@@ -8,6 +8,7 @@
#include "gstlibcamera-utils.h"
+#include <optional>
#include <string>
#include <libcamera/control_ids.h>
@@ -435,61 +436,111 @@ gst_libcamera_stream_configuration_to_caps(const StreamConfiguration &stream_cfg
return caps;
}
-void gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
+/*
+ * We will want to distinguish between caps structures corresponding to
+ * raw and non-raw (processed) output images, as this will help inform
+ * our choice of preferred format.
+ *
+ * We identify Bayer as being the principle "raw" format here, but note
+ * that we are considering greyscale (images with one component) to be
+ * raw too (e.g. a raw monochrome sensor).
+ */
+static bool
+gst_libcamera_structure_is_raw_capture(const GstStructure *s)
+{
+ if (gst_structure_has_name(s, "video/x-bayer"))
+ return true;
+
+ if (gst_structure_has_name(s, "video/x-raw")) {
+ const gchar *format = gst_structure_get_string(s, "format");
+ if (!format)
+ return false;
+
+ const GstVideoFormatInfo *finfo =
+ gst_video_format_get_info(gst_video_format_from_string(format));
+
+ return finfo->n_components == 1;
+ }
+
+ return false;
+}
+
+/*
+ * Data recorded for each caps structure candidate, used to rank them
+ * against each other via operator<().
+ */
+struct CapsCandidate {
+ guint index;
+ bool is_raw;
+ bool is_fixed;
+ guint delta;
+
+ bool operator<(const CapsCandidate &other) const
+ {
+ /*
+ * Raw formats are likely to be useful only to applications that
+ * specifically ask for them. Other applications will typically be
+ * unable to handle them and fail, so prefer non-raw candidates.
+ */
+ if (is_raw != other.is_raw)
+ return !is_raw;
+
+ /* Prefer a reliable fixed value over a range. */
+ if (is_fixed != other.is_fixed)
+ return is_fixed;
+
+ /* Otherwise the closest size match wins. */
+ return delta < other.delta;
+ }
+};
+
+bool gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
GstCaps *caps, GstVideoTransferFunction *transfer)
{
GstVideoFormat gst_format = pixel_format_to_gst_format(stream_cfg.pixelFormat);
guint i;
- gint best_fixed = -1, best_in_range = -1;
GstStructure *s;
- /*
- * These are delta weight computed from:
- * ABS(width - stream_cfg.size.width) * ABS(height - stream_cfg.size.height)
- */
- guint best_fixed_delta = G_MAXUINT;
- guint best_in_range_delta = G_MAXUINT;
-
/* First fixate the caps using default configuration value. */
g_assert(gst_caps_is_writable(caps));
- /* Lookup the structure for a close match to the stream_cfg.size */
+ /*
+ * Build a candidate for every available caps structure, and keep
+ * track of the best one seen so far, as ranked by
+ * CapsCandidate::operator<().
+ */
+ std::optional<CapsCandidate> best;
+
for (i = 0; i < gst_caps_get_size(caps); i++) {
s = gst_caps_get_structure(caps, i);
gint width, height;
- guint delta;
+ bool is_fixed = gst_structure_has_field_typed(s, "width", G_TYPE_INT) &&
+ gst_structure_has_field_typed(s, "height", G_TYPE_INT);
- if (gst_structure_has_field_typed(s, "width", G_TYPE_INT) &&
- gst_structure_has_field_typed(s, "height", G_TYPE_INT)) {
+ if (is_fixed) {
gst_structure_get_int(s, "width", &width);
gst_structure_get_int(s, "height", &height);
-
- delta = ABS(width - (gint)stream_cfg.size.width) * ABS(height - (gint)stream_cfg.size.height);
-
- if (delta < best_fixed_delta) {
- best_fixed_delta = delta;
- best_fixed = i;
- }
} else {
gst_structure_fixate_field_nearest_int(s, "width", stream_cfg.size.width);
gst_structure_fixate_field_nearest_int(s, "height", stream_cfg.size.height);
gst_structure_get_int(s, "width", &width);
gst_structure_get_int(s, "height", &height);
+ }
- delta = ABS(width - (gint)stream_cfg.size.width) * ABS(height - (gint)stream_cfg.size.height);
+ guint delta = ABS(width - (gint)stream_cfg.size.width) * ABS(height - (gint)stream_cfg.size.height);
- if (delta < best_in_range_delta) {
- best_in_range_delta = delta;
- best_in_range = i;
- }
- }
+ CapsCandidate candidate{ i, gst_libcamera_structure_is_raw_capture(s), is_fixed, delta };
+
+ if (!best || candidate < *best)
+ best = candidate;
+ }
+
+ if (!best) {
+ GST_WARNING("Failed to find a suitable caps structure to configure the stream");
+ return false;
}
- /* Prefer reliable fixed value over ranges */
- if (best_fixed >= 0)
- s = gst_caps_get_structure(caps, best_fixed);
- else
- s = gst_caps_get_structure(caps, best_in_range);
+ s = gst_caps_get_structure(caps, best->index);
if (gst_structure_has_name(s, "video/x-raw")) {
const gchar *format = gst_video_format_to_string(gst_format);
@@ -529,6 +580,8 @@ void gst_libcamera_configure_stream_from_caps(StreamConfiguration &stream_cfg,
stream_cfg.colorSpace = colorspace_from_colorimetry(colorimetry, transfer);
}
+
+ return true;
}
void gst_libcamera_get_framerate_from_caps(GstCaps *caps,
@@ -18,7 +18,7 @@
GstCaps *gst_libcamera_stream_formats_to_caps(const libcamera::StreamFormats &formats);
GstCaps *gst_libcamera_stream_configuration_to_caps(const libcamera::StreamConfiguration &stream_cfg,
GstVideoTransferFunction transfer);
-void gst_libcamera_configure_stream_from_caps(libcamera::StreamConfiguration &stream_cfg,
+bool gst_libcamera_configure_stream_from_caps(libcamera::StreamConfiguration &stream_cfg,
GstCaps *caps, GstVideoTransferFunction *transfer);
void gst_libcamera_get_framerate_from_caps(GstCaps *caps, GstStructure *element_caps);
void gst_libcamera_clamp_and_set_frameduration(libcamera::ControlList &controls,
@@ -605,7 +605,8 @@ gst_libcamera_src_negotiate(GstLibcameraSrc *self)
/* Fixate caps and configure the stream. */
caps = gst_caps_make_writable(caps);
- gst_libcamera_configure_stream_from_caps(stream_cfg, caps, &transfer[i]);
+ if (!gst_libcamera_configure_stream_from_caps(stream_cfg, caps, &transfer[i]))
+ return false;
gst_libcamera_get_framerate_from_caps(caps, element_caps);
}
Existing code was preferring fixed size outputs over ones with ranges, resulting in raw output formats being preferred even when applications ("cheese" is one such example) aren't expecting them and subsequently fail. The revised version still prefers fixed size outputs over ones with ranges, but will prefer non-raw (meaning non-Bayer) formats where these are available. This still allows applications that explicitly request raw formats to get them, but other applications will normally get non-raw formats which they handle better. Fixes, for example, "cheese" on Raspberry Pi. Signed-off-by: David Plowman <david.plowman@raspberrypi.com> --- src/gstreamer/gstlibcamera-utils.cpp | 115 +++++++++++++++++++-------- src/gstreamer/gstlibcamera-utils.h | 2 +- src/gstreamer/gstlibcamerasrc.cpp | 3 +- 3 files changed, 87 insertions(+), 33 deletions(-)