On 28-04-2019 07:19 AM, myp...@gmail.com wrote:
On Sat, Apr 27, 2019 at 8:22 PM Gyan <ffm...@gyani.pro> wrote:
On 27-04-2019 05:25 PM, Carl Eugen Hoyos wrote:
2019-04-27 13:17 GMT+02:00, Jun Zhao <mypopy...@gmail.com>:
perfer avctx->framerate first than use avctx->time_base when
setting the frame rate to encoder. 1/time_base is not the
average frame rate if the frame rate is not constant.
But why would the average framerate be a good choice to set
the encoder timebase?
Also, note that x264/5 RC looks at the framerate.
See
https://code.videolan.org/videolan/x264/commit/c583687fab832ba7eaf8626048f05ad1f861a855
I can generate a difference with x264 by setting -enc_time_base to
different values (with vsync vfr).
Maybe check that this change does not lead to a significant change in
output. Although I think this would be still an improvement for those
cases where r_frame_rate >> avg_frame_rate
Gyan
Yes, framerate and time_base is not close correlation in vfr case,
e,g, I can setting the framerate = 60fps, but time_base = 1/1000 s,
then setting pts like:
time_base = 1/1000 s = 1 millisecond
framerate = 60 fps per second
PTS 0----16----33----50----66----83----100 ...
PTS delta 16 17 17 16 17 17 ...
we will get 16ms * 20 frames + 17 ms * 40 frames = 1000ms
I'm aware of the relationship between TB and PTS. My point is x264's RC
adjusts its quantizer based on fps. You're changing that value so the
output bitrate will change for the same input with the same encoder
config if (avg_frame_rate) != (ticks * 1/TB).
Gyan
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