[Ffmpeg-devel-irc] ffmpeg.log.20180704

[burek]

[01:37:53 CEST] <leif> When ffprobe shows `60 kb/s (default)` is that saying that ffmpeg couldn't figure out what the bitrate was, or its using whatever the default for the container is?
[01:37:58 CEST] <leif> (Or something else)
[03:55:20 CEST] <^Neo> Good evening friends, I have an HDMI capture card and want to capture Dolby Digital AC3 coming in as IEC61937 and convert it to regular AC3... I haven't been able to find a command line example for it though :(
[10:56:40 CEST] <Nacht> Heh, the encoding speed for AV1 is almost funny ^^
[11:00:44 CEST] <bencoh> how do you define "almost funny" in this context? :)
[11:03:07 CEST] <TheAMM> You almost laugh at how slow it is but then get sad over how slow it is
[11:03:19 CEST] <TheAMM> Because it's happening to you, schadenfreude doesn't tip it over to the fun side
[11:03:58 CEST] <Nacht> Exactly that :D
[11:04:11 CEST] <bencoh> :D
[11:04:25 CEST] <Nacht> I was expecting slow, like really slow. But it seems I have still have too high standards
[11:04:54 CEST] <TheAMM> Encoding sub-1fps is a special kind of hell
[11:05:04 CEST] <TheAMM> (although my laptop manages that easily with vp9)
[11:06:13 CEST] <Nacht> I haven't got the fastest of laptops there is. But it's nice to know I got a new method of torturing it now
[11:12:52 CEST] <atbd> hi, i'm creating a program which cut a tiny portion of a video and transcode mpegts to mp4. It works except for video's duration, ffprobe returns a false one (37s instead of 19s). I'm setting AVFormatContext::duration and also AVStream::duration but no changement. How can i set the right duration ?
[11:49:30 CEST] <DHE> yeah I encoded a minute or two of video over a few weeks... AV1 needs a LOT of work...
[14:22:25 CEST] <lkiesow> Hi, I'm trying to extract and scale an image to a specific resolution and save it as JPEG using FFmpeg. Scaling it to a resolution like 250x144 or 250x146 works but not 250x145. The encoder always seems to generate an even resolution. It does work if I output a PNG file instead. Any idea what I can do about that? Is it possible to generate JPEG files with uneven width?
[14:28:42 CEST] <furq> lkiesow: -pix_fmt yuv444p
[14:29:10 CEST] <^Neo> Is there a way to capture a dolby digital IEC 61937 stream from an ALSA hardware input?
[14:31:44 CEST] <DHE> lkiesow: many codecs have such restrictions due to the underlying encoding spec requiring it
[14:32:00 CEST] <DHE> as for alterantives, have you tried other applications like ImageMagick and seeing if they do produce what you want?
[14:39:08 CEST] <lkiesow> furq: Makes sense, thanks. png would automatically choose rgb24.That's why it did work. But using jpeg I was using yuvj420p. Changing that makes it work.
[14:39:23 CEST] <furq> oh yeah i guess yuvj44p
[14:39:24 CEST] <furq> 444p
[14:40:28 CEST] <lkiesow> DHE: JPEG itself does not have that restriction and I want to use FFmpeg since it's an automated process and we are using FFmpeg for lot's of other stuff as well
[14:41:04 CEST] <lkiesow> It was just that switching from png to jpeg broke the command which confused me :)
[14:41:16 CEST] <DHE> oh... yeah yuv444 makes sense...
[14:41:46 CEST] <lkiesow> again, thanks for the hint. That helped. And now& back to work :D
[15:28:05 CEST] <dtatulea> Hi. I am streaming a h264 video (avc3 MP4) over WebSocket to a Media Source Extension Source Buffer. Ffox and Chrome can handle it on Linux, but on Windows, Firefox and Edge can't handle it: the first frame is shown but no updates after that. Any ideas where I could start looking into this? ffplay doesn't show any errors or warnings either...
[15:28:34 CEST] <dtatulea> I was directed from the firefox #media channel to this channel.
[15:29:07 CEST] <JEEB> on linux they're probably using FFmpeg, on windows they're using the included (most likely hwdec-backed) Media Foundation decoders
[15:29:21 CEST] <JEEB> testing the same bit stream in the Windows Videos app probably will help?
[15:29:47 CEST] <JEEB> (or windows media player although I guess that is now more dead than it isn't)
[15:32:06 CEST] <dtatulea> JEEB: yep, doesn't work there
[15:34:08 CEST] <JEEB> dtatulea: pastebin result of `ffprobe -v verbose FILE`
[15:34:11 CEST] <JEEB> and link here
[15:35:44 CEST] <dtatulea> https://pastebin.mozilla.org/9089101
[15:41:46 CEST] <dtatulea> JEEB: I wonder if it makes sense to build the basic player from the windows media foundation sdk and try to play that file. Maybe I get more information about what is wrong.
[15:42:27 CEST] <Blacker47> maybe 120 fps is a bit too high?
[15:44:55 CEST] <DHE> avc3 as the fourcc?
[15:48:26 CEST] <dtatulea> Blacker47: when encoding, the frame rate is 25. But as I dumped the mp4 data to a file instead of streaming, there's nothing to indicate time.
[15:49:41 CEST] <JEEB> if that's just the time base I don't think that's a real problem?
[15:49:52 CEST] <JEEB> since FFmpeg makes files with pretty big time bases
[15:50:00 CEST] <JEEB> and those work
[15:50:19 CEST] <JEEB> if it's actual frame rate of the samples' PTS then that can be a problem
[15:51:34 CEST] <DHE> it could be, but if it's really also only 1 reference frame and 1024x1024 pixels, it sounds like it might still make level 4.x decoder requirements.. right?
[15:52:01 CEST] <DHE> just an estimate without breaking out the calculator
[15:57:05 CEST] <JEEB> I think profile/level should be mentioned in the pastebin, no?
[15:57:14 CEST] <JEEB> I don't have the time to check it myself, unfortunately
[15:57:23 CEST] <dtatulea> If not, I can let you know what they are.
[15:59:34 CEST] <dtatulea> Constrained High Profile, Level 3.
[16:00:03 CEST] <furq> "constrained high"?
[16:00:25 CEST] <furq> oh that is actually a thing
[16:00:30 CEST] <furq> i've never seen anyone use that before
[16:00:39 CEST] <DHE> yeah, there's actually a lot of profiles no one really uses
[16:01:17 CEST] <dtatulea> Actually, I think it's only High.
[16:01:24 CEST] <dtatulea> 100
[16:01:38 CEST] <dtatulea> with constrain set 0
[16:01:54 CEST] <furq> i can't imagine there are any decoders that distinguish between the two
[16:02:13 CEST] <furq> certainly not software or consumer gpu ones
[16:02:36 CEST] <^Neo> JEEB, you seem very smart, any idea about my IEC61937/ALSA question?
[16:02:41 CEST] <DHE> it's really just a question of whether the decoder supports a specific feature. "main" + any 1 "high" feature = a "high" profile video
[16:05:19 CEST] <DHE> and a "high" decoder should have no problem with any lower profile (constrained high, main, baseline, constrained baseline... did I miss any?)
[16:05:21 CEST] <dtatulea> DHE: Regarding the "avc3 as the fourcc", yes?
[16:05:36 CEST] <DHE> dtatulea: well iirc the right fourcc is "avc1"
[16:05:42 CEST] <dtatulea> s/yes?/yes./
[16:05:50 CEST] <furq> DHE: you forgot progressive high
[16:06:14 CEST] <DHE> is there such thing as Intra-High? (keyframes only)
[16:06:53 CEST] <furq> and acid high, hard high, detroit high
[16:07:17 CEST] Action: DHE goes to read the wikipedia article on h264, clearly he's behind the times
[16:07:49 CEST] <furq> there are a bunch of intra high profiles but they're all for 10-bit or 4:2:2/4:4:4
[16:07:57 CEST] <dtatulea> DHE: You mean in the mp4 ftyp or in the visual sample entry? For the visual sample entry I need it to specify that it's avcC.
[16:08:01 CEST] <andriy> whois kam187_
[16:10:29 CEST] <JEEB> ^Neo: looking at the changes I have to review in ALSA-related code in other projects I don't want to comment on it since I will probably not find too much positive to say about it
[16:10:43 CEST] <JEEB> partially because I don't think there's a "best practices" thing for ALSA's APIs either
[16:18:21 CEST] <Nonakto> Hello, I need to display a video (.mp4) on a web page by creating a video stream (no file!). Anybody have any information? Tell me where to look? Thank you!
[16:19:47 CEST] <DHE> like, encode and render on demand?
[16:20:09 CEST] <Nonakto> yes
[16:21:07 CEST] <DHE> besides being a potential CPU consumption risk, MP4 doesn't lend itself to that very well. it's really intended to be a pre-rendered file
[16:22:16 CEST] <Nonakto> Okay thanks :)
[16:28:56 CEST] <dtatulea> DHE: How about streaming live content over to a Media Source Extension? You still need to use MP4 then.
[16:29:26 CEST] <dtatulea> There is no other way. Or?
[16:41:22 CEST] <DHE> dtatulea: well there are fragmented MP4 files, but I'm mainly concerned that transcoding will be involved...
[16:42:36 CEST] <Mavrik> muxing at least
[16:42:42 CEST] <Mavrik> DASH uses MP4 files right?
[16:43:45 CEST] <JEEB> it can use fmp4, matroska or mpeg-ts
[16:43:46 CEST] <JEEB> :D
[16:43:55 CEST] <JEEB> FFmpeg supports two out of those
[16:47:47 CEST] <Mavrik> The question is more what do browsers support :)
[16:47:55 CEST] <Mavrik> I have somewhere in my mind that only MP4 really works.
[16:48:25 CEST] <DHE> iirc Dash originally specified fmp4 as the file format. so that will certainly be best supported
[16:48:32 CEST] <JEEB> both matroska and fmp4 seem to work last I tested
[16:48:41 CEST] <JEEB> of course matroska is the webm subset
[16:48:46 CEST] <JEEB> so vp9+stuff
[16:57:27 CEST] <andriy_> Hello, when looking through libavcodec code I noticed that some functions have an underscore between "av" and "codec",  while others don't. i.e.  avcodec_find_encoder_by_name vs av_codec_set_pkt_timebase. Does the additional underscore mean anything?
[16:59:24 CEST] <JEEB> av_* are just general public API symbols in FFmpeg, avcodec notes it's specific to avcodec (also could be hysterical raisins)
[17:02:17 CEST] <andriy_> thanks JEEB
[23:17:17 CEST] <Hello71> JEEB: doesn't ffmpeg support decoding mpegts
[00:00:00 CEST] --- Thu Jul  5 2018