[Ffmpeg-devel-irc] ffmpeg.log.20180927

[burek]

[13:43:36 CEST] <odinsbane> I used ffmpeg -i file.mov -c:v copy file.avi I'm not sure if anything changed.
[15:27:51 CEST] <Accord> so I created an audio file filled with silence with "ffmpeg -y -f lavfi -i anullsrc=channel_layout=stereo:sample_rate=44100"
[15:28:24 CEST] <Accord> then I ran silencedetect and all I got is silence_start
[15:28:37 CEST] <Accord> does that mean that it's silent until the end or it's just not working?
[15:30:56 CEST] <Accord> guess it just means it's till the end
[15:31:16 CEST] <Accord> I've concatenated the silent file with a normal one and silencedetect found it
[15:49:49 CEST] <durandal_1707> Accord: you are using old version of ffmpeg, in master that bug have been fixed
[15:49:59 CEST] <Accord> ah, ok
[18:06:21 CEST] <analogical> does anyone know how extract files from a SACD iso-file?
[18:16:27 CEST] <furq> analogical: https://github.com/sacd-ripper/sacd-ripper
[18:16:36 CEST] <furq> sacd_extract from that
[18:19:30 CEST] <analogical> furq, thank you but I'm looking for a binary not source code
[18:20:01 CEST] <furq> there are windows binaries in the release section
[18:26:39 CEST] <JEEB> do note that they are built by a 3rd party
[18:26:45 CEST] <JEEB> oh, wrong software
[18:26:48 CEST] <JEEB> sorry for that
[19:13:24 CEST] <^Neo> hello friends, can someone suggest how to upconvert from p24 to p29.97/p59.94 with repeat fields signaled in the output? Is just setting -g 29.97/59.94 sufficient?
[19:21:06 CEST] <furq> ^Neo: if you mean -r then that'll just repeat frames
[19:21:18 CEST] <furq> i'm not sure that ffmpeg can do it without reencoding
[19:22:18 CEST] <furq> i know dgpulldown on windows can do it for mpeg2video
[19:22:36 CEST] <furq> i've not needed to do this since tools starting with "dg" were still relevant
[19:50:49 CEST] <cfaber> Hi folks, I'm trying to figure out a fast way to dump single frames throughout a video file. I'm using the following commandline: ffmpeg -i test.mkv -ss 00:19:26.000 -vframes 1 out.jpg the problem is that htis takes about 4 minutes on a resonably fast system for a video that's only about 20 minutes long, I can perform a similar action in under a second with mplayer -vo:png dump. So what am I doing wrong and how can I speed this process
[19:51:23 CEST] <cfaber> The time it takes to dump the frame depends on how far into the video I'm seeking
[19:52:17 CEST] <kepstin> cfaber: move the -ss before the -i
[19:52:27 CEST] <cfaber> ahha
[19:53:27 CEST] <kepstin> -ss before -i means seek, it's quick. -ss after -i means "decode and discard until this timestamp", it's slow
[19:54:17 CEST] <kepstin> specifically, that's -ss as an input option vs. as an output option.
[19:54:20 CEST] <cfaber> great, that did it, thank you!
[19:54:27 CEST] <cfaber> right makes sense
[19:54:39 CEST] <cfaber> I didn't know that the argument order was that sensitive
[19:54:45 CEST] <cfaber> but makes perfect sense
[19:54:55 CEST] <cfaber> thanks kepstin
[19:56:53 CEST] <kepstin> for most ffmpeg options, the location in the command line is important. In general, you put a particular option in front of the input or output file that it's supposed to affect
[20:54:18 CEST] <^Neo> furq: Thanks! yes, I meant -r. So will I see repeat_pict be non-zero in this case?
[20:59:59 CEST] <JEEB> -r would just actually change the frame rate
[21:00:09 CEST] <JEEB> if you need soft pulldown you'd have to set something in the video encoder
[21:06:59 CEST] <furq> if you're reencoding with x264 then -x264-params pulldown=32
[21:08:03 CEST] <furq> i'm guessing you need it for mpeg2video though
[21:09:13 CEST] <^Neo> ah! that's exactly what I wanted. Great! TYVM!
[23:00:48 CEST] <Filarius> I do hobby project using 8x8 DCT from x264 sources and I have questions, I wrote my questions at #x264dev several times but all was ignored...
[23:01:45 CEST] <Filarius> last question is about I copy 8x8 DCT and IDCT to Python and I found its far not lossless, is it my mistake or it how it must be
[23:02:40 CEST] <Filarius> *made Python implementation of that algorthim using x264 sources
[00:00:00 CEST] --- Fri Sep 28 2018