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Simplification to planar channel blending.
This commit is contained in:
David Reid
@@ -1892,9 +1892,6 @@ mal_uint64 mal_format_converter_read_deinterleaved(mal_format_converter* pConver
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// channel is willing to _give_ 50% of it's total volume to the front plane, and the front/center speaker is willing to _take_ 100% of it's total volume
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// from the front, you can imagine that 50% of the front/left speaker will be given to the front/center speaker.
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//
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// This blending technique is not perfect, but it should provide a logical and reasonable estimate. This will not work well with speaker positions such as
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// front/center/left (where the speaker is to the left of the front/center speaker) because the algorithm uses a simplified spatial model.
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//
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// Usage
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// -----
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// To use the channel router you need to specify three things:
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@@ -17239,7 +17236,7 @@ static inline float mal_vec3_distance(mal_vec3 a, mal_vec3 b)
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return mal_vec3_length(mal_vec3_sub(a, b));
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}
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#if 0
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#define MAL_PLANE_LEFT 0
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#define MAL_PLANE_RIGHT 1
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#define MAL_PLANE_FRONT 2
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@@ -17301,64 +17298,6 @@ float g_malChannelPlaneRatios[MAL_CHANNEL_POSITION_COUNT][6] = {
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{ 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_30
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{ 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_31
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};
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#endif
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// The position of each speaker in a virtual 3D space. Used for spatial blending.
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mal_vec3 g_malDefaultChannel3DPositions[MAL_CHANNEL_POSITION_COUNT] = {
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_NONE
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_MONO
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{-1.0f, 0.0f, -1.0f}, // MAL_CHANNEL_FRONT_LEFT
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{+1.0f, 0.0f, -1.0f}, // MAL_CHANNEL_FRONT_RIGHT
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{ 0.0f, 0.0f, -1.0f}, // MAL_CHANNEL_FRONT_CENTER
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_LFE
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{-1.0f, 0.0f, +1.0f}, // MAL_CHANNEL_BACK_LEFT
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{+1.0f, 0.0f, +1.0f}, // MAL_CHANNEL_BACK_RIGHT
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{-0.5f, 0.0f, -1.0f}, // MAL_CHANNEL_FRONT_LEFT_CENTER
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{+0.5f, 0.0f, -1.0f}, // MAL_CHANNEL_FRONT_RIGHT_CENTER
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{ 0.0f, 0.0f, +1.0f}, // MAL_CHANNEL_BACK_CENTER
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{-1.0f, 0.0f, 0.0f}, // MAL_CHANNEL_SIDE_LEFT
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{+1.0f, 0.0f, 0.0f}, // MAL_CHANNEL_SIDE_RIGHT
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{ 0.0f, +1.0f, 0.0f}, // MAL_CHANNEL_TOP_CENTER
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{-1.0f, +1.0f, -1.0f}, // MAL_CHANNEL_TOP_FRONT_LEFT
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{ 0.0f, +1.0f, -1.0f}, // MAL_CHANNEL_TOP_FRONT_CENTER
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{+1.0f, +1.0f, -1.0f}, // MAL_CHANNEL_TOP_FRONT_RIGHT
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{-1.0f, +1.0f, +1.0f}, // MAL_CHANNEL_TOP_BACK_LEFT
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{ 0.0f, +1.0f, +1.0f}, // MAL_CHANNEL_TOP_BACK_CENTER
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{+1.0f, +1.0f, +1.0f}, // MAL_CHANNEL_TOP_BACK_RIGHT
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_0
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_1
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_2
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_3
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_4
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_5
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_6
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_7
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_8
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_9
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_10
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_11
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_12
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_13
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_14
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_15
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_16
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_17
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_18
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_19
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_20
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_21
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_22
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_23
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_24
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_25
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_26
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_27
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_28
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_29
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_30
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{ 0.0f, 0.0f, 0.0f}, // MAL_CHANNEL_AUX_31
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};
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float mal_calculate_channel_position_planar_weight(mal_channel channelPositionA, mal_channel channelPositionB)
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{
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@@ -17385,67 +17324,20 @@ float mal_calculate_channel_position_planar_weight(mal_channel channelPositionA,
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// - back/left: 2 planes (back and left) = 1/2 = half it's total volume on each plane
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// - top/front/left: 3 planes (top, front and left) = 1/3 = one third it's total volume on each plane
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//
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// Now that we know how much volume each speaker emits for each of the planes it emits audio from we need to know how many planes are shared
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// between the two speakers:
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// - front/left (in) and front/left (out): 2 shared planes (front and left)
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// - front/left (in) and side/left (out): 1 shared plane (left)
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// - front/left (in) and back/left (out): 1 shared plane (left)
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// - front/left (in) and top/front/left (out): 2 shared planes (front and left)
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//
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// We now have enough information to know how much audio the input speaker gives to each of it's outputs:
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//
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// volumeToGive = volumePerInputSpeakerPlane * sharedPlaneCount
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//
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// We can also determine how much volume an output speaker should take:
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//
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// volumeToTake = volumePerOutputSpeakerPlane * sharedPlaneCount
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//
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// Thus, the final contribution is:
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//
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// contribution = volumeToGive * volumeToTake
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//
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// Contributions for each of our examples:
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//
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// front/left to front/left = (1/2 * 2) * (1/2 * 2) = 0.5*2.0 * 0.5*2.0 = 1.0*1.0 = 1.0
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// front/left to side/left = (1/2 * 1) * (1/1 * 1) = 0.5*1.0 * 1.0*1.0 = 0.5*1.0 = 0.5
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// front/left to back/left = (1/2 * 1) * (1/2 * 1) = 0.5*1.0 * 0.5*1.0 = 0.5*0.5 = 0.25
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// front/left to top/front/left = (1/2 * 2) * (1/3 * 2) = 0.5*2.0 * 0.33*2.0 = 1.0*0.66 = 0.66
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// The amount of volume each channel contributes to each of it's planes is what controls how much it is willing to given and take to other
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// channels on the same plane. The volume that is willing to the given by one channel is multiplied by the volume that is willing to be
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// taken by the other to produce the final contribution.
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mal_vec3 physicalPosA = g_malDefaultChannel3DPositions[channelPositionA];
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mal_vec3 physicalPosB = g_malDefaultChannel3DPositions[channelPositionB];
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// Contribution = Sum(Volume to Give * Volume to Take)
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float contribution =
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g_malChannelPlaneRatios[channelPositionA][0] * g_malChannelPlaneRatios[channelPositionB][0] +
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g_malChannelPlaneRatios[channelPositionA][1] * g_malChannelPlaneRatios[channelPositionB][1] +
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g_malChannelPlaneRatios[channelPositionA][2] * g_malChannelPlaneRatios[channelPositionB][2] +
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g_malChannelPlaneRatios[channelPositionA][3] * g_malChannelPlaneRatios[channelPositionB][3] +
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g_malChannelPlaneRatios[channelPositionA][4] * g_malChannelPlaneRatios[channelPositionB][4] +
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g_malChannelPlaneRatios[channelPositionA][5] * g_malChannelPlaneRatios[channelPositionB][5];
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mal_uint32 planeCountA = 0;
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if (physicalPosA.x < 0 || physicalPosA.x > 0) planeCountA += 1;
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if (physicalPosA.y < 0 || physicalPosA.y > 0) planeCountA += 1;
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if (physicalPosA.z < 0 || physicalPosA.z > 0) planeCountA += 1;
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mal_uint32 planeCountB = 0;
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if (physicalPosB.x < 0 || physicalPosB.x > 0) planeCountB += 1;
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if (physicalPosB.y < 0 || physicalPosB.y > 0) planeCountB += 1;
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if (physicalPosB.z < 0 || physicalPosB.z > 0) planeCountB += 1;
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mal_uint32 sharedPlaneCount = 0;
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if (physicalPosA.x < 0 && physicalPosB.x < 0) sharedPlaneCount += 1;
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if (physicalPosA.x > 0 && physicalPosB.x > 0) sharedPlaneCount += 1;
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if (physicalPosA.y < 0 && physicalPosB.y < 0) sharedPlaneCount += 1;
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if (physicalPosA.y > 0 && physicalPosB.y > 0) sharedPlaneCount += 1;
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if (physicalPosA.z < 0 && physicalPosB.z < 0) sharedPlaneCount += 1;
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if (physicalPosA.z > 0 && physicalPosB.z > 0) sharedPlaneCount += 1;
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mal_assert(sharedPlaneCount <= planeCountA);
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mal_assert(sharedPlaneCount <= 3);
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if (sharedPlaneCount == 0) {
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return 0;
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}
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mal_assert(planeCountA > 0);
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mal_assert(planeCountB > 0);
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float contributionA = 1.0f/planeCountA * sharedPlaneCount;
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float contributionB = 1.0f/planeCountB * sharedPlaneCount;
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return contributionA * contributionB;
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return contribution;
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}
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float mal_channel_router__calculate_input_channel_planar_weight(const mal_channel_router* pRouter, mal_channel channelPositionIn, mal_channel channelPositionOut)
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@@ -17465,11 +17357,13 @@ mal_bool32 mal_channel_router__is_spatial_channel_position(const mal_channel_rou
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return MAL_FALSE;
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}
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if (mal_vec3_length(g_malDefaultChannel3DPositions[channelPosition]) == 0) {
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return MAL_FALSE;
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for (int i = 0; i < 6; ++i) {
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if (g_malChannelPlaneRatios[channelPosition][i] != 0) {
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return MAL_TRUE;
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}
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}
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return MAL_TRUE;
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return MAL_FALSE;
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}
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mal_result mal_channel_router_init(const mal_channel_router_config* pConfig, mal_channel_router* pRouter)
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