frmdec: do not abuse ff_codec_get_id()

Signed-off-by: Paul B Mahol <onemda@gmail.com>
lavfi/aevalsrc: try to honor specified duration

If nb_samples divide sample_rate and if nb_samples allow it, aevalsrc
should generate the exact amount of samples according to duration.

Example:
aevalsrc=0::n=480:s=48000:d=5.21 should generate 250080 samples.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
swr: minor simplification for the noise shaping pos update

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
swr: use local variable for ns_errors

71 -> 63 kcycles

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
swr: use a local variable for ns_coeffs

maybe a very tiny bit faster

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>