[Ffmpeg-devel-irc] ffmpeg.log.20140402

burek burek021 at gmail.com
Thu Apr 3 02:05:01 CEST 2014

[02:06] <voip> I am trying to convert PAL rtmp stream to ac3 NTSC. As result i have very high CPU usage. Can you check pls, everything is OK with ffmpeg commands, can i use more optimal settings ? http://pastebin.com/2rDYULaD
[02:08] <c_14> voip: You're encoding to h264, high cpu usage is to be expected. If you want the encoding to be faster you could try adding -preset ultrafast after -vcodec libx264
[06:42] <salamanderrake> ok, recorded some video with simplescreenrecoreder into a raw video and audio file, called it video.raw, it is 31 gigs in size I want to split the audio and video into seperate files, how would I go about doing that or should I re-incode/compress the file first into a normal format/container like mp4/x264?
[06:51] <salamanderrake> well when I run ffmpeg -i video.rawvideo I get  ...video.rawvideo: Invalid data found when processing input
[06:54] <thebombzen> salamanderrake: you can't interleave raw video and raw audio in a rawvideo format. it must be in some container format, or you did it incorrectly
[06:54] <thebombzen> do you know what container format simplescreenrecorder records into?
[06:56] <salamanderrake> I broke it then
[06:57] <salamanderrake> I selected the settings, let me look
[06:59] <salamanderrake> thebombzen, http://imgur.com/4YKnric
[06:59] <salamanderrake> you select other the the rawvideo
[07:00] <thebombzen> yea the rawvideo container is a container that's exactly what it sounds like
[07:00] <thebombzen> rawvideo. if you want both uncompressed I recommend matroska
[07:01] <salamanderrake> in the container or codec side of things?
[07:01] <salamanderrake> so container matroska and codec rawvideo?
[07:02] <salamanderrake> so is my recording lost for good?
[07:27] <Jack64> salamanderrake:
[07:27] <Jack64> you use libx264 as a codec and mkv as container
[07:29] <salamanderrake> thats what I will be doing from now on, I just wanted to do a rawvideo and uncompressed audio test.
[07:30] <Jack64> ok
[08:00] <Keshl> Are there any studies on perceived video quality when sacrificing frame resolution vs quantizer? oÉo?
[08:01] <Jack64> Keshl: not sure about studies, but general consensus is (not using quantizer, but constant rate factor) crf = 0 is true lossless and crf=18 is considered visually lossless
[08:02] <Keshl> I know that much, but what I'm noticing is that it's actually possible to get a smaller filesize by lowering the resolution and upping the crf, and there's no loss of visual quality.
[08:02] <Keshl> And I'm just curious if that's consistent across all types of content or not.
[08:03] <Jack64> Keshl: perhaps you say that if you are downsizing 1080p to 720p and watching it on a 720p monitor
[08:03] <Keshl> No, I'm not.
[08:03] <Keshl> 1080p monitor, downscaling 1080p to 1366p with a higher quantizer, and then playing fullscreen.
[08:03] <Jack64> how big is it?
[08:03] <Keshl> Is what, oÉo?
[08:03] <Jack64> monitor obviously
[08:03] <Keshl> Not obvious. You could've meant file.
[08:04] <Jack64> ok, sorry -.-
[08:04] <Keshl> 17 inches, byut I'm about one foot away from it. Takes up almost my entire field of vision.
[08:04] <Jack64> still, it's too small to detect changes
[08:04] <Jack64> you can only visually detect the difference between 1080p and 720p in screens over 40"
[08:05] <Keshl> Not when you're so close that it takes up your entire field of vision. <.<
[08:05] <Jack64> it's like watching 720p and 1080p on an iPad retina... I can barely see the difference
[08:05] <Keshl> Or when there's details that are 1 pixel large on 1080p. Those get lost on 720p.
[08:05] <Jack64> that's true
[08:05] <Jack64> so I guess this question is too dependent on the viewer for you to get a really *true* answer
[08:05] <Keshl> (Although, ffmpeg's x264 encoder seems to /really/ know how to preserve those when downscaling)
[08:05] <Keshl> Indeed it is.
[08:06] <Jack64> so I think you should play with crf and res, maybe even try a 2 pass
[08:06] <Keshl> I'm doing the first bit now, oÉo.
[08:06] <Jack64> and then see what the best configs are for your case :)
[08:07] <Keshl> That's what I'm doin' now. I was just curious if there was anybody else who did this before me, and if so, if I could bleam stuff from it. oÉo.
[08:07] <Jack64> Keshl: It's an interesting topic
[08:08] <Keshl> My best guess is that on slower scenes, more resolution is better. Faster stuff, more quantizer is better.
[08:08] <Keshl> But I'll have to do a few tests to see if that holds true.
[08:08] <Jack64> right
[08:09] Action: Keshl notes a CRF of 51 is not very useful..
[08:09] <Jack64> hah yesterday some guy showed up saying he was using crf 63 and the output was low quality..
[08:10] <Keshl> I don't think he understood it's backwords. XD
[08:10] <Jack64> he did after coming here :)
[08:10] <Jack64> anyways, I googled for ffmpeg quality tests crf quantizer resolution and nothing came up
[08:10] <Keshl> Same here.
[08:10] <Jack64> might do those tests myself
[08:11] <Jack64> and post them
[08:11] <Keshl> I tried "resolution vs quantizer" and such.
[08:11] <Jack64> it's relevant and no-one has done it
[08:11] <Keshl> Jack64: Can you do them on slower-moving scenes?
[08:11] <Keshl> The majority of mine are fast-motion.
[08:11] <Jack64> well it's not something you can just jump into cause selecting the input file(s) is not trivial
[08:12] <Keshl> I know. I have a lot of fast-moving scenes with lots of varied content, but very little slow stuff. That's kinda why I asked you to do the slow stuff, oÉo.
[08:12] <Jack64> there are a few gurus here like klaxa and JEEB who can probably help selecting relevant input files (big buck bunny maybe or some FRAPS input)
[08:12] <Jack64> raw FRAPS input is probably a good source
[08:12] <Jack64> 1080p raw
[08:12] <Keshl> I've got raw captures already.
[08:13] <Keshl> Milkdrop visualizations, mostly.
[08:13] <Jack64> never heard of Milkdrop, you make the vizs yourself?
[08:13] Action: Jack64 just googled it
[08:14] <Keshl> Sort of.
[08:14] <Keshl> Milkdrop is a plugin for Winamp that comes with about 250 visualziation presets, but it mixes them together as the music plays in real-time.
[08:14] <Jack64> seems cool
[08:14] <Keshl> Sometimes it ends up making REALLY epic stuff.
[08:14] <Keshl> I've learnt that it's best to just always have something recording it in case epic stuff happens. XD
[08:14] <Jack64> so you keep it for...?
[08:15] <Keshl> Myself, mostly.
[08:15] <Jack64> ah ok
[08:15] <Keshl> Sometimes I share it, but I'm a bit obsessed with quality so the files tend to be big.
[08:15] <Keshl> With a 200kb upload speed that's.. Annoying.
[08:15] <Jack64> yes it is
[08:15] <Jack64> even with 2000kb if you have 30GB raw 1080p files it's still... annoying
[08:15] <Keshl> So I'm trying to figure out how to encode some of them better without absoutely killing the quality, cuz there's a lot of /really/ fine details in some.
[08:16] <Keshl> Oh, no, I encode them with x264 before sending. Usually gets it down to about 1 gig.
[08:16] <Jack64> that's not that bad
[08:16] <Jack64> (http://gizmodo.com/why-one-of-worlds-most-remote-places-has-the-fastest-i-1556126257)
[08:16] <Keshl> Do the math. It's bad. XD
[08:17] <Jack64> I got 2900kb/s I can run a webserver at home :)
[08:17] <Jack64> it's pretty cool
[08:17] <Keshl> ...Lucky .É.
[08:17] <Jack64> everyone should have 1gbps up and down -.-
[08:17] <Jack64> everyone should have BW to run a server at home
[08:18] <Jack64> should be like a human right xD
[08:18] <Jack64> but I digress. so what are you testing now? crf 18?
[08:19] <Keshl> That is what the videos are encoded with, but right now I'm testing just to fgind what point resolution and quantizer converge in terms of visual quality.
[09:48] <Jack64> ttyl, bye !
[11:45] <superware> I'm muxing h.264 to mp4 (av_read_frame, av_write_frame), is there a way to embed a data-stream, maybe an AVMEDIA_TYPE_DATA or AVMEDIA_TYPE_ATTACHMENT stream?
[11:46] <termos> Is there a best practice for the different time_base and pts values when using libffmpeg?
[12:06] <mrpyo> hello
[12:07] <mrpyo> wow, who would think video library irc channel would have so many users...
[12:19] <dvnl> hello All! can somebody provide me a working C example of decoding a raw h264/hevc stream from file and saving the frames to a .yuv video file? I've tried several methods, but unfortunately none of them worked.
[12:28] <superware> dvnl: try the mixing/demuxing examples
[12:28] <superware> muxing
[12:34] <dvnl> superware I check on them, thank you
[15:39] <justinfront> Hi I am converting videos from EX1 sony but the output only runs in VLC not quick time can anyone suggest what settings I should change.
[15:39] <justinfront> ffmpeg -i 663_0196_01.MP4 -c:v libx264 -preset veryfast -vf scale=1280:-1 -crf 23 -c:a libmp3lame -b:a 192k -ar 44100 output.mp4
[15:40] <justinfront> it's a salsa performance video and some of the other dancers will not have VLC s
[15:40] <justinfront> o
[15:40] Last message repeated 1 time(s).
[15:40] <justinfront> so quicktime support would be better
[15:43] <sacarasc> You could try maybe -profile:v baseline and work your way up from that to see if it works?
[15:43] Action: sacarasc shrugs.
[15:46] <justinfront> from google it suggests -pix_fmt yuv420p  will try but just worried that may not be ideal for flash player when online?
[16:01] <justinfront> seems to be fine just no sound :( it looks slow but hard to tell?
[16:19] <brontosaurusrex> justinfront, don't use mp3 for audio
[16:20] <brontosaurusrex> and "-pix_fmt yuv420p" will be fine with flash
[16:21] <justinfront> brontosaurusrex what should I change the line for audio?
[16:21] <brontosaurusrex> justinfront, to something that will use aac encoding
[16:21] <brontosaurusrex> justinfront, and that would depend on what AAC encoders are available in your version of ffmpeg
[16:23] <justinfront> Do I need to add stuff does this add the info on encoders? http://pastebin.com/wHp0kAgf
[16:25] <brontosaurusrex> justinfront, on OSX you can use native aac encoder and then just mux it in with ffmpeg.
[16:26] <justinfront> it is nice to have a workflow that is the same on win/linux since this mac is slow I may switch to maybe doing some on a thinkpad
[16:27] <brontosaurusrex> thats true
[16:28] <justinfront> is there a good place to get a handle on all this stuff I keep googling but just ends up in random flags without me really having any overview
[16:28] <brontosaurusrex> with fdk_aac, which you don't have, i have -c:a libfdk_aac -vbr 5, but thats probably not the right way ... so .....
[16:29] <brontosaurusrex> justinfront, first hit http://trac.ffmpeg.org/wiki/AACEncodingGuide
[16:29] <brontosaurusrex> absosmurfly everything you need on that single page
[16:31] <justinfront> says I need to +nonfree to get libfaac
[16:31] <brontosaurusrex> so?
[16:31] <justinfront> http://superuser.com/questions/468622/ffmpeg-macports-libfaac-missing-need-new-audio-encoder
[16:32] <brontosaurusrex> use some other aac encoder then ...
[16:32] <justinfront> just going to use macports and see if it gets them
[16:36] <brontosaurusrex> it should get FAAC
[16:45] <justinfront> Can I create a list of files/folder that I want processed or do I need to run each one in turn?
[16:57] <thebombzen> justinfront: if it's nonfree, all that means is you can't distribute the binaries
[16:58] <thebombzen> it's still perfectly legal for personal use. If you need distributability and quality, try using QuickTime's encoder (cause all the distributable free-as-in-freedom encoders for FFmpeg are kinda bad)
[16:59] <thebombzen> and justinfront: you need to do each one in turn. If you're using Bash, such as on a Mac, you can always do something like this:
[17:00] <thebombzen> find -name \*.wav -exec ffmpeg -i {} -c:a libfdk_aac -vbr 5 {}.m4a
[17:01] <justinfront> I was at the moment distributing it only to friends via a private vimeo group so we can see where we messup, don't want to make performance public since then people will not want to see it live. just a student group.
[17:01] <justinfront> the original file is the ex1 sony file not a wav?
[17:02] <justinfront> need to use the music on the video so steps corrispond
[17:03] <justinfront> student as in not proffessional dancers rather than the other student meaning.
[22:40] <lilibox_> hi
[22:42] <lilibox_> i am on old centos and i need build ffmpeg with shared libraries, ./configure --enabel-shared causes this error: /usr/bin/ld: libavutil/lls1.o: relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC
[22:42] <lilibox_> after make examination :(
[22:42] <lilibox_> please, does exist any easy help for me?
[22:49] <lkiesow> lilibox_: Did you try --extra-cflags=" -fPIC"
[22:51] <lilibox_> no, :(, please tell me where to do
[22:51] <lilibox_> is it option switch or anything inside Makefile?
[22:51] <lilibox_> thank you
[22:54] <c_14> ./configure --extra-cflags="-fPIC" [other stuff]
[22:54] <lilibox_> i did it now, and i got the same error :(
[22:54] <lilibox_> do i must clean anything by make command before the new compiling attempt?
[22:54] <lkiesow> lilibox_: For which version of CentOS do you want FFmpeg?
[22:55] <lilibox_> some realy old, centos 5.7
[22:55] <lilibox_> 2.6.18-274.el5
[22:56] <lilibox_> i am ok with any build supports prores
[22:57] <lilibox_> but my knowledges and technical abilities are limited :)
[22:57] <lilibox_> and i am on 64bit version
[22:58] <lilibox_> static build is ok, i tried it
[23:00] <c_14> Have you tried following the wiki?
[23:00] <c_14> I know it says 6.x, but it might work.
[23:00] <c_14> https://trac.ffmpeg.org/wiki/CentosCompilationGuide
[23:03] <sonak> how to check if a mp3 file is encrypted or not?
[23:04] <sonak> is there any free software or command line to validate it?
[23:05] <c_14> You could try playing it?
[23:06] <sonak> it play fine
[23:06] <c_14> Then it's probably not encrypted.
[23:06] <c_14> Unless someone decided to OR it with 0 and call it encrypted.
[23:06] <sonak> any software or tool to confirm that?
[23:08] <c_14> ffprobe should tell you if and what type of media file it is
[23:10] <sonak> i tried that it just says mp3
[23:10] <sonak> :)
[23:11] <c_14> Question: When you say encrypted do you mean DRM?
[23:11] <c_14> Or do you mean encryption.
[23:15] <sonak> encryption
[23:16] <c_14> In that case, if it says mp3 then it's not encrypted. If ffprobe can't figure out what it is, then it's encrypted or random data.
[23:17] <sonak> ok
[23:21] <c_14> Or not a media file, but that's an edge case.
[00:00] --- Thu Apr  3 2014

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