--- /dev/null
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <string.h>
+
+#include <audio_utils/channels.h>
+
+#include <log/log.h>
+
+/*
+ * Convert a buffer of N-channel, interleaved PCM16 samples to M-channel PCM16 channels
+ * (where N < M).
+ * in_buff points to the buffer of PCM16 samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted PCM16 samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > N are filled with silence.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t expand_channels_16(const int16_t* in_buff, int in_buff_chans,
+ int16_t* out_buff, int out_buff_chans,
+ size_t num_in_bytes)
+{
+ /*
+ * Move from back to front so that the conversion can be done in-place
+ * i.e. in_buff == out_buff
+ * NOTE: num_in_samples * out_buff_channels must be an even multiple of in_buff_chans
+ */
+ size_t num_in_samples = num_in_bytes / sizeof(int16_t);
+
+ size_t num_out_samples = (num_in_samples * out_buff_chans) / in_buff_chans;
+
+ int16_t* dst_ptr = out_buff + num_out_samples - 1;
+ size_t src_index;
+ const int16_t* src_ptr = in_buff + num_in_samples - 1;
+ int num_zero_chans = out_buff_chans - in_buff_chans;
+ for (src_index = 0; src_index < num_in_samples; src_index += in_buff_chans) {
+ int dst_offset;
+ for (dst_offset = 0; dst_offset < num_zero_chans; dst_offset++) {
+ *dst_ptr-- = 0;
+ }
+ for (; dst_offset < out_buff_chans; dst_offset++) {
+ *dst_ptr-- = *src_ptr--;
+ }
+ }
+
+ /* return number of *bytes* generated */
+ return num_out_samples * sizeof(int16_t);
+}
+
+/*
+ * Convert a buffer of N-channel, interleaved PCM16 samples to M-channel PCM16 channels
+ * (where N > M).
+ * in_buff points to the buffer of PCM16 samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted PCM16 samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > M are thrown away.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t contract_channels_16(const int16_t* in_buff, size_t in_buff_chans,
+ int16_t* out_buff, size_t out_buff_chans,
+ size_t num_in_bytes)
+{
+ /*
+ * Move from front to back so that the conversion can be done in-place
+ * i.e. in_buff == out_buff
+ * NOTE: num_in_samples * out_buff_channels must be an even multiple of in_buff_chans
+ */
+ size_t num_in_samples = num_in_bytes / sizeof(int16_t);
+
+ size_t num_out_samples = (num_in_samples * out_buff_chans) / in_buff_chans;
+
+ size_t num_skip_samples = in_buff_chans - out_buff_chans;
+
+ int16_t* dst_ptr = out_buff;
+ const int16_t* src_ptr = in_buff;
+ size_t src_index;
+ for (src_index = 0; src_index < num_in_samples; src_index += in_buff_chans) {
+ size_t dst_offset;
+ for (dst_offset = 0; dst_offset < out_buff_chans; dst_offset++) {
+ *dst_ptr++ = *src_ptr++;
+ }
+ src_ptr += num_skip_samples;
+ }
+
+ /* return number of *bytes* generated */
+ return num_out_samples * sizeof(int16_t);
+}
+
+/*
+ * Convert a buffer of N-channel, interleaved PCM32 samples to M-channel PCM32 channels
+ * (where N < M).
+ * in_buff points to the buffer of PCM32 samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted PCM32 samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > N are filled with silence.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t expand_channels_32(const int32_t* in_buff, size_t in_buff_chans,
+ int32_t* out_buff, size_t out_buff_chans,
+ size_t num_in_bytes)
+{
+ /*
+ * Move from back to front so that the conversion can be done in-place
+ * i.e. in_buff == out_buff
+ * NOTE: num_in_samples * out_buff_channels must be an even multiple of in_buff_chans
+ */
+ size_t num_in_samples = num_in_bytes / sizeof(int32_t);
+
+ size_t num_out_samples = (num_in_samples * out_buff_chans) / in_buff_chans;
+
+ int32_t* dst_ptr = out_buff + num_out_samples - 1;
+ const int32_t* src_ptr = in_buff + num_in_samples - 1;
+ size_t num_zero_chans = out_buff_chans - in_buff_chans;
+ size_t src_index;
+ for (src_index = 0; src_index < num_in_samples; src_index += in_buff_chans) {
+ size_t dst_offset;
+ for (dst_offset = 0; dst_offset < num_zero_chans; dst_offset++) {
+ *dst_ptr-- = 0;
+ }
+ for (; dst_offset < out_buff_chans; dst_offset++) {
+ *dst_ptr-- = *src_ptr--;
+ }
+ }
+
+ /* return number of *bytes* generated */
+ return num_out_samples * sizeof(int32_t);
+}
+
+/*
+ * Convert a buffer of N-channel, interleaved PCM32 samples to M-channel PCM32 channels
+ * (where N > M).
+ * in_buff points to the buffer of PCM32 samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted PCM16 samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > M are thrown away.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t contract_channels_32(const int32_t* in_buff, size_t in_buff_chans,
+ int32_t* out_buff, size_t out_buff_chans,
+ size_t num_in_bytes)
+{
+ /*
+ * Move from front to back so that the conversion can be done in-place
+ * i.e. in_buff == out_buff
+ * NOTE: num_in_samples * out_buff_channels must be an even multiple of in_buff_chans
+ */
+ size_t num_in_samples = num_in_bytes / sizeof(int32_t);
+
+ size_t num_out_samples = (num_in_samples * out_buff_chans) / in_buff_chans;
+
+ size_t num_skip_samples = in_buff_chans - out_buff_chans;
+
+ int32_t* dst_ptr = out_buff;
+ const int32_t* src_ptr = in_buff;
+ size_t src_index;
+ for (src_index = 0; src_index < num_in_samples; src_index += in_buff_chans) {
+ size_t dst_offset;
+ for (dst_offset = 0; dst_offset < out_buff_chans; dst_offset++) {
+ *dst_ptr++ = *src_ptr++;
+ }
+ src_ptr += num_skip_samples;
+ }
+
+ /* return number of *bytes* generated */
+ return num_out_samples * sizeof(int32_t);
+}
+
+/*
+ * Convert a buffer of N-channel, interleaved samples to M-channel
+ * (where N > M).
+ * in_buff points to the buffer of samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * sample_size_in_bytes Specifies the number of bytes per sample.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > M are thrown away.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t contract_channels(const void* in_buff, size_t in_buff_chans,
+ void* out_buff, size_t out_buff_chans,
+ unsigned sample_size_in_bytes, size_t num_in_bytes)
+{
+ switch (sample_size_in_bytes) {
+ case 2:
+ return contract_channels_16((const int16_t*)in_buff, in_buff_chans,
+ (int16_t*)out_buff, out_buff_chans,
+ num_in_bytes);
+
+ /* TODO - do this conversion when we have a device to test it with */
+ case 3:
+ ALOGE("24-bit channel contraction not supported.");
+ return 0;
+
+ case 4:
+ return contract_channels_32((const int32_t*)in_buff, in_buff_chans,
+ (int32_t*)out_buff, out_buff_chans,
+ num_in_bytes);
+
+ default:
+ return 0;
+ }
+}
+
+/*
+ * Convert a buffer of N-channel, interleaved samples to M-channel
+ * (where N < M).
+ * in_buff points to the buffer of samples
+ * in_buff_channels Specifies the number of channels in the input buffer.
+ * out_buff points to the buffer to receive converted samples.
+ * out_buff_channels Specifies the number of channels in the output buffer.
+ * sample_size_in_bytes Specifies the number of bytes per sample.
+ * num_in_bytes size of input buffer in BYTES
+ * returns
+ * the number of BYTES of output data.
+ * NOTE
+ * channels > N are filled with silence.
+ * The out and sums buffers must either be completely separate (non-overlapping), or
+ * they must both start at the same address. Partially overlapping buffers are not supported.
+ */
+static size_t expand_channels(const void* in_buff, size_t in_buff_chans,
+ void* out_buff, size_t out_buff_chans,
+ unsigned sample_size_in_bytes, size_t num_in_bytes)
+{
+ switch (sample_size_in_bytes) {
+ case 2:
+ return expand_channels_16((const int16_t*)in_buff, in_buff_chans,
+ (int16_t*)out_buff, out_buff_chans,
+ num_in_bytes);
+
+ /* TODO - do this conversion when we have a device to test it with */
+ case 3:
+ ALOGE("24-bit channel expansion not supported.");
+ return 0;
+
+ case 4:
+ return expand_channels_32((const int32_t*)in_buff, in_buff_chans,
+ (int32_t*)out_buff, out_buff_chans,
+ num_in_bytes);
+
+ default:
+ return 0;
+ }
+}
+
+size_t adjust_channels(const void* in_buff, size_t in_buff_chans,
+ void* out_buff, size_t out_buff_chans,
+ unsigned sample_size_in_bytes, size_t num_in_bytes)
+{
+ if (out_buff_chans > in_buff_chans) {
+ return expand_channels(in_buff, in_buff_chans, out_buff, out_buff_chans,
+ sample_size_in_bytes, num_in_bytes);
+ } else if (out_buff_chans < in_buff_chans) {
+ return contract_channels(in_buff, in_buff_chans, out_buff, out_buff_chans,
+ sample_size_in_bytes, num_in_bytes);
+ } else if (in_buff != out_buff) {
+ memcpy(out_buff, in_buff, num_in_bytes);
+ }
+
+ return num_in_bytes;
+}
+
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