[x264-devel] Request for i_slice_max_size setting explanation

[Jason Garrett-Glaser]

On Wed, Jan 11, 2012 at 4:52 AM, Alexander Sbitnev
<alexander.sbitnev at gmail.com> wrote:
>  Does setting i_slice_max_size to 1400 means NAL units can go up to 1400
> bytes in size?
> I've tried 1400 and maximum NAL size i currently seen was 1391 bytes. Is
> there some constant value involved, limiting NAL size up to
> (i_slice_max_size - CONST). Or is it just a very small chances to see NAL
> units going all the way up to its maximum size?

It's very hard to exactly fill a NAL, and x264 doesn't try.

x264 allocates a few extra bytes for "just in case", though that is
perhaps less necessary now that x264 exactly tracks NAL escape bytes.

Jason