[Ffmpeg-devel-irc] ffmpeg.log.20180303

burek burek021 at gmail.com
Sun Mar 4 03:05:01 EET 2018

[00:51:16 CET] <Aison> what do I have to enable that ffmpeg supports this codec:
[00:51:17 CET] <Aison> Stream #0:1: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 600x600 [SAR 1:1 DAR 1:1], 90k tbr, 90k tbn, 90k tbc
[07:47:42 CET] <Rasi> hi
[07:48:41 CET] <Rasi> when i have a 8bit encoded movie at RF 22 and I want to re-do the encode with 10bit to roughly archieve same quality, would I choose a lower RF setting?
[07:49:43 CET] <Rasi> cause I just made a hevc 10bit encoding at RF22 (full hd resolution) and it gave me a file with 11Mb/s overall bitrate
[07:49:51 CET] <Rasi> which seems insanely huge
[07:49:53 CET] <furq> with x264 you'd use the same crf
[07:49:56 CET] <furq> no idea about x265
[07:51:39 CET] <Rasi> i guess my question is more about x264<>x265 instead of 8bit<>10bit
[07:51:41 CET] <Rasi> :P
[07:52:49 CET] <Rasi> oh
[07:53:05 CET] <Rasi> just checked another movie i did with 8bit hevc and also RF 22
[07:53:13 CET] <Rasi> that one only had 2Mb/s
[07:53:54 CET] <Rasi> i know crf does not guarantee specific file sizes, but a difference of 9Mb/s seems insane
[08:03:53 CET] <kerio> crf between libx264 and libx265 is different tho
[08:22:38 CET] <Rasi> i will redo the movie with hevc 8 bit now and see if its as huge
[10:03:27 CET] <Rasi> hmm
[10:03:33 CET] <Rasi> seems to get equally huge
[10:04:36 CET] <Rasi> image is rather noisy, i guess thats the reason
[10:04:45 CET] <Rasi> didnt expect such a massive increase though
[10:04:52 CET] <Rasi> 4 times of my usual bitrate
[10:19:43 CET] <Rasi> hmm no
[10:19:50 CET] <Rasi> denoising it gives the same bitrate
[10:19:58 CET] <Rasi> wtf is happening here
[10:20:17 CET] <Rasi> 30 seconds clip RF22 results in a biteate of 13Mb/s
[10:20:32 CET] <Rasi> https://fb.53280.de/YrZD/
[10:20:35 CET] <Rasi> these are my settings
[10:22:18 CET] <Rasi> how would nl denoise appear in encoder settings?
[10:27:20 CET] <furq> it wouldn't
[10:31:50 CET] <Rasi> ok
[10:32:00 CET] <Rasi> with x264 i get around half the bitrate
[10:32:19 CET] <Rasi> at the same crf, which is probably not saying much since crfs between the 2 are most likely different
[10:33:04 CET] <Rasi> and using denoise on the x264 one decreases it even further to a quarter of it
[10:33:15 CET] <Rasi> now i wonder why denoising on the x265 one didnt do anything
[10:34:54 CET] <furq> fwiw i wouldn't even bother with x265 for HD if you're only using preset slower
[10:34:57 CET] <furq> slow
[10:35:36 CET] <furq> you only get big gains relative to x264 if you use the really slow presets
[10:36:12 CET] <furq> or if you're encoding UHD, or you actually need high bit depth and don't want to have no compat
[10:44:28 CET] <Rasi> ehm in this case the gain is enormous
[10:44:38 CET] <Rasi> x264 without filter goes up to 19MB/s
[10:44:47 CET] <Rasi> thats 30% more
[10:45:12 CET] <Rasi> both with matroska full hd preset
[10:45:26 CET] <Rasi> which as far as i know dont encode in slow preset
[10:46:10 CET] <Rasi> just tried x265 with crf=25 which takes it down to ~3000Kb/s
[10:46:15 CET] <Rasi> and still looks good
[13:28:10 CET] <kerio> Rasi: the default crf for x265 is 28
[14:24:01 CET] <bt__> Hi, muxing a vp8 video stream to webm using libavformat. The video is playing fine first few seconds but then pixalates and displays junk. what can be the reason for this ? Parameters of my video stream : resolution - 640X480, bitrate - 1000Kbps, 30 fps.
[14:47:05 CET] <dani2629> hi i am trying to install an application on Linux Ubuntu www.toonloop.com and i am required to enter the command "sudo apt-get install ffmpeg gettext gstreamer0". It returns me Unable to locate package gstreamer0.10-ffmpeg" what shoud I do?
[14:55:45 CET] <BtbN> gstreamer 0.10 is ancient and dead. Also, not a question for this channel.
[15:02:56 CET] <dani2629> thank you
[18:52:45 CET] <jack_thompson> av_register_all() was deprecated? the fucking init function? really? xD
[18:53:04 CET] <jack_thompson> man... this will never have a stable API... lol
[19:42:32 CET] <BtbN> Because it's not needed anymore? Why would it be left behind doing nothing?
[20:15:33 CET] <dustfinger> how do I pass a configure param to ffmpeg? specifically I want to pass --list-indevs.
[20:18:50 CET] <JEEB> dustfinger: you just call the configure script with that parameter?
[20:18:58 CET] <JEEB> in my case I have my build root
[20:19:08 CET] <JEEB> and I call configure script from that dir, and all's fine?
[20:20:49 CET] <dustfinger> Actually, I don't think I really need that now. I see I can just run ffmpeg -devices and it will list the audio / video devices. My goal is just to figure out what I need to provide for the -i videio:audio option.
[20:22:20 CET] <JEEB> yes, those are the currently built in things
[20:22:38 CET] <JEEB> as opposed to all that are theoretically available irrelevant of where you are trying to run the configure script system-wise
[20:23:03 CET] <JEEB> for example vfwcap and avfoundation both show up on the configure script because they're available under /some/ systems
[20:30:24 CET] <dustfinger> I am actually trying to figure out what options to pass to ffmpeg via kdenlive so that I can capture scree / audio. These are the devices that ffmpeg sees: https://paste.pound-python.org/show/3L4nurfW4J0r8wWlbJtp/. I have 2 mics. One internal, the other use a Blue Yeti USB. The blue Yeti is listed as B20: https://paste.pound-python.org/show/KCjhGwjuerPOTF6056Yj/ This is what kdenlive is passing to ffmpeg: -f alsa -i
[20:30:24 CET] <dustfinger>  [video:audio] crf 25 -ab 192k -vcodec libx264 -acodec libvorbis -preset veryfast -threads 0. What do I put for video:audio?
[20:33:18 CET] <sfan5> -f x11grab -s 1920x1080 -i $DISPLAY -f alsa -i pulse
[20:33:38 CET] <sfan5> if it's capturing the wrong mic, open pavucontrol and switch the source
[20:34:02 CET] <dustfinger> sfan5: Does -i pulse assume I have pulse audio? I don't have pulse audio.
[20:34:17 CET] <sfan5> it does yes, no idea how that works on alsa
[20:34:32 CET] <sfan5> -f alsa -i B20  maybe?
[20:34:47 CET] <debianuser> dustfinger: `-f alsa -i default` :)
[20:35:16 CET] <debianuser> dustfinger: (optionally use env ALSA_CARD=B20 to select where to capture from :) )
[20:35:19 CET] <dustfinger> debianuser: Hey, thanks. I did not see that you were here :-)
[20:35:37 CET] <dustfinger> debianuser: Thanks, I will try that now.
[20:36:44 CET] <debianuser> Heh, usually I'm not, it's just I have too much free time today. :)
[20:38:29 CET] <dustfinger> debianuser: Yes, that worked. I have a lot to learn. Thank you very much again for your time.
[20:38:36 CET] <debianuser> You're welcome!
[20:40:12 CET] <debianuser> (to others: initially the question was asked in #alsa and was about capturing audio with recordmydesktop, we've solved that, and dustfinger switched to ffmpeg then)
[20:43:10 CET] <dustfinger> debianuser: That is right. I am trying to get my audio equipment setup to work with a variety of tools. I can now take a screen capture with kdenlive, but the audio does not capture. If I play the mov with mplayer there is no audio.
[20:43:38 CET] <dustfinger> At least kdenlive does not just produce a crash log when I run the capture. So this is a big improvement :-)
[20:45:35 CET] <debianuser> dustfinger: By the way, if you can't pass env.variables, you can pass card name as an argument to "default" pcm i.e. `-f alsa -i default:CARD=B20` (or shorter: `-f alsa -i default:B20`)
[20:46:10 CET] <dustfinger> debianuser: Okay, I will try that.
[20:49:06 CET] <debianuser> (that only works with usual alsa-only configs, won't work if you have configs installed by pulse or any other custom "pcm.!default" definition somewhere)
[20:50:58 CET] <dustfinger> debianuser: still no sound. I double checked that things are still working with recordmydesktop for audio and they are. Just no sound via kdenlive to ffmpeg. I will try to just run ffmpeg directly from command line to take kdenlive out of the picture.
[20:53:40 CET] <dustfinger> That was a worth while excercise. ffmpeg says that it cannot find the codec for some format: https://paste.pound-python.org/show/YBk2pJZ6kP3xF5SohnXE/
[20:53:46 CET] <dustfinger> I must be missing support for something.
[20:54:40 CET] <sfan5> your problem is using mplayer in the year of 2018
[20:54:47 CET] <dustfinger> I created the output.mov via this command: ffmpeg -f alsa -i default:CARD=B20 -crf 25 -ab 192k -vcodec libx264 -acodec libvorbis -preset veryfast -threads 0 output.mov
[20:55:01 CET] <dustfinger> sfan5: hmm. that could be. OKay, I will try another player.
[20:56:50 CET] <debianuser> dustfinger: I don't know if you can put vorbis audio into .mov container...
[20:57:11 CET] <debianuser> and if you can't - no other player would help you :)
[20:57:17 CET] <debianuser> try .mkv instead of .mov
[21:01:55 CET] <dustfinger> debianuser: Okay, I have it working with this command: ffmpeg -f alsa -i default:CARD=B20 -crf 25 -ab 192k -vcodec libx264 -acodec copy -preset veryfast -threads 0 output.mkv
[21:02:59 CET] <dustfinger> I will have to just spend some time reading up on things now. I know from teh man page that acodec is the audio codec, but I don't know the list of things I can pass there. I just searched online and saw someone put copy, so I tried it out and it worked. I don't even know if that is a valid mkv?
[21:03:21 CET] <sfan5> mkv would've been able to hold vorbis
[21:03:53 CET] <sfan5> ffmpeg -encoders | grep "^ A"  will give you a list btw
[21:04:11 CET] <dustfinger> sfan5: Thanks!
[21:05:18 CET] <dustfinger> Thanks for everyones help. I have to go now, but I appreciate everyones time. I will spend some time reading more now that I have a number of tools that I can play with that I know my mic is working with. I feel like I have a place to stand.
[21:13:59 CET] <dustfinger> If anyone can recommend any online articles that would help educate me about audio / video codecs, podcasting etc please let me know. I will also spend more time reading through the ffmpeg related man pages.
[21:15:32 CET] <dustfinger> My immediate goal is to create a screen capture of my desktop with audio and edit that with kdenlive with the ultimate goal of making an online course.
[21:30:36 CET] <debianuser> dustfinger: hm... the basics are: a movie file is a "container", sort of like a .zip archive, it contains video tracks, audio tracks, subtitles, fonts, etc. Each audio and video track must be decoded with a specific "codec". And like there're different archive formats (.zip, .rar, .tar, .7z), there're different container formats (.avi, .mkv, .mp4, .mov, .3gp, etc).
[21:30:59 CET] <debianuser> The trick is that some containers can contain only a limited subset of codecs. .mkv is probably the most universal one, it can contain multiple video, audio and subtitle tracks with additional notes, chapters, fonts, etc. An old .avi can only contain old codecs, and may have problems with modern x264, x265, etc. While .mp4 can contain x264 and x265, but you can't put theora video into it. Etc.
[21:31:08 CET] <debianuser> Another trick is that different devices support different containers and codecs. E.g. a DVD player may support .avi and .mp4 but not .mkv, and a mobile phone may support .mp4 but won't be able to play .mkv. And so on.
[21:31:28 CET] <debianuser> TL;DR: If you don't know what you're going to use it for, or if you just want to upload it to youtube - any format is fine. E.g. .mkv + x264 for video + mp3/vorbis for audio should work. If you're targeting mobile phones - .mp4 + x264 baseline + libfdk_aac is probably the most compatible. For old DVD players .avi + mpeg4 + mp3 is the best.
[21:32:37 CET] Action: debianuser also wonders if there's a website explaining those basics...
[21:33:17 CET] <sfan5> debianuser: old DVD players will actually only support mpeg2 + mp2(?)
[21:33:46 CET] <JEEB> they should also support PCM and most likely AC3
[21:33:55 CET] <JEEB> since IIRC those were there since the beginning
[21:34:57 CET] <ChocolateArmpits> don't forget mpeg1
[21:35:09 CET] <JEEB> DVD is not MPEG-1 Video
[21:35:23 CET] <JEEB> if it's a DVD player it works with MPEG-2 Video
[21:35:29 CET] <ChocolateArmpits> only ?
[21:35:32 CET] <JEEB> (even though the two formats are similar)
[21:35:55 CET] <JEEB> they might support more, but if it's a *DVD* player that has unknown capabilities
[21:36:05 CET] <JEEB> then you give it what you'd think it can handle
[21:36:33 CET] <JEEB> also generally I would expect MPEG-1 Video encoders to have worse output than MPEG-2 Video encoders (?). also interlacism was only added with MPEG-2 Video IIRC, which DVD video IIRC mandated under specific cases
[22:34:13 CET] <TaZeR> you should go with mpeg-4 whenever possible
[22:46:30 CET] <classict_> hi, somebody can point how use vdpau hwaccel?
[22:50:58 CET] <aphirst> classict_, normally you just enable the setting in your mpv.conf, assuming you're sure you need it and understand the pros/cons of using hwaccel
[22:51:50 CET] <classict_> ok, thanks.
[00:00:00 CET] --- Sun Mar  4 2018

More information about the Ffmpeg-devel-irc mailing list