[Ffmpeg-devel-irc] ffmpeg.log.20191222

[burek]

[03:25:50 CET] <causasui> I've been making 'infinite loop' videos with `-filter-complex "[0]reverse[r];[0][r]concat"` and it works well. However I have a new use case, where I want to make such a loop with just a segment of a video. but passing `-ss` or `-st` switches seems to cause the filter to be ignored. do I need to do a streamcopy step before I run this filter?
[03:49:49 CET] <causasui> that seems to do it yes
[04:12:33 CET] <causasui> now my problem is that when I do `-ss '20'` it seems to work but when I do `-ss '21'` or even `-ss '20.05'` there doesn't seem to be any video in the output
[17:38:07 CET] <snooky> hi all
[20:44:23 CET] <Protected> Good evening. I'm experiencing a baffling issue when creating mpeg-dash files (format 'dash'). According to the documentation, "The segment filename might contain (..) an ffmpeg-specific "$ext$" identifier (...) ffmpeg will replace (...) with muxing formats extensions such as mp4, webm etc.". I'm using that in the segment filename templates, but ffmpeg copies $ext$ to the filename verbatim.
[20:44:23 CET] <Protected> Is that a really recent feature? I'm using ffmpeg 4.1.4
[22:03:46 CET] <raisen> How can I update the streaming video once source.png changes on this command: ffmpeg -f image2 -loop 1 -i source.png -f mpegts  "udp://127.0.0.1:3333?listen" ? I tried to cat > source.png, rename but didn't work
[22:11:11 CET] <BtbN> I don't think it will ever re-read the file.
[22:12:15 CET] <raisen> BtbN: that makes sense why it wouldn't work. Is there a way to reread the file?
[22:13:02 CET] <TheAMM> One idea is to create a named pipe and then write the image into it every time you want to send a new one
[22:13:23 CET] <TheAMM> or maybe even something like (while :; do cat source.png: sleep 1; done) | ffmpeg -i - ...
[22:13:33 CET] <TheAMM> even just*
[22:13:48 CET] <raisen> hmm, let me try.. very beginning ffmpeg user here
[22:23:15 CET] <raisen> hmm, ffmpeg is complaining that the output file is empty and no video is played when i run ffplay. I tried with: (while :; do cat source.png; sleep 1; done) | ffmpeg -i - -f mpegts "udp://127.0.0.1:3333?listen"
[22:23:26 CET] <Hello71> mpng? lol
[22:24:08 CET] <TheAMM> Try -f image2pipe -i -
[22:24:27 CET] <TheAMM> can't guide you to the end though, good luck if you're very beginning user, maybe someone else has a moment
[22:25:35 CET] <raisen> TheAMM: Thanks for your help. I got the same result. I'll post on the mailing list
[23:25:15 CET] <Abbott> I am trying to concatenate video files and I am using this command: drew at yoga% ffmpeg -i rare1.mp4 -i black1.mp4 -i hunt.mp4 -i black1.mp4 -i dare.mp4 -filter_complex "[0:v:0][0:a:0][1:v:0][1:a:0][2:v:0][2:a:0][3:v:0][3:a:0][4:v:0][4:a:0][5:v:0][5:a:0]concat=n=5:v=1:a=1[outv][outa]" -map "[outv]" -map "[outa]" final.mp4
[23:26:01 CET] <Abbott> but I get an error: https://bpaste.net/raw/OAXFW
[23:26:09 CET] <Abbott> how can I propery concatenate all these files
[23:26:58 CET] <nicolas17> you're giving it 6 inputs: 0 1 2 3 4 5
[23:28:07 CET] <nicolas17> I don't think [5] corresponds to any actual input file there
[23:28:12 CET] <Abbott> oh, you're right
[23:28:26 CET] <Abbott> removing that I get paste that error, but then I get an error about the files being different resolutions
[23:32:39 CET] <Abbott> ffmpeg -i rare1.mp4 -i black1.mp4 -i hunt.mp4 -i black1.mp4 -i dare.mp4 -filter_complex "[0:v:0][0:a:0][1:v:0][1:a:0][2:v:0][2:a:0][3:v:0][3:a:0][4:v:0][4:a:0][5:v:0][5:a:0]concat=n=5:v=1:a=1[outv][outa],scale=w=1280:h=720" -map "[outv]" -map "[outa]" final.mp4
[23:33:00 CET] <Abbott> that doesn't work, how would I add the scale filter to that command to scale all of the inputs before the concat filter
[23:33:47 CET] <nicolas17> [0]scale=whatever[scaled0]; and then feed scaled0 instead of 0 to the concat filter
[23:34:09 CET] <nicolas17> each video will need its own scale filter
[23:34:13 CET] <nicolas17> well, the ones that need scaling
[23:37:35 CET] <Abbott> I'm not sure where to put that
[23:37:37 CET] <Abbott> ffmpeg -i rare1.mp4 -i black1.mp4 -i hunt.mp4 -i black1.mp4 -i dare.mp4 -filter_complex "[0]scale=w=1280:h=720[scaled0][1]scale=w=1280:h720[scaled1][2]scale=w=1280:h=720[scaled2][3]scale=w=1280:h=720[scaled3][4]scale=w=1280:h=720[scaled4],[scaled0:v:0][0:a:0][scaled1:v:0][1:a:0][scaled2:v:0][2:a:0][scaled3:v:0][3:a:0][scaled4:v:0][4:a:0]concat=n=5:v=1:a=1[outv][outa]" -map "[outv]" -map "[outa]"
[23:37:39 CET] <Abbott> final.mp4
[23:39:32 CET] <nicolas17> you need to separate with semicolons
[23:39:41 CET] <nicolas17> [inputs]filter[outputs];[inputs]filter[outputs];[inputs]filter[outputs]
[23:43:07 CET] <shibboleth> is it normal for -hwaccel to only show cuda/cuvid and not nvdec/nvenc?
[23:44:20 CET] <BtbN> cuvid is legacy, and I'm pretty sure at this point only maps directly to cuda.
[23:51:16 CET] <Abbott> ok got it. thanks nicolas17
[23:58:54 CET] <Abbott> If I want to use 2 pass encoding to make a 1.44M file out of a 30 second clip, I figure I use a bitrate of 1440K/30s = 48k, right? but the file I got out was 184k
[23:59:28 CET] <nicolas17> no, you're mixing bytes and bits
[00:00:00 CET] --- Mon Dec 23 2019