Add support for partial processing to nodes.

This includes a leading trimming node to act as a test.

extras/nodes/ma_ltrim_node/ma_ltrim_node.c

+
+#include "ma_ltrim_node.h"
+
+MA_API ma_ltrim_node_config ma_ltrim_node_config_init(ma_uint32 channels, float threshold)
+{
+    ma_ltrim_node_config config;
+
+    MA_ZERO_OBJECT(&config);
+    config.nodeConfig = ma_node_config_init();  /* Input and output channels will be set in ma_ltrim_node_init(). */
+    config.channels   = channels;
+    config.threshold  = threshold;
+
+    return config;
+}
+
+
+static void ma_ltrim_node_process_pcm_frames(ma_node* pNode, const float** ppFramesIn, ma_uint32* pFrameCountIn, float** ppFramesOut, ma_uint32* pFrameCountOut)
+{
+    ma_ltrim_node* pTrimNode = (ma_ltrim_node*)pNode;
+    ma_uint32 framesProcessedIn  = 0;
+    ma_uint32 framesProcessedOut = 0;
+    ma_uint32 channelCount       = ma_node_get_input_channels(pNode, 0);
+    
+    /*
+    If we haven't yet found the start, skip over every input sample until we find a frame outside
+    of the threshold.
+    */
+    if (pTrimNode->foundStart == MA_FALSE) {
+        while (framesProcessedIn < *pFrameCountIn) {
+            ma_uint32 iChannel = 0;
+            for (iChannel = 0; iChannel < channelCount; iChannel += 1) {
+                float sample = ppFramesIn[0][framesProcessedIn*channelCount + iChannel];
+                if (sample < -pTrimNode->threshold || sample > pTrimNode->threshold) {
+                    pTrimNode->foundStart = MA_TRUE;
+                    break;
+                }
+            }
+
+            if (pTrimNode->foundStart) {
+                break;  /* The start has been found. Get out of this loop and finish off processing. */
+            } else {
+                framesProcessedIn += 1;
+            }
+        }
+    }
+
+    /* If there's anything left, just copy it over. */
+    framesProcessedOut = ma_min(*pFrameCountOut, *pFrameCountIn - framesProcessedIn);
+    ma_copy_pcm_frames(ppFramesOut[0], &ppFramesIn[0][framesProcessedIn], framesProcessedOut, ma_format_f32, channelCount);
+
+    framesProcessedIn += framesProcessedOut;
+
+    /* We always "process" every input frame, but we may only done a partial output. */
+    *pFrameCountIn  = framesProcessedIn;
+    *pFrameCountOut = framesProcessedOut;
+}
+
+static ma_node_vtable g_ma_ltrim_node_vtable =
+{
+    ma_ltrim_node_process_pcm_frames,
+    NULL,
+    1,  /* 1 input channel. */
+    1,  /* 1 output channel. */
+    MA_NODE_FLAG_DIFFERENT_PROCESSING_RATES
+};
+
+MA_API ma_result ma_ltrim_node_init(ma_node_graph* pNodeGraph, const ma_ltrim_node_config* pConfig, const ma_allocation_callbacks* pAllocationCallbacks, ma_ltrim_node* pTrimNode)
+{
+    ma_result result;
+    ma_node_config baseConfig;
+
+    if (pTrimNode == NULL) {
+        return MA_INVALID_ARGS;
+    }
+
+    MA_ZERO_OBJECT(pTrimNode);
+
+    if (pConfig == NULL) {
+        return MA_INVALID_ARGS;
+    }
+
+    pTrimNode->threshold  = pConfig->threshold;
+    pTrimNode->foundStart = MA_FALSE;
+
+    baseConfig = pConfig->nodeConfig;
+    baseConfig.vtable          = &g_ma_ltrim_node_vtable;
+    baseConfig.pInputChannels  = &pConfig->channels;
+    baseConfig.pOutputChannels = &pConfig->channels;
+
+    result = ma_node_init(pNodeGraph, &baseConfig, pAllocationCallbacks, &pTrimNode->baseNode);
+    if (result != MA_SUCCESS) {
+        return result;
+    }
+
+    return MA_SUCCESS;
+}
+
+MA_API void ma_ltrim_node_uninit(ma_ltrim_node* pTrimNode, const ma_allocation_callbacks* pAllocationCallbacks)
+{
+    /* The base node is always uninitialized first. */
+    ma_node_uninit(pTrimNode, pAllocationCallbacks);
+}

extras/nodes/ma_ltrim_node/ma_ltrim_node.h

+/* Include ma_ltrim_node.h after miniaudio.h */
+#ifndef ma_ltrim_node_h
+#define ma_ltrim_node_h
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+The trim node has one input and one output.
+*/
+typedef struct
+{
+    ma_node_config nodeConfig;
+    ma_uint32 channels;
+    float threshold;
+} ma_ltrim_node_config;
+
+MA_API ma_ltrim_node_config ma_ltrim_node_config_init(ma_uint32 channels, float threshold);
+
+
+typedef struct
+{
+    ma_node_base baseNode;
+    float threshold;
+    ma_bool32 foundStart;
+} ma_ltrim_node;
+
+MA_API ma_result ma_ltrim_node_init(ma_node_graph* pNodeGraph, const ma_ltrim_node_config* pConfig, const ma_allocation_callbacks* pAllocationCallbacks, ma_ltrim_node* pTrimNode);
+MA_API void ma_ltrim_node_uninit(ma_ltrim_node* pTrimNode, const ma_allocation_callbacks* pAllocationCallbacks);
+
+#ifdef __cplusplus
+}
+#endif
+#endif  /* ma_ltrim_node_h */

extras/nodes/ma_ltrim_node/ma_ltrim_node_example.c

+#define MINIAUDIO_IMPLEMENTATION
+#include "../../../miniaudio.h"
+#include "ma_ltrim_node.c"
+
+#include <stdio.h>
+
+#define DEVICE_FORMAT       ma_format_f32       /* Must always be f32 for this example because the node graph system only works with this. */
+#define DEVICE_CHANNELS     0                   /* The input file will determine the channel count. */
+#define DEVICE_SAMPLE_RATE  0                   /* The input file will determine the sample rate. */
+
+static ma_decoder          g_decoder;         /* The decoder that we'll read data from. */
+static ma_data_source_node g_dataSupplyNode;  /* The node that will sit at the root level. Will be reading data from g_dataSupply. */
+static ma_ltrim_node       g_trimNode;        /* The trim node. */
+static ma_node_graph       g_nodeGraph;       /* The main node graph that we'll be feeding data through. */
+
+void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
+{
+    (void)pInput;
+    (void)pDevice;
+
+    /* All we need to do is read from the node graph. */
+    ma_node_graph_read_pcm_frames(&g_nodeGraph, pOutput, frameCount, NULL);
+}
+
+int main(int argc, char** argv)
+{
+    ma_result result;
+    ma_decoder_config decoderConfig;
+    ma_device_config deviceConfig;
+    ma_device device;
+    ma_node_graph_config nodeGraphConfig;
+    ma_ltrim_node_config trimNodeConfig;
+    ma_data_source_node_config dataSupplyNodeConfig;
+
+    if (argc < 1) {
+        printf("No input file.\n");
+        return -1;
+    }
+
+
+    /* Decoder. */
+    decoderConfig = ma_decoder_config_init(DEVICE_FORMAT, DEVICE_CHANNELS, DEVICE_SAMPLE_RATE);
+
+    result = ma_decoder_init_file(argv[1], &decoderConfig, &g_decoder);
+    if (result != MA_SUCCESS) {
+        printf("Failed to load decoder.\n");
+        return -1;
+    }
+
+
+    /* Device. */
+    deviceConfig = ma_device_config_init(ma_device_type_playback);
+    deviceConfig.playback.pDeviceID = NULL;
+    deviceConfig.playback.format    = g_decoder.outputFormat;
+    deviceConfig.playback.channels  = g_decoder.outputChannels;
+    deviceConfig.sampleRate         = g_decoder.outputSampleRate;
+    deviceConfig.dataCallback       = data_callback;
+    result = ma_device_init(NULL, &deviceConfig, &device);
+    if (result != MA_SUCCESS) {
+        return result;
+    }
+
+
+    /* Node graph. */
+    nodeGraphConfig = ma_node_graph_config_init(device.playback.channels);
+
+    result = ma_node_graph_init(&nodeGraphConfig, NULL, &g_nodeGraph);
+    if (result != MA_SUCCESS) {
+        printf("Failed to initialize node graph.");
+        goto done0;
+    }
+
+
+    /* Trimmer. Attached straight to the endpoint. Input will be the data source node. */
+    trimNodeConfig = ma_ltrim_node_config_init(device.playback.channels, 0);
+
+    result = ma_ltrim_node_init(&g_nodeGraph, &trimNodeConfig, NULL, &g_trimNode);
+    if (result != MA_SUCCESS) {
+        printf("Failed to initialize ltrim node.");
+        goto done1;
+    }
+
+    ma_node_attach_output_bus(&g_trimNode, 0, ma_node_graph_get_endpoint(&g_nodeGraph), 0);
+
+
+    /* Data supply. */
+    dataSupplyNodeConfig = ma_data_source_node_config_init(&g_decoder);
+
+    result = ma_data_source_node_init(&g_nodeGraph, &dataSupplyNodeConfig, NULL, &g_dataSupplyNode);
+    if (result != MA_SUCCESS) {
+        printf("Failed to initialize data source node.");
+        goto done2;
+    }
+
+    ma_node_attach_output_bus(&g_dataSupplyNode, 0, &g_trimNode, 0);
+
+
+
+    /* Now we just start the device and wait for the user to terminate the program. */
+    ma_device_start(&device);
+
+    printf("Press Enter to quit...\n");
+    getchar();
+
+    /* It's important that we stop the device first or else we'll uninitialize the graph from under the device. */
+    ma_device_stop(&device);
+
+
+/*done3:*/ ma_data_source_node_uninit(&g_dataSupplyNode, NULL);
+done2: ma_ltrim_node_uninit(&g_trimNode, NULL);
+done1: ma_node_graph_uninit(&g_nodeGraph, NULL);
+done0: ma_device_uninit(&device);
+
+    return 0;
+}
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