[Ffmpeg-devel-irc] ffmpeg.log.20171213

[burek]

[00:09:48 CET] <ArsenArsen> how do I set the avfoundation video frame location?
[01:13:15 CET] <illegal> https://trac.ffmpeg.org/ticket/5718 Is there a way to encode with opus with a surround sound input? according to teh last comment none of the methods work, why isn't this default anyways if every other audio encoder doesn't have this problem if I may ask? it certainly doesn't happen with aac
[01:24:32 CET] <furq> illegal: -af channelmap worked last time i tried
[01:24:42 CET] <furq> also iirc this is dependent on the input format layout
[01:24:58 CET] <furq> the only time it's come up in here was with a dts input and i couldn't reproduce it with anything else
[01:28:08 CET] <alexpigment> illegal: sorry to ask this qusetion as it's really a tangent, but why opus?
[01:28:35 CET] <furq> why not
[01:28:51 CET] <alexpigment> presumably you've got a source format you're encoding from, presumably it's from a video, and presumably there's no real benefit to transcoding
[01:28:55 CET] <furq> illegal: channelmap definitely still works with 3.3.4, i don't have a 3.4 build here to test with
[01:29:16 CET] <alexpigment> (i realize i'm presuming a lot)
[01:29:18 CET] <illegal> furq, af thing apparently worked after updating again to a new nightly just now
[01:29:23 CET] <furq> fun
[01:29:26 CET] <illegal> but still shouldn't this be done by default?
[01:29:29 CET] <furq> yeah
[01:29:44 CET] <furq> it used to be done by default, there's some regression that nobody's bothered fixing because there's a workaround
[01:30:19 CET] <furq> all of my knowledge of this is from the bug report that you linked and have presumably read
[01:30:23 CET] <furq> so i can't really add much
[01:30:31 CET] <illegal> alexpigment, I like it better than aac, at least my ears did when I did some test nothing much to be honest, is also free as in open sores.
[01:30:43 CET] <alexpigment> illegal: sure, but what's your source audio format?
[01:30:43 CET] <furq> if it is dts then you'll get a significant rate saving
[01:30:45 CET] <alexpigment> ac3?
[01:30:56 CET] <illegal> furq, I am not encoding from dts mainly from flac which probably came from a dts source
[01:31:03 CET] <furq> oh right
[01:31:08 CET] <furq> 5.1 flac is even bigger
[01:31:09 CET] <alexpigment> ok, flac to opus makes sense
[01:31:14 CET] <alexpigment> i'll stop asking now ;)
[01:31:17 CET] <furq> dts to opus makes some sense really
[01:31:29 CET] <alexpigment> sure, i was just making sure it wasn't lossy to lossy
[01:31:37 CET] <furq> regular dts is lossy
[01:31:45 CET] <furq> it's only dtsma or something which is lossless
[01:31:50 CET] <alexpigment> i i thought you were talking about master
[01:32:05 CET] <alexpigment> if it was dts, i'd probably just leave it, unless there were some sort of compatibility issues with the player
[01:32:15 CET] <alexpigment> if it were ac3, i'd 100% leave it in ac3
[01:32:23 CET] <illegal> furq, it's probably the loseless version
[01:32:25 CET] <furq> if i'm downscaling something with dts audio i'll normally transcode it
[01:32:40 CET] <furq> otherwise it ends up being a third of the total size
[01:32:46 CET] <furq> ac3 is never big enough to bother messing with
[01:33:12 CET] <alexpigment> right, and ac3 is supported by basically everything (including players and receivers), which is actually a pro compared to opus
[01:33:43 CET] <alexpigment> to me, the only benefit to opus is that it's free and that it's relatively modern. that's about all i can say
[01:34:15 CET] <alexpigment> anyway, i'll shut up and let the guy get to his 5.1 transcode ;)
[01:34:33 CET] <furq> well the benefit is obviously that it's very small
[01:34:51 CET] <furq> it's just not often that you get the chance to benefit from that without some other compromise
[01:34:53 CET] <alexpigment> furq: compared to the video, I just can't imagine that's really every a huge concern
[01:34:57 CET] <furq> right
[01:35:02 CET] <alexpigment> *ever
[01:35:54 CET] <furq> i mean i've done a 576p encode from a blu-ray with dts-hd before
[01:36:05 CET] <alexpigment> yeah, dts-hd is huge
[01:36:17 CET] <furq> that would've been 2100kbps of audio for a 2700kbps video
[01:36:22 CET] <furq> that's too big
[01:36:26 CET] <alexpigment> you can extract the "lossless" part of the audio though, right?
[01:36:30 CET] <furq> shrug
[01:36:32 CET] <alexpigment> and just keep the lossy core
[01:36:42 CET] <alexpigment> not that i'd recommend it, but at least that's one option
[01:37:25 CET] <alexpigment> ffmpeg -i DTS-HD_MA.dts -bsf:a dca_core -c:a copy TS-Core.dts
[01:37:28 CET] <alexpigment> that's apparently how you do that
[01:37:42 CET] <furq> hopefully ffmpeg defaults to decoding the lossless version
[01:37:42 CET] <alexpigment> for future reference if you ever decide to do that or need to recommend it
[01:37:51 CET] <furq> because otherwise i transcoded the core
[01:37:56 CET] <alexpigment> well, i would hope so, but i wouldn't bet my life on it
[01:38:03 CET] <furq> yeah i didn't even check
[01:38:07 CET] <alexpigment> :)
[01:38:16 CET] <alexpigment> well, next time do a copy and check the bitrate ;)
[01:39:00 CET] <furq> i don't think i remembered what dtshd was at the time
[01:39:22 CET] <furq> it's not a film i care about anyway so it doesn't matter
[01:39:42 CET] <alexpigment> either way, people put wayyyy too much stock in lossless audio when they butcher the hell out of the video bitrate. i'm known to many friends as an "audiophile" and I wouldn't notice the difference between dts and dts hd without a side-by-side and some luck, i'm sure
[01:40:26 CET] <alexpigment> furq: it's cool man. american pie 3 is still ok with transcoded dts core
[01:40:45 CET] <furq> i'd be shocked if jon kirchner's dog could abx dts from dtsma
[01:40:56 CET] <alexpigment> haha
[01:42:18 CET] <alexpigment> i do find it funny how some DVDs have like DTS + AC3 or PCM + AC3 or whatever, as well as a commentary track, and the video is like 3mbps after everything is said and done
[01:42:39 CET] <furq> yeah i don't see why you'd ever put dts on a video dvd
[01:42:40 CET] <alexpigment> just pick one. no one cares
[01:42:58 CET] <furq> let alone dts and ac3 together
[01:43:07 CET] <alexpigment> furq: well, i'm sure it's some under-the-table bribing between the dts people and the movie studios
[01:43:25 CET] <furq> i can't imagine hollywood would let something like that happen
[01:44:00 CET] <alexpigment> some real principled people in that industry
[01:44:44 CET] <furq> also i'm pretty sure this bluray was just dtshd and not "dts-hd master audio"
[01:44:49 CET] <furq> so it was lossy anyway
[01:44:57 CET] <furq> it's good that they didn't give it a confusing name
[01:45:09 CET] <alexpigment> doesn't dtshd also do the core thing though?
[01:45:17 CET] <furq> idk i'm just reading what wikipedia says
[01:45:27 CET] <furq> https://en.wikipedia.org/wiki/DTS_(sound_system)#DTS-HD_High_Resolution_Audio
[01:45:29 CET] <alexpigment> i think dts hd is master audio
[01:45:36 CET] <furq> nah there's two different ones apparently
[01:45:50 CET] <furq> dtshd is upto 7.1 at upto 24/96
[01:45:54 CET] <furq> and then ma is the lossless extension
[01:46:08 CET] <alexpigment> ah
[01:46:19 CET] <alexpigment> dtshd non-ma also has a dts core
[01:46:20 CET] <furq> the bitrate was only 2100kbps for 5.1 so that can't have been lossless
[01:46:28 CET] <alexpigment> true
[01:47:00 CET] <alexpigment> but yeah, i think about 1700 of that is lost of most people, including myself
[01:47:09 CET] <furq> yeah
[01:47:34 CET] <furq> four of the channels are lost on me because i only have a stereo setup
[01:47:40 CET] <alexpigment> same here
[01:47:46 CET] <alexpigment> i have two big floor speakers
[01:47:56 CET] <alexpigment> they sound so good that i've never gotten around to buying the rest
[01:49:27 CET] <alexpigment> i'd rather have 2 really good speakers than a home-theater-in-a-box with the tiny satellite speakers and the budget subwoofer
[01:58:24 CET] <thebombzen> is there a way to get ffmpeg -i bluray:foo to read the chapters?
[02:01:16 CET] <alexpigment> thebombzen: not sure how accurate this still is: https://trac.ffmpeg.org/ticket/3953
[02:01:56 CET] <alexpigment> tsmuxer can apparently do it though, fwiw
[02:02:40 CET] <alexpigment> was it something i said? ;)
[03:02:42 CET] <corporate_shill> Can I encode 4K 60hz lossless from a capture card?
[03:02:56 CET] <corporate_shill> Ive tried everything but my buffer keeps overflowing
[03:03:06 CET] <corporate_shill> -rtbufsize 2G doesnt work
[03:03:24 CET] <corporate_shill> Any help is much appreciated
[03:56:33 CET] <alexpigment> corporate_shill: i don't have any experience 1st hand with capturing lossless 4k 60hz, but how fast are you hard drives?
[03:56:52 CET] <alexpigment> i would think you would need at least a pci-e ssd
[03:57:05 CET] <alexpigment> if not a raid of them
[03:57:56 CET] <furq> oh he left
[03:58:02 CET] <furq> well for reference that's 750MB/s so yeah
[03:58:29 CET] <alexpigment> yeah, the idea of 4k60 lossless kinda gives me chills ;)
[03:58:30 CET] <furq> or 933 for 10-bit
[03:59:08 CET] <alexpigment> man
[03:59:16 CET] <alexpigment> that would fill up your drives so fast
[03:59:21 CET] <furq> that's uncompressed but still
[03:59:33 CET] <alexpigment> well, lossless it's going to get you much further
[03:59:37 CET] <alexpigment> *isn't
[03:59:46 CET] <furq> even half that is still going to need more than sata3
[03:59:48 CET] <alexpigment> maybe 1/10th?
[04:00:04 CET] <alexpigment> yeah, i knew sata was out of the question
[04:00:04 CET] <furq> i'd expect better than that
[04:00:11 CET] <alexpigment> well, realtime
[04:00:14 CET] <furq> maybe like 66% if you're lucky
[04:00:16 CET] <furq> that's true though
[04:01:08 CET] <alexpigment> it's questions like that that make me realize we're in a weird situation where the current standards of video aren't really feasible for the average person
[04:01:41 CET] <alexpigment> that's one of the reasons i've been heavily researching hardware encoding, because that's what we're all going to be using as 4k goes mainstream
[04:02:00 CET] <alexpigment> a core i7 from today is much faster than a core i7 from 2010, but it's not that much faster
[04:18:13 CET] <lolDude> hi
[04:18:29 CET] <lolDude> I wanna write video and audio from rtsp
[04:18:40 CET] <lolDude> is there any book about video coding?
[08:41:14 CET] <SortaCore> why does avcodec_parameters_copy not copy time_base and framerates?
[10:33:04 CET] <BlueInk> Hello everybody, I would like to know if there is a way to check the effectiveness of an encoding process. I'd like to encode six hours of video material with the least amount of disk space possible, while retaining a good quality. size is a premium for this task. the source material is a talkshow 720p at 60. Step 1: I could go to 30 fps to half the data, but ffmpeg/h264 has so many settings that hard to see where to
[10:33:04 CET] <BlueInk> adjust for more savings. Is there any good reading material on how to set the right encoding flags for a given material?
[10:34:02 CET] <furq> there isn't really anything worth touching other than crf, preset and tune in 99% of cases
[10:34:14 CET] <furq> as far as x264 options specifically
[10:34:53 CET] <furq> just cut a clip, pick a crf, encode it with -preset veryslow, and see if it meets your needs
[10:35:18 CET] <furq> dropping the framerate will give a marginal saving but not as much as you'd think
[10:35:43 CET] <furq> and if it's a talkshow then it's probably not worth denoising to get rid of grain
[10:36:47 CET] <BlueInk> wow thank you for the very quick response
[10:50:58 CET] <JC_Yang> crash in filter_mb_dir(), would it be a bug or corrupt stream?
[10:51:44 CET] <JC_Yang> within h264 loop filter
[10:52:23 CET] <JC_Yang> how tolerant is libavcodec to corrupt stream?
[10:58:28 CET] <BtbN> A crash is always a bug.
[11:06:35 CET] <JC_Yang> it's not hard to reproduce, but the stream is from ip cam, I didn't really decode it but just try_decode() done by avformat_find_stream_info(). I'm not familiar with the codebase and algo, any suggestions?
[11:26:19 CET] <BtbN> open a bug with a sample that makes it crash.
[11:27:36 CET] <JC_Yang> that's not so easy, that's a rtsp stream, an it may not always crash, just sometimes,
[11:49:44 CET] <BlueInk> Got 5 hours in 1.8Gb, with good enough quality. I think that's everything I could ask for.
[13:43:18 CET] <Fyr> guys, what does the following mean:
[13:43:19 CET] <Fyr> Stream #1:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv420p
[13:43:19 CET] <Fyr> ?
[13:43:33 CET] <Fyr> is it yuv420p or yuv444p?
[13:44:09 CET] <JEEB> it's yuv420p
[13:44:15 CET] <JEEB> the profile for *any* lossless is that one
[13:44:32 CET] <JEEB> as lossless coding is only permitted in the High 4:4:4 predictive profile
[13:44:35 CET] <JEEB> in H.264
[13:44:47 CET] <Fyr> ok, thanks.
[13:48:48 CET] <Fyr> is there a difference between yuv420p(progressive) and yuv420p?
[13:49:34 CET] <Fyr> the output files came from the almost identical input files.
[13:49:50 CET] <Fyr> however, FFMPEG chose different colorspace.
[13:53:24 CET] <JEEB> Fyr: it's just extra data if it specifically states it's progressive.
[13:53:31 CET] <JEEB> colorspace is the same with 4:2:0, planar
[13:53:50 CET] <JEEB> (YCbCr which is called 'YUV' in FFmpeg due to hysteric raisins)
[13:54:28 CET] <Fyr> JEEB, why is it different for almost identical files?
[13:55:15 CET] <JEEB> it was able to specifically infer that from one of the files :P
[13:55:20 CET] <JEEB> another didn't have it specifically set
[13:55:31 CET] <JEEB> it's just how ffmpeg.c or ffprobe prints it out
[13:55:39 CET] <JEEB> if you need something machine-readable use ffprobe and -of json
[13:55:50 CET] <JEEB> with -show_streams and -show_format
[18:07:06 CET] <zerodefect> Using the ffmpeg C-API, is there any way to handle 24-bit audio (perhaps say in 32-bit samples to make it easier for processing).  I've seen this page here: https://trac.ffmpeg.org/wiki/audio%20types
[18:07:21 CET] <zerodefect> The AVSampleFormat doesn't seem to have any enumerations for any sort of 24-bit
[18:11:20 CET] <DHE> it will produce a AV_SAMPLE_FMT_S32[P] sample
[18:14:13 CET] <zerodefect> @DHE, so is S32(p) actually 32/24-bit or 32/32-bit?
[18:15:07 CET] <DHE> I presume it would effectively resample the 24 bit into 32 bit during "encoding"
[18:22:02 CET] <zerodefect> Ok. That is was I suspected. It's an interesting problem. I think SDI in broadcast uses 24-bit packed into 32-bit. I appreciate that ffmpeg is not developed solely with broadcast in mind :)
[18:23:01 CET] <durandal_1707> zerodefect: 24 bit is shifted by 8 to become 32bit
[18:23:52 CET] <zerodefect> In what scenario? When converting from 24 to 32-bit?
[18:24:19 CET] <durandal_1707> when decoding
[18:24:52 CET] <durandal_1707> its just internal representation
[18:24:57 CET] <zerodefect> Ah right, I see what you're saying. Thanks.
[18:25:01 CET] <zerodefect> Yeah
[18:26:18 CET] <zerodefect> It's only a pain in that I have some I/O interfaces that expect 24-bit. I don't want to re-invent the wheel and perform the conversion myself (inefficiently).
[18:29:55 CET] <mbrrr> What is a good way (or any way) to take a video input at 30fps and output a slideshow like stream of every 90th frame? I've tried the select video filter and I can output a video but it looks terrible. I can capture still images that look great but can't seem to get them to 'stream'. I can use the segment format to continuously grab and overwrite a a few images but can't get them to play in a loop on my network. Any thoughts? I need
[18:29:55 CET] <mbrrr> stream with good picture quality, very low fps, and no audio.
[18:38:24 CET] <DHE> durandal_1707: it's a bit more complex than that. you usually want to map "0000" to "00000000" (to use a small size for example) but "1000" to "10001000" so that "1111" maps to "11111111" with a nice smooth transition curve
[18:39:00 CET] <DHE> it's pedantic, but most correct
[19:03:16 CET] <alexpigment> mbrrr: you mention that you tried the "select video filter". what filter specifically?
[19:03:54 CET] <alexpigment> mbrrr: it seems weird that a filter would make the quality bad; that seems more to do with what CRF or bitrate you specified for the output video
[19:04:45 CET] <alexpigment> mbrrr: also, is your source fairly lossy? a lot of videos "look" fine when played, but each invidivual frame is pretty messy. this would be exacerbated in the video you're trying to make
[19:05:05 CET] <DHE> there's actually a fitler named 'select'
[19:05:45 CET] <alexpigment> DHE: well, he apparently left, but I'm still thinking the filter is not the reason for the quality concerns he described
[19:09:03 CET] <alexpigment> mbrr (mbrrr?): welcome back. did you miss my messages?
[19:10:33 CET] <alexpigment> well, i tried
[19:12:50 CET] <DHE> wonder if maybe he just wants setfps=0.3 or something like that. as for quality, some encoder numbers likely need cranking. :)
[19:14:28 CET] <alexpigment> it does have me wondering: is there a filter that chooses the least macroblock-y frame from within a range?
[20:06:26 CET] <beo> hello, can someone tell me whats wrong with this script for making sshots from video files in batch? --> for %%A IN (*.mp4) DO ffmpeg -ss 00:00:10 -i "%%A" -frames:v 1 "%%A.png"
[20:08:17 CET] <sfan5> does it give you an error message?
[20:09:34 CET] <beo> im on windows, typical error "ffmpeg has stopped working"
[20:09:44 CET] <beo> but it is working with jpg, i just found out
[20:09:57 CET] <beo> png output is crashing ffmpeg
[20:11:08 CET] <beo> im using nightly, if that makes any difference
[20:11:13 CET] <beo> hm
[20:11:16 CET] <BtbN> do it manually, and if it still crashes, report a bug with a crashing sample.
[20:15:09 CET] <beo> i tried stable
[20:15:49 CET] <beo> it is only crashing in Nightly 20171212 build
[20:15:54 CET] <beo> :)
[20:21:25 CET] <beo> actually no, its some other build, i dont know how to check which it is exactly
[20:21:30 CET] <beo> latest is ok
[20:21:55 CET] <sfan5> sounds like the bug in question was already fixed, then
[20:24:05 CET] <beo> yes
[22:56:40 CET] <blackburn1911> Hello people
[23:04:27 CET] <blackburn1911> I have a "problem" with this command https://pastebin.com/rU5XZnsu . I want to make the text rolling from right to left every 20 seconds. The problem with the command is like the text disappearing before finishing rolling the text
[23:05:07 CET] <blackburn1911> I want to make a loop or something. Every 20 seconds, show the rolling text and so on
[00:00:00 CET] --- Thu Dec 14 2017