[x264-devel] Degrade video quality by time

[Alex Giladi]

Try setting b_vfr_input=0

On Mon, Oct 31, 2011 at 2:17 AM, Alex S <flashsupporter at gmail.com> wrote:
> sorry for delay. I tried your crf param and intra-refresh option.
> certainly, with crf=23, quality is very high but It degraded by time (it is
> right because 164kbps may be too low in this case). Output video seems
> displaying a line of object movement (as if we do not have IDR but in fact
> we have).
> However, what I need is quality (we even could accept block) should not
> degraded
>
> On Fri, Oct 28, 2011 at 12:53 PM, Alex Jurkiewicz <alex at jurkiewi.cz> wrote:
>>
>> I'm not clear on which of my suggestions you tried.
>>
>> Are you sure your video does not simply get more complex as it goes on?
>>
>> On Fri, Oct 28, 2011 at 3:00 PM, Alex S <flashsupporter at gmail.com> wrote:
>> > Thanks for your information!
>> > However, it is still degraded quality by time (but in different effect
>> > and
>> > VBV overflow more).
>> > Is there anyway that bits is overallocated constant overtime (mean, at
>> > low
>> > bitrate, quality can be low but does not degrade by time)?
>> >
>> > On Thu, Oct 27, 2011 at 10:11 AM, Alex Jurkiewicz <alex at jurkiewi.cz>
>> > wrote:
>> >>
>> >> You must specify a bufsize for VBV encoding to work. More info:
>> >>
>> >> http://mewiki.project357.com/wiki/X264_Encoding_Suggestions#VBV_Encoding
>> >>
>> >> Single pass bitrate-based ratecontrol doesn't work so well, because
>> >> the ratecontrol algorithm has no information about the complexity of
>> >> future scenes. It often overallocates bits at the start and has to
>> >> underallocate later on.
>> >>
>> >> A common recommendation is to use CRF-based ratecontrol to pick a
>> >> 'target quality' and VBV settings to constrain the maximum bitrate to
>> >> below your maximum pipe size. This will use the lowest bitrate
>> >> required to achieve the given CRF value, capped given the VBV
>> >> settings.
>> >>
>> >> Try these options: rc_method=crf, crf=23, vbv_bufsize=164,
>> >> vbv_maxrate=164. Don't specify bitrate.
>> >>
>> >> Also, at such a low bitrate you might want to consider intra-refresh
>> >> as well, which will make the size of each frame more consistent. This
>> >> can improve streaming performance when you have small VBV buffers.
>> >>
>> >> Alex
>> >>
>> >> On Mon, Oct 24, 2011 at 2:23 PM, Alex S <flashsupporter at gmail.com>
>> >> wrote:
>> >> > I am using x264 in ABR and CBR mode. However, the quality is degraded
>> >> > by
>> >> > time.
>> >> > If I use CQP ratecontrol method, the quality is acceptable at bitrate
>> >> > 160kbps. However, with the same bitrate (or even higher) in ABR/CBR
>> >> > mode,
>> >> > video quality is degraded by time and unacceptable.
>> >> > Here is context setting in my code:
>> >> > x264_param_default_preset(&param, "veryfast", "zerolatency");
>> >> > x264_param_apply_profile(&param, "main");
>> >> > param.i_threads = 1;
>> >> > param.i_width = width;
>> >> > param.i_height = height;
>> >> > param.i_fps_num = fps;
>> >> > param.i_fps_den = 1;
>> >> > param.i_keyint_max = fps * 2
>> >> > param.b_intra_refresh = 0;
>> >> > param.rc.i_bitrate = 164     ;
>> >> > param.rc.i_vbv_max_bitrate = 164;
>> >> > param.rc.i_rc_method = X264_RC_ABR;
>> >> > param.b_repeat_headers = 1;
>> >> > param.b_annexb = 1;
>> >> > Could anybody help me to modify or add other setting parameters to
>> >> > solve
>> >> > the
>> >> > problem?
>> >> > Thank you!
>> >> > Alex
>> >> >
>> >> > _______________________________________________
>> >> > x264-devel mailing list
>> >> > x264-devel at videolan.org
>> >> > http://mailman.videolan.org/listinfo/x264-devel
>> >> >
>> >> >
>> >> _______________________________________________
>> >> x264-devel mailing list
>> >> x264-devel at videolan.org
>> >> http://mailman.videolan.org/listinfo/x264-devel
>> >
>> >
>> > _______________________________________________
>> > x264-devel mailing list
>> > x264-devel at videolan.org
>> > http://mailman.videolan.org/listinfo/x264-devel
>> >
>> >
>> _______________________________________________
>> x264-devel mailing list
>> x264-devel at videolan.org
>> http://mailman.videolan.org/listinfo/x264-devel
>
>
> _______________________________________________
> x264-devel mailing list
> x264-devel at videolan.org
> http://mailman.videolan.org/listinfo/x264-devel
>
>