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72 lines
2.4 KiB
72 lines
2.4 KiB
2 years ago
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---
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layout: default
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---
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# Simple API
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**Important Note:** The simple API is not designed to work on small chunks of a
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larger piece of audio. If you attempt to use it this way you are doing it wrong
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and will not get the results you want. For processing audio data in chunks you
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**must** use the [full api](api_full.md) or the [callback based api](api_callback.md).
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The simple API consists of a single function:
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```c
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int src_simple (SRC_DATA *data, int converter_type, int channels) ;
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```
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The use of this function rather than the more fully featured API requires the
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caller to know the total length of the input data before hand and that all input
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and output data can be held in the system's memory at once. It also assumes that
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there is a single constant ratio between input and output sample rates.
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Dealing with the easy stuff first, the **converter_type** parameter should be
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one of the values defined in **samplerate.h** and documented [here](api_misc.md#converters)
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while the **channels** parameter specifies the number of interleaved channels
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that the sample rate converter is being asked to process (number of input
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channels and output channels is always equal). There is no hard upper limit on
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the number of channels; it is limited purely by the amount of memory available.
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The first parameter to **src_simple** is a pointer to an **SRC_DATA** struct
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(more info [here](api_misc.md#src_data)) defined as follows:
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```c
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typedef struct
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{ const float *data_in;
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float *data_out ;
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long input_frames, output_frames ;
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long input_frames_used, output_frames_gen ;
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int end_of_input ;
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double src_ratio ;
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} SRC_DATA ;
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```
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The fields of this struct which must be filled in by the caller are:
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data_in
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: A pointer to the input data samples.
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input_frames
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: The number of frames of data pointed to by data_in.
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data_out
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: A pointer to the output data samples.
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output_frames
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: Maximum number of frames pointer to by data_out.
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src_ratio
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: Equal to output_sample_rate / input_sample_rate.
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When the **src_simple** function returns **output_frames_gen** will be set to
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the number of output frames generated and **input_frames_used** will be set to
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the number of input frames used to generate the provided number of output
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frames.
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The **src_simple** function returns a non-zero value when an error occurs. See
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[here](api_misc.md#error-reporting) for how to convert the error value into a
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text string.
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