Purvin Pandit | 1 Nov 20:19 2011
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Weighted prediction question

Hi

I notice that WP is being used to compensate for the poor rounding in motion compensation. Does anyone know how much benefit this gives? I tried few sequences but I dont notice any difference. Does this only work for particular sequences & resolutions?

Thanks,
-Purvin
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Edward Richards | 2 Nov 03:43 2011

x262 & H/264/MVC development

Hi team,

Can I contribute in some way to getting either/both of these two finished
faster?

x262 is under development: a best-in-class MPEG-2 encoder built using
the x264 framework.  Both P and B-frames are done and working.

Google Summer of Code is over, and the two projects, Trellis ME and
H.264/MVC support, are being finished up.

Rallymax.

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Kieran Kunhya | 2 Nov 11:28 2011

Re: x262 & H/264/MVC development

You can come onto #x264dev on freenode.
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Chris Waters | 6 Nov 23:14 2011
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Efficiently encoding synthetic data

Hi,

I want to encode a synthetically sequence of images into an H.264 video with as little CPU as possible. By synthetically generated I mean that my  program is generating the images – so I already know a number of characteristics of each frame. For example I know which parts of each frame differ from the previous frame – i.e. the rectangle containing the pixels that have changed from the previous frame.

I am trying to work out if there is a way to tell x264 that only pixels within a certain rectangle have changed when encoding each frame. It seems to me that if I could do this then a lot of computation could be saved because it wouldn't be necessary to do anything related to motion estimation. Basically the first frame in my video would be an I-frame and then every subsequent frame would be a P-frame containing only the pixels in the changed rectangle.

I am more concerned about reducing the CPU overhead than the size of the resulting file.

Can anyone give me any hints on where to look in the x264 source code to do something like this?

Thanks,

Chris.
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Alex S | 7 Nov 02:28 2011
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Re: Degrade video quality by time

Thank Alex! I have tried b_vfr_input=0 but nothing change. It seem b_vfr_input=0 as default.

On Tue, Nov 1, 2011 at 12:02 AM, Alex Giladi <alex.giladi <at> gmail.com> wrote:
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
>
>
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Michael kazmier | 7 Nov 04:24 2011
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Re: x262 & H/264/MVC development

> Can I contribute in some way to getting either/both of these two finished
> faster?
>
>
> x262 is under development: a best-in-class MPEG-2 encoder built using
> the x264 framework.  Both P and B-frames are done and working.
>

We need help.getting interlaced encoding support in x262 as well as fixing the bugs in encoding with subme > 5

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Jason Garrett-Glaser | 7 Nov 04:43 2011

Re: Efficiently encoding synthetic data

On Sun, Nov 6, 2011 at 2:14 PM, Chris Waters <watersco <at> gmail.com> wrote:
> Hi,
> I want to encode a synthetically sequence of images into an H.264 video with
> as little CPU as possible. By synthetically generated I mean that my
>  program is generating the images – so I already know a number of
> characteristics of each frame. For example I know which parts of each frame
> differ from the previous frame – i.e. the rectangle containing the pixels
> that have changed from the previous frame.
> I am trying to work out if there is a way to tell x264 that only pixels
> within a certain rectangle have changed when encoding each frame. It seems
> to me that if I could do this then a lot of computation could be saved
> because it wouldn't be necessary to do anything related to motion
> estimation

x264 already has fast pskip, which already does this (albeit at a small cost).

Jason
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BugMaster | 7 Nov 06:17 2011
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Re: Degrade video quality by time

On Mon, 7 Nov 2011 08:28:47 +0700, Alex S wrote:
> I have tried b_vfr_input=0 but nothing change. It seem b_vfr_input=0 as default.

Hi. May be you will provide encoded sample so we wouldn't guess what
you mean by degrade quality and will know real params you used. If you
can also provide short input sample to reproduce you problem it would
be also good.

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Tsahi Gilk | 9 Nov 19:52 2011

Re: Efficiently encoding synthetic data

What is fast pskip do?

I have the same situation with very small sub area of the frame is changed from frame to frame.

Tsahi.



ב-7 בנוב 2011, בשעה 05:44, "Jason Garrett-Glaser" <jason <at> x264.com> כתב/ה:

On Sun, Nov 6, 2011 at 2:14 PM, Chris Waters <watersco <at> gmail.com> wrote:
Hi,
I want to encode a synthetically sequence of images into an H.264 video with
as little CPU as possible. By synthetically generated I mean that my
 program is generating the images – so I already know a number of
characteristics of each frame. For example I know which parts of each frame
differ from the previous frame – i.e. the rectangle containing the pixels
that have changed from the previous frame.
I am trying to work out if there is a way to tell x264 that only pixels
within a certain rectangle have changed when encoding each frame. It seems
to me that if I could do this then a lot of computation could be saved
because it wouldn't be necessary to do anything related to motion
estimation

x264 already has fast pskip, which already does this (albeit at a small cost).

Jason
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James Gardiner | 10 Nov 22:26 2011
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48 fps in h.264/x264


Hello dev list.
I have a question for you.
The Hobbit is going to be shown in 48fps in cinemas.

I was looking into distribution standards for 48fps, and it does not seem to fit into any common standard.
Still, I tried using ffmpeg to convert a 48fps DPX source into a 48fps x264 mp4 file with no luck.

So, I thought I would ask you guys directly (Who should know) is it possible to make a 48fps h.264 compressed mp4/mkv file?

If so, can you point me in the direction, (general command arguments etc)

Regards,
James Gardiner
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