[Ffmpeg-devel-irc] ffmpeg.log.20170820

[burek]

[00:48:38 CEST] <dan3wik> Is it possible for FFmpeg to accept a web stream as an input?
[00:49:11 CEST] <dan3wik> I'd like to stream from a low power device using it's hardware encoder to encode h264
[00:49:23 CEST] <DHE> quite possibly. it can open HTTP based streams among others
[00:49:28 CEST] <dan3wik> And the convert that to mpeg1video on a more powerful system.
[00:49:49 CEST] <dan3wik> That mpeg1video would end up going to another server.
[00:50:01 CEST] <DHE> woah, mpeg1? why? unless it's going onto a video CD or something
[00:50:04 CEST] <dan3wik> Is there a way to make it listen?
[00:50:21 CEST] <dan3wik> The site I'm trying to connect it to only supports mpeg1video streams
[00:51:34 CEST] <dan3wik> Its for a low latency video stream
[01:39:07 CEST] <Accord> I have two audio files which I try to concat using -f concat and no -c copy ( I'm transcoding ) but the result reports more duration than there really is
[01:39:32 CEST] <Accord> both files are aac and the result is aac, the first one is created using anullsrc
[01:39:57 CEST] <Accord> when I play the result in vlc there's a gap between the two, seek bar freezes for a couple of seconds (excess duration) and then continues to the second file
[01:50:41 CEST] <atomnuker> f concat does a binary concat, it doesn't touch the headers
[01:50:54 CEST] <atomnuker> so it won't work for every format
[01:51:00 CEST] <atomnuker> use the concat filter
[02:05:42 CEST] <kerio> you can do h264 with one frame of latency
[02:42:23 CEST] <squarecircle> ohai
[02:43:06 CEST] <squarecircle> if I throw ffprobe at random files, I should be able to detect non video files
[02:43:08 CEST] <squarecircle> or?
[02:44:52 CEST] <leif> When I pass an AVChapter struct to an AVFormatContext, does it take ownership of it, or am I expected to free the memory myself?
[02:45:04 CEST] <squarecircle> I have to look for stream dicts with "video" keyes, I guess
[02:45:17 CEST] <leif> (I ask because it looks like the only way to construct an AVChapter is to malloc it myself.)
[06:05:31 CEST] <leif> It looks like I need to free it myself.
[06:17:54 CEST] <SpLiC3> What setting in ffmpeg would affect the refresh rate of the stats tools>statistics in vlc.
[06:21:44 CEST] <SpLiC3> The original http h.264 mpegts seems to be real time where as i can only seem to get it to update half as fast, this seems to affect read in some fashion and in turn buffer/cache on the client side.
[08:37:27 CEST] <H4x00m> hi
[08:39:44 CEST] <dan3wik> I'm trying to transcode a single video stream to a single target, could I do that with 'ffmpeg' or would I have to use 'ffserver'
[09:34:25 CEST] <Accord> atomnuker: thanks! concat filter seems to give correct duration
[10:49:25 CEST] <durandal_1707> dan3wik: ffserver do not use
[12:39:30 CEST] <Ingvix> hey, I'm trying to add a subtitle to multiple videos at once with a batch file but I'm guessing my command's a bit off. I'm trying to replace the second subtitle in the input video so the external sub takes it place as the second subtitle stream out of three sub streams. Here's the script and error output it gives to all of the video files: https://pastebin.com/s9sQauqT
[12:41:18 CEST] <klaxa> Ingvix: i think you want to use -map
[12:42:28 CEST] <Ingvix> should I use it for all the streams or just subtitles?
[12:44:46 CEST] <klaxa> you have to use it for all streams you want to have in your final file
[12:45:34 CEST] <Ingvix> right, thanks. I found a good example
[15:27:33 CEST] <bobob> How can I convert .srt into a bitmap stream? i read it should be possible with libass, I can't get it done
[15:46:38 CEST] <durandal_1707> bobob: you can only hardsub
[15:47:16 CEST] <BtbN> well, if you hardsub onto a generated static black background, and output as a bunch of images.
[15:48:10 CEST] <JEEB> libass should give you the plane already I think? you just tell it how big the canvas is
[15:48:17 CEST] <JEEB> then you overlay that on top of the video frame
[15:49:21 CEST] <bobob> could write down the command pls? ffmpeg canvas_size 1080p -i sub.srt sub.ass ?
[15:49:34 CEST] <JEEB> it requires custom code
[15:49:46 CEST] <JEEB> ass is also text based and that conversion can be easily done
[15:49:54 CEST] <JEEB> but your end result IIRC was to get DVB subtitles or so
[15:50:32 CEST] <JEEB> anyways, custom code is required that renders the subpictures on canvas and then you convert the canvas into a format that the DVB subtitle encoder takes in
[15:51:21 CEST] <bobob> yes
[15:53:13 CEST] <bencoh> wait, when did he mention dvb?
[15:53:19 CEST] <JEEB> during the last discussion
[15:53:23 CEST] <bencoh> ah, okay :)
[15:53:41 CEST] <JEEB> he now randomly just mentioned the "rendering subtitles into bitmaps" part for which I mentioned libass
[18:27:50 CEST] <dan3wik> Is there a way to make a transcoder relay where I can connect to the FFserver with '://ffserver/640/480/' and have it relay to '://destination/640/480/' without hardcoding it all?
[18:28:34 CEST] <BtbN> don't use ffserver, it's dead.
[18:28:55 CEST] <BtbN> And you also won't find anyone with any knowledge about how to use it.
[18:29:19 CEST] <dan3wik> Ok, is there a way I can do that with ffmpeg then?
[18:30:10 CEST] <dan3wik> The main issue I'm having with 'ffmpeg' is that I'm unable to listen for incoming connections with it
[18:30:12 CEST] <BtbN> do what?
[18:30:28 CEST] <BtbN> it can't really do that outside of some very limited special cases
[18:30:57 CEST] <dan3wik> Do you know of any alternatives that might work?
[18:31:06 CEST] <BtbN> nginx
[18:31:10 CEST] <BtbN> with rtmp
[21:48:00 CEST] <flok420> how can I set analyzeduration in the api? e.g. programatically using the c++ library
[21:49:08 CEST] <JEEB> seems like the usual AVOption
[21:49:51 CEST] <JEEB> so you set an AVOption to the input AVFormatContext
[21:53:06 CEST] <flok420> thanks
[21:53:24 CEST] <flok420> just tried setting it now in avformat_open_input and I see back the values set
[21:53:57 CEST] <flok420> unfortunately whatever I set it to (32MB and 60 seconds) I keep getting "Could not find codec parameters for stream 0 (Video: h264, 1 reference frame ([27][0][0][0] / 0x001B), none(left)): unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options" for an RTP stream by ffmpeg itself
[21:55:28 CEST] <iive> flok420: is the input an mpeg-ts steam?
[21:55:49 CEST] <flok420> yes, it is the result of:
[21:55:50 CEST] <flok420> fmpeg -f video4linux2 -i /dev/video0 -f alsa -i hw:0 -vcodec libx264 -s 320x240 -pix_fmt yuv420p -vb 200000 -minrate 200000 -maxrate 200000 -bufsize 2000000 -acodec libmp3lame -ab 128k -ar 44100 -ac 2 -f mpegts udp://127.0.0.1:10093
[21:56:24 CEST] <iive> are you running this localy, aka on same machine?
[21:56:35 CEST] <flok420> yes
[21:58:53 CEST] <flok420> the other end is listening on udp://127.0.0.1:10093/
[22:02:02 CEST] <iive> i don't see the video codec setting
[22:02:06 CEST] <iive> oh
[22:02:10 CEST] <iive> it's there
[22:03:00 CEST] <iive> try without sound...
[22:04:07 CEST] <flok420> works!
[22:04:17 CEST] <flok420> \o/
[22:04:29 CEST] <iive> try with mp2, ac3 or aac
[22:05:58 CEST] <flok420> it only works here without audio
[22:06:25 CEST] <flok420> e.g. -acodec ac3 -ab 128k -ar 44100 -ac 2    also fails
[22:06:38 CEST] <flok420> (and mp2 and aac)
[22:08:57 CEST] <iive> hum... no idea. maybe somebody would know
[22:09:37 CEST] <iive> does it work if you write to file and then try to play that file?
[22:10:00 CEST] <flok420> maybe this code is dodgy? https://pastebin.com/5jXTv3p7   I'm new to ffmpeg and tried adapting an example to get rid of the deprecated warnings
[22:12:06 CEST] <iive> i though you are using ffplay for playback.
[22:12:41 CEST] <flok420> oh, right, no I use the ffmpeg c++ libraries
[22:13:55 CEST] <iive> try ffplay
[22:14:30 CEST] <flok420> then i get audio but no video
[22:18:44 CEST] <JEEB> then it's possible that for some reason the parameter sets aren't getting repeated
[22:19:08 CEST] <JEEB> I thought mpeg-ts output should be doing that, though
[22:19:47 CEST] <flok420> slightly related: the rtp stream of an "Verint Video Solutions S1708e" is visualized fine using gstreamer but ffmplay doesn't show anything
[22:20:07 CEST] <JEEB> yea, but that thing isn't rtp anyways
[22:20:32 CEST] <JEEB> anyways, try writing that mpegts into a file through stdout (just "-" as the output file name)
[22:20:42 CEST] <JEEB> and pipe it into a file
[22:20:56 CEST] <JEEB> then try reading that one after cutting the initial X hundred bytes out of it
[22:21:33 CEST] <JEEB> (just make sure that the file contains multiple GOPs)
[22:21:56 CEST] <JEEB> because I think libx264 + mpegts muxing /should/ be repeating the parameter sets at random access points
[22:22:02 CEST] <JEEB> without them of course you cannot watch the stream
[22:22:27 CEST] <flok420> if I *do not cut off* those x hundred bytes, then it is also only audio and no video
[22:22:51 CEST] <flok420> stop
[22:22:54 CEST] <flok420> I take that back
[22:22:59 CEST] <flok420> it just takes a bit
[22:25:06 CEST] <JEEB> basically "not getting video" usually means you are missing the parameter sets, which either means that they aren't getting passed or the GOP length is long enough that the libavformat input reader didn't probe enough
[22:25:19 CEST] <JEEB> audio is usually decode'able as is
[22:25:48 CEST] <flok420> I cut of 10KB and now it still plays but only for a couple fo seconds, then video stops and audio continues
[22:26:20 CEST] <JEEB> if it plays at all the parameter sets are there somewhere
[22:27:01 CEST] <flok420> ok so the freezing is a different point?
[22:27:39 CEST] <JEEB> that's just lack of packets in that stream or something like that (you'd have to look into it with more detail to find the exact reason)
[22:29:37 CEST] <flok420> ok. and about that "Verint Video Solutions S1708e"; you say it is not rtp but it says transport protocol rtp/udp and compression mode "MPEG4 compliant Simple Profile"?
[22:29:52 CEST] <JEEB> no, I meant your ffmpeg command line
[22:29:58 CEST] <flok420> oh ok
[22:29:59 CEST] <JEEB> which had "udp://blah" in there
[00:00:00 CEST] --- Mon Aug 21 2017