[Ffmpeg-devel-irc] ffmpeg.log.20180515

[burek]

[02:31:17 CEST] <FishPencil> Is there a way to disable the linking of CoreMedia on macOS? It seems to be included regardless of the configure flags if it's available
[06:20:39 CEST] <Pandela> Aye quick question. Are there any sdl/sdl2 libraries I need installed on windows 7 for ffplay or ffmpeg sdl2 output to work? If I try to play any file with ffplay or use -f sdl; everything immediately crashes..
[06:23:16 CEST] <Pandela> This is both with ffmpeg 4.0 stable, and the current nightly build
[06:34:01 CEST] <Pandela> Perhaps some framework I don't have? Don't know the last time this machine was updated actually.
[07:33:59 CEST] <zumba_addict> can ffmpeg receive mjpeg from an external camera via udp?
[07:43:22 CEST] <Mavrik> IIRC yeah
[07:44:04 CEST] <zumba_addict> i got it working
[07:44:15 CEST] <zumba_addict> -i rtsp://.....
[07:44:26 CEST] <zumba_addict> i'll try it with udp://... later
[08:20:08 CEST] <cloud_> i got some problem when i using ffmpeg
[08:20:45 CEST] <cloud_> is anybody here?
[10:54:06 CEST] <ralphcor> Hi, I've a h264 that's 698x540 and I'm guessing that's why the TV won't play it.  I'm intending to use ffmpeg's pad filter to make it a nice 4:3 720x540.  I'm aware jpegtran(1) can manipulate a JPEG without loss and, knowing little about video formats, was wondering if a pad can work in a similar manner, or at least damaging only peripheral `blocks' at the sides.
[10:55:34 CEST] <durandal_1707> ralphcor: filters need transcoding
[11:05:53 CEST] <ralphcor> Ah, OK.  I was seeing video ones like mpdecimate (drop similar frames) and thought some might not lossily transcode.
[11:06:47 CEST] <durandal_1707> ralphcor: transcoding IS lossy unless you use lossless encoder
[11:25:56 CEST] <ralphcor> OK, put another way: `some filters change frame properties but not frame contents', e.g. fps and setpts.
[11:26:19 CEST] <ralphcor> I see your point WRT the definition of transcode.
[11:26:49 CEST] <durandal_1707> ralphcor: yes, lossy trascoding is lossy process
[12:22:11 CEST] <mort> Hey, I'm trying to cross-compile ffmpeg for aarch64. I want to enable the v4l2-based encoder and decoder, but adding '--enable-libv4l2' says that libv4l2 wasn't found using pkg-config. How can I cross compile with libv4l2?
[12:22:31 CEST] <mort> I can steal libv4l2.so from the target, but how do I make the configure script find it?
[12:23:00 CEST] <sfan5> steal the associated .pc file too
[12:24:19 CEST] <mort> there doesn't seem to be a v4l2 .pc-file on that system
[12:25:27 CEST] <mort> I suppose I could write my own. Does the configure script look in the host system's place for .pc files even when cross compiling? I can't find any in /usr/aarch64-linux-gnu
[12:26:33 CEST] <jkqxz> libv4l2 isn't related to the v4l2m2m codecs.
[12:27:27 CEST] <mort> Is v4l2-m2m enabled by default then? It was the only option other than --disable-v4l2-m2m I found related to v4l2 in './configure --help'
[12:28:01 CEST] <jkqxz> I think it's autodetected.  See if it appears in config.h.
[12:34:41 CEST] <mort> it seems to be enabled by default yes
[15:21:24 CEST] <baco> Hi, I am not being able to save into WebM format videos with codec AV1, I continuously receive the message "[webm @ ] Only VP8 or VP9 video and Vorbis or Opus audio and WebVTT subtitles are supported for WebM." but saving into WebM should be vialable according to AOM
[15:39:57 CEST] <pgorley> baco: it's most likely not yet implemented in ffmpeg
[16:52:57 CEST] <mort> What's the difference between an avframe's buf array and data array? av_frame_alloc and av_image_alloc allocates data and not buf, but the AVCodec I'm using segfaults because it uses buf[0], which is a null pointer
[16:56:42 CEST] <atomnuker> buf[] contain refcounting structures, if they're missing then the frame is not refcounted, which can cause issues if you feed it into code which needs refcounted frames
[16:57:18 CEST] <mort> I see
[17:00:07 CEST] <mort> atomnuker: how do I get a refcounted frame? I'm using av_frame_alloc, which the encoding/decoding example code is using too
[17:00:45 CEST] <mort> actually no, that uses avcodec_alloc_frame
[17:05:01 CEST] <zerodefect> Using the C-API whcih I'm playing around with in my spare time. I've created a simple graph using the overlay filter.  I note that when I feed the AVFrames in, the AVFrame output data address does not match the input AVFrame of the 'main' link. That surprised me a bit because I've set the 'main' frame to writable and setting the 'AV_BUFFERSRC_FLAG_KEEP_REF' flag when adding the frame to the
[17:05:01 CEST] <zerodefect> graph.
[17:19:48 CEST] <djk> trying to compile local and having an issue with aom "error: 'AV1_COMMON {aka struct AV1Common}' has no member named 'enhancement_layers_cnt'"
[17:28:40 CEST] <kepstin> djk: well, that's just a mismatch between the libaom version and ffmpeg version. expected since libaom is still under heavy development. if it doesn't work with master git versions of both, well, patches welcome? :/
[17:29:51 CEST] <kepstin> or is that just a build error within libaom itself?
[17:34:18 CEST] <djk> libaom build error and ffmpeg
[17:36:17 CEST] <kepstin> ... which one? are you getting that error when building libaom, or are you getting it when building ffmpeg?
[17:36:33 CEST] <djk> that error is libaom
[17:37:00 CEST] <kepstin> either way i guess the answer is the same, either submit a patch upstream or wait for someone else to fix it :/
[17:37:15 CEST] <kepstin> (and report libaom build errors to them, not to ffmpeg channel)
[17:42:12 CEST] <djk> kepstin: thank you I will try to let them know
[17:43:46 CEST] <mort> Is there some example code showing encoding with the new API? (i.e send_frame and receive_packet instead of encode_video2)
[17:54:35 CEST] <mort> it would've been really nice if https://ffmpeg.org/doxygen/trunk/encoding-example_8c-source.html had been updated to reflect the new API when the API changed
[18:09:41 CEST] <duffolonious> does 2.8 still get security updates?
[18:13:55 CEST] <durandal_1707> probably no
[18:14:49 CEST] <durandal_1707> actually 2.8.14 is latest one
[18:15:54 CEST] <duffolonious> yeah, with a February 18th, 2018 release - https://github.com/FFmpeg/FFmpeg/releases/tag/n2.8.14
[19:03:00 CEST] <GamleGaz> how do I set a custom frame->nb_samples? I tried setting the frame->nb_samples along with audio_ctx->frame_size but this produces glitchy audio, jumping in and out again, are there anything else I must do?
[19:04:03 CEST] <JEEB> audio decoders generally output frames of a specific size that they are coded in, so you will have to either cut yourself, or use libavfilter to cut stuff in there
[19:04:24 CEST] <GamleGaz> I meant for encoding
[19:04:41 CEST] <JEEB> very  few audio encoders support arbitrary frame sizes
[19:04:56 CEST] <atomnuker> yep, they signal what you need to send via avctx->frame_size
[19:05:18 CEST] <atomnuker> there's a fifo to buffer audio samples until you have enough
[19:05:25 CEST] <JEEB> yea, right. that was a thing
[20:25:28 CEST] <Jexzew> how to add a photo as a cover for a video file?
[20:26:11 CEST] <BtbN> "cover for a video file"?
[20:26:39 CEST] <Jexzew> yes. it work fine for audio files but not with video
[20:27:15 CEST] <Jexzew> like an album cover
[20:27:54 CEST] <JEEB> I don't think that's standardized in any way
[20:28:12 CEST] <BtbN> videos don't have that, as they have pictures on their own
[20:28:36 CEST] <kepstin> usually that's completely up to the file manager, they'll grab a frame from somewhere in the video (sometimes first frame, sometimes seek partway through)
[20:28:49 CEST] <JEEB> I know some things add an extra track or maybe even not a track but an attachment
[20:28:59 CEST] <JEEB> but yes, a lot of it is runtime (explorer.exe plugins etc)
[20:34:05 CEST] <TheAMM> I've only seen mp4s with a cover file, never made any
[20:34:34 CEST] <TheAMM> Windows has native support for the mp4 cover file though
[20:34:42 CEST] <Jexzew> it exist but still a mystery task
[20:35:06 CEST] <TheAMM> I'd expect mkv and webm teeechnically would support a cover file ala flac and ogg album art
[20:35:31 CEST] <TheAMM> But that's technically.
[20:36:16 CEST] <Jexzew> perhaps it can be done if ffmpeg not treating the photo as video stream
[20:37:59 CEST] <TheAMM> I wonder if it's an id3 tag
[20:38:15 CEST] <TheAMM> There really is little technical word in my google results
[20:38:21 CEST] <TheAMM> But some people use "mp3tag"
[20:39:07 CEST] <kepstin> you can, technically, throw an id3 tag on the end of pretty much anything, but that's a pretty horrible hack even if it does work.
[20:39:30 CEST] <TheAMM> That's why I wonder if it's id3
[20:39:33 CEST] <kepstin> I would expect for mp4 files there's some specific atom that apple uses for cover images in itunes
[20:39:46 CEST] <Jexzew> what about m4a? is it ID3?
[20:40:13 CEST] <kepstin> no, mp4 has native tagging support (although it's poorly defined, it's pretty much "try to copy what itunes does")
[20:40:34 CEST] <TheAMM> VLC seems to be able to tag mp4 metadata
[20:42:17 CEST] <TheAMM> And yeah ffmpeg can at least tag the title
[20:42:32 CEST] <TheAMM> Album/cover art, I wouldn't hold my breath
[20:43:25 CEST] <TheAMM> Last I checked, ffmpeg can't tag ogg with albumart
[20:43:33 CEST] <TheAMM> Oh, but that reminds me
[20:43:41 CEST] <TheAMM> mutagen might support mp4, lessee
[20:44:15 CEST] <BtbN> m4a is mp4.
[20:44:26 CEST] <TheAMM> Yep, mutagen does support mp4
[20:44:35 CEST] <TheAMM> And covers as well
[20:44:44 CEST] <TheAMM> https://mutagen.readthedocs.io/en/latest/api/mp4.html#mutagen.mp4.MP4Cover
[20:44:50 CEST] <Jexzew> hey suddenly i found the answer
[20:44:53 CEST] <kepstin> I've never tried using mutagen to put cover art into video mp4 files, but yeah, i guess it could work? :)
[20:45:03 CEST] <TheAMM> I expect it would
[20:45:40 CEST] <TheAMM> I wrote myself a script to encode opus with album art, by extracting (or specifying) the cover file, encoding with ffmpeg and then using mutagen to add the image
[20:46:20 CEST] <jpabq> Given an AVFrame, is there a way of determining what streamid / PID it is part of?  I am working on frames from a transport stream.
[20:46:49 CEST] <djk> I have an rtmp stream to facebook with null audio that I would like to modify and add streaming of several audio sources. Still a novice on all the options and how they work. Here is what I have currently https://paste.ofcode.org/EYfNFNbsM8KWsnaTZKb8dr
[20:47:02 CEST] <Jexzew> MP4 container + ID3 Tag with APIC frame
[20:47:17 CEST] <TheAMM> Hey I was right twice
[20:48:21 CEST] <atomnuker> TheAMM: you can add them, no problem
[20:48:29 CEST] <atomnuker> sorry, I meant Jexzew
[20:48:33 CEST] <atomnuker> to both mp4 and mkv
[20:48:34 CEST] <kepstin> jpabq: no, avframes don't store any reference back to a stream. you should just remember which stream you got the frame from and store them separately or tag them somehow yourself.
[20:48:49 CEST] <atomnuker> its just a secondary video stream with the cover art disposition added (and a different title)
[20:48:52 CEST] <JEEB> jpabq: no. only AVPackets have a stream index
[20:49:30 CEST] <JEEB> so you have to keep a handle on where the video or audio or subtitle frame came from if you need to know after-the-fact
[20:49:43 CEST] <jpabq> kepstin: okay....   I am trying to do some manipulation in a filter.   From within the filter, I have not been able to figure out how to access that info.
[20:51:04 CEST] <Jexzew> alternatives to ID3?
[20:51:09 CEST] <kepstin> jpabq: the thing that knows what stream is going into a filter is the code that sets up the filter chain. If you need that info in a filter, maybe pass it as a filter parameter?
[20:51:42 CEST] <jpabq> kepstin: that sounds like the best option.   Thanks.   Thank you too, JEEB.
[20:52:51 CEST] <Jexzew> native video tags?
[20:53:10 CEST] <furq> mp4 has its own metadata
[20:53:12 CEST] <furq> use that
[20:53:21 CEST] <furq> also you can add album art to m4a with ffmpeg iirc
[20:56:24 CEST] <Jexzew> what is it
[20:56:40 CEST] <Jexzew> how to
[20:57:34 CEST] <furq> -i foo.m4a -i bar.png -c copy -disposition:v attached_pic -f mp4 baz.m4a
[20:57:50 CEST] <furq> for some reason you need -f mp4, apparently the ipod muxer doesn't support it
[20:59:19 CEST] <Jexzew> it works for video?
[20:59:28 CEST] <furq> ?
[20:59:42 CEST] <Jexzew> m4a = audio
[20:59:47 CEST] <Jexzew> mp4 = video
[20:59:52 CEST] <furq> they're the same format
[21:01:07 CEST] <Jexzew> in my case, the pic became a video stream if it muxed with video files (video audio stream)
[21:01:30 CEST] <furq> that's how ffmpeg displays it, yeah
[21:01:34 CEST] <furq> does it actually work in your music player
[21:01:45 CEST] <Jexzew> no
[21:02:07 CEST] <furq> shrug
[21:02:10 CEST] <furq> https://trac.ffmpeg.org/ticket/2798
[21:02:12 CEST] <furq> should work
[21:02:17 CEST] <Jexzew> not in file manager too
[21:02:18 CEST] <furq> i guess you need a recent ffmpeg
[21:04:18 CEST] <Jexzew> ticket still not solved
[21:04:49 CEST] <Jexzew> also not showed up as thumbnail
[21:11:15 CEST] <Jexzew> know how to edit ID3 frame?
[21:15:18 CEST] <jpabq> kepstin: JEEB:  It does no look like AVOption supports variable # of arguments.   Is that correct?   If so, I will need to pass the PIDs in as a string and parse them out of that.
[21:16:25 CEST] <thresh> can someone explain to me why the bsymbolic flag as specified in https://ffmpeg.org/platform.html#Advanced-linking-configuration is needed?
[21:20:00 CEST] <JEEB> had to scroll a bit of https://flameeyes.blog/2012/10/07/symbolism-and-elf-files-or-what-does-bsymbolic-do/ to figure out what that is
[21:20:38 CEST] <JEEB> "What they do is duplicate the GOT entries for the symbols that are both called and defined in a shared object: the loader points to one, but the object itself points to the other. This way, itll always call its own copy. An almost identical solution is applied, just at compile-time rather than link-time, when you use protected visibility (instead of default or hidden)."
[21:20:50 CEST] <JEEB> lessee when that recommendation originally got there
[21:20:54 CEST] <Jexzew> ID3 implementations i use does add attached picture but not as thumbnail
[21:21:05 CEST] <thresh> yeah but I don't see protected visibility in fft.o for ff_cos_32 (which I have issue with)
[21:21:14 CEST] <thresh> but then again I'm not very smart
[21:22:03 CEST] <JEEB> yea, I think that's to work around not having protected visibility
[21:22:09 CEST] <JEEB> I just got git blame open
[21:22:36 CEST] <Jexzew> hmm need to fork ffmpeg
[21:22:41 CEST] <JEEB> ok, so it was by andrew keiley and commited into tree by koda
[21:23:03 CEST] <JEEB> thresh: it was 2014 though so koda might not remember too well. you can always try to refresh his memory ;)
[21:23:22 CEST] <thresh> ya
[21:23:41 CEST] <JEEB> http://git.videolan.org/?p=ffmpeg.git;a=commit;h=33a7b453a8e1f090c694ea4f36769dc837be88f0
[21:23:47 CEST] <JEEB> that's the relevant commit
[21:24:03 CEST] <thresh> yeah I've seen it too :-)
[21:24:12 CEST] <djk> how do I specific multiple windows playback devices for audio input to stream out rtmp?
[21:24:25 CEST] <thresh> I'm wonder what actual tech/design choice lead to that being needed
[21:24:42 CEST] <thresh> I don't see a lot of libraries requiring that
[21:32:03 CEST] <kepstin> djk: i think you'd need to have a separate input for each audio source (use filters or whatever to combine them)
[21:33:45 CEST] <Jexzew> https://archive.org/download/Mujahideen_Explosives_Handbook/Mujahideen_Explosives_Handbook.pdf
[21:34:05 CEST] <djk> real novice here so what would be the syntax?
[21:34:55 CEST] <djk> This is what I have but it uses a null device for no audio https://paste.ofcode.org/EYfNFNbsM8KWsnaTZKb8dr
[22:51:04 CEST] <exastiken> Hi, I'm having trouble doing a debug compile of ffmpeg for callgrind with x265 also debug compiled. It keeps hiding the ffmpeg function names for functions inside the ffmpeg object.
[22:51:19 CEST] <exastiken> functions inside x265 are fine however.
[22:51:47 CEST] <JEEB> --disable-stripping in configure
[22:52:02 CEST] <JEEB> or if you are using the command line app, ffmpeg_g
[22:52:14 CEST] <JEEB> (although in case of disable-stripping ffmpeg_g = ffmpeg
[22:55:40 CEST] <exastiken> I have used ffmpeg_g and disable-stripping
[22:58:23 CEST] <kepstin> make sure you're running the newly built ffmpeg and not another copy, e.g. system version?
[22:58:42 CEST] <exastiken> yep, newly built ffmpeg
[22:58:57 CEST] <kepstin> (although this should be the case with ffmpeg_g, that won't ever get installed)
[23:13:33 CEST] <JEEB> dunno, it gives me debug symbols just fine if I don't strip :P
[00:00:00 CEST] --- Wed May 16 2018