Variable: DEFAULT_CACHE_SECS

const DEFAULT_CACHE_SECS: 30 = 30;

Defined in: packages/player/src/player.ts:1455

Default --cache-secs, i.e. how far ahead the demuxer is allowed to read on a network stream.

mpv's own default is 1000 * 60 * 60 seconds (demux/demux.c, demux_conf.defaults.min_secs_cache, mpv 0.35.1), and demux.c takes min_secs = MPMAX(demuxer-readahead-secs, cache-secs) whenever the cache is active — which --cache=auto makes true for anything that looks like a network stream. The only brake left is --demuxer-max-bytes, whose default is 150 MiB: on a 128 kbit/s radio stream that is ~2.7 hours of audio which mpv will happily download, over mobile data, while paused. (Measured on-device: a paused Shoutcast entry's buffered readout climbed past 45 s and kept going.)

30 s is the balance point. It does not delay startup — how far ahead the demuxer reads is independent of when playback starts, which is gated by the AO queue (--audio-buffer, 0.2 s) and not by the cache, since --cache-pause-initial defaults to no (mpv 0.35.1 options.rst). It leaves 30 s of slack to ride out a mobile-network stall, and mpv only needs --cache-pause-wait (1 s) buffered to resume after one. The cost is that a stall longer than 30 s rebuffers where mpv's default would not have; that is the deliberate trade for bounded memory and bounded data use.

Override per player with mpvOptions: { 'cache-secs': '…' }.