely insane
[21:29:29 CET] <furq> they got rid of that recommendation now
[21:29:45 CET] <furq> honestly you shouldn't reencode the audio at all
[21:30:31 CET] <furq> get rid of -profile high, let x264 set that automatically (it'll probably be high anyway)
[21:30:34 CET] <furq> and -coder 1
[21:30:38 CET] <edgy> furq: not sure whether -g 30 or -g 15 maybe?
[21:30:38 CET] <edgy> furq: I copied this from somewhere
[21:30:44 CET] <furq> just get rid of it entirely
[21:31:01 CET] <furq> x264 has sensible defaults for all of this stuff
[21:31:30 CET] <furq> and then just use -c:a copy and get rid of all the other audio stuff
[21:32:49 CET] <edgy> furq: thanks, though this stuff is a bit difficult for me but if i might ask, why do you recommend removing -bf 2?
[21:33:54 CET] <furq> there's just no reason to manually set bframes when youtube is reencoding anyway
[21:34:17 CET] <furq> as a general rule you shouldn't touch any x264 option other than preset, tune and crf unless you know what you're doing
[21:35:04 CET] <furq> basically i would do -i foo.mp4 -c:v libx264 -c:a copy -preset slow -crf 18 -pix_fmt yuv420p bar.mkv
[21:35:07 CET] <furq> brb
[21:36:24 CET] <edgy> furq: Thanks! what's tune and what's brb? execuse my english
[21:37:09 CET] <HarveyPwca> edgy: brb = be right back
[21:38:02 CET] <edgy> HarveyPwca: thanks and tune?
[21:38:10 CET] <HarveyPwca> Not a clue.
[21:39:01 CET] <relaxed> edgy: it's detailed here, https://trac.ffmpeg.org/wiki/Encode/H.264
[21:39:34 CET] <durandal_1707> HarveyPwca: how big is input file?
[21:39:53 CET] <edgy> relaxed: thanks!
[21:39:59 CET] <HarveyPwca> 4.7Gb
[21:42:45 CET] <HarveyPwca> I should also note that this situation only occurs when I'm doing filename.vob to newfilename.vob. If I'm doing filename.mkv to newfilename.mkv (or *.mp4 or *.mkv to *.mp4) there's no slowdown at all. Zips right through these similarly sized files in ~20min or less.
[21:44:11 CET] <HarveyPwca> in.vob to out.vob can take 4 or more hours.
[21:44:36 CET] <furq> not that i think that's intended behaviour, but why would you copy it to another vob
[21:45:44 CET] <relaxed> HarveyPwca: you're trying to create an SVCD?
[21:45:51 CET] <HarveyPwca> furq: I'm removing extraneous audio and subtitle streams by selecting only those streams I want to keep.
[21:46:14 CET] <durandal_1707> HarveyPwca: does same happens if you instead of final vob use -f null - ? if no than vob muxer is doing something silly
[21:47:21 CET] <HarveyPwca> What is "-f null -"?
[21:47:41 CET] <furq> well it's not the vob muxer for starters
[21:47:42 CET] <HarveyPwca> Or did you mean "-f null"?
[21:48:48 CET] <nicolas17> "-f null" picks the null muxer which does nothing and sends data nowhere, but ffmpeg still wants a filename, "-" is enough to satisfy it
[21:50:08 CET] <HarveyPwca> Ah...just looked up the null command and read it a bit. Will try that now. Give me a couple of minutes to respond.
[21:52:45 CET] <relaxed> also try -f dvd
[21:53:04 CET] <furq> or just remux to mkv instead of vob
[21:53:13 CET] <HarveyPwca> Zowie!  That sucker screams speed wise. Gets up into the 200x+ speeds. However, after a few seconds I get this:
[21:53:34 CET] <HarveyPwca> [null @ 0x55e076b50260] Application provided invalid, non monotonically increasing dts to muxer in stream 1: 6474240 >= 6474240
[21:55:24 CET] <HarveyPwca> The value * >= * increments with same message.
[21:56:31 CET] <HarveyPwca> furg: Never thought to just remux. I'll try that now. Let you know in a moment the results.
[21:57:16 CET] <nicolas17> you *are* doing a remux, just into the same format as the input :P
[21:57:36 CET] <furq> yeah there's no point using vob as the output
[21:57:51 CET] <furq> especially if it's bigger than 1GB because then it's an entirely worthless format
[21:57:56 CET] <HarveyPwca> Yes. I'm seeing that now.
[21:57:57 CET] <furq> given that you can't put it back onto a dvd
[21:58:56 CET] <HarveyPwca> Well, actually the file gets smaller than the original because I'm negatively discarding the unwanted audio streams.
[21:59:19 CET] <nicolas17> you won't turn 4.7GB into 900MB by discarding audio :)
[21:59:20 CET] <HarveyPwca> Most of the time the file starts at 4.7Gb and ends up being half that or less.
[22:01:24 CET] <tdr> that would have to be a lot of audio streams and channels
[22:01:50 CET] <nicolas17> or long video with really bad video quality
[22:01:57 CET] <HarveyPwca> Okay. The .vob to .mp4 finished in record time. Video and Audio are correct but waaayyyy off in being synced.
[22:03:17 CET] <HarveyPwca> I think the .vob files are seriously borked somehow. Will just go back and re-rip the film. Thanks for all the help everyone. :-)
[22:38:20 CET] <grosso> hi
[22:38:32 CET] <grosso> can I ask a question?
[22:38:41 CET] <tdr> dont ask to ask
[22:38:46 CET] <grosso> ok
[22:39:10 CET] <grosso> i'm trying to receive a rtsp stream
[22:39:38 CET] <grosso> so far I can receive it, my problem is just the "output" part of the command line
[22:40:11 CET] <grosso> no mather what I put as "output" the command never writes it in real time
[22:41:04 CET] <grosso> so, if i set to output a sequence of images, it don't write anything, then when the streamer stops, it begins to write the images
[22:43:44 CET] <grosso> what command should I use to write a video file or a sequence of images while stream is coming?
[22:44:06 CET] <grosso> i.e. "realtime"
[22:44:11 CET] <tdr> you should prob paste what you're using now so folks can see what may be wrong
[22:44:21 CET] <grosso> ok,here I go
[22:46:12 CET] <grosso> ffmpeg -rtsp_flags listen -i rtsp:// test.mp4
[22:47:40 CET] <grosso> or ffmpeg -rtsp_flags listen -i rtsp:// -r 25 img-%02d.png
[22:49:43 CET] <nicolas17> are you sure your CPU and disk can write 25 PNG images per second?
[22:49:45 CET] <relaxed> ffmpeg -i 'rtsp://' -c copy output.mkv
[22:49:59 CET] <grosso> no, I'm not shure
[22:51:13 CET] <grosso> i don't need specifically 25 png per second, what I really need is any way to display that output in the screen of an android device, so no ffplay
[22:52:02 CET] <relaxed> install mpv on the android device and play them stream using it
[22:52:17 CET] <nicolas17> you could have started at that
[22:52:19 CET] <nicolas17> http://xyproblem.info/
[22:52:36 CET] <relaxed> it's called mpv-android in the playstore
[22:54:22 CET] <grosso> ok, I will try it... but, any players that I have tested, including vlc don't have that "listen" option so can't receive my stream
[22:57:01 CET] <relaxed> is that necessary? Can you start the stream, then play it?
[22:57:05 CET] <grosso> so you think mvp-android should receive this stream? so far only ffmpeg and ffplay have worked for me
[22:57:18 CET] <nicolas17> where would that ffmpeg process run anyway?
[22:57:45 CET] <relaxed> mpv uses ffmpeg's demuxers/codecs, so it should be fine
[22:58:06 CET] <nicolas17> relaxed: yeah but can you tell mpv-android to "listen"?
[22:58:25 CET] <relaxed> paging JEEB
[22:59:44 CET] <grosso> the parameter "listen" tells the player act as a server... it is absolutely necessary since the sending end expects a server
[22:59:52 CET] <relaxed> gotcha
[23:05:59 CET] <grosso> nicolas17 i'm running ffmpeg in android... there are lots of compilations, but what don't exist is ffplay which is exactely what I need... so what I'm trying to do is receive with ffmpeg and output to wathever that I can then see on android... a video or a sequence of pictures, even raw images... but it has to be "realtime" that is, i need to see it as it comes to ffmpeg
[23:09:24 CET] <grosso> I will try this:  ffmpeg -i 'rtsp:// -c copy output.mkv
[23:28:23 CET] <grosso> that command actually works, but... 1) no audio (original audio is AAC 1 channel) 2) I still have this problem: file is generated when sending end stops, rather than been generated "realtime"
[00:00:00 CET] --- Sat Nov  3 2018

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