[Ffmpeg-devel-irc] ffmpeg.log.20150314

[burek]

[00:49:38 CET] <ac_slater> hey all. Where are the public logs kept?
[00:50:33 CET] <c_14> http://ffmpeg.gusari.org/irclogs/
[00:53:36 CET] <ac_slater> c_14: thanks mate
[07:48:50 CET] <debianuser> Hello. How can I change the aspect ratio of an .avi file without reencoding it? `ffmpeg -i aspectbad.avi -map 0 -c copy -aspect 16:9 aspectgood.avi` looks like changing both SAR and DAR resulting in file looking exactly same as it was: http://pastebin.com/VwMKND5a Are there any other options I missed?
[08:43:54 CET] <sagax> hi! setup favicon.ico for ffserver Status page it's realy?
[09:46:14 CET] <dsl420> debianuser, i am pretty sure you cant
[09:47:01 CET] <relaxed> you can correct it at playback with most players
[10:38:47 CET] <AndChat734064> Hi there, whats the status of hardware accelerated video encoding in Linux?
[12:14:20 CET] <debianuser> dsl420: but... why? :'-(
[12:19:28 CET] <debianuser> AndChat734064: Last time I checked it was slower than software-based encoding and was giving worse quality than regular software libx264. Some things were successfully hardware-accelerated (x264 lookahead via opencl with small lookahead options, "higher lookahead values may end up being slower on the GPU.")
[12:22:17 CET] <debianuser> But often something simple like x264 -preset veryfast is faster and better quality than hardware accelerated options.
[12:28:09 CET] <AndChat734064> I have seen vaapi x264 work amazingly. but I can't get ubuntu to play nice with it.
[12:29:22 CET] <AndChat734064> Quicksync is great on a haswell but I have had no luck invoking it with Wine. I really don't want to go back to Windoze.
[12:30:24 CET] <debianuser> vaapi is for video decoding, not for encoding, isn't it?
[12:31:07 CET] <debianuser> And, well, decoding can be hardware accelerated. :) As long as it supports the profile that was used for encoding.
[12:31:30 CET] <AndChat734064> vaapi can do encoding :)
[12:34:07 CET] <debianuser> Oh, I didn't know that. :)
[12:34:19 CET] <debianuser> AndChat734064: About Quicksync and encoding in general, check: http://arstechnica.com/civis/viewtopic.php?f=6&t=1239375 - people say there that "x264 wiped the floor with absolutely everything". :)
[12:35:39 CET] <AndChat734064> Honestly. Intel really got it right around the Haswell. I'm a stickler for quality, and it is really great.
[12:36:46 CET] <AndChat734064> I might have to concede with VAAPI and just assume that if it aint being used that widely, then there's probably a reason.
[12:37:17 CET] <AndChat734064> Transmageddon is the one linux encoder that supports vaapi encoding.
[12:40:16 CET] <Jonas__> when I grab audio from pulse, the sound will gradually start lagging behind
[12:40:40 CET] <Jonas__> restarting ffmpeg gets the sound up to date again, and it once again starts to lag behind over time
[12:41:00 CET] <Jonas__> is there any way to force ffmpeg to timestamp the sound as the time it arrives?
[12:41:35 CET] <Jonas__> I assume the timestamps drift somehow, over time, but since the actual sound is coming in at the right times in "real time", it should be fixable somehow
[12:44:02 CET] <pomaranc> did you try the aresample audio filter?
[12:46:09 CET] <Jonas__> I'm not really sure how to use aresample to do it, I was looking at asetpts to adjust the presentation timestamp
[12:47:31 CET] <Jonas__> with aresample, I wouldn't know what to adjust, the input is already at the right hz by the sound of it, and "stretching/squeezing" according to timestamps doesn't seem useful if the timestamps are already off
[12:57:40 CET] <Jonas__> it appears that after 1428.97 sec the audio lags by about 3.63 sec
[12:59:35 CET] <Jonas__> I was hoping the delay would be something related to the 48khz / 44.1khz ratio, that some kind of misrepresentation by pulse or something along the way might cause trouble
[13:00:40 CET] <Jonas__> but at 0.00254 sec worth of lag introduced every second of playtime, that doesn't like up
[13:00:54 CET] <Jonas__> *line up
[13:03:16 CET] <Jonas__> I guess I can just stretch audio by (1+3.63/1428.97) and see how that goes
[13:19:05 CET] <AndChat734064> what is ITU.h26n?
[14:49:44 CET] <t4nk157> hello friends.
[14:51:27 CET] <t4nk157> can anybody knows, how can we recognize DTMB (Digital Terrestrial Multimedia Broadcast) video? Also i want datasheet of it. please guide me if anyone knows.
[14:59:41 CET] <Guest47150> how to convert an PNG image to 3s wmv video ?
[15:00:12 CET] <c_14> ffmpeg -loop 1 -i in.png -t 3 out.wmv
[15:07:48 CET] <Guest47150> c_14, seems worked,thanks
[15:15:09 CET] <Guest47150> I have two WMV files, but their media info is different ,how can I concat them into a single WAV file ?
[15:15:16 CET] <Guest47150> 2.wmv info  https://bpaste.net/show/afefd3435bbe
[15:15:25 CET] <Guest47150> 5.wmv info  https://bpaste.net/show/4a6fd2badeef
[15:16:29 CET] <BtbN> wav? realy?
[15:16:37 CET] <BtbN> So, uncompressed audio?
[15:18:15 CET] <Guest47150> sorry ,I need to concat them into a single WMV file
[15:24:51 CET] <c_14> https://trac.ffmpeg.org/wiki/Concatenate#differentcodec
[17:32:54 CET] <eFfeM> hi, I was looking for a fast way to go back to a specific keyframe in my stream. I thought I'd store the pos from the packet associated with that stream, but I seem to be unable to find the function to seek back to that pos. closest I came is av_seek_frame but that one is timestamp based; this seems less efficient; is there a way just to seek to a specific keyframe using pos ?
[18:30:12 CET] <thamburan> I did a small project in python using ffmpeg. I'd like to contribute to ffmpeg. Where to start.
[18:32:21 CET] <c_14> Contribute as in code?
[19:03:10 CET] <eFfeM> wrt my question above: is there a way just to do something like fseek() in C to reposition to a keyframe without having to interpret the intermediate data ?
[19:03:25 CET] <skulltower> Hello. Could anyone give me some clues on how to build ffmpeg so that I can use it via code? I am able to build it into an executable bu that doesn't work for me. I think that I'm missing something.. I am able to get the shared libs but I want to be able to use ffmpeg's main method directly.
[19:03:40 CET] <eFfeM> don't want to read all of the file
[19:04:48 CET] Action: eFfeM looking at ByteIOContext
[20:09:21 CET] <octarin> Hi
[20:18:19 CET] <octarin> I just encountered this bug with ffmpeg (through mpv) and i would like to know wether it's a bug with the native ffmpeg or with the package from my distro (arch).
[20:18:24 CET] <octarin> [ffmpeg] tcp: Failed to resolve hostname blog.m%C3%A9ric.fr: Name or service not known
[20:18:27 CET] <octarin> Failed to open http://blog.méric.fr/jmlp/jmlp-swing.webm
[20:18:55 CET] <octarin> it seems to happen because of the accent in the domain
[20:23:19 CET] <c_14> looks like a deficiency in ffmpeg, you'll have to convert the domain to punycode manually
[20:25:03 CET] <octarin> would this deficiency worth to be fixed ?
[20:27:00 CET] <c_14> probably, I could see support for punycode conversion as a useful feature
[20:29:35 CET] <octarin> Should I report it as a bug, or to the mailing list, or let you think about it ?
[20:31:15 CET] <c_14> I'd probably do it if I had time. Not sure when that'll be though. Probably make a feature-request on trac.
[20:32:56 CET] <octarin> Ok, thanks for answering :)
[21:20:38 CET] <atgnag> Silly question: Will a video transcoded from 4K to 360p be better quality than if it was transcoded from 720p?
[21:31:43 CET] <c_14> depends, at the same bitrate and if you don't upscale, yes
[21:32:00 CET] <c_14> (assuming comparable encoding settings)
[21:33:10 CET] <atgnag> c_14: I'm just assuming scaling down from 4K as the only parameter.
[23:34:50 CET] <Amethist> hi all
[23:34:56 CET] <Amethist> i need help
[23:37:29 CET] <Amethist> Akira^^:  help?
[23:39:25 CET] <c_14> If you explained your problem, people might be able to help you.
[23:40:16 CET] <Amethist> i want invoke ffmpeg in php
[23:40:21 CET] <Amethist> exec dont work
[23:40:32 CET] <Amethist> c_14:
[23:41:29 CET] <c_14> What's the error? What are you invoking it as? Is it in your PATH, did you specify the full path to the ffmpeg executable, does the user executing php have the necessary acces rights.
[23:43:25 CET] <Amethist> if i use DOS to execute it work
[23:43:34 CET] <Amethist> there is not error
[23:43:38 CET] <Amethist> it just do nothing
[23:44:07 CET] <klaxa> can you show us the script?
[23:45:10 CET] <Amethist> https://trac.ffmpeg.org/wiki/PHP
[23:45:45 CET] <Amethist> <?php
[23:45:46 CET] <Amethist>     echo "Starting ffmpeg...\n\n";
[23:45:46 CET] <Amethist>     echo shell_exec("ffmpeg -i ?C:\fff\aa.mp4 -ss 00:00:14.435 -vframes 1 C:\fff\img%03d.jpg");
[23:45:46 CET] <Amethist>     echo "Done.\n";
[23:45:46 CET] <Amethist> ?>
[23:47:26 CET] <klaxa> and what's the output of that?
[23:47:37 CET] <klaxa> (please don't paste in the channel, use pastebin or something similar)
[23:48:38 CET] <Amethist> kk
[23:49:08 CET] <Amethist> dont need echo
[23:49:18 CET] <Amethist> ignore that echo
[23:52:49 CET] <Amethist> klaxa:  can u help?
[23:53:12 CET] <klaxa> if you can tell me what the output of that script is
[00:00:00 CET] --- Sun Mar 15 2015