[Ffmpeg-devel-irc] ffmpeg.log.20121127

[burek]

[00:01] <perryg> howdy, could i get some help writing a command converting a 2 channel, 16 bit, 48000hz, wave file to a 16 bit 16000 hz headerless (raw) PCM file?
[00:01] <perryg> the PCM file being mono
[00:02] <perryg> i've got ffmpeg -i audio_006.wav -ar 16000 -acodec pcm_s16le test.pcm
[00:02] <perryg> but that throws an error
[00:03] <llogan> ffmpeg -formats | grep -i pcm
[00:03] <llogan> "-f s16le" for example
[00:03] <llogan> i guess
[00:04] <llogan> also, you forgot "-ac 1" or equivalent audio filter
[00:06] <perryg> ffmpeg -i audio_006.wav -ar 16000 -f s16le -acodec pcm_s16le -ac 1 test.pcm
[00:06] <perryg> that at least runs
[00:08] <perryg> i'm trying to create an API that takes these wave files and runs them through dragon dictation's API. they're very picky about how the audio is formatted
[00:08] <perryg> that goes through but the caption is garbage
[00:09] <llogan> a friend recently attempted to use dragon to IM me, and all it said was, "Saw from saw for the. The fed could."
[00:09] <llogan> ok!
[00:10] <perryg> ha, yeah, since the output file is headerless, i'm a little blind as to how dragon is interpreting it, but I can't get a good conversion
[00:10] <perryg> er a good response from them
[00:11] <perryg> yeah, dragon might just be garbage
[00:14] <llogan> i don't the other guy "trained" it enough
[00:15] <perryg> yeah, this is intended to work without training, but I think the API might just not be there yet
[00:17] <llogan> did ffmpeg make a good output for you? you can play it back with ffplay: ffplay -ar 16000 -f s16le -ac 1 test.pcm
[00:21] <perryg> i forgot about ffplay, i was loading it in audacity, checking now
[00:22] <perryg> foo, used the brew installer. didn't include ffplay
[00:23] <perryg> loading now
[01:08] <lakcaj> llogan, thanks for the info on the patch
[01:27] <tg2> guys is there an easy way to dump the info about keyframes (duration + bytelocation) in a video?
[01:28] <tg2> ffprobe with  -show_frames  ?
[01:33] <tg2> goal being to manually generate an flv manifest of keyframes and their locations (in the timeline and at the byte location)
[02:18] <Aristide> Hi !
[02:19] <Aristide> What is a lightest video and audio codec for ffmpeg ? (for CPU ressources)
[02:38] <llogan> Aristide: "-c copy"
[02:41] <tg2> is there a way to limit ffprobe's --show-frames output to I frames only?
[02:41] <tg2> without parsing through grep?
[07:25] <defaultro> good evening folks, what would be the best encoding so that when we upload to youtube, the quality isn't much affected?
[08:23] <llogan> defaultro: you upload the highest quality that is practical for you. that usually either means the original content, or re-encoded with libx264 encoder
[08:23] <llogan> since youtube is going to re-encode whatever you give it anyway
[08:25] <llogan> possibly starting with something like: ffmpeg -i input -c:v libx264 -preset slow -crf 18 -c:a copy output.mkv
[09:00] <defaultro> thanks llogan
[15:24] <leandrosansilva> Hello to all. Do I need do call av_free() in a AVCodecContext after I close it?
[15:24] <leandrosansilva> or ... do avcodec_close frees the AVCodecContext which it closes?
[15:26] <ubitux> look at the doxy of avcodec_alloc_context3
[15:28] <leandrosansilva> ubitux, the answer is yes... thx :-)
[15:29] <juanmabc> if you need to alloc, open, close, seems expected behaviour to free
[15:29] <juanmabc> too
[15:30] <juanmabc> makes it reusable between open/closes maybe
[15:37] <Mavrik> hmm, using libavfilter for filtering audio/video frames change my PTS to some wierd values
[15:38] <Mavrik> is there a way to control that?
[15:56] <juanmabc> there is a setpts filter
[16:58] <dericed> i'm looking for a suggested command to produce IMX50 using ffmpeg. I see an example here: http://www.itbroadcastanddigitalcinema.com/ffmpeg_howto.html#Encoding_D10 but it looks out-of-date.
[17:11] <mateo`> dericed: dericed: hi, something like this should be ok: http://pastie.org/5443193
[17:45] <dericed> mateo`: thanks
[17:45] <dericed> i also need to at a pad filter to ensure the output is 720x512
[17:52] <DelphiWorld> Hey everyone
[17:52] <mateo`> dericed: sure :)
[17:53] <DelphiWorld> it's pocible to create a Multi track MPEG2TS using FFMPEG?
[17:53] <mateo`> dericed: also you may have to merge the audio tracks to generate a proper D10 layout
[17:54] <DelphiWorld> any *clue* ?
[17:55] <mateo`> dericed: you also may have to use the fieldorder filter if you're dealing with ntsc input content
[17:57] <Mavrik> DelphiWorld: what's a "multi-track" mpeg2-ts?
[17:57] <DelphiWorld> Mavrik: multi audio stream, encapsulated in a MPEG2TS container
[17:57] <Mavrik> btw, anyone here with libavfilter experience? is there a documentation about what happens to PTS when frames go through filters?
[17:57] <DelphiWorld> Mavrik: like a tv channel that have multi stream
[17:58] <Mavrik> DelphiWorld: IIRC it is possible
[17:58] <DelphiWorld> Mavrik: how please? :)
[17:58] <Mavrik> you define several inputs and then use "-map" to map them all to a single output
[17:58] <Mavrik> as different streams
[17:59] <DelphiWorld> Mavrik: then the end user can chouse ?
[17:59] <Mavrik> that depends on the player :)
[17:59] <Mavrik> but usually yes
[17:59] <Mavrik> :)
[18:00] <DelphiWorld> Mavrik: :)
[18:00] <DelphiWorld> Mavrik: i may bugs you soon, ok ?
[18:10] <dericed> mateo`: this is turning into a huge command. Compared to 'ffmbc -i file -target imx50 outfile'
[18:11] <dericed> btw can someone point me to where the target options are defined in ffmpeg. i'm interested in developing one for imx.
[18:13] <mateo`> dericed: yes this is a huge command ... i use some tools to generate it automatically
[18:13] <ubitux> dericed: opt_target() in ffmpeg_opt.c
[18:27] <dericed> ubitux: thanks
[20:28] <danverde> Is this the correct forum to ask development questions about using libavfilter and libavcodec in my own applications?
[20:37] <DelphiWorld> danverde: this is not a forum:P
[20:41] <danverde> my bad. channel :)
[21:04] <Mavrik_> danverde, yeah
[21:04] <Mavrik_> to some extent :)
[21:05] <sacarasc> DelphiWorld: Strictly speaking, it is a forum.
[21:05] <DelphiWorld> :)
[21:22] <elkng> can ffmpeg do something with *.caf files ?
[00:00] --- Wed Nov 28 2012