[x264-devel] [x264-devel]the size of vbv buffer

[jogging song]

Hi, everyone

 In X264, I set a small value for vbv_bufsize and get a message "The VBV
buffer size  to samll, and
using xxx kbit". In the code, I find its default value is three times
average frame size.
    h->param.rc.i_vbv_buffer_size = 3 * h->param.rc.i_vbv_max_bitrate /
rc->fps;
can anyone suggest how to set the value for vbv_bufsize. I think the buffer
at least should be able to cantain the
biggest frame that the encoder generates.

The default vaue for vbv_buffer_init is 0.9. When I set vbv_buffer_init to
0, I find that the first I frame
gets a bigger QP than 0.9. In my opinion, when the vbv buffer contains less
bits, Rate Control should give out
a small QP to fill the buffer.

   In Rate Control, vbv buffer is filled by
rct->buffer_fill_final += rct->buffer_rate - bits;
   The bits exceeding the average frame size will accumulate in the VBV
buffer. In video coding, I find the value is
near the size of vbv buffer. VBV buffer is the input buffer of decoders. In
anytime of video decoding, bitstream for
next frame should be feeded in input buffer, then decoders begin to decode
the bitstream. If accumulating bits in vbv
buffer is near its size, decoders can't put more bits in the input buffer.
Am I right?

Thanks
Jogging
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.videolan.org/pipermail/x264-devel/attachments/20070326/438d0b52/attachment.htm