mirror of
https://github.com/lhns/steam-frame-nix.git
synced 2026-10-06 01:00:13 +02:00
Pierre Kisters
fd97347e18
Jellyfin Desktop hard-sets mpv's hwdec=auto-copy, whose probe list leaves out V4L2 M2M, and the Flatpak can't see the Frame's V4L2 decoder. An LD_PRELOAD shim (preloaded straight from the store, only that path exposed read-only) rewrites hwdec to v4l2m2m-copy,auto-copy; devices=all makes the decoder visible. Overrides via nix-flatpak, or a home-manager-owned override file without it.
97 lines
3.8 KiB
C
97 lines
3.8 KiB
C
// LD_PRELOAD shim for libmpv apps that set hwdec to an "auto*" value, such as
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// Jellyfin Desktop (hwdec=auto-copy). mpv's auto probe list leaves out V4L2
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// M2M decoders, so the Steam Frame's hardware decoder (qcom-iris) is never
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// tried. An "auto*" hwdec is rewritten to $SFN_MPV_HWDEC (default below); an
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// explicit value such as "no" is left alone. mpv falls back to software
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// decoding per stream if the decoder can't handle it.
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//
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// The preload applies to every process in the Flatpak sandbox; the wrappers
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// only run when a process calls libmpv, and need nothing but libc.
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#define _GNU_SOURCE
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#include <dlfcn.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define DEFAULT_HWDEC "v4l2m2m-copy,auto-copy"
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// From mpv/client.h (stable ABI).
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typedef struct mpv_handle mpv_handle;
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enum { MPV_FORMAT_STRING = 1, MPV_FORMAT_NODE = 6 };
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enum { MPV_ERROR_GENERIC = -20 };
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typedef struct mpv_node {
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union { char *string; int flag; int64_t int64; double double_; void *list; void *ba; } u;
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int format;
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} mpv_node;
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// The replacement for an automatic hwdec value, or NULL to keep `value`.
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static const char *hwdec_for(const char *name, const char *value) {
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if (!name || !value || strcmp(name, "hwdec") != 0 || strncmp(value, "auto", 4) != 0) return NULL;
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const char *v = getenv("SFN_MPV_HWDEC");
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if (!v || !*v) v = DEFAULT_HWDEC;
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static int logged;
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if (!__atomic_exchange_n(&logged, 1, __ATOMIC_RELAXED))
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fprintf(stderr, "mpv-hwdec-shim: hwdec \"%s\" -> \"%s\"\n", value, v);
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return v;
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}
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// `data` of an mpv_set_* call in `format`, with a rewritten hwdec in *node or
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// *str if applicable.
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static void *rewrite(const char *name, int format, void *data, mpv_node *node, const char **str) {
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const char *v;
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if (!data) return data;
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if (format == MPV_FORMAT_STRING && (v = hwdec_for(name, *(char **)data))) {
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*str = v;
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return str;
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}
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if (format == MPV_FORMAT_NODE && ((mpv_node *)data)->format == MPV_FORMAT_STRING &&
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(v = hwdec_for(name, ((mpv_node *)data)->u.string))) {
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node->format = MPV_FORMAT_STRING;
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node->u.string = (char *)v;
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return node;
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}
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return data;
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}
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// The real function (libmpv's), looked up once; returns MPV_ERROR_GENERIC if
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// it can't be found (no libmpv in the process: then nothing calls us anyway).
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#define NEXT(fn) \
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static __typeof__(fn) *next; \
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__typeof__(fn) *real = __atomic_load_n(&next, __ATOMIC_RELAXED); \
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if (!real) { \
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real = (__typeof__(fn) *)dlsym(RTLD_NEXT, #fn); \
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if (!real) return MPV_ERROR_GENERIC; \
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__atomic_store_n(&next, real, __ATOMIC_RELAXED); \
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}
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int mpv_set_property(mpv_handle *ctx, const char *name, int format, void *data) {
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NEXT(mpv_set_property);
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mpv_node n; const char *s;
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return real(ctx, name, format, rewrite(name, format, data, &n, &s));
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}
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int mpv_set_option(mpv_handle *ctx, const char *name, int format, void *data) {
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NEXT(mpv_set_option);
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mpv_node n; const char *s;
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return real(ctx, name, format, rewrite(name, format, data, &n, &s));
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}
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int mpv_set_property_async(mpv_handle *ctx, uint64_t ud, const char *name, int format, void *data) {
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NEXT(mpv_set_property_async);
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mpv_node n; const char *s;
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return real(ctx, ud, name, format, rewrite(name, format, data, &n, &s));
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}
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int mpv_set_property_string(mpv_handle *ctx, const char *name, const char *data) {
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NEXT(mpv_set_property_string);
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const char *v = hwdec_for(name, data);
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return real(ctx, name, v ? v : data);
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}
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int mpv_set_option_string(mpv_handle *ctx, const char *name, const char *data) {
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NEXT(mpv_set_option_string);
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const char *v = hwdec_for(name, data);
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return real(ctx, name, v ? v : data);
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}
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