they're at different layers. libmpv is a full media player: demuxing, decoding (via FFmpeg), DSP, output. cpal is just a thin cross-platform PCM sink on top of CoreAudio/ALSA/WASAPI/etc.
Rockbox already brings its own decoders (20+ codecs), its own DSP chain (crossfeed, EQ, replaygain, gapless), and its own mixer. I just need the host OS to accept PCM frames. cpal is the minimal portable shim for that; pulling in libmpv would mean discarding Rockbox's audio pipeline and replacing it with FFmpeg's, which would basically defeat the point of building on Rockbox firmware.
they're at different layers. libmpv is a full media player: demuxing, decoding (via FFmpeg), DSP, output. cpal is just a thin cross-platform PCM sink on top of CoreAudio/ALSA/WASAPI/etc.
Rockbox already brings its own decoders (20+ codecs), its own DSP chain (crossfeed, EQ, replaygain, gapless), and its own mixer. I just need the host OS to accept PCM frames. cpal is the minimal portable shim for that; pulling in libmpv would mean discarding Rockbox's audio pipeline and replacing it with FFmpeg's, which would basically defeat the point of building on Rockbox firmware.