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-rw-r--r--media/base/channel_mixer.cc70
1 files changed, 53 insertions, 17 deletions
diff --git a/media/base/channel_mixer.cc b/media/base/channel_mixer.cc
index fa4cbb6..420ecda 100644
--- a/media/base/channel_mixer.cc
+++ b/media/base/channel_mixer.cc
@@ -11,6 +11,7 @@
#include <cmath>
#include "base/logging.h"
+#include "media/audio/audio_parameters.h"
#include "media/base/audio_bus.h"
#include "media/base/vector_math.h"
@@ -20,14 +21,11 @@ namespace media {
// value for stereo -> mono and mono -> stereo mixes.
static const float kEqualPowerScale = static_cast<float>(M_SQRT1_2);
-static int ValidateLayout(ChannelLayout layout) {
+static void ValidateLayout(ChannelLayout layout) {
CHECK_NE(layout, CHANNEL_LAYOUT_NONE);
CHECK_NE(layout, CHANNEL_LAYOUT_MAX);
-
- // TODO(dalecurtis, crogers): We will eventually handle unsupported layouts by
- // simply copying the input channels to the output channels, similar to if the
- // user requests identical input and output layouts today.
CHECK_NE(layout, CHANNEL_LAYOUT_UNSUPPORTED);
+ CHECK_NE(layout, CHANNEL_LAYOUT_DISCRETE);
// Verify there's at least one channel. Should always be true here by virtue
// of not being one of the invalid layouts, but lets double check to be sure.
@@ -52,24 +50,60 @@ static int ValidateLayout(ChannelLayout layout) {
DCHECK_EQ(layout, CHANNEL_LAYOUT_MONO);
}
- return channel_count;
+ return;
+}
+
+ChannelMixer::ChannelMixer(ChannelLayout input_layout,
+ ChannelLayout output_layout) {
+ Initialize(input_layout,
+ ChannelLayoutToChannelCount(input_layout),
+ output_layout,
+ ChannelLayoutToChannelCount(output_layout));
}
-ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
- : input_layout_(input),
- output_layout_(output),
- remapping_(false) {
+ChannelMixer::ChannelMixer(
+ const AudioParameters& input, const AudioParameters& output) {
+ Initialize(input.channel_layout(),
+ input.channels(),
+ output.channel_layout(),
+ output.channels());
+}
+
+void ChannelMixer::Initialize(
+ ChannelLayout input_layout, int input_channels,
+ ChannelLayout output_layout, int output_channels) {
+ input_layout_ = input_layout;
+ output_layout_ = output_layout;
+ remapping_ = false;
+
// Stereo down mix should never be the output layout.
CHECK_NE(output_layout_, CHANNEL_LAYOUT_STEREO_DOWNMIX);
- int input_channels = ValidateLayout(input_layout_);
- int output_channels = ValidateLayout(output_layout_);
+ if (input_layout_ != CHANNEL_LAYOUT_DISCRETE)
+ ValidateLayout(input_layout_);
+ if (output_layout_ != CHANNEL_LAYOUT_DISCRETE)
+ ValidateLayout(output_layout_);
// Size out the initial matrix.
matrix_.reserve(output_channels);
for (int output_ch = 0; output_ch < output_channels; ++output_ch)
matrix_.push_back(std::vector<float>(input_channels, 0));
+ // First check for discrete case.
+ if (input_layout_ == CHANNEL_LAYOUT_DISCRETE ||
+ output_layout_ == CHANNEL_LAYOUT_DISCRETE) {
+ // If the number of input channels is more than output channels, then
+ // copy as many as we can then drop the remaining input channels.
+ // If the number of input channels is less than output channels, then
+ // copy them all, then zero out the remaining output channels.
+ int passthrough_channels = std::min(input_channels, output_channels);
+ for (int i = 0; i < passthrough_channels; ++i)
+ matrix_[i][i] = 1;
+
+ remapping_ = true;
+ return;
+ }
+
// Route matching channels and figure out which ones aren't accounted for.
for (Channels ch = LEFT; ch < CHANNELS_MAX;
ch = static_cast<Channels>(ch + 1)) {
@@ -102,7 +136,8 @@ ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
// When down mixing to mono from stereo, we need to be careful of full scale
// stereo mixes. Scaling by 1 / sqrt(2) here will likely lead to clipping
// so we use 1 / 2 instead.
- float scale = (output == CHANNEL_LAYOUT_MONO && input_channels == 2) ?
+ float scale =
+ (output_layout_ == CHANNEL_LAYOUT_MONO && input_channels == 2) ?
0.5 : kEqualPowerScale;
Mix(LEFT, CENTER, scale);
Mix(RIGHT, CENTER, scale);
@@ -111,7 +146,8 @@ ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
// Mix center into front LR.
if (IsUnaccounted(CENTER)) {
// When up mixing from mono, just do a copy to front LR.
- float scale = (input == CHANNEL_LAYOUT_MONO) ? 1 : kEqualPowerScale;
+ float scale =
+ (input_layout_ == CHANNEL_LAYOUT_MONO) ? 1 : kEqualPowerScale;
MixWithoutAccounting(CENTER, LEFT, scale);
Mix(CENTER, RIGHT, scale);
}
@@ -128,7 +164,7 @@ ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
// Mix back LR into back center.
Mix(BACK_LEFT, BACK_CENTER, kEqualPowerScale);
Mix(BACK_RIGHT, BACK_CENTER, kEqualPowerScale);
- } else if (output > CHANNEL_LAYOUT_MONO) {
+ } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
// Mix back LR into front LR.
Mix(BACK_LEFT, LEFT, kEqualPowerScale);
Mix(BACK_RIGHT, RIGHT, kEqualPowerScale);
@@ -151,7 +187,7 @@ ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
// Mix side LR into back center.
Mix(SIDE_LEFT, BACK_CENTER, kEqualPowerScale);
Mix(SIDE_RIGHT, BACK_CENTER, kEqualPowerScale);
- } else if (output > CHANNEL_LAYOUT_MONO) {
+ } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
// Mix side LR into front LR.
Mix(SIDE_LEFT, LEFT, kEqualPowerScale);
Mix(SIDE_RIGHT, RIGHT, kEqualPowerScale);
@@ -172,7 +208,7 @@ ChannelMixer::ChannelMixer(ChannelLayout input, ChannelLayout output)
// Mix back center into side LR.
MixWithoutAccounting(BACK_CENTER, SIDE_LEFT, kEqualPowerScale);
Mix(BACK_CENTER, SIDE_RIGHT, kEqualPowerScale);
- } else if (output > CHANNEL_LAYOUT_MONO) {
+ } else if (output_layout_ > CHANNEL_LAYOUT_MONO) {
// Mix back center into front LR.
// TODO(dalecurtis): Not sure about these values?
MixWithoutAccounting(BACK_CENTER, LEFT, kEqualPowerScale);
generated by cgit v1.1 at 2025-10-13 16:49:55 +0000