[Ffmpeg-devel-irc] ffmpeg.log.20150629

[burek]

[00:28:24 CEST] <anoop_r>  http://www.qfs.mobi/f2403835
[00:28:55 CEST] <anoop_r> please check this and forward your valuable feed back to keepitsimplepltd at yandex.com
[01:01:50 CEST] <user> hi channel
[01:03:30 CEST] <Guest60595> May I ask a question related to using ffmpeg as web-cam simulator ? (I search a lot so far about my problem...with not success)
[01:04:11 CEST] <c_14> web-cam simulator?
[01:06:16 CEST] <Guest60595> I have done a setup with v4l2loopback and snd-aloop. FFmpeg serve as a video stream generator for simulating a web-cam.
[01:06:29 CEST] <c_14> What's the problem?
[01:07:45 CEST] <Guest60595> I use a static 800x600 png as video input source and -f v4l2 /dev/video0 as output.
[01:08:54 CEST] <Guest60595> I want a lightweight as possible video stream with 1 fps. I can't motivate ffmpeg to deliver that.
[01:09:37 CEST] <c_14> ffmpeg -loop 1 -i png -r 1 -f v4l2 /dev/video0
[01:13:01 CEST] <Guest60595> Ok problem 1. solved. Bug: -framerate 1 do not work -r 1 do. THANK YOU.
[01:18:19 CEST] <Guest60595> 2. problem: The CPU consume is 151.2% (two cores). I tried to switch: -f rawvideo -pixel_format yuv420p No error messages but the status line state still rawvideo (RGB[24] Any idea ?
[01:23:12 CEST] <c_14> -pix_fmt not -pixel_format
[01:29:46 CEST] <Guest60595> OK. -pix_fmt change now the outout (I get this from some a howto, I should had verified it. apologies) But flash broadcast app does not recognize yuv420p and it not change the very high cpu usage. :(
[01:31:06 CEST] <c_14> add -re before -i png
[01:33:18 CEST] <Guest60595> 59% cpu. I can live with that. You are know this beast very well :-) Thank you.
[01:41:14 CEST] <Guest60595> I will put 2-3 (working, tested) lines together as a example for using ffmpeg to create a nice virtual web-cam. I thing a good addition for the FFMprg Documentation.
[01:41:28 CEST] <Guest60595> bye
[02:23:03 CEST] <nashgul> hi
[07:19:34 CEST] <wn33dk> Hi, does anyone have time for a noob question?
[07:22:00 CEST] <wn33dk> I have a video format that has embedded subtitles (mkv).   I would like to convert this to another format, but have the subtitles be on and part of the recording itself.  Thanks in advance if anyone can help.
[09:14:49 CEST] <brewtany> hi, how can i set ts file start time exactly?
[09:24:32 CEST] <pentanol> brewtany ffmpeg -ss
[09:25:07 CEST] <brewtany> pentanol: -ss cannot set the start time of ts
[09:25:32 CEST] <brewtany> pentanol: i want to create  ts files for m3u8 file
[09:28:20 CEST] <brewtany> first I do this
[09:28:21 CEST] <brewtany> ffmpeg -y -i 11.mp4 -c:v libx264 -f mpegts -filter:v setpts=PTS+10.0/TB 11.tst
[09:28:54 CEST] <brewtany> then how can I set the start time exactly at 10seconds?
[09:29:14 CEST] <pentanol> -ss 10
[09:31:04 CEST] <brewtany> but when : ffmpeg -y -i 12.mp4 -c:v libx264 -f mpegts -filter:v setpts=PTS+20.0/TB 12.tst
[09:31:11 CEST] <brewtany> -ss 20 not work.
[09:31:43 CEST] <brewtany> ffmpeg -y -copyts -ss 20 -i 12.tst -c copy -f mpegts  12.ts
[09:31:58 CEST] <brewtany> Input #0, mpegts, from '12.ts':
[09:31:59 CEST] <brewtany>   Duration: 00:00:05.00, start: 27.866667, bitrate: 348 kb/s
[09:34:16 CEST] <pentanol> brewtany ffmpeg show time what it plays
[09:34:30 CEST] <pentanol> sorry I need to go
[09:34:44 CEST] <brewtany> help~
[09:34:48 CEST] <brewtany> plz don't go
[09:35:09 CEST] <brewtany> show time?
[12:23:09 CEST] <sine0> exit
[12:23:11 CEST] <sine0> fail
[12:25:01 CEST] <maqr> i'm trying to force a key frame at exactly 0.05 seconds into my video stream, i thought that would be done with '-force_key_frames:v 00:00:00.05', but that doesn't seem to do it (as checked with ffprobe -show_frames)... any idea what i could be doing wrong?
[12:27:48 CEST] <maqr> i think it might have something to do with my stream being generated from testsrc
[15:37:56 CEST] <mateo`> hello there o/, i'm trying to mux raw h264 into an mp4 container using the avformat API. What i get from the decoder is the codec data, then the actual frames. Muxing the codec data then all the frames using av_interleaved_write_frame seems to work (with an error at the beginning of the stream "no frame!") but i'm wondering if i'm not supposed to set the codec data more specifically somewhere else (ie: in
[15:37:58 CEST] <mateo`> AVCodec/AVCodecContext for example) ?
[16:39:21 CEST] <BtbN> Has anyone ever seen a camera that outputs files which file identifies as FoxPro FPT?
[17:07:17 CEST] <Anoia> I don;t recognise an fpt image ofrmat
[17:07:45 CEST] <BtbN> FoxPro seems to be some kind of DBMS oO
[17:08:57 CEST] <Anoia> it is
[17:09:07 CEST] <Anoia> https://support.microsoft.com/en-us/kb/130686 says it's a "table memo"
[17:09:18 CEST] <Anoia> if it is inded a .fpt file
[17:12:42 CEST] <BtbN> it has no extension
[17:12:54 CEST] <BtbN> file just says it is
[17:13:05 CEST] <BtbN> but i'm not sure if it's right
[17:14:31 CEST] <DHE> ffprobe ?
[17:14:47 CEST] <BtbN> is unable to make anything of the file
[17:14:55 CEST] <BtbN> might as well give it a bit of random noise
[17:16:00 CEST] <janicez> lol
[17:20:44 CEST] <Anoia> Windows won;t say what type it is if it didn;t have an extension (it doesn;t do magic number detection)
[17:20:51 CEST] <Anoia> it does hide soem extensions though
[17:22:55 CEST] <BtbN> Who said anything about windows?
[17:24:34 CEST] <Anoia> You mentioned FoxPro, which is a Microsoft package (only on windows IIRC)
[17:25:56 CEST] <BtbN> yes, because "FoxPro FPT" is litteraly what file says
[17:37:08 CEST] <Anoia> oh, the "file" command? That's normally based on a magic number
[17:50:53 CEST] <_Vi> How do I limit avformat_find_stream_info when calling FFmpeg tool? It reads and caches entire video and then I get a lot of " Delay between the first packet and last packet in the muxing queue is ...".
[19:14:21 CEST] <Timster> Hey, guys - could somebody explain me the principle behind Keyframe Intervals / GoP-Length? I am asking in regard to visual quality. Is a higher, or a lower amount better?
[19:15:27 CEST] <DHE> varies by codec. in H264 there's no harm in any setting except that any seek always lands on a keyframe/GOP boundary
[19:15:41 CEST] <kepstin-laptop> in most recent codecs, longer interval between keyframes means smaller files for equivalent file size, at the expense of making seeking more expensive
[19:15:46 CEST] <DHE> MPEG2 will suffer quality issues over the longer term and will usually suggest 2 keyframes per second (approximately)
[19:16:13 CEST] <Timster> Ok, and if we talk about libx264?
[19:16:13 CEST] <DHE> keyframes are always large though, so there's that
[19:16:37 CEST] <DHE> that's H264. larger intervals is better for bitrate, but worse for seek accuracy.
[19:17:03 CEST] <Timster> Ok, and what do you mean with "better for bitrate"?
[19:18:42 CEST] <kepstin-laptop> keyframes are big. With x264, using fewer of them means more efficient encoding in most cases.
[19:19:22 CEST] <kepstin-laptop> (x264 will still by default still put in keyframes on scene changes and stuff even with a large keyframe interval setting)
[19:20:04 CEST] <Timster> Ok, thanks. Let's say I use -r 40 and -g 80 - would the keyframe interval be fixed to 2 seconds by that, or do I need to use something else to really fix key frames?
[19:20:57 CEST] <Timster> *so force it to be 2 seconds
[19:22:02 CEST] <kepstin-laptop> if you're encoding with x264 and want fixed keyframe timing, you have to disable scenecut detection. I don't remember the ffmpeg option for that...
[19:22:43 CEST] <kepstin-laptop> (but I'm not sure why you would want that, unless you're doing something like segmented files for streaming)
[19:23:00 CEST] <Timster> Yeah, it's for streaming. Maybe: -x264opts "keyint={{fps}*2}:min-keyint={{fps}*2}:no-scenecut" ?
[19:26:58 CEST] <DHE> scenecut=-1 is the preferred syntax in the most recent versions (I ride Git though)
[19:27:06 CEST] <maqr> if i know i'm going to need to take a screenshot at a very specific time, like 0.05 seconds into an x264 stream... can i force a keyframe to be exactly there?
[19:28:32 CEST] <Timster> DHE: So in my case it would be -r 40 -x264opts "keyint=80;scenecut=-1" ?
[19:28:46 CEST] <DHE> colon, not semicolon
[19:29:17 CEST] <DHE> and that looks right
[19:29:19 CEST] <maqr> when i try force_key_frames it doesn't seem to work
[19:32:07 CEST] <Timster> Oh, OK - thanks - will try that. So you say with libx264 there is no visual difference between different amounts of keyframes - it's just about the bitrate as well as the seek accuracy? In my setup, the stream gets reencoded at a last stage where I need to have a 2 seconds Keyframe Interval - so does it matter how big or little it is in the first encoding before that?
[19:32:45 CEST] <Timster> Like to get the best out of the second encoding?
[19:33:17 CEST] <DHE> assuming disk space is a non-concern (we're talking a few percentage points anyway) I would say don't worry about it
[19:33:33 CEST] <DHE> though transcoding a transcoded video is considered bad form
[19:39:13 CEST] <Timster> Ok, thanks a bunch!
[19:40:36 CEST] <Timster> Would you recommend -strict -2 ?
[19:41:52 CEST] <DHE> only if it says you need it, and you accept the warning it gives you about it
[19:42:49 CEST] <Timster> Could you explain what it does exactly and what the ad- and disadvantages might be?
[19:44:32 CEST] <DHE> it unlocks codecs that are considered "experimental"
[19:44:46 CEST] <DHE> and/or codec features of the same quality
[19:46:30 CEST] <Timster> Ok, thanks. One last question - as I need to have CBR as well, -x264opts "keyint=80:scenecut=-1" will not work for me, right? So I need to stick to -g 80?
[19:55:24 CEST] <maqr> oh, i see what i was doing wrong, heh
[19:57:09 CEST] <maqr> if i put "-ss time -q:v 1 -vframes 1 foo.jpg" at the end of my ffmpeg command that uses testsrc, it can pull out a frame that won't actually be in the video's encoding... how can i tell the -ss command to use the encoded output as the input stream, instead of the source input stream?
[19:57:51 CEST] <maqr> in other words, i'm saying "-ss 00.00.00:0.05" and it's giving me a frame with "5" on it, which i thought was right, but i'm at 30fps and that frame can't exist
[19:58:25 CEST] <maqr> i could just change it to "0.0333", but i'm wondering if there's a way to tell -ss to use the encoded stream instead of the source stream anyway
[20:01:24 CEST] <Nolski> Hey, has anyone had to loop a section of a video n times?
[20:01:56 CEST] <Timster> Gtg, bye
[20:15:27 CEST] <llogan> Nolski: one method here: https://trac.ffmpeg.org/wiki/Concatenate
[20:15:34 CEST] <llogan> search for "loop a video"
[20:29:01 CEST] <Nolski> llogan: the issue is if I want to loop a /section/ of a video
[20:29:54 CEST] <Nolski> Would I have to rip the video out and then concat it inbetween two videos?
[20:31:50 CEST] <llogan> yes, that would be one way. either use the concat demuxer or concat filter.
[22:32:24 CEST] <rizotas> hi, i'm installing vlc from source, but I got this /usr/bin/ld: /usr/local/lib/libpostproc.a(postprocess.o): relocation R_X86_64_32S against `.rodata' can not be used when making a shared object; recompile with -fPIC /usr/local/lib/libpostproc.a: error adding symbols: Bad value, then I compiled ffmpeg from source with --enable-pic, but I get the same error
[22:44:47 CEST] <Marcin_PL> Hello. What I am missing on vps (debian7), that avconv reading input stream prints metadata (icy-sth, StreamTitle etc.) on my Deb8 at home, and on vps it can't?
[22:45:22 CEST] <JEEBsv> possibly just an older version in an older version of debian
[22:45:51 CEST] <Marcin_PL> Huh, wait&
[22:46:33 CEST] <JEEBsv> most people who use OSS multimedia build stuff themselves since you generally want only X things (something in between of 2 to 4) in addition to what is in the code base itself
[22:47:25 CEST] <JEEBsv> like, libx264 and fdk-aac for AVC/AAC encoding and pretty much all the decoders are in the code base
[22:47:36 CEST] <JEEBsv> or libvpx and libopus
[22:47:48 CEST] <Marcin_PL> avconv version 11.4-6:11.4-1~deb8u1 mine, avconv version 0.8.17-6:0.8.17-1 on vps& Huh, 0.8 to 11.4? How it is possible?
[22:47:54 CEST] <Marcin_PL> I'll try install
[22:48:05 CEST] <JEEBsv> yes, old things have old versions :P
[22:48:07 CEST] <JEEBsv> nothing new really
[22:48:15 CEST] <JEEBsv> although quite ouch with 0.8
[22:48:43 CEST] <JEEBsv> also this stuff is from Libav, not FFmpeg
[22:49:03 CEST] <Marcin_PL> Isn't that just a fork?
[22:49:26 CEST] <JEEBsv> yes, libav and ffmpeg-new are both forks of ffmpeg-old
[22:49:27 CEST] <Marcin_PL> Debian treats it that way
[22:49:38 CEST] <Marcin_PL> Ah.
[22:50:08 CEST] <Marcin_PL> I can't have those libraries from the repo&
[22:50:08 CEST] <JEEBsv> anyways, as of very late you can get both ffmpeg and libav binaries packaged in debian
[22:50:21 CEST] <JEEBsv> Marcin_PL: yes. you have to build. thankfully it's not really hard
[22:50:30 CEST] <Marcin_PL> I see
[22:50:43 CEST] <JEEBsv> git, build-essential(s), yasm (>=1.2)
[22:50:50 CEST] <Marcin_PL> Perhaps I'd decide to upgrade server to deb8
[22:51:26 CEST] <JEEBsv> if that's an alternative for you, sure :P
[22:51:43 CEST] <Marcin_PL> The point is, everything is working, but I want now to monitor stream name to auto start recording
[22:51:44 CEST] <JEEBsv> I'm just going to say that in any case those packages are going to get old relatively quickly
[22:52:02 CEST] <JEEBsv> so getting used to building OSS multimedia is not a bad idea
[22:52:37 CEST] <relaxed> Marcin_PL: I have static builds if that would be easier.
[22:52:42 CEST] <Marcin_PL> Well I must rethink that, cause the server is quite slow
[22:54:29 CEST] <JEEBsv> not that you build these things daily
[22:54:41 CEST] <JEEBsv> unless you are into keeping up with master HEAD
[22:56:47 CEST] <Marcin_PL> Well, I'll try things out, thanks for help
[23:16:49 CEST] <rizotas> thanks you are very useful
[23:17:00 CEST] <Nolski> How do I concat 3 videos?
[23:29:56 CEST] <relaxed> Nolski: there are numerous ways, which container?
[23:41:46 CEST] <Nolski> relaxed: it depends. They will all be in the same container
[23:53:04 CEST] <Nolski> It seems that 'ffmpeg -i "concat:beginning.mp4|loops.mp4|end.mp4" -c copy looped.mp4' throws No such file or directory
[23:56:34 CEST] <llogan> don't use the concat protocol with those inputs. use concat demuxer or concat filter
[00:00:00 CEST] --- Tue Jun 30 2015