[Ffmpeg-devel-irc] ffmpeg.log.20190103

[burek]

[05:21:44 CET] <johnjay> is there a way to capture the audio of the system but on android with ffmpeg in termux?
[07:32:08 CET] <hungrywolf> can some one tell me how to get AVCodecContext from AVFormatContext
[07:39:41 CET] <hungrywolf> or even just from a stream
[08:42:30 CET] <kepstin> hungrywolf: decoding? just look up the decoder by the stream codec id: https://git.videolan.org/?p=ffmpeg.git;a=blob;f=doc/examples/demuxing_decoding.c;h=69a31a893519cdb91bd1f39cad6b7df02b160e59;hb=HEAD#l167
[08:46:22 CET] <kepstin> for encoding, well, containers usually support multiple codecs. ffmpeg has a "default" audio and video codec for each container, but it's not always the best choice. You'll probably want to look up a specific encoder by name (e.g. "libx264") when encoding.
[09:18:21 CET] <meiamsome> Hello. I am currently trying to use the command line to stream a .mov file into a fake v4l2 camera and a pulseaudio output. What I have so far is that this: `ffmpeg -re -i big_buck_bunny_480p_h264.mov -map 0:0 -flush_packets 1 -vf scale=640x480 -f v4l2 /dev/video0` (output here: https://pastebin.com/qutCvYmf ) will stream to the webcam correctly, and setting up pulse with this: `ffmpeg -re -i big_buck_bunny_480p_h264.mov -map 0:0 -flush_packets 1
[09:18:21 CET] <meiamsome> -vf scale=640x480 -f v4l2 /dev/video0 -map 0:2 -f pulse a` (output here: https://pastebin.com/YjvMVGAf ) works correctly for the audio output, but it causes the webcam video stream to start lagging (It looks like a couple of frames all get pushed out at once and then there is a time gap). Does anyone have any suggestions?
[11:58:34 CET] <meiamsome> I have a HLS file here that appears to have some encoding issues, but I can't work out what the root problem is - does anyone know of a good way to debug these? https://live-test.ugcpro.tv/5c2dd0704e90820203149ef1/master.m3u8
[13:03:56 CET] <hungrywolf> kepstin: thank you
[21:14:48 CET] <analogical> can FFmpeg be used to remove metadata and tags from videofiles?
[21:15:18 CET] <furq> analogical: -map_metadata -1
[21:15:24 CET] <furq> it only removes container metadata though
[21:20:42 CET] <analogical> furq, it worked! Now how do I apply that to all the files in the same directory?
[22:01:51 CET] <seni_> how big of a performance difference does ASM make?
[22:03:14 CET] <Mavrik> In ffmpeg, a lot.
[22:03:42 CET] <Mavrik> As in - don't run encoders/decoders/filters for video without it.\
[22:04:19 CET] <seni_> what about audio?
[22:05:02 CET] <durandal_1707> same
[22:10:34 CET] <seni_> what's a lot? is it 2x slower? because I can live with that? or is it 1000x slower?
[22:11:21 CET] <Mavrik> Well, measure.
[22:11:27 CET] <seni_> also, is there a recommended stable version? getting errors when compiling for android, this is after disabling ASM
[22:12:01 CET] <Mavrik> Since the speed difference is different depending on what codec you're using (and if codec even has ASM code).
[22:12:27 CET] <Mavrik> CPU encoding on Android will be fun :D
[23:54:40 CET] <MichaelJoel> I see how to use the -to but can not find how to force it to begin at a certain time within a video???
[23:56:31 CET] <c_14> -ss
[23:56:57 CET] <MichaelJoel> thanks!
[00:00:00 CET] --- Fri Jan  4 2019