[x264-devel] Problem on using x264_encoder_encode

[Alessandro Ferrari]

2009/8/25 Jason Garrett-Glaser <darkshikari at gmail.com>

> On Tue, Aug 25, 2009 at 11:12 AM, Alessandro
> Ferrari<alessandroferrari87 at gmail.com> wrote:
> > 2009/8/25 Jason Garrett-Glaser <darkshikari at gmail.com>
> >>
> >> On Tue, Aug 25, 2009 at 10:51 AM, Alessandro
> >> Ferrari<alessandroferrari87 at gmail.com> wrote:
> >> > 2009/8/25 Jason Garrett-Glaser <darkshikari at gmail.com>
> >> >>
> >> >> On Tue, Aug 25, 2009 at 2:57 AM, Alessandro
> >> >> Ferrari<alessandroferrari87 at gmail.com> wrote:
> >> >> > Hi dear community,
> >> >> >                              I have a problem with the encoding
> using
> >> >> > x264.
> >> >> > After I call x264_encoder_encode( h, &nal, &i_nal, pic, &pic_out)
> >> >> > function
> >> >> > I have nal= NULL, i_nal=0 and the function return 0. I'm sure that
> >> >> > pic
> >> >> > contain the correct image. The x264_t h is open using the default
> >> >> > parameters, i only change width and length of the video. The
> function
> >> >> > don't
> >> >> > give me any error, it seems that it not encode any data. I include
> >> >> > the
> >> >> > code
> >> >> > of encoding function that I implement watching x264.c.
> >> >>
> >> >> x264 has an encoding delay depending on your parameters; it will not
> >> >> return frames until a number of frames have been inputted.  This
> delay
> >> >> is used for lookahead purposes.  Keep inputting frames and you will
> >> >> eventually get frames out.
> >> >>
> >> >> Dark Shikari
> >> >
> >> > I have a strange error when i try to access  at the fields of x264_t.
> I
> >> > have
> >> > this compilation error:
> >> > transcoder.c:173: error: dereferencing pointer to incomplete type
> >> > The automatic code completion of my ide don't find any fields for the
> >> > pointer at x264_t h, but the compiler correct recognize the presence
> of
> >> > the
> >> > type x264_t. I include on the x264.h header. Can this the cause of
> >> > problem?
> >> > Many thanks.
> >>
> >> x264_t is an opaque handler for the encoder; you are not supposed to
> >> be able to access its internal variables.
> >>
> >> Dark Shikari
> >
> > Ok, now I understand. I have any possibilities to change this frame
> delay?
> >
>
> The encoder-side frame delay is as follows (measured in frames):
>
> With b-adapt = 0 or 1:
> MAX( param.rc.i_lookahead, param.i_bframes ) + threads - 1
>
> With b-adapt = 2:
> MAX( param.rc.i_lookahead, MAX(param.i_bframes,3)*4 ) + threads - 1
>
> Note that both VBV lookahead (for increased VBV quality and
> compliance) and Macroblock Tree ratecontrol (for better quality
> distribution among frames) require a significant lookahead; both of
> these features will be disabled if you turn off the lookahead.
> Obviously, for low-latency applications like videoconferencing, you
> have no choice.
>
> Dark Shikari
>

I have to implement a transcoder that receive a frame by network and
downsize it for mobile device with low latency. B-adapt is set to 1, and i
have only one threads, i cannot access to param.rc.lookahead, and I don't
know if by default lookahead is disabled or not. If lookahead is disabled i
think that frame-delay is 1, in this case i think that the problem is not
caused by frame delay. Any suggest? Thanks.
Best regards
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