[Ffmpeg-devel-irc] ffmpeg.log.20131120

[burek]

[03:02] <ryannathans> I did a .\ffmpeg.exe -i G:\11\%04d.jpg -codec:v libtheora -qscale:v 10 output.ogg     every odd second of the video is the first frame
[03:02] <ryannathans> What did I do wrong?
[03:05] <ryannathans> Oh wow. My image sequence is corrupted.
[03:20] <shevy> does ffmpeg accept more than one file via -i ?
[04:07] <relaxed> shevy: yes, ffmpeg -i 1.ext -i 2.ext ...
[04:37] <shevy> relaxed ok cool
[07:07] <ryannathans> With ffmpeg, am I able to pull frames from a cctv card (already done, in jpg form) and encode them to a video realtime?
[07:07] <ryannathans> I guess it's a jpeg stream encoded to ogg
[13:17] <Samus_Aran> I was testing encoding a short clip at various libx264 -preset's: slow, medium, fast, ultrafast.  they all came out to 60MB, except for the ultrafast which was 82MB
[13:17] <Samus_Aran> any idea why the presets aren't changing the output size at all over that huge range?
[13:18] <Samus_Aran> sample command: ffmpeg -y -threads 1 -i 00145.MTS -acodec pcm_s16le -filter:v 'scale=2048:-1, unsharp=luma_amount=1.3' -vcodec libx264 -preset medium -crf 14 -sn test-2K-crf14-medium.mkv
[13:19] <JEEB> the crf value does not mean the same thing over presets
[13:20] <JEEB> anyways, there _is_ a difference between the presets, just that ultrafast is the "dumbest", and thus you most probably get a relatively big change with that
[13:21] <JEEB> just pick the slowest preset that is fast enough for your use case
[13:22] <JEEB> (note: I wouldn't be surprised if with the same crf and one of the slower presets you'd actually get a _bigger_ file than with some of the faster ones, because the encoder will "see" more things, which of course also affects the results of the CRF algorithm)
[13:22] <Samus_Aran> 640KB difference between fast and slow, not really worth using the slower ones, I guess
[13:22] <Samus_Aran> my computer takes ages on medium
[13:22] <JEEB> as my note just mentioned, you can't really just compare the file sizes between presets :P
[13:22] <JEEB> since the result is not the same
[13:23] <Samus_Aran> right.  I don't get why they make video encoders so confusing
[13:23] <JEEB> but yes, if you have a slow PC and you want it to go faster, that is a proper reason to just pick a faster one
[13:24] <Samus_Aran> it just seemed odd that there was an enormous jump of 22MB when there's only a 640KB jump between slow and fast
[13:24] <Samus_Aran> I should try the veryfast one and see how that goes
[13:26] <Samus_Aran> when I was playing with crf, and capturing a single frame to compare, it was easy to tell apart crf0 and crf18, which I thought was supposed to be visually lossless
[13:27] <Samus_Aran> crf14 and crf0 look slightly different, but it's hard to notice one being better or worse
[13:28] <JEEB> there is no one true number
[13:28] <JEEB> one of the most generic reasons for that is first of all that people have different perceptions of quality
[13:29] <Samus_Aran> I am very impressed with the unsharp mask filter on content from my Sony camera, combined with the upscaling it looks better than the original
[13:29] <Samus_Aran> I'm upscaling so YouTube gives more bits when it downscales
[13:29] <Samus_Aran> now I want to try out other filters, there's so many
[13:29] <JEEB> second of all, if you encode f.ex. SD stuff and then view it on a HD screen you will have the artifacts zoomed, so they matter more
[13:30] <JEEB> so yeah... you can generally find your preferred CRF value depending on the type of the source (animation, computer generated graphics, live action with grain etc. etc.) and the resolution
[13:31] <Samus_Aran> I almost always need to use unsharp mask on photos from this camera, as they are always under-sharp.  didn't know I could do it so easily for video
[13:31] <Samus_Aran> super impressed
[13:31] <Samus_Aran> when I was comparing single frames at various crf values, sometimes one area of the image would be better at one crf, and another area worse
[13:32] <Samus_Aran> like line definition versus shaded areas
[13:32] <JEEB> I really am not going to go into that because it's up to you how to rape your video @ filtering . Just gonna say that it's a brain thing with sharpening, at least with quick comparisons your brain will like the "sharper" picture.
[13:33] <Samus_Aran> for me the difference is things like fabric that actually look like fabric once sharpened
[13:33] <Samus_Aran> blurry mess otherwise
[13:34] <Samus_Aran> I'm going to be fiddling with the amount so it's not overdone
[13:40] <Samus_Aran> veryfast at crf14 is 5MB less than fast
[13:42] <Samus_Aran> it doesn't make any sense at all how -preset slow can produce an 8% larger file than -preset veryfast
[13:46] <JEEB> <JEEB> (note: I wouldn't be surprised if with the same crf and one of the slower presets you'd actually get a _bigger_ file than with some of the faster ones, because the encoder will "see" more things, which of course also affects the results of the CRF algorithm)
[13:50] <Samus_Aran> JEEB: that doesn't explain an enormous 8% difference in the opposite direction from fast to veryfast
[16:34] <Mavrik> hmm, is there a case where DVB subtitles might have different DTS than PTS?
[16:57] <dharriso> Hi guys im using the ffmpeg API to transcode an MP4 file that contains a single track audio file. This works as expected no problems. My question is why does the MP4 file have twice the amount of sample than the input audio file. So input file  has 5768 samples and the output has 1156 samples
[16:58] <dharriso> Im using ffmpeg 0.8, libfdk for AAC audio encoding
[16:58] <viric> 0.8? very old
[16:58] <dharriso> viric: yes i know
[16:59] <dharriso> we are looking to upgrade sometime soon but we have legacy
[17:09] <LithosLaptop> maybe the output sample rate doubled?
[17:15] <dharriso> LithosLaptop: I keep sample rate, channels the same as the original but reduce the bitrate by 50%
[17:16] <dharriso> sample rate is 44100
[17:16] <dharriso> input audio is HE-AAC LC v1
[17:17] <LithosLaptop> and output is LC-AAC?
[17:19] <dharriso> yes
[17:19] <dharriso> AAC LC 44100, 2 channels
[17:21] <dharriso> so is that the ssue going to LC for HE-AAC
[17:21] <dharriso> showing my ignorance of these details
[17:21] <LithosLaptop> 44.1Khz HE-AACv2 = LC-AAC 22.05Khz + SBR Info to recreate 44.1Khz
[17:23] <dharriso> so is that what you wuld expect in relation to doublin the samples
[17:23] <dharriso> i mean doubling the number of samples
[17:24] <LithosLaptop> to confirm maybe encode try encoding to HE-AAC with -profile:a aac_he
[17:25] <LithosLaptop> *to confirm maybe try encoding to HE-AAC with -profile:a aac_he
[17:25] <dharriso> yes will try that now thanks
[17:26] <LithosLaptop> or -profile:a aac_he_v2
[17:27] <dharriso> alternaively reduce sample rate to 22050?
[17:27] <dharriso> will try this now
[17:33] <slackerr> how to tell ffmpeg make progressive frame while encoding if source is interlaced
[17:42] <dharriso> LithosLaptop: set the profile to HE-AACv2 as you suggested and now I get the same number of samples as before
[17:43] <dharriso> i mean the same number of sample for input and output 5768
[17:43] <dharriso> this is what i wanted to understand thanks
[17:45] <LithosLaptop> cool
[17:45] <LithosLaptop> no prob
[17:49] <dharriso> LithosLaptop: recommend any reference material i could read some background on this
[17:51] <LithosLaptop> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.129.4563&rep=rep1&type=pdf
[17:59] <dharriso> LithosLaptop: thanks
[18:06] <K1978> Hi! I am wondering if this http://superuser.com/questions/678450/copy-multiple-parts-of-a-video-to-a-single-destination-file-with-changed-playbac is possible using ffmpeg?
[18:09] <therube> speaking of HE-AAC & in particular on lower bitrates, 32kbps, on playback, when i seek, i'l typically hear "glitches", pops or "tears".  is that "normal" or some sort of failure in the decoder?
[18:12] <therube> i notice that in MPLayer, ffplay, MPC, perhaps less so in VLC, not certain, & then a quick look with Winamp, it was hard to determine because they reduce output volume level on seeking (or something like that)
[18:19] <therube> [aac @ 029e02e0] Reserved SBR extensions is not implemented.
[18:48] <viric> screen -r
[18:48] <viric> oops
[18:49] <klaxa> tmux > screen
[18:52] <viric> I'm lazy to relearn. But GPL > BSD
[18:53] <Mavrik> yellow > brown
[19:00] <klaxa> e^(pi * i) <3
[19:01] <viric> agreed
[19:57] <Zeranoe1> When using -vf ass=subtitles.ass should the subtitles be burned onto the resulting video? I'm not seeing them show up.
[20:00] <cbsrobot> Ithink you can use subtiles=file.ass nowadays
[20:00] <cbsrobot> *subtitles=file.ass
[20:01] <cbsrobot> if you have freetype and fontconfig enabled it should work
[20:04] <Zeranoe1> I'm not seeing them in the output video... But I don't get any errors and libass seems to be reading each line
[23:45] <mbrain_> hi, i have 20.000 images and i want to create a timelapse video but it will be huge video. so i want to input every 60th photo. like 001.jpg 061.jpg 122.jpg...
[23:46] <mbrain_> what should be the input pattern?
[23:49] <mbrain_> no one? :(
[00:00] --- Thu Nov 21 2013