[Ffmpeg-devel-irc] ffmpeg.log.20111231

burek burek021 at gmail.com
Sun Jan 1 02:05:01 CET 2012

[00:49] <emerica> Did some more tests with the ac3 sync on hardware decoder problem, some results here. http://pastebin.ca/2097568
[02:13] <Matty> In have a problem with packing ASS subtitles into Matroska files. I run "ffmpeg -i video.avi" -i subs.srt video.mkv". Resulting file contains ASS subtitle track. But VLC and mplayer do not show subtitles, while playing video.mkv . Does somebody know what am I doing wrong?
[02:14] <pasteeater> Matty: I am very subtitle ignorant, but you can use a pastebin site to show your ffmpeg command and the complete console output
[02:27] <sam1> ffmpeg  could  burn  ass  subtitle,you could convert *.srt to *.ass 
[02:28] <Matty> Here is console output of "ffmpeg -i sample.avi -i subs.srt -y sample.mkv" producinf MKV file with subtitles that do not show in all players I tested. http://pastebin.com/PUJdb2Uv
[02:30] <Matty> I could burn the subtitiles, but I want to include more subtitles for later switch. Moreover I want to play the file on Android device and the MX VIdeo player displays only ASS subtitles.
[02:32] <sam1> hi , Matty , what's format  subtitle  do you burn?
[02:32] <fortress> how do i get ffmpeg to disregard the subtitle stream ?
[02:33] <sam1> -sn   
[02:33] <fortress> thank you!
[02:34] <sam1> you are welcome
[02:35] <Matty> I do not want to burn them in. I want to pack them in matroska file. Packing srt works fine, but ass produces broken subtitles that other players do not display.
[02:36] <sam1>  Matty: I could burn the subtitiles,    ??  you said you could do it .
[02:37] <sam1> i want to konw how do you do that 
[02:37] <emerica> http://code.google.com/p/ass2srt/ as workaround maybe if srt works for you
[02:38] <Matty> I can burn them in video like this: "ffmpeg -i sample.avi -vf ass=subs.ass -y sample.mkv"
[02:40] <Matty> srt works fine. Unfortunetly I want to play the file where only ass is supported.
[02:40] <sam1> dou you burn other formats?  ,e.g  *.sub  *.srt ?
[02:40] <emerica> ahh ok, so the text itself is packed in the mkv, more used to dvbsub and userdata captions here
[02:41] <Matty> I do not know how to burn sub or srt using ffmpeg. Mplayer can to that.
[02:42] <sam1> i konw  mplayer could do it.  i only burn *.ass 
[02:43] <Matty> By the way ffmpeg can convert srt to ass "ffmpeg -i subs.srt subs.ass".
[02:44] <sam1> thanks matty 
[02:45] <Matty> I think the problem with ASS in MKV is that ffmpeg fails to add some fields that seems to be requred in mkv. Resulting in subtitles with empty text in VLC, mplayer and others.
[02:50] <emerica> i dont see them in ffplay either, not sure it it's supposed to
[02:51] <Matty> I have never seen subtitles in ffplay.
[02:54] <emerica> i've seen captions i *think*
[02:54] <emerica> or dvbsub
[02:55] <emerica> probly dvb sub bitmap subtitles
[02:56] <emerica> if i convert my srt to ass with ffmpeg, then do it, vlc see em
[03:00] <Matty> I see the too. Problem is when ASS subtitles are part of mkv file. Not burn in the video, but as separate subtitle track.
[03:01] <Matty> I use command "ffmpeg -i video.avi -i subs.srt video.mkv".
[03:04] <Matty> It results in matroska file fith 3 tracks: video, audio and subtitles.
[03:04] <emerica> try ffmpeg -i bad.ass good.ass  ; ffmpeg -i sample.avi -i good.ass out.mkv    is what im saying 
[03:04] <pasteeater> did you know it's converting your srt -> ass? did you want to keep it as srt or change to ass?
[03:04] <emerica> thats what i found ya
[03:04] <emerica> so seemed like it should do ass/ssa either way
[03:05] <Matty> I want them to be included as ASS. I know ffmpeg is converting them.
[03:05] <Matty> Using ASS as input do not help.
[03:06] <emerica> the sameple here http://matroska.org/technical/specs/subtitles/ssa.html  muced into my test ts to mkv and subs show in vlc
[03:06] <emerica> yesterday git  clone
[03:06] <emerica> i had to change the timecode a bit to be in my sample
[03:17] <Matty> Wow, sample ASS works.
[03:19] <emerica> a step forward ;)
[03:19] <Matty> Those converted from srt by ffmpeg do not.
[03:19] <Matty> I think I have found the problem.
[03:19] <emerica> mine did, an example from wikipedia
[03:20] <emerica> it was just two lines though, no formatting if you can in srt
[03:22] <Matty> Sample subtitles contain all possible fields. Those by ffmpeg only: Layer, Start, End and Text.
[03:24] <Matty> I run "ffmpeg -i subs.srt sample.ff.mkv" "ffmpeg -i subs.srt subs.ass" and "mkvmerge -o sample.mm.mkv subs.ass".
[03:25] <Matty> The result are two almost identical samples one by ffmpeg, second by mkvmerge. 
[03:29] <Matty> The one by ffmpeg miss align fields in subtitles so mplayer and vlc do not show subtitle text(it seems empty to them). FFmpeg takes fileds from source file and do not recpect those fileds are mandatory in ASS packed in MKV.
[03:38] <Matty> Now I think this is a bug in the way how ffmpeg integrates ASS into Matroska files. I will fill a bug report about it, maybe I can even fix the code.
[03:39] <Matty> Than you very mych for help.
[03:51] <JohnP789> I'm having trouble with audio not being encoded with libfaac on some input file.  
[03:51] <JohnP789> http://pastebin.com/MnN4vW02
[03:51] <JohnP789> There's an audio stream shown in the stream mapping during encode, but the output file has no audio stream in it.  
[03:51] <JohnP789> Any ideas on what I'm doing wrong?
[07:50] <defaultro> is -r 60000/1001 enough to change frame rate?
[09:54] <Granjow> Good morning :) What is the best way if I want to use ffmpeg for reading and seeking in videos -- start with the code from the decoding/encoding example or something else?
[10:01] <metvik> reading and seeking in videos to what end?
[10:06] <Granjow> metvik: I first want to extract all frames, but scaled (thumbnail size), and later on individual ones in full size
[10:13] <metvik> for #1, perhaps try: ffmpeg -i <input-video> -s <new-width>x<new-height> -f image2 "output-%05d.png"
[10:14] <metvik> for #2, there is ffmpeg -i <input-video>  -f image2 -ss <hh:mm:ss> -vframes 1 "output-%05d.png"
[10:16] <Granjow> metvik: Could I also do this with the library directly?
[10:16] <Granjow> (programmatically)
[10:19] <metvik> i wouldn't be quite certain how, but i'm also interested to know how if anyone else has a solution
[15:57] <hivemind> uh
[15:57] <hivemind> i see the guide for ubuntu, but aren't see the guide for Debian
[16:57] <defaultro> am I right folks that I can concatentate multiple mp4 files?
[17:05] <knobo> Am I suppose to be able to send a stream like this: ffmpeg -i videofile.flv -re -acodec copy -vcodec copy -f flv rtmp://localhost/live/test
[17:05] <knobo> and play it by doing ffplay rtmp://localhost/live/test?
[17:38] <metvik> highzeth, I'm trying to convert LATM AAC audio to ADTS AAC audio (copy) but it results in a silent audio file.
[17:39] <metvik> s/highzeth/Hi
[17:40] <metvik> Googling found "[Change] LATM/LOAS AAC: Output to MP4 with FFmpeg muxer was not converting audio to ADTS resulting in silent audio." in VideoReDo's changelog.
[17:41] <metvik> input: ffmpeg -i input.aac -acodec copy -f adts output.aac
[17:41] <metvik> output: http://pastebin.com/0kKy3yRv
[17:49] <Granjow> Good afternoon :) I'm trying to read a video and save the frames as PNG, but I get a segfault in avcodec_decode_video2 here on line 74: http://codepad.org/tGV14pgu
[17:50] <Granjow> Why is this?
[17:50] <Granjow> It happens with the first frame already.
[18:02] <Granjow> Problem found -- did not avcodec_open2 the codec.
[18:18] <Granjow> Now it segfaults on sws_scale on line 84 and I'm really clueless. Still http://codepad.org/tGV14pgu
[18:25] <Granjow> ... which I could solve by not following the tuorial and use avpicture_fill but avpicture_alloc instead
[20:00] <LRN> Happy New Year!
[22:28] <alesan> hi
[22:33] <alesan> so I need to convert this 1920x1080 60fps video in a smaller, say DVD resolution, 30fps video
[22:33] <alesan> so that I can actually play it on my computer
[22:33] <alesan> ideas? can ffmpeg do it?
[22:33] <alesan> I mean, the fps conversion
[22:37] <pasteeater> alesan: it can drop frames to make a 30 fps output
[22:39] <alesan> ok, I am not sure what the best thing would be... simply dropping or mess up some frame-merging algorithm...
[22:40] <pasteeater> is it 1080p or 1080i?
[22:40] <alesan> p
[22:40] <pasteeater> you could just try resizing and the computer will probably be able to handle 60 fps decode
[22:41] <pasteeater> is there a particular output format you want?
[22:41] <alesan> H.264 would be good so I can transfer it on the internet
[22:41] <alesan> or you mean container?
[22:41] <pasteeater> both
[22:41] <alesan> I am open to any container that is good for this job. No particular preferenmces
[22:41] <alesan> preferences
[22:42] <alesan> it has 5.1 sound that I would not mind being converted to simple stereo
[22:42] <alesan> (it's from a Panasonic TM900 btw)
[22:43] <pasteeater> ffmpeg -i input -c:v libx264 -preset medium -crf 24 -vf scale=640:-1 -an -t 60 output.mkv
[22:43] <alesan> oh, .mkv :) I like that
[22:44] <pasteeater> this will ignore audio so you can focus on a video size that works well
[22:44] <alesan> I'll check the man page to understand your options
[22:44] <pasteeater> and make a 60 second output just as a test
[22:44] <pasteeater> so you don't have to encode the whole thing
[22:44] <alesan> the test video I am working on is 13s only
[22:44] <pasteeater> ok. omit -t 60
[22:44] <alesan> later I have a 5 minutes one that is my real "target"
[22:45] <pasteeater> adjust crf value for quality. lower is higher quality.
[22:45] <pasteeater> use the highest crf value that still gives an acceptable quality
[22:45] <alesan> sure
[22:45] <alesan> hm
[22:45] <alesan> it complains... about subtitles?
[22:46] <pasteeater> you can keep or remove subtitles
[22:46] <alesan> http://pastebin.com/QFZzb55r
[22:46] <alesan> subtitles... I shoot this video myself with a camcorder... what subtitles?
[22:46] <alesan> interesting...
[22:47] <pasteeater> do you want the subtitles?
[22:47] <alesan> no, I do not even know what subtitles there are
[22:48] <pasteeater> then add -sn i think
[22:49] <alesan> ok it's encoding...
[22:50] <alesan> this still is a 60fps video
[22:50] <alesan> I would like to try to convert it to a 25fps
[22:51] <alesan> or 30
[22:51] <alesan> trying with -r 30
[22:52] <alesan> seems OK
[22:52] <alesan> now I would like to put audio back in
[22:53] <alesan> removing "-na"...
[22:53] <alesan> -an
[22:54] <pasteeater> you can copy the audio or re-encode it.
[22:57] <alesan> how was to get the list of available presets?
[22:57] <pasteeater> x264 --help
[22:57] <pasteeater> generally you use the slowest one you have patience for
[22:57] <Shimmy> https://ffmpeg.org/trac/ffmpeg/ticket/844 please change status to completed, and thanks for completing it
[23:00] <Shimmy> Sorry for my last line, there is still a problem with the RSS, it only shows the title header, no content
[23:00] <pasteeater> Shimmy: i see you modified it. did you want to keep it open?
[23:00] <pasteeater> ah, i missed your last line in this channel
[23:01] <Shimmy> Yes, should be kept open
[23:01] <Shimmy> maybe u or i can do it, just need access to the server
[23:01] <Shimmy> and make the rss include the content of each article
[23:03] <pasteeater> that will be a little harder to implement
[23:09] <Granjow> Why do I get a «Could not open file» with av_write_frame() here on line 113? http://codepad.org/GL3N1Lhr
[23:10] <qxt> Is there a cmd in ffmpeg that I can define the size of a video with the audio. Or do I have to take the time and bit rates and calculate manually? 
[23:12] <qxt> Need the highest quality from a BluRay 48GB video to fit on a 700MB disk.
[23:13] <qxt> As of now my 2ed pass looks something like this  -pass 2 -vcodec libx264 -preset fast -b 512k -acodec libfaac -ab 128k -ac 2 output.mp4
[23:13] <qxt> just not the same bit rates
[23:29] <pasteeater> qxt: manually i think
[23:30] <pasteeater> and use -preset veryslow if you want the highest quality for your desired bitrate, although, it is very slow.
[23:30] <pasteeater> what's the duration of the input?
[23:32] <qxt> pasteeater looks that way. Been Google'n for a while. The movie is Drive its 1:40:47 long
[23:32] <qxt> pasteeater kick ass movie btw 
[23:32] <pasteeater> nice
[23:32] <qxt> :)
[23:35] <pasteeater> that would end up with around -b:v 786k -b:a 128k
[23:35] <pasteeater> for 675MB output for "safety"
[23:36] <pasteeater> or (700 MB * 8192 [converts MB to kilobits]) / 6047 seconds = ~948.3 kilobits/s
[23:36] <pasteeater> i think
[23:37] <metvik> is there an accurate way to account for overhead?
[23:37] <pasteeater> i don't know
[23:38] <metvik> would you happen to know anything about encoding AAC audio via ffmpeg?
[23:38] <pasteeater> depends on the question
[23:39] <metvik> I'm trying to convert LATM AAC audio to ADTS AAC audio (copy) but it results in a silent audio file.
[23:39] <metvik> <metvik> Googling found "[Change] LATM/LOAS AAC: Output to MP4 with FFmpeg muxer was not converting audio to ADTS resulting in silent audio." in VideoReDo's changelog.
[23:39] <metvik> <metvik> input: ffmpeg -i input.aac -acodec copy -f adts output.aac
[23:39] <metvik> <metvik> output: http://pastebin.com/0kKy3yRv
[23:40] <qxt> pasteeater Wow talk about spoon feeding. I just am running it as -codec libfaac -ab 128k and the video at 786k. Thx I'll let you know how it works out =)
[23:44] <qxt> pasteeater was wondering if I should use veryslow during the first pass also. My computer can deal with the time.
[23:45] <pasteeater> you should use the same preset for both passes
[23:45] <pasteeater> or encoding will fail
[23:46] <qxt> pasteeater puuu, that was a close one. Had fast on the first pass and veryslow on the 2ed one. 
[23:53] <qxt> BTW Happy NEW YEAR in 7 min!!! =D
[23:54] <pasteeater> not for another 10 hours and 7 mins here
[23:55] <JEEB> the internets is a funny place
[23:56] <JEEB> there is no certain time zone for the internet
[23:56] <JEEB> although someone tried to bring up something called 'the internet time'
[23:57] <qxt> Got to have a skål on my balcony. Fireworks like crazy. Back in 5 min or so!
[00:00] --- Sun Jan  1 2012

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