[x264-devel] VBV single frame prediction

[Paul McDermott]

Hi All,

I'm working on an application where we need to make an accurate as possible prediction of what the output frame size will be in VBV single frame encoding mode.

Currently I'm seeing a lot of fluctuation in the actual output frame size compared to what I've set the target frame size too using bitrate and vbv_max_bitrate and vbv_buffer_size, anywhere from 5-50%+ is required to be padded in the buffer.

I understand that this is expected at some level and *some* overhead is required to avoid overflow, but is there anything that can be done to predictably force the encoder to use more bytes available to it up to the max_bitrate? Also, is it expected that the encoder could be out by as much as 50% of more on the target size?

The reason being the application of the encoding is with an aim to save network bytes vs. video quality - need to make use of as many bytes as possible rather than adding this waste padding post-encoding. I've an example of what's being output from the encoder here in annexb format if anyone wants a look - https://www.fileconvoy.com/dfl.php?id=g781609c1931ef8509994117496219f4e1154c6ece

Thanks in advance,
Paul McDermott
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