[Ffmpeg-devel-irc] ffmpeg.log.20180604

burek burek021 at gmail.com
Tue Jun 5 03:05:02 EEST 2018

[00:58:01 CEST] <TheAMM> Actually turns out -async 1 doesn't always work
[00:58:18 CEST] <TheAMM> Guess it's that delay in opening up the inputs
[01:00:05 CEST] <JEEB> uhh, do you mean the async protocol or the option that now maps into the resampling filter that adds silence?
[11:17:24 CEST] <dragmore88> hi, im trying to encode an AAC track with ffmpeg 4.0 from a prores source and i have verified that track 6&7 is the stereo tracks, but the output is silenced.. anyone ? ./ffmpeg -loglevel verbose -i got.mov -filter_complex "[0:a:6][0:a:7]amerge=inputs=2,pan=stereo[aout1]" -map "[aout1]" -acodec aac -b:a 128k result.m4a
[11:19:13 CEST] <durandal_1707> dragmore88: pan needs more arguments...
[11:19:59 CEST] <durandal_1707> iirc just giving output channel layout will give you silence
[11:20:19 CEST] <dragmore88> thx, could u elaborate with an example ?
[11:20:42 CEST] <dragmore88> when encoding ac3, i dont need a pan, but the aac encoder complains..
[11:21:53 CEST] <durandal_1707> examples cost extra coins
[11:22:00 CEST] <dragmore88> hehe
[11:22:08 CEST] <dragmore88> 1 BC pr example?
[11:23:37 CEST] <dragmore88> from the track manual adding -ac 2 should be enough, as long as i have specified the input tracks
[11:23:38 CEST] <dragmore88> ./ffmpeg -loglevel verbose -i got.mov -filter_complex "[0:a:6][0:a:7]amerge=inputs=2,pan=stereo|[aout1]" -map "[aout1]" -acodec aac -ac 2 -b:a 128k result.m4a
[11:23:59 CEST] <dragmore88> still i get a 3Kbps bitrate..
[11:24:16 CEST] <durandal_1707> see pan filter examples here: https://trac.ffmpeg.org/wiki/AudioChannelManipulation
[11:24:28 CEST] <dragmore88> yupp.. the one im reffering to
[11:24:43 CEST] <dragmore88> "Or use -ac 2 instead of the pan audio filter:
[11:24:43 CEST] <dragmore88> ffmpeg -i input1.wav -i input2.wav -filter_complex "[0:a][1:a]amerge=inputs=2[aout]" -map "[aout]" -ac 2 output.mp3
[11:24:44 CEST] <dragmore88> "
[11:24:53 CEST] <durandal_1707> pan=stereo|c0=c0+c2|c1=c1+c3
[11:25:21 CEST] <furq> amerge with two inputs should mix to stereo anyway
[11:25:49 CEST] <dragmore88> ./ffmpeg -loglevel verbose -i got.mov -filter_complex "[0:a:6][0:a:7]amerge=inputs=2[aout1]" -map "[aout1]" -acodec aac -ac 2 -b:a 128k result.m4a
[11:25:53 CEST] <durandal_1707> his tracks are stereo
[11:26:00 CEST] <dragmore88> this one seem to work, i removed the pan and added -ac 2
[11:26:20 CEST] <furq> it'll be 8 mono tracks won't it
[11:26:35 CEST] <dragmore88> my example is a prores with 2x mono tracks
[11:26:41 CEST] <dragmore88> track 6 & 7
[11:26:45 CEST] <dragmore88> -> stereo
[11:26:46 CEST] <furq> yeah you don't need to do anything other than amerge then
[11:27:18 CEST] <dragmore88> my problem was adding pan to the mix with no |c0=c0 etc..
[11:43:39 CEST] <binarym> hi all. I use the command line here: https://pastebin.com/2A7TiD49 to generate a timestamped HLS stream from a webcam
[11:44:19 CEST] <binarym> here is the playlist generated: https://pastebin.com/HbqiX0DY
[11:44:39 CEST] <binarym> my problem is that i would like the playlist to wrap too.
[11:45:09 CEST] <binarym> and the #EXT-X-MEDIA-SEQUENCE:0 to be incremeted
[11:45:13 CEST] <binarym> is it possible with ffmpeg ?
[11:46:32 CEST] <binarym> in the HLS stream, in my understanding, if i generate 4 chunks (out00{0,1,2,3}.ts) and the wrap
[11:46:40 CEST] <binarym> s/the wrap/then wrap/
[11:47:05 CEST] <binarym> then, the playlist is supposed to "wrap" too: EXT-X-MEDIA-SEQUENCE get incremented
[11:47:15 CEST] <binarym> and previous chunk are removed/overwrite ...
[11:49:27 CEST] <binarym> ok ... digging into the doc, i discovered the "hls" muxer... let's try it
[13:31:24 CEST] <zerodefect> Using the C-API to decode a stream of audio (st 337m) from a memory buffer. I have created a custom AVIOContext to read from the memory buffer - works fine. But...
[13:33:20 CEST] <DHE> well don't leave us in suspense!
[13:33:55 CEST] <zerodefect> If data from the source is still pending, does it suffice to return 'AVERROR(EAGAIN)'. The documentation for the 'read_packet' function does say, "For stream protocols, must never return 0 but rather a proper AVERROR code". I want to ensure I'm not bending things.
[13:34:34 CEST] <zerodefect> Never knew my question were that exciting :)
[13:34:40 CEST] <zerodefect> *questions
[13:37:10 CEST] <DHE> there is an AVERROR_EOF and I assume the intention is you would use this
[13:41:47 CEST] <c_14> Wouldn't you only use EOF if there is no more data? If there will be more data soon", EAGAIN should be the correct return code
[13:42:04 CEST] <zerodefect> Thanks both.
[13:42:18 CEST] <zerodefect> So if I call 'av_read_frame'... I only want to read one audio frame's worth of data, can I make the assumption that will happen?
[13:43:47 CEST] <DHE> I assume you have what basically amounts to a file pre-loaded into RAM. the regular AVFormatContext will parse it as usual. you're just emulating a "file" in RAM
[13:45:13 CEST] <zerodefect> @DHE. Fair assumption, but in this case, I'm receiving the data buffer through a network and then loading the payload into the memory buffer.
[13:46:56 CEST] <DHE> ah. well in that case EAGAIN makes sense since more data will be available later
[13:51:37 CEST] <zerodefect> Yes, those were my thoughts. I understand how EAGAIN works in a codec context - there is an input and output buffer and data is pushed and pulled.  In the context of an AVIOContext does it make sense if I think a traditional file workflow? For all the IO reader knows, it is responsbile for pulling the data (there is no concept of push because all the data that will be input already exists - at
[13:51:37 CEST] <zerodefect> least in a file workflow). My concern is if this extends to custom IO contexts.
[13:51:55 CEST] <zerodefect> Maybe I'm making a mountain out of a mole hill and I just need to suck it up and try it and see what happens :)
[14:10:33 CEST] <DHE> EAGAIN loosely means "try again later"
[16:53:21 CEST] <hashworks> Hi! I have a video file with hardcoded subtitles. Is there a way to mark that? I'm able to set the language for the video stream, is that what it means?
[16:53:35 CEST] <hashworks> hardcoded as in they are in the video stream
[16:58:12 CEST] <Mavrik> hashworks: what do you mean mark that?
[16:58:34 CEST] <Mavrik> Also the subtitles probably aren't hardcoded if you can disable them (hardcoded usually means they're baked into the video without option of removal)
[17:00:51 CEST] <DHE> like, add metadata indicating that the video has a language associated with it?
[17:00:59 CEST] <hashworks> Mavrik: Nope, I can't disable them
[17:01:09 CEST] <hashworks> They are burned into the video stream
[17:01:30 CEST] <hashworks> And I want to indicate that the video has subtitles that can't be adjusted
[17:01:36 CEST] <Mavrik> Hmm.
[17:02:48 CEST] <Mavrik> There might be a container flag but it's unlikely that's something standard.
[17:02:58 CEST] <hashworks> Hm&
[17:03:04 CEST] <hashworks> Whats the Video Stream Language Tag for?
[17:03:16 CEST] <hashworks> For something like filmed text?
[17:03:27 CEST] <Mavrik> Probably yeah
[17:03:34 CEST] <Mavrik> I doubt anything uses it tho
[17:13:58 CEST] <JEEB> hashworks: basically if you had multiple video tracks with language specific stuff
[17:14:16 CEST] <JEEB> otherwise pretty much unused or randomly tagged for content language
[17:34:43 CEST] <TAFB_WERK> in the unifi controller, if I want to see how much data went through an AP from friday until sunday, can I do that? Can't seem to see it other than the traffic graph, which doesn't total it up
[17:38:02 CEST] <Mavrik> Wrong channel? :)
[17:39:38 CEST] <TAFB_WERK> lol, whops :)
[17:39:54 CEST] <TAFB_WERK>  ./j ##ubnt
[19:41:14 CEST] <Daegalus> Question, is there an alternative ffmpeg for windows page? the current linked on is down, and according to Web Archive, has been down for almost a month
[19:42:12 CEST] <julesverne> sounds like you might be using a broken link.
[19:42:44 CEST] <julesverne> nope. i'm wrong.
[19:42:56 CEST] <julesverne> but.. definitely hasn't been down for a month.
[19:43:17 CEST] <julesverne> i dloaded it a couple days ago from there.
[19:45:26 CEST] <BtbN> well, expired certs do that
[19:45:29 CEST] <Daegalus> ah ok, seems like just an Expired cert issue that the maintainer hasnt noticed
[19:45:41 CEST] <Daegalus> or gotten around to taking care of
[19:45:48 CEST] <julesverne> yep
[20:31:19 CEST] <eltoozero> Any solid examples of drawtext text expansion floating around?
[20:39:52 CEST] <DHE> -vf drawtext=expansion=normal:text="Frame number %{n}"            # Renders a simple frame number in the top-left corner
[20:39:55 CEST] <DHE> Something like that?
[20:40:08 CEST] <DHE> shell escaping or quoting is up to you
[21:14:17 CEST] <eltoozero> @DHE looking for a more complicated example, for instance, can I show text starting at a specific frame number?
[21:16:49 CEST] <eltoozero> I found a one-liner exmaple, but it seems like I should be able to specify a textfile= containing a bunch of %{} statements.
[00:00:00 CEST] --- Tue Jun  5 2018

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