Take into account the filter size when calculating the delay

[mmomtchev]

When calculating the number of samples that AudioResampler::pop will return, the filter size must be taken into account:

avcpp/src/audioresampler.cpp

Line 209 in c3311e6

auto delay = swr_get_delay(m_raw, m_dstRate);

libswresample uses a filter and needs a number of bytes after the end of the sample to be able to resample - 16 in my case.

Otherwise, it risks returning partial frames.

The total value is available in SwrContext->filter_size, the number of samples needed is half that.

Ref: https://stackoverflow.com/questions/39587839/libswresample-swr-convert-not-producing-enough-samples

[h4tr3d]

Sounds like this field was added a far ago:

da9587952a8 (Michael Niedermayer 2012-04-26 01:35:22 +0200 127)     int filter_size;                                /**< length of each FIR filter in the resampling filterbank relative to the cutoff frequency */

approve! Thanks!