diff --git a/modules/usbaudio/audio_hw.c b/modules/usbaudio/audio_hw.c
index b2005c6..8945791 100644
--- a/modules/usbaudio/audio_hw.c
+++ b/modules/usbaudio/audio_hw.c
@@ -231,7 +231,7 @@
  *   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_samples size of input buffer in SAMPLES
+ *   num_in_bytes size of input buffer in BYTES
  * returns
  *   the number of BYTES of output data.
  * NOTE
@@ -241,16 +241,18 @@
  * support 4-channel devices.
  * TODO Move this to a utilities module.
  */
-static size_t expand_channels_16(const short* in_buff, int in_buff_chans,
-                                 short* out_buff, int out_buff_chans,
-                                 size_t num_in_samples)
+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
      */
-    int num_out_samples = (num_in_samples * out_buff_chans)/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;
 
     short* dst_ptr = out_buff + num_out_samples - 1;
     size_t src_index;
@@ -267,7 +269,7 @@
     }
 
     /* return number of *bytes* generated */
-    return num_out_samples * sizeof(short);
+    return num_out_samples * sizeof(int16_t);
 }
 
 /*
@@ -277,7 +279,7 @@
  *   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_samples size of input buffer in SAMPLES
+ *   num_in_bytes size of input buffer in BYTES
  * returns
  *   the number of BYTES of output data.
  * NOTE
@@ -287,24 +289,26 @@
  * support 4-channel devices.
  * TODO Move this to a utilities module.
  */
-static size_t contract_channels_16(short* in_buff, int in_buff_chans,
-                                   short* out_buff, int out_buff_chans,
-                                   size_t num_in_samples)
+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
      */
-    int num_out_samples = (num_in_samples * out_buff_chans)/in_buff_chans;
+    size_t num_in_samples = num_in_bytes / sizeof(int16_t);
 
-    int num_skip_samples = in_buff_chans - out_buff_chans;
+    size_t num_out_samples = (num_in_samples * out_buff_chans) / in_buff_chans;
 
-    short* dst_ptr = out_buff;
-    short* src_ptr = in_buff;
+    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) {
-        int dst_offset;
+        size_t dst_offset;
         for (dst_offset = 0; dst_offset < out_buff_chans; dst_offset++) {
             *dst_ptr++ = *src_ptr++;
         }
@@ -312,7 +316,169 @@
     }
 
     /* return number of *bytes* generated */
-    return num_out_samples * sizeof(short);
+    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.
+ *   This conversion is safe to do in-place (in_buff == out_buff)
+ * We are doing this since we *always* present to The Framework as STEREO device, but need to
+ * support 4-channel devices.
+ * TODO Move this to a utilities module.
+ */
+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 PCM16 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 > N are thrown away.
+ *   This conversion is safe to do in-place (in_buff == out_buff)
+ * We are doing this since we *always* present to The Framework as STEREO device, but need to
+ * support 4-channel devices.
+ * TODO Move this to a utilities module.
+ */
+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);
+}
+
+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;
+    }
+}
+
+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;
+    }
+}
+
+static 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;
 }
 
 /*
@@ -477,7 +643,7 @@
     return (mask->bits[0] & 0x0004) != 0;
 }
 
-static int get_format_for_mask(struct pcm_mask* mask)
+static audio_format_t get_format_for_mask(struct pcm_mask* mask)
 {
     int num_slots = sizeof(mask->bits)/ sizeof(mask->bits[0]);
     int bits_per_slot = sizeof(mask->bits[0]) * 8;
@@ -560,6 +726,10 @@
     0                       /* 49 - SNDRV_PCM_FORMAT_DSD_U16_LE */
 };
 
+/*
+ * Scans the provided format mask and returns the first non-8 bit sample
+ * format supported by the devices.
+ */
 static int get_pcm_format_for_mask(struct pcm_mask* mask) {
     int num_slots = sizeof(mask->bits)/ sizeof(mask->bits[0]);
     int bits_per_slot = sizeof(mask->bits[0]) * 8;
@@ -569,21 +739,21 @@
     int slot_index, bit_index, table_index;
     table_index = 0;
     int num_written = 0;
-    for (slot_index = 0; slot_index < num_slots; slot_index++) {
+    for (slot_index = 0; slot_index < num_slots && table_index < table_size; slot_index++) {
         unsigned bit_mask = 1;
-        for (bit_index = 0; bit_index < bits_per_slot; bit_index++) {
+        for (bit_index = 0; bit_index < bits_per_slot  && table_index < table_size; bit_index++) {
             if ((mask->bits[slot_index] & bit_mask) != 0) {
-                /* just return the first one */
-                return table_index < table_size
-                           ? pcm_format_value_map[table_index]
-                           : (int)AUDIO_FORMAT_INVALID;
+                if (table_index != 0) { /* Don't pick 8-bit */
+                    /* just return the first one */
+                    return pcm_format_value_map[table_index];
+                }
             }
             bit_mask <<= 1;
             table_index++;
         }
     }
 
-    return 0; // is this right?
+    return -1; /* error */
 }
 
 static bool test_out_sample_rate(struct audio_device_profile* dev_profile, unsigned rate) {
@@ -739,6 +909,8 @@
         return -EINVAL;
     }
 
+    int ret = 0;
+
     /*
      * This Logging will be useful when testing new USB devices.
      */
@@ -758,11 +930,15 @@
     }
     config->period_count = pcm_params_get_min(alsa_hw_params, PCM_PARAM_PERIODS);
 
-    config->format = get_pcm_format_for_mask(pcm_params_get_mask(alsa_hw_params, PCM_PARAM_FORMAT));
+    int format = get_pcm_format_for_mask(pcm_params_get_mask(alsa_hw_params, PCM_PARAM_FORMAT));
+    if (format == -1) {
+        ret = -EINVAL;
+    } else {
+        config->format = format;
+    }
 
     pcm_params_free(alsa_hw_params);
-
-    return 0;
+    return ret;
 }
 
 /*
@@ -1032,10 +1208,12 @@
     int num_device_channels = cached_output_hardware_config.channels;
     int num_req_channels = 2; /* always, for now */
     if (num_device_channels != num_req_channels) {
+        audio_format_t audio_format = out_get_format(&(out->stream.common));
+        unsigned sample_size_in_bytes = audio_bytes_per_sample(audio_format);
         num_write_buff_bytes =
-                expand_channels_16(write_buff, num_req_channels,
-                                   out->conversion_buffer, num_device_channels,
-                                   num_write_buff_bytes / sizeof(short));
+             adjust_channels(write_buff, num_req_channels,
+                             out->conversion_buffer, num_device_channels,
+                             sample_size_in_bytes, num_write_buff_bytes);
         write_buff = out->conversion_buffer;
     }
 
@@ -1452,16 +1630,14 @@
         if (num_device_channels != num_req_channels) {
             out_buff = buffer;
             /* Num Channels conversion */
-            if (num_device_channels < num_req_channels) {
+            if (num_device_channels != num_req_channels) {
+                audio_format_t audio_format = in_get_format(&(in->stream.common));
+                unsigned sample_size_in_bytes = audio_bytes_per_sample(audio_format);
+
                 num_read_buff_bytes =
-                    expand_channels_16(read_buff, num_device_channels,
-                                       out_buff, num_req_channels,
-                                       num_read_buff_bytes / sizeof(short));
-            } else {
-                num_read_buff_bytes =
-                    contract_channels_16(read_buff, num_device_channels,
-                                         out_buff, num_req_channels,
-                                         num_read_buff_bytes / sizeof(short));
+                    adjust_channels(read_buff, num_device_channels,
+                                    out_buff, num_req_channels,
+                                    sample_size_in_bytes, num_read_buff_bytes);
             }
         }
     }