core-format: Add pa_format_info_from_sample_spec2()

The function will be used in pa_sink_input_new() and
pa_source_output_new() to convert the sample spec given by the client
to a format info object. The set_format, set_rate and set_channels
will be set according to the stream flags (PA_SINK_INPUT_FIX_FORMAT
etc.).

src/pulsecore/core-format.c

@@ -117,6 +117,43 @@ int pa_format_info_get_channel_map(pa_format_info *f, pa_channel_map *map) {
     return 0;
 }
 
+pa_format_info *pa_format_info_from_sample_spec2(const pa_sample_spec *ss, const pa_channel_map *map, bool set_format,
+                                                 bool set_rate, bool set_channels) {
+    pa_format_info *format = NULL;
+
+    pa_assert(ss);
+
+    format = pa_format_info_new();
+    format->encoding = PA_ENCODING_PCM;
+
+    if (set_format)
+        pa_format_info_set_sample_format(format, ss->format);
+
+    if (set_rate)
+        pa_format_info_set_rate(format, ss->rate);
+
+    if (set_channels) {
+        pa_format_info_set_channels(format, ss->channels);
+
+        if (map) {
+            if (map->channels != ss->channels) {
+                pa_log_debug("Channel map is incompatible with the sample spec.");
+                goto fail;
+            }
+
+            pa_format_info_set_channel_map(format, map);
+        }
+    }
+
+    return format;
+
+fail:
+    if (format)
+        pa_format_info_free(format);
+
+    return NULL;
+}
+
 int pa_format_info_to_sample_spec2(pa_format_info *f, pa_sample_spec *ss, pa_channel_map *map, pa_sample_spec *fallback_ss,
                                    pa_channel_map *fallback_map) {
     int r, r2;

src/pulsecore/core-format.h

@@ -22,6 +22,8 @@
 
 #include <pulse/format.h>
 
+#include <stdbool.h>
+
 /* Gets the sample format stored in the format info. Returns a negative error
  * code on failure. If the sample format property is not set at all, returns
  * -PA_ERR_NOENTITY. */
@@ -42,6 +44,22 @@ int pa_format_info_get_channels(pa_format_info *f, uint8_t *channels);
  * -PA_ERR_NOENTITY. */
 int pa_format_info_get_channel_map(pa_format_info *f, pa_channel_map *map);
 
+/* Convert a sample spec and an optional channel map to a new PCM format info
+ * object (remember to free it). If map is NULL, then the channel map will be
+ * left unspecified. If some fields of the sample spec should be ignored, pass
+ * false for set_format, set_rate and set_channels as appropriate, then those
+ * fields will be left unspecified. This function returns NULL if the input is
+ * invalid (for example, setting the sample rate was requested, but the rate
+ * in ss is invalid).
+ *
+ * pa_format_info_from_sample_spec() exists too. This "version 2" was created,
+ * because the original function doesn't provide the possibility of ignoring
+ * some of the sample spec fields. That functionality can't be added to the
+ * original function, because the function is a part of the public API and
+ * adding parameters to it would break the API. */
+pa_format_info *pa_format_info_from_sample_spec2(const pa_sample_spec *ss, const pa_channel_map *map, bool set_format,
+                                                 bool set_rate, bool set_channels);
+
 /* Convert the format info into a sample spec and a channel map. If the format
  * info doesn't contain some information, the fallback sample spec and channel
  * map are used to populate the output.