mirror of https://github.com/mpv-player/mpv
131 lines
3.6 KiB
C
131 lines
3.6 KiB
C
#include <stdlib.h>
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#include <assert.h>
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#include <pthread.h>
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#include <libavutil/buffer.h>
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#include "mpv_talloc.h"
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#include "misc/dispatch.h"
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#include "osdep/atomic.h"
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#include "video/mp_image.h"
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#include "dr_helper.h"
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struct dr_helper {
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pthread_t thread;
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struct mp_dispatch_queue *dispatch;
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atomic_ullong dr_in_flight;
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struct mp_image *(*get_image)(void *ctx, int imgfmt, int w, int h,
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int stride_align);
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void *get_image_ctx;
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};
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static void dr_helper_destroy(void *ptr)
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{
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struct dr_helper *dr = ptr;
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// All references must have been freed on destruction, or we'll have
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// dangling pointers.
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assert(atomic_load(&dr->dr_in_flight) == 0);
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}
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struct dr_helper *dr_helper_create(struct mp_dispatch_queue *dispatch,
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struct mp_image *(*get_image)(void *ctx, int imgfmt, int w, int h,
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int stride_align),
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void *get_image_ctx)
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{
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struct dr_helper *dr = talloc_ptrtype(NULL, dr);
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talloc_set_destructor(dr, dr_helper_destroy);
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*dr = (struct dr_helper){
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.thread = pthread_self(),
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.dispatch = dispatch,
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.dr_in_flight = ATOMIC_VAR_INIT(0),
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.get_image = get_image,
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.get_image_ctx = get_image_ctx,
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};
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return dr;
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}
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struct free_dr_context {
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struct dr_helper *dr;
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AVBufferRef *ref;
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};
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static void dr_thread_free(void *ptr)
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{
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struct free_dr_context *ctx = ptr;
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unsigned long long v = atomic_fetch_add(&ctx->dr->dr_in_flight, -1);
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assert(v); // value before sub is 0 - unexpected underflow.
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av_buffer_unref(&ctx->ref);
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talloc_free(ctx);
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}
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static void free_dr_buffer_on_dr_thread(void *opaque, uint8_t *data)
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{
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struct free_dr_context *ctx = opaque;
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// The image could be unreffed even on the DR thread. In practice, this
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// matters most on DR destruction.
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if (pthread_equal(ctx->dr->thread, pthread_self())) {
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dr_thread_free(ctx);
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} else {
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mp_dispatch_run(ctx->dr->dispatch, dr_thread_free, ctx);
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}
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}
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struct get_image_cmd {
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struct dr_helper *dr;
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int imgfmt, w, h, stride_align;
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struct mp_image *res;
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};
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static void sync_get_image(void *ptr)
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{
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struct get_image_cmd *cmd = ptr;
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struct dr_helper *dr = cmd->dr;
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cmd->res = dr->get_image(dr->get_image_ctx, cmd->imgfmt, cmd->w, cmd->h,
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cmd->stride_align);
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if (!cmd->res)
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return;
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// We require exactly 1 AVBufferRef.
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assert(cmd->res->bufs[0]);
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assert(!cmd->res->bufs[1]);
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// Apply some magic to get it free'd on the DR thread as well. For this to
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// work, we create a dummy-ref that aliases the original ref, which is why
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// the original ref must be writable in the first place. (A newly allocated
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// image should be always writable of course.)
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assert(mp_image_is_writeable(cmd->res));
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struct free_dr_context *ctx = talloc_zero(NULL, struct free_dr_context);
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*ctx = (struct free_dr_context){
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.dr = dr,
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.ref = cmd->res->bufs[0],
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};
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AVBufferRef *new_ref = av_buffer_create(ctx->ref->data, ctx->ref->size,
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free_dr_buffer_on_dr_thread, ctx, 0);
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if (!new_ref)
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abort(); // tiny malloc OOM
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cmd->res->bufs[0] = new_ref;
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atomic_fetch_add(&dr->dr_in_flight, 1);
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}
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struct mp_image *dr_helper_get_image(struct dr_helper *dr, int imgfmt,
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int w, int h, int stride_align)
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{
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struct get_image_cmd cmd = {
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.dr = dr,
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.imgfmt = imgfmt, .w = w, .h = h, .stride_align = stride_align,
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};
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mp_dispatch_run(dr->dispatch, sync_get_image, &cmd);
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return cmd.res;
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}
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