On 29.01.2024 19:31, Anton Khirnov wrote:
Tested-by: Jiří Eliášek, Misha Aizatulin
---
Now requested an infinite timeout from
IDXGIOutputDuplication_AcquireNextFrame() when a frame is required.
---
doc/filters.texi | 15 +++++++++++----
libavfilter/vsrc_ddagrab.c | 9 +++++++--
2 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 1d70f4d934..b9b539acee 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -28713,10 +28713,10 @@ it'll always be captured.
@item framerate
Maximum framerate at which the desktop will be captured - the interval between
successive frames will not be smaller than the inverse of the framerate. When
-the desktop is not being updated often enough, the filter will duplicate
-a previous frame. Note that there is no background buffering going on, so when
-the filter is not polled often enough then the actual inter-frame interval may
-be significantly larger.
+@var{dup_frames} is true (the default) and the desktop is not being updated
+often enough, the filter will duplicate a previous frame. Note that there is no
+background buffering going on, so when the filter is not polled often enough
+then the actual inter-frame interval may be significantly larger.
Defaults to 30 FPS.
@@ -28749,6 +28749,13 @@ Passes all supported output formats to DDA and returns what DDA decides to use.
Filter initialization will fail if 10 bit format is requested but unavailable.
@end table
+@item dup_frames
+When this option is set to true (the default), the filter will duplicate frames
+when the desktop has not been updated in order to maintain approximately
+constant target framerate. When this option is set to false, the filter will
+wait for the desktop to be updated (inter-frame intervals may vary
significantly
+in this case).
+
@end table
@subsection Examples
diff --git a/libavfilter/vsrc_ddagrab.c b/libavfilter/vsrc_ddagrab.c
index 9c59faf53e..7109f5752b 100644
--- a/libavfilter/vsrc_ddagrab.c
+++ b/libavfilter/vsrc_ddagrab.c
@@ -101,6 +101,7 @@ typedef struct DdagrabContext {
int out_fmt;
int allow_fallback;
int force_fmt;
+ int dup_frames;
} DdagrabContext;
#define OFFSET(x) offsetof(DdagrabContext, x)
@@ -124,6 +125,8 @@ static const AVOption ddagrab_options[] = {
OFFSET(allow_fallback),
AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
{ "force_fmt", "exclude BGRA from format list (experimental, discouraged by
Microsoft)",
OFFSET(force_fmt),
AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
+ { "dup_frames", "duplicate frames to maintain framerate",
+ OFFSET(dup_frames),
AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
nit: align description properly
{ NULL }
};
@@ -688,7 +691,7 @@ static int next_frame_internal(AVFilterContext *avctx, ID3D11Texture2D **desktop
hr = IDXGIOutputDuplication_AcquireNextFrame(
dda->dxgi_outdupl,
- dda->time_timeout,
+ need_frame ? INFINITE : dda->time_timeout,
My main worry with this is that the filter could potentially be sitting
there for a really, really long time.
And also... see below.
&frame_info,
&desktop_resource);
if (hr == DXGI_ERROR_WAIT_TIMEOUT) {
@@ -1067,7 +1070,9 @@ static int ddagrab_request_frame(AVFilterLink *outlink)
now -= dda->first_pts;
if (!dda->probed_texture) {
- ret = next_frame_internal(avctx, &cur_texture, 0);
+ do {
+ ret = next_frame_internal(avctx, &cur_texture, !dda->dup_frames);
+ } while (ret == AVERROR(EAGAIN) && !dda->dup_frames);
This is unfortunately not quiet correct, as it misunderstands the
need_frame parameter.
The need_frame parameter is meant for the initial probing period, where
an actual _frame_ is needed, outside of the probing, mouse-location-only
updates are perfectly valid though.
So with this implementation, if the desktop remains static, but the
mouse is moved, this loop will keep asking for a frame, and not record
the mouse movement.
My idea for a fix would be to just pass 0 to need_frame as it was, but
keep the outer loop like this.
And either make the INFINITE timeout depend on the dup_frames option
directly, or just don't pass INFINITE, and let it loop.
} else {
cur_texture = dda->probed_texture;
dda->probed_texture = NULL;
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