[Ffmpeg-devel-irc] ffmpeg.log.20151030

burek burek021 at gmail.com
Sat Oct 31 02:05:01 CET 2015

[01:00:00 CET] <foreverska> Is there a way to build ffmpeg so I don't have to depend on the system's libraries?  I tried --disable-shared but that doesn't work.
[01:21:53 CET] <iive> foreverska: don't forget , you also need static libraries (*.a) of all system libraries, in addition to the correct options
[01:26:19 CET] <Anonaly> hi, I am using ffmpeg (winff) to convert AVI videos to mp4 so they will play on a usb stick on my TV,
[01:26:27 CET] <Anonaly> hoever the output of ffmpeg is choppy ?
[01:27:45 CET] <Anonaly> actually I am using winFF
[01:27:55 CET] <Anonaly> I don't think I have ffmpeg installed
[01:27:58 CET] <Anonaly> (ubuntu 14.04)
[01:37:01 CET] <DHE> foreverska: I've done exactly that. I chose gentoo to do it because... well, you know.
[01:37:12 CET] <DHE> you usually get static libs anyway
[01:37:48 CET] <furq> foreverska: http://johnvansickle.com/ffmpeg/
[01:38:27 CET] <foreverska> I can't do that because I need NVENC and decklink support
[01:38:58 CET] <DHE> oh... well you're screwed then
[01:39:11 CET] <DHE> best you can hope for is reduced library usage. just basics like glibc and the opencl stuff
[05:42:14 CET] <foreverska> tee is pretty tough to use
[05:49:12 CET] <foreverska> make sure I'm barking up the right terminal switch, I need to grab input from a card, throw it through NVENC and then resize it three ways into three different files.  tee is the key, right?
[10:52:22 CET] <dominikm> Hi, I'm a little bit confused about avcodec_decode_audio4 function. As it can not read whole AVPacket it needs to be called again with AVPacket containing remaining data but I'm really not sure if I need to shift pointer in AVPacket or just reuse same AVPacket. Can somebody please help me with it? I've also tried to find the answer in http://dranger.com/ffmpeg/tutorial03.html but audio_pkt_data variable there is even more confusing as it does just noth
[11:11:46 CET] <Mavrik> dominikm, yes, you need to move pkt.data pointer and reduse pkt.size field if you're doing inline
[11:12:08 CET] <Mavrik> also, setting pkt.dts and pkt.pts to AV_NOPTS_VALUE after first decode helped in some broken decoder cases.
[11:13:11 CET] <Mavrik> dominikm, sample: http://pastebin.ca/3226312
[12:28:24 CET] <dominikm> Mavrik: great, thank you very much
[13:03:13 CET] <bencc> can I call ffprobe show_frames for only part of a video?
[13:03:42 CET] <bencc> let's say from 00:01:00 to 0:01:30 seconds
[17:22:39 CET] <hendry> what's the most efficient container format (un-encoded) for ffmpeg to output a screencast to?
[17:23:25 CET] <Mavrik> hendry, do you care for filesize? are you going to reencode later? with what?
[17:23:49 CET] <hendry> Mavrik: file size is not a major issue, i am going to re-encode it later
[17:24:28 CET] <Mavrik> I found losless huffyuv to be rather good and very light on CPU
[17:24:36 CET] <Mavrik> But it's openable mostly only by ffmpeg.
[17:26:18 CET] <hendry> Mavrik: that's fine. what would the "container" be named and the "encoder" i wonder? http://s.natalian.org/2015-10-31/obs-ffpmeg.png
[17:26:42 CET] <Mavrik> huffyuv/avi
[17:27:22 CET] <Mavrik> There's also ffv1 which is losless as well.
[17:31:45 CET] <hendry> Mavrik: thanks, yes the file size is pretty big now :)
[17:32:28 CET] <hendry> damn, for some reason my audio is cut off near the end
[17:33:08 CET] <hendry> my default audio encoder is libmp3lame, is there a better choice?
[17:33:34 CET] <furq> if you don't care about filesize then you might as well stick with pcm
[17:35:19 CET] <hendry> there is lot of different types of pcm*
[17:36:14 CET] <hendry> furq: http://s.natalian.org/2015-10-31/which-pcm.png
[17:37:25 CET] <Mavrik> PCM doesn't play well with all containers though :/
[17:38:04 CET] <hendry> is there something like huffyuv, but not quite as large files? something between it and h264 ultrafast?
[17:39:22 CET] <hendry> pcm_s32le seemed to work
[17:40:27 CET] <Mavrik> hendry, as I said, try ffv1
[17:42:04 CET] <hendry> Mavrik: darn, ffv1 was laggy
[17:51:28 CET] <furq> if you want slightly larger files and higher quality than x264 ultrafast then why not try x264 veryfast
[17:51:38 CET] <furq> or superfast, whichever is one up from ultrafast
[18:30:17 CET] <StephenS> hey fellas, what would be the correct way to rotate/transform a video which has rotation 270 by default, since it has been taken with front camera on android..?
[18:30:37 CET] <StephenS> When I used back camera I usually did rotate = 0, but for this 270 rotation, it doesnt work
[18:40:52 CET] <c_14> Rotate does radians, use 3PI/2 or transpose or hflip/vflip or somethnig
[18:44:47 CET] <StephenS> c_14, I use transpose, but not sure what rotation to set
[18:45:13 CET] <StephenS> currently I have ffmpeg -i vid.mp4 -vf transpose=1 -metadata:s:v:0 rotate=0 -strict -2 outme.mp4
[18:45:33 CET] <StephenS> while this works for videos recorded with back camera, for front camera which have default rotation tag 270, this does not work
[18:45:46 CET] <StephenS> it's like it doesnt even rotate, I need to transform it/convert and then to remove rotation tag
[18:46:01 CET] <StephenS> I guess rotate=0 is fine, but transpose?
[18:46:02 CET] <c_14> If it has a rotation tag, just don't set anything. Recent versions of ffmpeg'll rotate it automatically.
[18:47:40 CET] <StephenS> c_14, well I just want to remove rotation tag, because browsers are reading video differently, which I do with rotation=0, however my video still remain "in rotation clockwise"
[18:47:44 CET] <StephenS> what to set for transpose?
[18:48:58 CET] <StephenS> I can see here https://ffmpeg.org/ffmpeg-filters.html#transpose
[18:49:09 CET] <StephenS> will 0, 4, cclock_flip work?
[18:50:24 CET] <c_14> You want clock_flip
[18:50:35 CET] <StephenS> ok, whats the syntax?
[18:50:45 CET] <c_14> transpose=clock_flip
[18:51:34 CET] <StephenS> that worked, thanks a lot!
[18:51:41 CET] <StephenS> You just saved me 5 hours of debugging :)
[18:56:51 CET] <StephenS> c_14, is it possible to add watermark image on video while flipping/transposing video? so I dont have two processes doing similar stuff?
[18:59:02 CET] <c_14> use the overlay filter in a filtergraph
[19:03:01 CET] <StephenS> filter graph or filter_complex?
[19:07:06 CET] <c_14> filter_complex is the option, but a filter_complex is a filter graph
[19:11:28 CET] <StephenS> ok Ill check that tmrw morning, seems not too complicated.
[21:44:27 CET] <shenkz> SOrry for the dumb question, but what metadata format does FLAC use? ID3v2.4?
[21:45:07 CET] <shenkz> And is it okay to bundle ffmpeg with an application's installer?  It's for internal and personal use only
[21:47:07 CET] <c_14> FLAC uses mainly vorbis tags (though you can add id3 tags and most players will read them)
[21:47:20 CET] <c_14> shenkz: are you modifying ffmpeg?
[21:47:38 CET] <c_14> If no, it's fine as long as you also distribute/offer to distribute the ffmpeg source code through the same means.
[21:47:44 CET] <c_14> Note: ianal
[00:00:00 CET] --- Sat Oct 31 2015

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