[x264-devel] HRD buffer overflow

[Steve Li]

Hi all,

I am getting HRD buffer overflow warnings from the Tektronix analyzer when I analyze the output of the x264 encoder. Below are the x264 parameters:

profile=High
level=4
i_nal_hrd=2 (CBR)
rc.i_bitrate=3500
rc.vbv_buffer_size=3500

Input is 1920x1080p29.97

The warning happens quite often in the output (over 20 warnings within 10 secs). Here is one of the warnings from the Tektronix analyzer:
Hypothetical Reference Decoder SchedSelIdx = 0 model has overflowed by 7 bits at time 1.000s.The overflow occurred during the decoding of frame 21, bitstream position 0x65e57 (dec. 417367).  The total HRD buffer occupancy is 3500007 bits and the maximum limit is 3500000 bits.  HRD parameters were derived from the sequence_header.

The warning seems to happen on certain settings only. If I change the bitrate or vbv_buffer_size to some other values, the warnings are gone.

Steve

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