ao_coreaudio: refactor chmap detection

b2f9e0610 introduced this functionality with code that was quite 'monolithic'.
Split the functionality over several functions and ose the new macros to get
array properties.

1 files changed, 81 insertions, 0 deletions

diff --git a/audio/out/ao_coreaudio_utils.c b/audio/out/ao_coreaudio_utils.c
index 221aeb4ddb..195d285b3e 100644
--- a/audio/out/ao_coreaudio_utils.c
+++ b/audio/out/ao_coreaudio_utils.c
@@ -340,3 +340,84 @@ bool ca_change_format(AudioStreamID stream,
 
     return format_set;
 }
+
+void ca_bitmaps_from_layouts(AudioChannelLayout *layouts, size_t n_layouts,
+                             uint32_t **bitmaps, size_t *n_bitmaps)
+{
+    *n_bitmaps = 0;
+    *bitmaps = talloc_array_size(NULL, sizeof(uint32_t), n_layouts);
+
+    for (int i=0; i < n_layouts; i++) {
+        uint32_t bitmap = 0;
+
+        switch (layouts[i].mChannelLayoutTag) {
+        case kAudioChannelLayoutTag_UseChannelBitmap:
+            (*bitmaps)[(*n_bitmaps)++] = layouts[i].mChannelBitmap;
+            break;
+
+        case kAudioChannelLayoutTag_UseChannelDescriptions:
+            if (ca_bitmap_from_ch_desc(&layouts[i], &bitmap))
+                (*bitmaps)[(*n_bitmaps)++] = bitmap;
+            break;
+
+        default:
+            if (ca_bitmap_from_ch_tag(&layouts[i], &bitmap))
+                (*bitmaps)[(*n_bitmaps)++] = bitmap;
+        }
+    }
+}
+
+bool ca_bitmap_from_ch_desc(AudioChannelLayout *layout, uint32_t *bitmap)
+{
+    // If the channel layout uses channel descriptions, from my
+    // exepriments there are there three possibile cases:
+    // * The description has a label kAudioChannelLabel_Unknown:
+    //   Can't do anything about this (looks like non surround
+    //   layouts are like this).
+    // * The description uses positional information: this in
+    //   theory could be used but one would have to map spatial
+    //   positions to labels which is not really feasible.
+    // * The description has a well known label which can be mapped
+    //   to the waveextensible definition: this is the kind of
+    //   descriptions we process here.
+    size_t ch_num = layout->mNumberChannelDescriptions;
+    bool all_channels_valid = true;
+
+    for (int j=0; j < ch_num && all_channels_valid; j++) {
+        AudioChannelLabel label = layout->mChannelDescriptions[j].mChannelLabel;
+        if (label == kAudioChannelLabel_UseCoordinates ||
+            label == kAudioChannelLabel_Unknown ||
+            label > kAudioChannelLabel_TopBackRight) {
+            ca_msg(MSGL_WARN,
+                    "channel label=%d unusable to build channel "
+                    "bitmap, skipping layout\n", label);
+            all_channels_valid = false;
+        } else {
+            *bitmap |= 1ULL << (label - 1);
+        }
+    }
+
+    return all_channels_valid;
+}
+
+bool ca_bitmap_from_ch_tag(AudioChannelLayout *layout, uint32_t *bitmap)
+{
+    // This layout is defined exclusively by it's tag. Use the Audio
+    // Format Services API to try and convert it to a bitmap that
+    // mpv can use.
+    uint32_t bitmap_size = sizeof(uint32_t);
+
+    AudioChannelLayoutTag tag = layout->mChannelLayoutTag;
+    OSStatus err = AudioFormatGetProperty(
+        kAudioFormatProperty_BitmapForLayoutTag,
+        sizeof(AudioChannelLayoutTag), &tag,
+        &bitmap_size, bitmap);
+    if (err != noErr) {
+        ca_msg(MSGL_WARN,
+                "channel layout tag=%d unusable to build channel "
+                "bitmap, skipping layout\n", tag);
+        return false;
+    } else {
+        return true;
+    }
+}