[Ffmpeg-devel-irc] ffmpeg.log.20191017

Fri Oct 18 03:05:05 EEST 2019

[00:06:26 CEST] <ironm> kepstin, it looks like I have to set CRF to 0 (The range of the CRF scale is 051, where 0 is lossless, 23 is the default, and 51 is worst quality possible)
[00:07:41 CEST] <kepstin> Why would you want to do that? Most people don't want or need lossless, and it has less player compatibility
[00:08:09 CEST] <ironm> kepstin, I would like to keep the quality of mp4 input files
[00:08:50 CEST] <cehoyos> Test with the default, if the quality is not good enough, lower the value.
[00:08:53 CEST] <ironm> what is the right syntax to set CRV? .. such one does not work :   -map "[out]" -CFR "0" output_col_2x2.mp4
[00:09:02 CEST] <cehoyos> Do not use 0 unless you know exactly what you are doing (which you do not)
[00:09:28 CEST] <ironm> cehoyos, thank you, I did. The size of the output is approx two times smaller
[00:09:45 CEST] <ironm> with the default
[00:09:45 CEST] <cehoyos> The size is *completely* irrelevant.
[00:09:48 CEST] <furq> don't use 0 unless you want it to be 50 times bigger
[00:09:56 CEST] <cehoyos> What is relevant is your visual experience
[00:10:06 CEST] <ironm> furq, hi, thank you.
[00:10:21 CEST] <ironm> what is the right syntax to set CRF to 0 ?
[00:11:02 CEST] <ironm> cehoyos, I don't mind (size) as there are short clips (15 to 20 seconds only)
[00:11:10 CEST] <cehoyos> To say it differently: It could be that the size doubles and the quality is still not good enough, in this case the hardware encoder cannot nearly do such a good work as your software encoder so a smaller file with identical quality is not a surprise.
[00:11:20 CEST] <ironm> Highest quality is most important for me
[00:11:31 CEST] <cehoyos> You do and you want your output file to play in completely outdated players.
[00:11:48 CEST] <cehoyos> Like all current proprietary players
[00:11:51 CEST] <ironm> cehoyos, I do not decode and encode
[00:11:58 CEST] <cehoyos> Yes, you do
[00:12:13 CEST] <kepstin> You should look at the resulting video, and if it looks not good enough, try lowering the crf value a few steps. The option name is -crf
[00:12:18 CEST] <cehoyos> (That's what I meant when I wrote above "which you do not")
[00:12:30 CEST] <ironm> cehoyos, aas I understood it is kind of one to one copy
[00:12:35 CEST] <cehoyos> No
[00:12:38 CEST] <kepstin> It is not.
[00:13:07 CEST] <ironm> 4 x FullHD mp4 inp ut => 4K mp4 output
[00:13:09 CEST] <cehoyos> Please understand that many of the people who post here understand a lot more than you about using FFmpeg, so not following their advice will not help you
[00:13:49 CEST] <kepstin> You're making a brand new video which displays images taken from the decoded old videos, and then has to be newly encoded from scratch.
[00:13:54 CEST] <ironm> cehoyos, I follow all of your advises and I am really thankful
[00:14:26 CEST] <ironm> kepstin, the input are mp4 files from GoPro7 hero black
[00:14:38 CEST] <cehoyos> I believe you already told us
[00:14:40 CEST] <kepstin> ironm: that's not relevant
[00:14:46 CEST] <ironm> I see
[00:15:01 CEST] <kepstin> Doesn't matter where the videos are from, you're making a new video
[00:15:23 CEST] <ironm> yes, it is a new video
[00:16:23 CEST] <cehoyos> Since the videos are so short, you could also encode three videos with crf 28, crf 23 and crf 20 to see the difference. Like this you can decide which value suits you.
[00:16:54 CEST] <ironm> kepstin, is ffmpeg capable to recalculate the "wide" Video mode of GoPro7 (4k / 60fps) to a kind of linear mode (4K / 60fps)
[00:17:19 CEST] <cehoyos> The player should allow slow playback to make seeing the difference easier.
[00:17:42 CEST] <ironm> cehoyos, I afraid, GoPro7 does not support those codecs
[00:17:49 CEST] <kepstin> ironm: I don't know what you're taking about. Is this a color space thing?
[00:18:02 CEST] <cehoyos> Which codecs?
[00:18:09 CEST] <ironm> kepstin, no, the geometry of the video
[00:18:57 CEST] <kepstin> You can change video geometry with ffmpeg filters if you know what changes you need to make
[00:19:09 CEST] <cehoyos> But there is no change from 4k to 4k...
[00:19:38 CEST] <ironm> cehoyos, Selected video codec: [ffh264] vfm: ffmpeg (FFmpeg H.264)
[00:19:59 CEST] <cehoyos> I would expect that this is also the codec that the GoPro uses, no?
[00:20:04 CEST] <ironm> kepstin, GoPro7 action cameras have small lenses
[00:20:15 CEST] <cehoyos> But my question was more how your comment was related to my suggestion...
[00:20:22 CEST] <ironm> so recordings in wide mode do not look linear
[00:20:49 CEST] <cehoyos> There is a filter that does a correction of lense "errors"
[00:20:59 CEST] <kepstin> Oh, wide angle lens with a fisheye effect
[00:21:11 CEST] <ironm> cehoyos, No, those codecs are not supported (GoPro7 actin camera )
[00:21:19 CEST] <cehoyos> Which codecs?
[00:21:22 CEST] <ironm> kepstin, exactly
[00:22:06 CEST] <ironm> cehoyos, I see .. I misunderstood -- "crf 28, crf 23 and crf 20"
[00:22:09 CEST] <ironm> sorry
[00:22:27 CEST] <cehoyos> You should really test those values
[00:22:53 CEST] <ironm> cehoyos, what ist the syntax to set those crf  values to 0 etc ?
[00:23:14 CEST] <ironm> cehoyos,  how to set them on the command line ?
[00:23:23 CEST] <cehoyos> You do not want to set the value to 0, you want to test the default value and values that are slightly lower.
[00:23:38 CEST] <cehoyos> But only after visual inspection.
[00:23:42 CEST] <kepstin> Keep in mind that x264 is a better encoder than the one built into the GoPro so it can make smaller videos that don't look worse
[00:23:54 CEST] <cehoyos> kepstin: He doesn't believe that
[00:24:12 CEST] <ironm> kepstin, yes. I can  follow now
[00:24:46 CEST] <ironm> cehoyos, how can I set crf value to 1 ?
[00:25:05 CEST] <cehoyos> I go to bed now, thank you for the entertainment!
[00:25:18 CEST] <ironm> cehoyos, what do I not believe ?
[00:25:43 CEST] <ironm> have a good sleep cehoyos ! .. and thanks a lot
[00:26:27 CEST] <ironm> kepstin,  at the moment I am quite happy to create 4K output from FullHD inputs
[00:27:13 CEST] <kepstin> ironm: the default crf is 23. If you use your eyes to look at the video and its not good enough, lower it by a small amount, to say 20 or 18
[00:28:21 CEST] <ironm> kepstin, thanks a lot. My problem is that I do not know how to change the crf value on the command line level
[00:29:15 CEST] <kepstin> I've already told you, and other people have linked docs that say
[00:29:31 CEST] <ironm> *_*
[00:29:42 CEST] <ironm> I have checked some doceds
[00:29:56 CEST] <ironm> docs, but did not got the right syntax
[00:30:58 CEST] <ironm> s o r r y
[00:42:18 CEST] <ironm> kepstin, thank you very much for your help. gn8
[01:05:17 CEST] <Zeioth> If I'm obligated to reencode an MP3, what's the best way to avoid losing quality?
[01:06:41 CEST] <klaxa> a lossless codec :^)
[01:08:31 CEST] <pink_mist> why do you need to reëncode it in the first place?
[01:10:07 CEST] <Zeioth> I'm appliying a fade effect to the audio
[01:10:14 CEST] <Zeioth> apparently it cannot be done without reencoding
[01:10:26 CEST] <pink_mist> indeed it can't
[01:10:50 CEST] <pink_mist> I'd suggest trying to find a lossless version of the original audio, and reëncode that instead
[01:10:56 CEST] <pink_mist> if you can
[01:11:02 CEST] <pink_mist> otherwise, what klaxa said
[01:11:20 CEST] <Zeioth> I'm afraid it's not an option in my case
[01:12:02 CEST] <Zeioth> I'm gonna try with the parameter -b:a 320k
[01:13:22 CEST] <furq> use -q:a 0
[01:16:23 CEST] <Zeioth> that's what I was looking for thanks
[01:26:08 CEST] <Zeioth> (Actually I can use FLAC, thank you for noting that too)
[02:35:17 CEST] <Retal> Hello guys, when i trancoding live streams some streams using 350MiB CUDA memory, as result i have error: cu->cuCtxCreate(&hwctx->cuda_ctx, 4, cu_device) failed -> CUDA_ERROR_OUT_OF_MEMORY: out of memory.
[02:35:17 CEST] <Retal> Is it possible decrease CUDA memory usage?
[04:23:52 CEST] <Fenrirthviti> Retal: That can be a red herring error, it can occur when the GPU is at high load as well.
[05:43:36 CEST] <auser0> hey guys
[05:43:39 CEST] <auser0> what does that mean
[05:43:40 CEST] <auser0> adts @ 0x55b6966c0380] Only AAC streams can be muxed by the ADTS muxer
[05:43:41 CEST] <auser0> Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
[05:44:29 CEST] <furq> pastebin the command and full output
[06:25:19 CEST] <lain98> I have a video thats reported 30 fps by mediainfo. I checked the timestamps using ffprobe -show_frames and the timestamps appear to be consistent with 30fps. But ffmpeg reports the video as slightly more than fps, like 30.018 fps. Could this be an issue with fffmpeg demuxing or is it just incorrectly written stream header information in the file ?
[06:31:25 CEST] <lain98> also whats the difference between AVStream->r_frame_rate and AVStream->avg_frame_rate
[11:52:25 CEST] <Stemby> Hi, is it possible to merge these following two steps in a single step?
[11:52:33 CEST] <Stemby> $ ffmpeg -i myvideo_screencast.avi -filter:v "crop=1280:960" -c:v utvideo -c:a copy myvideo_video.avi
[11:52:41 CEST] <Stemby> $ ffmpeg -i myvideo_video.avi -vf scale=-1:1080 -c:v utvideo -c:a copy myvideo_big.avi
[11:52:54 CEST] <durandal_1707> 3yes
[11:53:25 CEST] <Stemby> durandal_1707: hi, thank you. How?
[11:53:43 CEST] <durandal_1707> consult doccumentation
[11:53:52 CEST] <Stemby> done
[11:54:29 CEST] <Stemby> probably I didn't consult the right documentation
[11:54:58 CEST] <Stemby> durandal_1707: can you pass me the link, please?
[11:56:28 CEST] <durandal_1707> Stemby: http://trac.ffmpeg.org/wiki/FilteringGuide
[12:05:02 CEST] <Stemby> durandal_1707: thank you, but I can't still find how to do what I need. I tried "ffmpeg -i myvideo_screencast.avi -vf scale=-1:1080 -filter:v "crop=1280:960" -c:v utvideo -c:a copy myvideo_video.avi" and "ffmpeg -i myvideo_screencast.avi -filter:v "crop=1280:960" -vf scale=-1:1080 -c:v utvideo -c:a copy myvideo_video.avi"
[12:05:13 CEST] <Stemby> In both, I get a wrong result
[12:07:06 CEST] <durandal_1707> Stemby: try harder reading and understanding documentation
[12:07:25 CEST] <durandal_1707> expecially examples
[12:18:45 CEST] <Stemby> durandal_1707: done
[12:19:09 CEST] <Stemby> durandal_1707: $ ffmpeg -i myvideo_screencast.avi -vf "crop=1280:960, scale=-1:1080" -c:v utvideo -c:a copy myvideo_video.avi
[12:19:15 CEST] <Stemby> durandal_1707: thank you
[16:26:53 CEST] <lordarkmemo> hi friends.  Im using ffmpeg to fragment a save in different file names.  like this ffmpeg -i input.mp4 -map 0 -c copy -f segment -segment_time 600 output_%03d.mp4. The problem is that is the video source is lose or if i cancel the ffmpeg command in cant reproduce the current file.  Is possible to add a flag than even with ffmpeg error the video file can be view?
[16:27:25 CEST] <kepstin> lordarkmemo: use a different format instead of mp4 as the output - try mkv.
[16:28:32 CEST] <lordarkmemo> kepstin: ok, but my video source is a video camera, that have default mp4.  I want to avoid transcoding.
[16:28:46 CEST] <lordarkmemo> kepstin: but why mkv?,
[16:29:03 CEST] <kepstin> mkv doesn't have the issue where a file that's only partially written can't be played
[16:29:12 CEST] <lordarkmemo> kepstin: ok
[16:29:23 CEST] <kepstin> no transcoding needed, it will work fine with -c copy
[16:31:02 CEST] <lordarkmemo> kepstin: ok perfect.  So this way ffmpeg -i input.mp4 -map 0 -c copy -f segment -segment_time 600 output_%03d.mkv
[17:38:16 CEST] <lordarkmemo> kepstin: thank you, it works!
[17:38:39 CEST] <lordarkmemo> kepstin: mkv is as efficient as mp4 regarding compression?
[17:39:22 CEST] <DHE> it's a container, not a codec
[17:39:30 CEST] <DHE> the difference will be maybe a percentage
[17:45:28 CEST] <lordarkmemo> DHE: thank you
[18:37:43 CEST] <Atlenohen> Hello
[18:38:21 CEST] <Atlenohen> Does ffmpeg have some kind of filter or analysis that detects amount of change from frame to frame?
[18:38:33 CEST] <Atlenohen> that one could use as a condition?
[00:00:00 CEST] --- Fri Oct 18 2019