[Ffmpeg-devel-irc] ffmpeg.log.20151011

burek burek021 at gmail.com
Mon Oct 12 02:05:02 CEST 2015

[00:05:29 CEST] <PlanC> anyone on here that moderates https://trac.ffmpeg.org/wiki/CompilationGuide/Centos?
[00:06:07 CEST] <PlanC> on "libopus", change "git clone git://git.opus-codec.org/opus.git" to "git clone http://git.opus-codec.org/opus.git" (git:// -> http://)
[00:06:58 CEST] <durandal_1707> No, anyone can change that
[00:18:16 CEST] <dextarr> Hey, is anyone around?
[00:18:42 CEST] <durandal_1707> No
[00:20:21 CEST] <dextarr> durandal, hey, how's it going>
[00:21:21 CEST] <durandal_1707> No chat allowed
[00:21:51 CEST] <dextarr> This is a user support channel.. I get it.
[00:22:10 CEST] <dextarr> I'm after any help on getting quicksync going in Ubuntu
[00:40:16 CEST] <PlanC> the libopus config has an error in it
[01:32:29 CEST] <StephenS> hwo to get thumnil from video for the very first frame?
[01:32:35 CEST] <StephenS> I guess 00 will give me black frame
[02:11:21 CEST] <PovAddict> 2-hour movie .mp4 file, has an h264/avc1 video stream, two audio streams (stereo and surround), a subtitle stream
[02:11:29 CEST] <PovAddict> but there is also this at the end of the ffprobe output:
[02:11:31 CEST] <PovAddict> Stream #0:4: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 151x227 [SAR 96:96 DAR 151:227], 90k tbr, 90k tbn, 90k tbc
[02:11:39 CEST] <PovAddict> what could that be? a thumbnail/poster?
[02:29:54 CEST] <Prelude_Zzzzz> hi, any ffmpeg encoding experts ? i need to fix quality issues and i need some help
[02:35:37 CEST] <dsl420> ask your question and you will see
[02:36:29 CEST] <PovAddict> what is "H. 264 BP / MP / HP"? seen in a SmartTV spec list for supported video formats
[02:38:12 CEST] <PovAddict> oh, profiles
[02:38:14 CEST] <PovAddict> baseline, main, high
[02:38:54 CEST] <PovAddict> it also says "H.264 FMO / ASO / RS, VC1 / AP L4 are not supported", how do I know if an .mp4 file uses any of those, whatever they are?
[02:39:44 CEST] <PovAddict> also "GMC 2 or above not supported" (global motion compensation?)
[02:40:37 CEST] <PovAddict> oh H264 doesn't even have GMC anyway
[02:41:13 CEST] <Prelude_Zzzzz> hi everyone.. trying to setup a good VBR stream and good quality.. The problem is i can't seem to find the right settings.. i get a lot of pixelation on channel chagnes or fast movements. Can anyone help? > http://pastebin.com/UqYUN8i7
[02:47:49 CEST] <DHE> 2 megabits on 720p is kinda on the low side. I'm not surprised
[02:48:15 CEST] <PovAddict> I wonder if 2 megabits on 720p would be enough for h.265 :)
[02:48:46 CEST] <DHE> it might. if the claims that it's "twice as good", then 4 megabit 720p at 30fps wouldn't be too bad...
[02:49:07 CEST] <DHE> not GREAT, but probably passable
[02:50:34 CEST] <DHE> from a scripting standpoint, you set all your variables from $1 and onwards, then continue to use $1,... in your commandline
[03:15:53 CEST] <Prelude_Zzzzz> so nothing anyone can help me with fixing up to make it a bit better ?
[03:16:09 CEST] <Prelude_Zzzzz> i am not great at GOP sizes and stuff
[03:16:13 CEST] <waressearcher2> is anyone here ?
[03:16:51 CEST] <PovAddict> Prelude_Zzzzz: as DHE said, 2mbps is low for 720p, you need a higher bitrate as a start, *then* try other quality optimizations
[03:16:53 CEST] <waressearcher2> I want to generate 10 seconds of silence and I use that command: "ffmpeg -f lavfi -i aevalsrc=0:0:0:0:0:0::duration=10 -ac 2 -ar 44100 -ab 320k -y -f ac3 silence.ac3" is that a right way to generate silence ?
[03:22:07 CEST] <DHE> Prelude_Zzzzz: given your HLS chunk size of 6 seconds you could raise it as high as 180, but at 90 it's not going to be a significant difference
[03:23:26 CEST] <PovAddict> wait a minute, that makes no sense
[03:23:38 CEST] <PovAddict> you're setting a dozen parameters for encoding, and then using -vcodec copy?
[03:23:57 CEST] <DHE> he's also setting c:v inside the params function...
[03:24:02 CEST] <DHE> I didn't notice the vcopy...
[03:25:12 CEST] <DHE> use of nvenc gets my attention. didn't know that was there...
[03:25:44 CEST] <Prelude_Zzzzz> hey guys.. that copy was a mistake
[03:25:46 CEST] <Prelude_Zzzzz> took that out
[03:26:00 CEST] <Prelude_Zzzzz> yes i am using nvenc to encode instead of CPU
[03:26:01 CEST] <DHE> can I see the real script then?
[03:27:03 CEST] <DHE> but the fundamental point stands: 2 megabit at 720p is too low a bitrate. anything beyond the stereotypical "talking heads" video is going to look pretty bad. full screen motion will kill it
[03:27:54 CEST] <DHE> and broadly speaking hardware H264 tends to be lower quality than what CPU-based encoding can provide. obviously generalizing since software encoders have a lot of settings to play with
[03:28:03 CEST] <Prelude_Zzzzz> sure.. http://pastebin.com/5xwwjs20
[03:28:18 CEST] <PovAddict> nvenc might also not support all the settings you're tweaking
[03:28:33 CEST] <Prelude_Zzzzz> well i am trying to use VBR
[03:28:43 CEST] <DHE> and to be especially pedantic ttl=100 on the input does nothing. :)
[03:28:50 CEST] <Prelude_Zzzzz> so i don't mind if it jumps to 4Mbit/s or 5Mbit/s so long as it stays at 2Mbit/s when talking heads
[03:29:06 CEST] <Prelude_Zzzzz> my VBR is not working very well. Fast moving things don't seem to peak the file sizes
[03:29:21 CEST] <Prelude_Zzzzz> ttl is just for the udp input
[03:29:33 CEST] <Prelude_Zzzzz> trying to keep IGMP snooping active
[03:29:58 CEST] <DHE> you have to understand how VBV works. there's a bucket of 1 megabit (-bufsize) and it fills at $bitrate bits/second. the decoder can produce video using bits from the bucket
[03:30:04 CEST] <DHE> that's not how it works
[03:30:17 CEST] <DHE> let me guess. the thing shuts down after about 4.5 minutes
[03:30:42 CEST] <Prelude_Zzzzz> what thing shuts down ?
[03:30:44 CEST] <DHE> TTL is set on outgoing traffic
[03:30:55 CEST] <Prelude_Zzzzz> no the input is fine
[03:30:57 CEST] <DHE> does your ffmpeg process just stop processing video because the UDP goes away?
[03:30:58 CEST] <Prelude_Zzzzz> i don't have any drops
[03:31:03 CEST] <DHE> oh good
[03:31:48 CEST] <Prelude_Zzzzz> works well for the most part but just motion issues of course.. i understand the bit rate but i am thinking maybe my settings are off and it could improve a lot more.. also maybe my VBR settings are not correct
[03:32:09 CEST] <Prelude_Zzzzz> it should jump up to my maxrate if it needs it for fast moving scenes
[03:32:11 CEST] <Prelude_Zzzzz> that is the idea
[03:32:19 CEST] <Prelude_Zzzzz> just not sure how to do it great
[03:32:38 CEST] <DHE> anyway. during high motion obviously you need to draw more bits from the bucket. you set the max at 3 megabits (for the 2M stream) so that's the peak draw. which means during motion there's about 1 second of buffer available for high bitrate mode before it's drained and forced back to 2 megabits
[03:33:10 CEST] <DHE> during less busy times it can fill up again
[03:34:06 CEST] <Prelude_Zzzzz> ok so what should i set it to so it has all the room it needs
[03:34:15 CEST] <Prelude_Zzzzz> why can't i go up to 50Mbit
[03:34:18 CEST] <Prelude_Zzzzz> 50Meg of data
[03:34:23 CEST] <Prelude_Zzzzz> space and ram is not a problem
[03:34:30 CEST] <PovAddict> Prelude_Zzzzz: even in clients?
[03:34:46 CEST] <DHE> because you're targeting a streaming client who are under the assumption that if they measure the internet connection speed at 3 megabits then it's safe to play this video
[03:35:13 CEST] <Prelude_Zzzzz> nah... most people will have 10-15Mbit/s
[03:35:23 CEST] <Prelude_Zzzzz> the problem is i don't want to wast bandwidth when not needed as they pay per GIG
[03:35:29 CEST] <Prelude_Zzzzz> so peaks are ok.. just not all the time
[03:35:30 CEST] <DHE> now, if they played from the start and this was all pre-encoded and saved, then it could work. but running live and joins at any moment it'll explode in their face
[03:35:47 CEST] <Prelude_Zzzzz> it's def live
[03:35:52 CEST] <DHE> yeah I can see that
[03:36:18 CEST] <PovAddict> if you have an average of 3mbps with peaks of 50mbps, the client would need to add a lot of delay between downloading and playing, so that it has time to catch up if a 50Mb second of video arrives and it can't download in real time
[03:36:40 CEST] <DHE> I thought he meant a peak of 3 megabits but a VBV buffer size of 50M
[03:37:00 CEST] <DHE> that way you can deal with ~50 seconds of high motion without your buffer being drained
[03:37:45 CEST] <DHE> but seriously I'm going to recommend you try higher bitrates. for the higher rate only I might suggest 4 megabit base, 5 megabit maximum, bufsize 5 megabits and see how that looks
[03:38:36 CEST] <DHE> for the lower rate rescale it to 640x360 and your current settings might be okay
[03:38:47 CEST] <DHE> this is the typical way HLS works. think what Netflix is like
[03:39:03 CEST] <PovAddict> could major_brand and/or compatible_brands make a smartTV give "not supported file format"?
[03:39:16 CEST] <DHE> I'm partially making up these numbers as I go, but they ballpark sound right
[03:41:37 CEST] <PovAddict> basicaly I have this: https://paste.debian.net/315328/
[03:41:50 CEST] <PovAddict> but the TV user manual says High profile is supported
[03:43:50 CEST] <PovAddict> hm scratch that, I have another sample
[03:45:50 CEST] <PovAddict> https://paste.debian.net/315329/ here you go; any ideas on what could be the incompatibility?
[03:49:30 CEST] <DHE> might be confused by all the streams. have you tried trimming it down for it?
[03:50:29 CEST] <DHE> just a guess, but it's the first thing I'd try
[04:20:02 CEST] <PovAddict> DHE: https://paste.debian.net/315330/ maybe I should try removing the subtitle stream too
[04:38:37 CEST] <PovAddict> DHE: ok, I can't figure out how to remove the subtitle stream :|
[05:47:02 CEST] <chungy> PovAddict: ffmpeg -i input -c copy -map 0:v -map 0:a output
[05:47:16 CEST] <chungy> Will copy all video and audio streams, and no subtitle streams in the output
[05:48:02 CEST] <PovAddict> I was using -acodec copy -vcodec copy -map 0:0 -map 0:1 to get the video stream and one of the two audio streams, but the output still had subs
[05:50:54 CEST] <chungy> you can shortcut with "-c copy" instead of specifying acodec and vcodec (which themselves, you can use c:a and c:v)
[05:51:03 CEST] <chungy> Can you paste the full ffmpeg output including command line used?
[05:54:16 CEST] <PovAddict> chungy: https://paste.debian.net/315335/
[05:59:10 CEST] <chungy> Some weirdness with the mp4 container. You might try "-map_chapters -1" to get rid of the chapter.
[05:59:28 CEST] <chungy> chapters are encoded as a subtitle stream in mp4.
[05:59:33 CEST] <PovAddict> ohhhhhh
[08:52:13 CEST] <pinPoint> what is this guy talking about: http://ntown.at/2014/01/23/howto-convert-to-prores-quicktime-on-windows/
[08:52:50 CEST] <pinPoint> what is quicktime DNxHD? what sort of madness is that?
[08:53:21 CEST] <pinPoint> "The Ultimate tool for this task is ffmbc, a commandline converter which is kind of a pro-version of ffmpeg. Unfortunately ffmbc is a bit slower when processing movies compared to ffmpeg, but it delivers the correct movie format and even the correct timecode if needed."
[14:32:48 CEST] <anYc> Hi, in case someone is interested, I finally managed to finish my frame-accurate cutting application for h264 videos and also wrote a blog article describing the problems I encountered. Both are available from https://github.com/anyc/avcut
[14:58:50 CEST] <RobotsOnDrugs> anYc: nice, i've only ever seen that feature in paid proprietary editors
[14:59:07 CEST] <RobotsOnDrugs> needs a license though
[17:09:01 CEST] <raket> i have problem with multisoundcard recording, ffmpeg -f alsa -ac 2 -i hw:0 -f alsa -ac 2 -i hw:1 -c:a libmp3lame lame.mp3 doesn't really work, if i switch hw:0 with hw:1 and hw:1 with hw:0, then only hw1 works and vice versa
[17:09:38 CEST] <c_14> you need to map them
[17:09:59 CEST] <c_14> Also, does mp3 support multiple streams in one file?
[17:11:07 CEST] <raket> i thought it would just mix it all togheter, also i'm reading on https://trac.ffmpeg.org/wiki/AudioChannelManipulation now
[17:14:42 CEST] <raket> c_14: thanks for your great support! after googling i found the answer and it works, ffmpeg -f alsa -ac 2 -i hw:0 -f alsa -ac 2 -i hw:1 -filter_complex "[0:a][1:a]amerge=inputs=2[aout]" -map "[aout]" -ac 2 output.mp3
[19:03:02 CEST] <anYc> RobotsOnDrugs: I read that avidemux can also do that but I wanted something more light-weight. Thanks, I will add a separate license file. I only wrote a short info in the header of the C file
[20:57:15 CEST] <fred1807> how do I ffmpeg -i *.mp4 --> .h264 ?
[20:57:33 CEST] <fred1807> I want to convert all .mp4 files to .h264 keeping the same base filename
[20:58:16 CEST] <ln-> you need shell scripting for that
[20:58:36 CEST] <fred1807> any example?
[21:00:18 CEST] <ln-> for x in *.mp4 ; do ffmpegblabla "$x" "$(basename $x .mp4)".h264 ; done
[21:00:32 CEST] <ln-> but you wouldn't run random commands given by random people on irc, right?
[21:00:53 CEST] <fritsch> :p
[21:00:54 CEST] <fred1807> seems proper, why not
[21:14:16 CEST] <DHE> is there a way to get the 'qp' value of an encoded h264 video frame? after the fact obviously. an estimate is fine
[22:16:07 CEST] <poofie>  can ffmpeg transcode video and stream it. Have a bunch of video that my not so smart TV does not like as mp4. That I could use a little script to stream then as webm
[22:17:12 CEST] <poofie> The files are on my "owncloud" server that inturn is on Debian.
[23:04:15 CEST] <GilP> Hey, I got a question, I have a camera connected through a network that transmits using udp with h264 encoding, I am using FFmpeg's API to read the camera's frames, the camera sends about 25 fps, but I have an odd problem that once every second I get 3-4 frames with a delay of 100ms, the followup "missed" frames arrive immediately after the first delayed one (0-2ms), it causes the video to
[23:04:15 CEST] <GilP> "freeze" for a bit every second, I can only assume it's either something in the camera itself or something network related (although it's too consistent), is there any way I can diagnose the problem better? or else solving this using a back buffer that will compensenate for the frame delay by creating a relatively small delay in the video itself?
[23:04:49 CEST] <PovAddict> every second? :|
[23:05:09 CEST] <JEEB> oh, The Longest Thread has finally bore fruit
[23:05:10 CEST] <JEEB> http://git.videolan.org/?p=ffmpeg.git;a=commit;h=01ecb7172b684f1c4b3e748f95c5a9a494ca36ec
[23:05:13 CEST] <JEEB> \o/
[23:05:46 CEST] <PovAddict> JEEB: I don't know how ffmpeg development works, but that looks like a massive thing to have in a single commit :/
[23:06:06 CEST] <JEEB> PovAddict: the guy was first thinking of separating it
[23:06:08 CEST] <GilP> Yeah, it seems to happen every second
[23:06:16 CEST] <JEEB> but it seems like he gave up
[23:06:23 CEST] <JEEB> that said, that patch has been through 10 iterations
[23:06:37 CEST] <JEEB> https://trac.ffmpeg.org/ticket/2686
[23:06:48 CEST] <JEEB> the thread that brought us that patch ^
[23:07:46 CEST] <PovAddict> two years ago :|
[23:07:58 CEST] <chungy> looks like more people need to reach Git Enlightenment.
[23:08:18 CEST] <PovAddict> at least the commit message is good enough
[23:08:20 CEST] <chungy> You can develop patch series naturally and constantly rebase until it's finally merged in
[23:08:32 CEST] <PovAddict> chungy: indeed
[23:08:34 CEST] <chungy> True, I know people that would only type "fix" at such a thing
[23:08:50 CEST] <PovAddict> chungy: trying to split a giant patch like that after the fact is a pain
[23:08:57 CEST] <chungy> mhm
[23:09:01 CEST] <JEEB> yeah, I guess he began just hacking on it
[23:09:19 CEST] <JEEB> some stuff was improved by another guy with smaller patches
[23:09:40 CEST] <chungy> "another guy" only highlights Git's benefits even more :P
[23:09:51 CEST] <PovAddict> just hope you don't end up at that commit running a git-bisect :)
[23:09:56 CEST] <chungy> Anyway, the patch should be nice enough
[23:10:00 CEST] <chungy> haha yeah that's what I thought
[23:10:09 CEST] <JEEB> yeah
[23:12:22 CEST] <GilP> anyone can help? (the long message above)
[23:12:59 CEST] <PovAddict> GilP: I guess buffering would solve your problem
[23:13:05 CEST] <PovAddict> I don't know the ffmpeg API though
[23:14:24 CEST] <GilP> Do you know if the option exists in ffmpeg itself?
[23:17:41 CEST] <Filarius> hello, I`m looking for way to remove slow camera shaking. Deshake and vidstabdetect works okay for fast short shaks, but I can`t tune it to make camera be more still for 2-3 seconds. It not going to be "Tripod", camera of video had to turn around several times.
[23:36:40 CEST] <BELTO> hey Im currently using this to slow motion video ffmpeg -i in.mp4 -filter_complex "[0:v]setpts=2.0*PTS[v];[0:a]atempo=0.5[a]" -map "[v]" -map "[a]" -strict -2 out.mp4
[23:37:07 CEST] <BELTO> however, is it possible to slow down only first part of video, like 80% of video and then to get back to normal the rest 20% of video?
[00:00:00 CEST] --- Mon Oct 12 2015

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