60062/1001 fps ?

[XanaMuui]

Hi,

I'm trying to encode at 60 fps for the first time and while enconding using x264 I get this information:

ffms [info]: 1280x720p 0:1 @ 60062/1001 fps (vfr)
resize [warning]: converting from rgb24 to yuv420p
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSEMisalign LZCNT
x264 [info]: profile High, level 4.0

Where did that value for the fps came from? The original video is in 60 fps.

Stream #0:0: Video: lagarith (LAGS / 0x5347414C), rgb24, 1280x720, 360658 kb/s, 60 fps, 60 tbr, 60 tbn, 60 tbc
Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s

this are the commands passed to x264:
--crf 18 --profile high --preset placebo --tune film --qpmin 12 --vbv-maxrate 6000 --vbv-bufsize 6000 --output "E:\test_done.mp4" "E:\test_done.avi"

Is that fps normal or is it a bug? Because after the enconding MPC file info shows 60.002 fps.

[kabelbrand]

That might be an issue with your source file. It's recognised as variable frame rate (vfr) instead of cfr too.

Just add --fps 60/1 to your command line and the encode will be 60fps exactly.

[XanaMuui]

Thanks however even adding the "--fps 60/1" it still shows the same but now with cfr

ffms [info]: 1280x720p 0:1 @ 60062/1001 fps (cfr)
x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSEMisalign LZCNT
x264 [info]: profile High, level 5.0

EDIT: Nevermind. It says that however the resulting file now is 60fps, not 60.002 fps. Weird little glitch. I'm going to make some more tests just to make sure.

[kabelbrand]

That's alright, the --fps option also implies --force-cfr and the ffms info line just displays how the input is interpreted.

[foxyshadis]

Thanks however even adding the "--fps 60/1" it still shows the same but now with cfr



EDIT: Nevermind. It says that however the resulting file now is 60fps, not 60.002 fps. Weird little glitch. I'm going to make some more tests just to make sure.

60/1 is wrong, you want 60000/1001, or the audio will slowly go out of sync. That's assuming it's actually pure 60fps and the framerate was just slightly shifted to make the video track the same length as a slightly shorter audio track.

[colours]

Roughly speaking, FFMS tries to automatically round frame rates to "nice" numbers, and it considers fractions with denominator 1001 "nice" because NTSC uses frame rates like 24000/1001, 30000/1001 and 60000/1001. However, sometimes the automatic detection goes wrong for whatever reason and you get weird stuff like 60062/1001, which probably should have been exactly 60 fps instead.

Or is there a reason for you to believe that it really should be 60.002 fps?

Also, if you're obsessed about quality, you should do the colourspace conversion outside of x264 (Dither_convert_rgb_to_yuv in AviSynth, or z in Vapoursynth) rather than letting x264 delegate it to swscale, since swscale is not exactly known for being very high-quality.