Use helper function to set format in v4l2 input.

Since the helper function also needs to pack/unpack the resolution, the
pack/unpack functions were moved to the helper library and prefixed with
v4l2_ in order to avoid possible collisions.

plugins/linux-v4l2/v4l2-helpers.c

@@ -133,4 +133,39 @@ int_fast32_t v4l2_set_input(int_fast32_t dev, int *input)
 		: v4l2_ioctl(dev, VIDIOC_S_INPUT, input);
 }
 
+int_fast32_t v4l2_set_format(int_fast32_t dev, int *resolution,
+		int *pixelformat, int *bytesperline)
+{
+	bool set = false;
+	int width, height;
+	struct v4l2_format fmt;
+
+	if (!dev || !resolution || !pixelformat || !bytesperline)
+		return -1;
+
+	/* We need to set the type in order to query the settings */
+	fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+
+	if (v4l2_ioctl(dev, VIDIOC_G_FMT, &fmt) < 0)
+		return -1;
+
+	if (*resolution != -1) {
+		v4l2_unpack_tuple(&width, &height, *resolution);
+		fmt.fmt.pix.width  = width;
+		fmt.fmt.pix.height = height;
+		set = true;
+	}
+
+	if (*pixelformat != -1) {
+		fmt.fmt.pix.pixelformat = *pixelformat;
+		set = true;
+	}
 
+	if (set && (v4l2_ioctl(dev, VIDIOC_S_FMT, &fmt) < 0))
+		return -1;
+
+	*resolution   = v4l2_pack_tuple(fmt.fmt.pix.width, fmt.fmt.pix.height);
+	*pixelformat  = fmt.fmt.pix.pixelformat;
+	*bytesperline = fmt.fmt.pix.bytesperline;
+	return 0;
+}

plugins/linux-v4l2/v4l2-helpers.h

@@ -131,6 +131,38 @@ static const int v4l2_framerates[] =
 	0
 };
 
+/**
+ * Pack two integer values into one
+ *
+ * Obviously the input integers have to be truncated in order to fit into
+ * one. The effective 16bits left are still enough to handle resolutions and
+ * framerates just fine.
+ *
+ * @param a integer one
+ * @param b integer two
+ *
+ * @return the packed integer
+ */
+static inline int v4l2_pack_tuple(int a, int b)
+{
+	return (a << 16) | (b & 0xffff);
+}
+
+/**
+ * Unpack two integer values from one
+ *
+ * @see v4l2_pack_tuple
+ *
+ * @param a pointer to integer a
+ * @param b pointer to integer b
+ * @param packed the packed integer
+ */
+static void v4l2_unpack_tuple(int *a, int *b, int packed)
+{
+	*a = packed >> 16;
+	*b = packed & 0xffff;
+}
+
 /**
  * Start the video capture on the device.
  *
@@ -187,6 +219,22 @@ int_fast32_t v4l2_destroy_mmap(struct v4l2_buffer_data *buf);
  */
 int_fast32_t v4l2_set_input(int_fast32_t dev, int *input);
 
+/**
+ * Set the video format on the device.
+ *
+ * If the action succeeds resolution, pixelformat and bytesperline are set
+ * to the used values.
+ *
+ * @param dev handle for the v4l2 device
+ * @param resolution packed value of the resolution or -1 to leave as is
+ * @param pixelformat index of the pixelformat or -1 to leave as is
+ * @param bytesperline this will be set accordingly on success
+ *
+ * @return negative on failure
+ */
+int_fast32_t v4l2_set_format(int_fast32_t dev, int *resolution,
+		int *pixelformat, int *bytesperline);
+
 #ifdef __cplusplus
 }
 #endif

plugins/linux-v4l2/v4l2-input.c

@@ -62,36 +62,22 @@ struct v4l2_data {
 
 	char *set_device;
 	int set_input;
-	int_fast32_t set_pixfmt;
-	int_fast32_t set_res;
+	int set_pixfmt;
+	int set_res;
 	int_fast32_t set_fps;
 
 	/* data used within the capture thread */
 	int_fast32_t dev;
 
 	uint64_t frames;
-	int_fast32_t width;
-	int_fast32_t height;
+	int width;
+	int height;
 	int_fast32_t pixfmt;
-	uint_fast32_t linesize;
+	int linesize;
 
 	struct v4l2_buffer_data buffers;
 };
 
-/*
- * used to store framerate and resolution values
- */
-static int pack_tuple(int a, int b)
-{
-	return (a << 16) | (b & 0xffff);
-}
-
-static void unpack_tuple(int *a, int *b, int packed)
-{
-	*a = packed >> 16;
-	*b = packed & 0xffff;
-}
-
 /**
  * Prepare the output frame structure for obs and compute plane offsets
  *
@@ -368,7 +354,7 @@ static void v4l2_resolution_list(int dev, uint_fast32_t pixelformat,
 			dstr_printf(&buffer, "%dx%d", frmsize.discrete.width,
 					frmsize.discrete.height);
 			obs_property_list_add_int(prop, buffer.array,
-					pack_tuple(frmsize.discrete.width,
+					v4l2_pack_tuple(frmsize.discrete.width,
 					frmsize.discrete.height));
 			frmsize.index++;
 		}
@@ -380,7 +366,7 @@ static void v4l2_resolution_list(int dev, uint_fast32_t pixelformat,
 		for (const int *packed = v4l2_framesizes; *packed; ++packed) {
 			int width;
 			int height;
-			unpack_tuple(&width, &height, *packed);
+			v4l2_unpack_tuple(&width, &height, *packed);
 			dstr_printf(&buffer, "%dx%d", width, height);
 			obs_property_list_add_int(prop, buffer.array, *packed);
 		}
@@ -414,7 +400,7 @@ static void v4l2_framerate_list(int dev, uint_fast32_t pixelformat,
 				&frmival) == 0) {
 			float fps = (float) frmival.discrete.denominator /
 				frmival.discrete.numerator;
-			int pack = pack_tuple(frmival.discrete.numerator,
+			int pack = v4l2_pack_tuple(frmival.discrete.numerator,
 					frmival.discrete.denominator);
 			dstr_printf(&buffer, "%.2f", fps);
 			obs_property_list_add_int(prop, buffer.array, pack);
@@ -428,7 +414,7 @@ static void v4l2_framerate_list(int dev, uint_fast32_t pixelformat,
 		for (const int *packed = v4l2_framerates; *packed; ++packed) {
 			int num;
 			int denom;
-			unpack_tuple(&num, &denom, *packed);
+			v4l2_unpack_tuple(&num, &denom, *packed);
 			float fps = (float) denom / num;
 			dstr_printf(&buffer, "%.2f", fps);
 			obs_property_list_add_int(prop, buffer.array, *packed);
@@ -511,7 +497,7 @@ static bool resolution_selected(obs_properties_t props, obs_property_t p,
 		return false;
 
 	obs_property_t prop = obs_properties_get(props, "framerate");
-	unpack_tuple(&width, &height, obs_data_get_int(settings,
+	v4l2_unpack_tuple(&width, &height, obs_data_get_int(settings,
 				"resolution"));
 	v4l2_framerate_list(dev, obs_data_get_int(settings, "pixelformat"),
 			width, height, prop);
@@ -596,10 +582,8 @@ static void v4l2_destroy(void *vptr)
  */
 static void v4l2_init(struct v4l2_data *data)
 {
-	struct v4l2_format fmt;
 	struct v4l2_streamparm par;
 	struct dstr fps;
-	int width, height;
 	int fps_num, fps_denom;
 
 	blog(LOG_INFO, "Start capture from %s", data->set_device);
@@ -618,26 +602,19 @@ static void v4l2_init(struct v4l2_data *data)
 	blog(LOG_INFO, "Input: %d", data->set_input);
 
 	/* set pixel format and resolution */
-	unpack_tuple(&width, &height, data->set_res);
-	fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-	fmt.fmt.pix.width = width;
-	fmt.fmt.pix.height = height;
-	fmt.fmt.pix.pixelformat = data->set_pixfmt;
-	fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
-	if (v4l2_ioctl(data->dev, VIDIOC_S_FMT, &fmt) < 0) {
+	if (v4l2_set_format(data->dev, &data->set_res, &data->set_pixfmt,
+			&data->linesize) < 0) {
 		blog(LOG_ERROR, "Unable to set format");
 		goto fail;
 	}
-	data->width = fmt.fmt.pix.width;
-	data->height = fmt.fmt.pix.height;
-	data->pixfmt = fmt.fmt.pix.pixelformat;
-	data->linesize = fmt.fmt.pix.bytesperline;
-	blog(LOG_INFO, "Resolution: %"PRIuFAST32"x%"PRIuFAST32,
-	     data->width, data->height);
-	blog(LOG_INFO, "Linesize: %"PRIuFAST32" Bytes", data->linesize);
+	v4l2_unpack_tuple(&data->width, &data->height, data->set_res);
+	data->pixfmt = data->set_pixfmt;
+	blog(LOG_INFO, "Resolution: %dx%d", data->width, data->height);
+	blog(LOG_INFO, "Pixelformat: %d", data->set_pixfmt);
+	blog(LOG_INFO, "Linesize: %d Bytes", data->linesize);
 
 	/* set framerate */
-	unpack_tuple(&fps_num, &fps_denom, data->set_fps);
+	v4l2_unpack_tuple(&fps_num, &fps_denom, data->set_fps);
 	par.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 	par.parm.capture.timeperframe.numerator = fps_num;
 	par.parm.capture.timeperframe.denominator = fps_denom;