[Ffmpeg-devel-irc] ffmpeg.log.20181209

[burek]

[18:58:49 CET] <FishPencil> I have a video that's been save with the smaller colorspace. How do I tell FFmpeg the input is the restricted color space and expand it to the full?
[19:04:13 CET] <durandal_1707> FishPencil: you mean color range or?
[19:04:44 CET] <FishPencil> durandal_1707: Yeah
[19:06:04 CET] <durandal_1707> FishPencil: setrange/setparams and scale filter
[19:12:05 CET] <FishPencil> durandal_1707: -vf scale=in_range=limited,setrange=full ?
[19:14:05 CET] <durandal_1707> FishPencil: -vf scale=in_range=limited:out_range=full , setrange=full just changes metadata but video remains same
[20:42:33 CET] <giaco> hello!
[20:44:44 CET] <giaco> I've an audio file that starts at t > 0, how to reset timestamps? (I think the correct word is PTS but not sure)
[21:26:28 CET] <Kanibal> Hi! I'm trying to use ffmpeg to extract a subtilte file from a mkv container like this:
[21:26:30 CET] <Kanibal> $ ffmpeg -i input.mkv -map 0:s:6 output.srt
[21:26:42 CET] <Kanibal> I'm getting the output:
[21:26:45 CET] <Kanibal> Stream mapping:
[21:26:47 CET] <Kanibal>   Stream #0:9 -> #0:0 (dvd_subtitle (dvdsub) -> subrip (srt))
[21:26:50 CET] <Kanibal> But then it fails with the error:
[21:26:55 CET] <Kanibal> Subtitle encoding currently only possible from text to text or bitmap to bitmap
[21:27:13 CET] <JEEB> yea, DVD/DVB/PGS (last is blu-ray) subtitles are images
[21:27:16 CET] <JEEB> and SRT is text
[21:27:17 CET] <Kanibal> As far as I am understanding, I *do* want to extract it as text (as a subrip srt file)
[21:27:22 CET] <Kanibal> oh.
[21:27:30 CET] <Kanibal> damn ...
[21:27:45 CET] <TheAMM> There are tools to OCR bitmap subtitles
[21:27:55 CET] <pink_mist> none are very good though
[21:28:01 CET] <TheAMM> They're not magic, no
[21:28:10 CET] <JEEB> there's even an OCR filter in libavfilter, but IIRC you do not get that text in an easily catchable format (and ffmpeg.c wouldn't support that anyways)
[21:28:11 CET] <TheAMM> but a whole lot better than manually typing them all out
[21:28:21 CET] <pink_mist> I've yet to see one that gets l/I right even half the time
[21:28:35 CET] <JEEB> Kanibal: you could try subtitle edit or so?
[21:28:41 CET] <TheAMM> subrip at least has some mild postprocessing
[21:28:42 CET] <JEEB> I think that had the least bad interface for OCR'ing
[21:28:48 CET] <TheAMM> But there was a more modern tool
[21:29:01 CET] <TheAMM> I'd think google can offer some
[21:29:04 CET] <JEEB> subrip -> suprip -> subtitle edit
[21:29:08 CET] <JEEB> if I recall correctly
[21:34:14 CET] <Kanibal> JEEB: It's just that I digitalized my DVD collection and now I want to play them on my TV
[21:34:40 CET] <Kanibal> but that dumb TV only takes srt-files *next* to the video file
[21:35:04 CET] <JEEB> well then you will have to either convert - or grab someone else's creations :P
[21:35:12 CET] <JEEB> not much else there to do
[21:35:29 CET] <JEEB> since you need to either do the OCR yourself, or hope that something on the internet is as good
[21:35:29 CET] <Kanibal> Should be possible. It's Game of Thrones :p
[21:35:41 CET] <JEEB> yeh
[21:36:08 CET] <Kanibal> Thanks for clearing up the problem though!
[21:48:11 CET] <runfalk> Hi, I'm trying to generate thumbnails from videos using ffmpeg -ss 00:01 -i video.mp4 -frames:v 1 -qscale:v <quality> out.jpg
[21:48:24 CET] <runfalk> how does the qscale parameter work?
[21:48:31 CET] <JEEB> 100% depends on the encoder
[21:48:49 CET] <runfalk> encoder being the output image format?
[21:49:28 CET] <JEEB> in this case it's the (M)JPEG encoder in FFmpeg, which is then multiplexed (lol) into the JPEG format :P
[21:49:39 CET] <JEEB> which probably is close to raw JPEG bit stream?
[21:51:44 CET] <runfalk> I'm writing a cms-plugin that can take an arbitrary video file and output a specific frame (thumbnailed)
[21:52:05 CET] <runfalk> I want to provide some way of specifying quality on something like a 0-100 scale
[21:52:19 CET] <JEEB> then you have to map that according to the output encoder :P
[21:52:35 CET] <JEEB> including which parameter it matches against
[21:52:39 CET] <runfalk> but the output encoder will always be the same for jpeg?
[21:52:43 CET] <JEEB> yes
[21:52:55 CET] <JEEB> so you will have to look up what the (M)JPEG encoder does in FFmpeg
[21:53:22 CET] <runfalk> all right, thank you!
[21:54:29 CET] <runfalk> do you happen to know what its name in the c-code is?
[22:24:41 CET] <runfalk> seems like it is integers between 2-31
[22:24:48 CET] <runfalk> 2 is high quality
[23:38:37 CET] <pi-> `ffmpeg -i in_audio.wav -i in_vid.mov -acodec aac -cutoff 22000 -vcodec copy -map 0:a:0 -map 1:v:0 -ab 384k -vcodec libx264 -crf 24 out.avi`
[23:38:58 CET] <pi-> Could anyone suggest why this output file plays with VLC but not QuickTime or Keynote?
[23:42:25 CET] <pink_mist> what's up with -vcodec copy -vcodec libx264?
[00:00:00 CET] --- Mon Dec 10 2018