[FFmpeg-user] How to specify Audio bit depth for test sources?

[Basin Ilya]

Hi.
Different test sources have different bit depth:

    ffplay -f lavfi aevalsrc="0"
    # Audio: pcm_f64le

    ffplay -f lavfi anullsrc
    # Audio: pcm_u8

If I want to do some PCM math in the audio filter, I'll need to adapt the filter for each different input bit depth.
There's no filter to change the depth. "aresample" only changes the sample rate.

-acodec option won't do here, because it takes effect AFTER filtering and some tools don't have it (ffplay).
-isf: I was unable to make it work

The only workaround is to use /dev/zero as the source. Then you can specify the needed input format.