[Ffmpeg-devel-irc] ffmpeg.log.20190207

[burek]

[00:32:21 CET] <DHE> friendofafriend: if it's x264, you might be able to extract the exact settings. otherwise ffprobe can only make high level guesses like the profile
[02:34:59 CET] <nativetexan> howdy
[02:39:59 CET] <saml_> how can I loop video until audio ends?
[06:25:17 CET] <dongs> hithere, why i cannot encode 5760x2880 video with nvenc? https://developer.nvidia.com/video-encode-decode-gpu-support-matrix says anything in pascal family should be able to do 8K. is it for hevc only?
[06:26:52 CET] <dongs> ok yeah hevc only. neverm ind.
[09:55:30 CET] <drag88> Hi, im getting an error during 10bit encoding via ffmpeg/x264, https://pastebin.com/n02558zK
[09:55:42 CET] <drag88> Unable to find a suitable output format for 'high10'
[09:55:52 CET] <drag88> Zerano builds should have 10bit support
[09:58:09 CET] <JEEB> that error makes it sound like high10 is a file name and as it doesn't have an extension lavf can't guess which container format you want :P
[10:17:23 CET] <drag88> @JEEB, mind taking a look at my syntax in the paste?
[10:36:22 CET] <JEEB> drag88: unfortunately not since $dayjob
[10:39:04 CET] <drag88> ok
[10:39:29 CET] <drag88> for reference: ffmpeg -loglevel verbose -i 2398.mov -pix_fmt yuv420p10le -codec:v libx264  -x264opts -profile:v high10 -preset veryslow -crf 10 -c:a copy -map 0:v -map 0:a -y TEST_CRF10_veryslow.mkv
[10:40:10 CET] <JEEB> yea, the -x264opts is where it starts going wrong :P
[10:40:17 CET] <JEEB> because -x264opts -profile:v
[10:40:32 CET] <JEEB> then high10 ends up being not an option but output path
[10:40:55 CET] <JEEB> so just remove -x264opts since you're not setting any options with it
[10:45:12 CET] <drag88> isnt -profile:v part of the x264opts?
[10:46:03 CET] <drag88> ure right.. i allways thought that it was a part of x264opts.. removed it = works
[17:25:43 CET] <th3_v0ice> How can I check if frame had decoding errors when it exits the decoder?
[17:28:28 CET] <DHE> frame->flags & AV_FRAME_FLAG_CORRUPT
[17:33:25 CET] <Mavrik> Is that even used?
[17:47:30 CET] <sybariten> Hello
[17:48:02 CET] <sybariten> Is it even possible to make estimations about what filesize an x minute video will have, given that its using a still picture all through it?
[17:48:26 CET] <sybariten> Where the pic dimensions are known ofcourse. I'm asking this for a podcast issue, and regarding storage at youtube
[17:51:11 CET] <kepstin> hmm, you don't have to regard storage at youtube, that's all on google :)
[17:51:34 CET] <kepstin> (they encode multiple formats at different bitrate in multiple codecs, so filesize is kinda meaningless there)
[17:57:59 CET] <furq> it'll almost certainly be smaller than the audio
[18:03:09 CET] <sybariten> kepstin: hmmm weeeelll.... i suppose part of me just wanted to not waste unnecessary bandwidth or storage
[18:03:44 CET] <sybariten> furq: hmm how so? I was thinking of taking the mp3 files of my podcast and just throw them into some video container with a still image
[18:04:14 CET] <kepstin> for unnecessary bandwidth, that's all on you - you just have to encode with settings (long gop) that minimize upload size
[18:04:25 CET] <kepstin> youtube's gonna re-encode it after they receive it anyways
[18:04:50 CET] <kepstin> their outgoing bandwidth is something you have no say over whatsoever
[18:05:40 CET] <th3_v0ice> DHE: Thanks. I will use that.
[18:06:32 CET] <th3_v0ice> Is it possible that the number of streams in AVFormatContext->nb_streams changes during the av_read_frame operation?
[18:07:08 CET] <furq> sybariten: ffmpeg -loop 1 -framerate 6 -i foo.png -i bar.mp3 -shortest -tune stillimage -preset veryfast -pix_fmt yuv420p -vf scale=-2:720 -g 120 -c:a copy baz.mkv
[18:07:14 CET] <furq> that's the one i use
[18:07:16 CET] <TheAMM> th3_v0ice: Multimedia is hell, so yes
[18:07:26 CET] <TheAMM> AFAIK, anyhow, but iirc that's mostly just on .ts
[18:07:44 CET] <sybariten> kepstin: really? I'm not sure i grasp this. I'm guessing long GOP means i should code it in a way that there are very few, hm, intraframes or whatever they are called?
[18:07:47 CET] <TheAMM> Someone will explain how I'm wrong, soon
[18:08:02 CET] <furq> i'm pretty sure youtube reencodes everything with 5-second gops anyway
[18:08:09 CET] <furq> so it doesn't matter for vod
[18:08:35 CET] <kepstin> sybariten: yeah. This basically means setting -g to a big value. The only reason to do this is to make the upload to youtube go faster.
[18:08:51 CET] <furq> it doesn't make as much of a difference as you'd think
[18:09:13 CET] <sybariten> kepstin: but lets say i have a 10 minute 100 megabyte mp4 file at HD size and a bitrate of 3 megabits. (I'm just making this up). What do you mean happens once it reaches youtube?
[18:09:18 CET] <furq> but if you're not going to use the file locally at all then you might as well
[18:09:18 CET] <kepstin> hmm. in combination with a low framerate, too... but yeah, gains are marginal
[18:09:30 CET] <furq> well youtube's minimum framerate is 6 for some reason
[18:09:32 CET] <furq> so i just give them that
[18:09:36 CET] <kepstin> sybariten: youtube re-encodes it using secret settings and it might get bigger or smaller
[18:09:41 CET] <sybariten> aha
[18:09:58 CET] <th3_v0ice> TheAMM: I am working with .ts file now, never expected this number to change actually.
[18:10:15 CET] <furq> sybariten: you'll be talking like 50kbps for a still image at 720p
[18:10:22 CET] <sybariten> ok
[18:10:27 CET] <kepstin> th3_v0ice: with ts files, ffmpeg by default only probes partway into the file, and ts can add/remove streams at any point
[18:10:44 CET] <kepstin> th3_v0ice: you can increase the probe size/duration so it finds more streams in the initial probe sometimes
[18:11:12 CET] <kevinnn> Hi, does anyone have a short simple example of how to use libav to transmit h264 frames via rtsp
[18:11:36 CET] <kevinnn> rephrased: I want an example of how to set up a simple rtsp server using libav
[18:13:05 CET] <th3_v0ice> kepstin: It becames very tiresome handling all of those changes actually. Is there a trigger that can help me call my code and update my allocated fields? Because I am allocating some arrays based on the nb_streams. Once that changes I am actually calling invalid pointers.
[18:13:15 CET] <sybariten> furq: thanks for the command line!
[18:14:07 CET] <sybariten> but lets just say for local storage reasons then: does the video filesize change much in a situation like this, between 1280x720 and 1920x1080 as a still image?
[18:14:18 CET] <sybariten> s/change/grow
[18:14:25 CET] <furq> it'd change a bit
[18:14:38 CET] <sybariten> but not in a magnitude of double perhaps
[18:14:48 CET] <furq> but you already get the best audio quality on youtube if you upload at 720p
[18:14:53 CET] <furq> so i don't see the point of going higher
[18:15:19 CET] <sybariten> nah, i was kind of thinking of using a 720 pixel image.
[18:18:42 CET] <kevinnn> also because the lack of good results on google I am questioning now if libav is even capable of doing an rtsp server...
[18:21:24 CET] Action: th3_v0ice slaps Jervis_ around a bit with a large trout
[19:00:34 CET] <trashPanda_> Hey, I have kinda a dumb question.  If I wanted to describe the difference between ffmpeg and libav, how would I characterize it?  Where does ffmpeg end and libav code start?  There appear to be two githubs, one for libav and one for ffmpeg but both have the same files inside.
[19:16:38 CET] <BtbN> libav is a separate Project
[19:32:54 CET] <kepstin> the differences are more in the people working on the code than the code itself
[19:33:28 CET] <kepstin> they both start from the same point, there's been code copied between them, etc.
[19:43:59 CET] <grayhatter> trashPanda_  theres an interesting article i found on stackexchange
[19:44:13 CET] <grayhatter> that's what i'd recommend
[20:14:05 CET] <mfolivas> need some suggestions guys/gals.  looking for other hardware encoders that could get us to 2x encoding speed with reasonable file sizes
[20:16:18 CET] Action: kepstin recommends using the "x86-64 cpu" encoder hardware running the "libx264" firmware, but in a pinch, the nvidia encoders are considered fairly decent.
[20:28:12 CET] <BtbN> Nvidia on Touring actually got a lot better, but haven't had the chance to test yet
[20:33:57 CET] <^Neo> does anyone know if there's an example read/write circular buffer AVIOContext implementation already in master branch?
[21:29:07 CET] <GlidingHorse> hi, i'm muxing to mpegts and I need the result to start at a different timestamp, i.e. the output's first pts must be X value
[21:29:30 CET] <GlidingHorse> but i can't find any way of achieving that
[21:30:08 CET] <GlidingHorse> always starts at 0, or the same as input (-copyts)
[21:30:17 CET] <GlidingHorse> i need to set an specific time
[21:33:18 CET] <JEEB> ffmpeg.c had itsoffset I think?
[21:34:39 CET] <kepstin> if you're re-encoding you could just the setpts filter to make arbitrary adjustments.
[21:35:29 CET] <GlidingHorse> thanks JEEB and kepstin, i didn't see itsoffset. i think that would be enought, if it's not i'll do the setpts filter
[21:36:11 CET] <kepstin> there's also an "mpegts_copyts" option on the muxer, there might be some cases where you have to turn that on to preserve timestamps
[21:39:19 CET] <JEEB> that only seems to affect addition of delay, which seems to be s->max_delay, which seems to be an option as well
[21:39:51 CET] <JEEB> so I'd not look into that too much
[21:39:53 CET] <JEEB> :P
[00:00:00 CET] --- Fri Feb  8 2019