Re: hmtx optimization over the Google Fonts collection

I think it's because the result is can be an input buffer that is less
friendly to brotli.

To give an example, lets take ArbutusSlab-Regular.ttf. It's hmtx barely
saves anything (Was 1734 now 1733 [bytes]). The main compression step gets
a smaller input but isn't able to compress it quite as well:

hmtx_opt: Compressed 63150 to 29992.
not opt: Compressed 63151 to 29939.

Plus we need an additional UIntBase128 to store the transform length.

On Wed, Jan 20, 2016 at 9:03 AM, Behdad Esfahbod <behdad@google.com> wrote:

> Hey,
>
> I'm sure everyone wants to know: why would any font get larger?
>
> On Wed, Jan 20, 2016 at 5:45 PM, Roderick Sheeter <rsheeter@google.com>
> wrote:
>
>> I did a test run of hmtx optimization over the Google Fonts collection
>> and thought the results might be of interest. A few key results:
>>
>>    - Of 1754 font files, 80.4% (1411) got smaller, 16.4% (288) had no
>>    change, and 3.1% (55) got larger.
>>    - For fonts with savings, average was 466 bytes or 1.08% of size
>>       - Across all fonts, average was 368 bytes or 0.86% of size
>>
>> Cheers, Rod S.
>>
>> Per-font results can be seen in
>> https://docs.google.com/spreadsheets/d/1dgL-il6fIHaHJghlzXz7aM_HEtes9G7Pt7TsnlsxsGc/edit?usp=sharing
>> .
>>
>>
>>
>