[Ffmpeg-devel-irc] ffmpeg.log.20140510

burek burek021 at gmail.com
Sun May 11 02:05:01 CEST 2014

[00:18] <brimestone> hey guys.. im trying to write something in Cocoa for Desktop ( Non iOS ) and i wondering if there is a API for ffmpeg?
[00:19] <sacarasc> The libav* stuff is the API.
[00:19] <brimestone> or framework
[00:19] <sacarasc> See the libraries documentation on http://ffmpeg.org/documentation.html
[00:20] <sacarasc> There's a bunc hof them.
[00:20] <brimestone> really, im been trying my lunch with AVFoundation, but very limited to ProRes and H264...
[00:20] <sacarasc> And the API docs is a little below that.
[00:22] <brimestone> so, basically, does this mean i can use ffmpeg without using NSTask?
[00:23] <sacarasc> If the very brief description of what NSTask means what I think, yes.
[00:23] <sacarasc> You don't need to run the ffmpeg binary yourself.
[00:24] <brimestone> i know im starting to be a bug.. but where should i start reading? the Doxygen?
[00:24] <sacarasc> Yeah.
[00:25] <sacarasc> For whichever branch of ffmpeg you're using.
[00:25] <sacarasc> I can't really help much, as I am only a user, not a coder. :D
[00:26] <brimestone> so if i want to decode and encode.. ill look at libavcodec
[00:35] <brimestone> Jesus! this is sooo way over my head
[00:38] <rafael2k> brimestone: taka a look at ffplay.c source code, inside ffmpeg source.
[00:44] <brimestone> yikes
[00:44] <brimestone> "u1 += u;" yikes!!!
[00:45] <brimestone> variable/object name short as 2 character
[00:58] <rafael2k> brimestone: this is C code, usually coding style differs from Objective C...
[01:06] <brimestone> rafael2k.. i took C back in Computer Engineering.. but that was more than 10 years ago
[01:07] <brimestone> rafael2k: do you know how i can start writting OSX tools using the libavcodec?
[01:17] <Bray90820> So While trying to covert a VOB to FLAC in ubuntu i get an error
[01:17] <Bray90820> http://pastebin.com/raw.php?i=Kq6gaR9T
[01:19] <c_14> Can you play the input file?
[01:19] <c_14> Also, you do know it's pretty useless converting a lossy source to lossless, right?
[01:27] <Bray90820> c_14: I can play it
[01:28] <Mavrik> brimestone, look into doc/examples of ffmpeg source
[01:29] <c_14> Does ffmpeg actually error out, or does it finish encoding?
[01:32] <Blue_Knight> woof woof
[01:33] <Bray90820> c_14: it finishes
[01:33] <Blue_Knight> is dvb supported as input?
[01:33] <c_14> Bray90820: Then as long as you can play the output it should be fine?
[01:33] <Bray90820> But why am i getting that error
[01:34] <sacarasc> Bray90820: It was a warning, not an error.
[01:35] <c_14> The source isn't perfect. Shit happens.
[01:35] <Bray90820> Ahh then nevermind
[01:35] <Bray90820> Actually it was an error
[01:35] <Bray90820> frame sync error
[01:36] <sacarasc> If it didn't end the encode, it was a warning.
[01:37] <Bray90820> ok
[03:17] <eristisk> I made a recording of a lecture directly from a PA system and it has this annoying, constant buzz that I'd like to remove as much as possible.  What can I use to do that?
[03:37] <Hello71> audacity.
[03:37] <Hello71> or possibly sox, but that isn't likely to end well
[04:20] <jedir0x> does avpicture_fill copy the data - or just copy the pointers to the data?
[10:06] <leggo> hello
[10:06] <Ardonik> leggo: I usually do my framerates with -r <desired_ofps>.
[10:07] <Ardonik> Keep in mind, now, that I'm not an expert!  These guys are.
[10:07] <leggo> (I'll repaste the options)
[10:07] <leggo> -threads {threads} {offset} {realtime} -i "{infile}" -threads {threads} -f flv -vcodec libx264 -bufsize 1024k -b:v 2125k -bt 2250k {framerate} -map 0:0 -map 0:1 -vf "yadif, scale={scalex}:{scaley}" -preset {vpreset} -tune film -vprofile baseline -level 30 -acodec libmp3lame -ab 256k -ar 44100 -ac 2 -async 1 -y "{outfile}"
[10:07] <leggo> this apparently sets the bitrate to 2560. how? I don't see 2560 anywhere in there.
[10:08] <leggo> also the framerate doesn't appear to be set anywhere, but it doesn't seem to be 30 fps.
[10:08] <Ardonik> -b:v is the output video bitrate (2125 kbits/s.)
[10:09] <leggo> so that would be 2125 kbits/s, not 2560?
[10:09] <Ardonik> Add that to -b:a (audio stream) and -b:s (subtitle stream) and you get the total output bitrate.
[10:09] <leggo> ah
[10:10] <Ardonik> I think you're running into a default framerate or something.  Try -r 25 or something.
[10:10] <Ardonik> Yes, I said "or something" twice.
[10:10] <leggo> is deinterlace set in there somewhere? the video feels as if it just throwing away half the frames.
[10:10] <Ardonik> Ugh...now you're getting into the deep magic.  My ffmpeg interlace-fu is weak.
[10:12] <leggo> what is {framerate} by the way?
[10:12] <Ardonik> The one you have just sitting there?  I dunno.
[10:12] <Ardonik> It seems to be missing a flag.
[10:14] <leggo> perhaps the program that runs ffmpeg fills that in with something
[10:15] <Ardonik> Meh, just put a "-r" before that {framerate} and see what happens.
[10:22] <leggo> ok that did make it appear smoother!
[10:22] <Ardonik> Excellent!
[10:28] <leggo> the program uses ffmpeg to reencode live tv and then stream it to tablet/phone. it looks great now
[10:29] <Ardonik> What about the interlacing?
[10:29] <leggo> I see no interlacing artifacts, so it must be doing it.
[10:29] <Ardonik> Curious, but so much the better.
[10:33] <leggo> thanks for help. I'll dwell more into ffmpeg one of these days, so maybe I could further tweak it. right now the bottle neck is my CPU, it is already at 100%, and if I increase the bitrate the video starts to buffer.
[10:34] <Ardonik> leggo: Yeah, that usually happens when you do massive encodes.
[10:35] <Ardonik> ffmpeg is one of the few modern processes that is actually CPU-bound these days!
[10:36] <leggo> having ancient core 2 duo here, haven't upgraded in 7 years.
[10:36] <Ardonik> Not that cane be done to improve the speed, then!  (Except for sacrificing encoding quality, naturally.)
[10:37] <Ardonik> And nicing the ffmpeg process will just make the encode slower.
[10:37] <Ardonik> (Which you may still want to do in order to actually have a usable system while the encoding takes place.)
[10:40] <leggo> yeah, I will see what I can do.
[15:33] <Waddles> Hi there. I'm a bit stuck on something so I was wondering if anyone here could help. At the moment I'm working on an application that just reads a file from any old source, (hopefully) identifies the format and starts outputting PCM audio into a buffer I have. The problem I am having is that, av_read_frame seems to report AVERROR_EOF before the end of the file.
[15:44] <Waddles> http://pastebin.com/WpedtGxr
[16:35] <Waddles> oh, don't worry. I fixed it. I wasn't calculating the correct number of samples properly. Thankyou.
[17:41] Action: haspor slaps jarainf around a bit with a large trout
[17:41] <haspor> sorry, ignore that
[17:41] Action: jarainf slaps haspor around a bit with a large trout
[17:42] <haspor> ok we are even now
[17:42] <Ardonik> Turnabout is fair play!
[17:43] <haspor> who could help me abit with ffmpeg lib, i need to decode at3 format, but get bad output
[17:44] <Ardonik> haspor: See the paste link in the topic.
[17:44] <haspor> all right
[17:47] <Ardonik> No, wait.  The paste link isn't in the topic at all!
[17:47] <Ardonik> http://ffmpeg.pastebin.com/
[17:48] <haspor> http://pastebin.com/gkDAa0Mh
[17:49] <haspor> the output is playing too fast and it should be more than 4 seconds
[17:49] <Ardonik> Oh, it's a library call.  Not my area of expertise, alas.
[17:49] <haspor> :(
[17:55] <Aiena> I am on linux but I want to help a freind on windows. I am wondering which builds I should get fro windows from the Zeranoe page. Should I use the git version on the stable release versions from the site ?
[18:01] <c_14> Unless you need some feature/bugfix that isn't in stable yet, it doesn't really matter. I usually go for git head though.
[18:02] <Aiena> c_14 thanks
[20:29] <allengreen> anybody?
[20:30] <c_14> Just ask and if somebody can help you, they will.
[20:32] <allengreen> ok, I just call ffmpeg function to decode mpeg2 file, and I got a lot of AVPackets, then I muxe the packets to mpeg2ts, the ts file can't played.
[20:32] <allengreen> I believe the muxe code is correctly.
[20:34] <allengreen> a es file to a ts file, then demux ts file, then muxe to ts file
[20:34] <allengreen> the result file can't be displayed.
[20:35] <c_14> I'm not very good with the ffmpeg libraries, you'll have to wait for someone who is.
[00:00] --- Sun May 11 2014

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