Emeric Vigier | eebea67 | 2012-08-06 17:36:30 -0400 | [diff] [blame] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> |
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| 6 | Secret Rabbit Code (aka libsamplerate) |
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| 8 | <META NAME="Author" CONTENT="Erik de Castro Lopo (erikd AT mega-nerd DOT com)"> |
| 9 | <META NAME="Version" CONTENT="libsamplerate-0.1.8"> |
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| 27 | <DIV CLASS="nav"> |
| 28 | <BR> |
| 29 | <A HREF="index.html">Home</A><BR> |
| 30 | <BR> |
| 31 | <A HREF="api_simple.html">Simple API</A><BR> |
| 32 | <A HREF="api_full.html">Full API</A><BR> |
| 33 | <A HREF="api_callback.html">Callback API</A><BR> |
| 34 | <A HREF="api_misc.html">Miscellaneous</A><BR> |
| 35 | <A HREF="api_misc.html#ErrorReporting">Error Handling</A><BR> |
| 36 | <BR> |
| 37 | <DIV CLASS="block"> |
| 38 | Author :<BR>Erik de Castro Lopo |
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| 45 | "/cgi-bin/Count.cgi?ft=6|frgb=55;55;55|tr=0|md=6|dd=B|st=1|sh=1|df=src_api.dat" |
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| 54 | <DIV CLASS="block"> |
| 55 | |
| 56 | <H1><B>Simple API</B></H1> |
| 57 | |
| 58 | <P> |
| 59 | <B>Important Note:</B> |
| 60 | The simple API is not designed to work on small chunks of a larger piece of |
| 61 | audio. |
| 62 | If you attempt to use it this way you are doing it wrong and will not get the |
| 63 | results you want. |
| 64 | For processing audio data in chunks you <b>must</b> use the |
| 65 | <a href="api_full.html">full api</a> |
| 66 | or the |
| 67 | <a href="api_callback.html">callback based api</a>. |
| 68 | </P> |
| 69 | |
| 70 | <br/><br/> |
| 71 | |
| 72 | <P> |
| 73 | The simple API consists of a single function : |
| 74 | </P> |
| 75 | <PRE> |
| 76 | int src_simple (SRC_DATA *data, int converter_type, int channels) ; |
| 77 | </PRE> |
| 78 | <P> |
| 79 | The use of this function rather than the more fully featured API requires the caller |
| 80 | to know the total length of the input data before hand and that all input and output |
| 81 | data can be held in the system's memory at once. |
| 82 | It also assumes that there is a single constant ratio between input and output sample |
| 83 | rates. |
| 84 | <!-- |
| 85 | If these conditions cannot be met, the full featured API should be used instead. |
| 86 | In addition, this documentation is complemented by this |
| 87 | <A HREF="ex_simple.html">example code</A>. --> |
| 88 | </P> |
| 89 | |
| 90 | <P> |
| 91 | Dealing with the easy stuff first, the <B>converter_type</B> parameter should be |
| 92 | one of the values defined in <B>samplerate.h</B> and documented |
| 93 | <A HREF="api_misc.html#Converters">here</A> while the <b>channels</b> parameter |
| 94 | specifies the number of interleaved channels that the sample rate converter |
| 95 | is being asked to process (number of input channels and output channels is always |
| 96 | equal). |
| 97 | There is no hard upper limit on the number of channels; it is limited purely |
| 98 | by the amount of memory available. |
| 99 | </P> |
| 100 | |
| 101 | |
| 102 | <P> |
| 103 | The first parameter to <B>src_simple</B> is a pointer to an <B>SRC_DATA</B> struct |
| 104 | (more info <A HREF="api_misc.html#SRC_DATA">here</A>) defined as follows: |
| 105 | </P> |
| 106 | <PRE> |
| 107 | typedef struct |
| 108 | { float *data_in, *data_out ; |
| 109 | |
| 110 | long input_frames, output_frames ; |
| 111 | long input_frames_used, output_frames_gen ; |
| 112 | |
| 113 | int end_of_input ; |
| 114 | |
| 115 | double src_ratio ; |
| 116 | } SRC_DATA ; |
| 117 | </PRE> |
| 118 | <P> |
| 119 | The fields of this struct which must be filled in by the caller are: |
| 120 | </P> |
| 121 | <PRE> |
| 122 | data_in : A pointer to the input data samples. |
| 123 | input_frames : The number of frames of data pointed to by data_in. |
| 124 | data_out : A pointer to the output data samples. |
| 125 | output_frames : Maximum number of frames pointer to by data_out. |
| 126 | src_ratio : Equal to output_sample_rate / input_sample_rate. |
| 127 | </PRE> |
| 128 | <P> |
| 129 | When the <B>src_simple</B> function returns <B>output_frames_gen</B> will be |
| 130 | set to the number of output frames generated and <B>input_frames_used</B> will |
| 131 | be set to the number of input frames used to generate the provided number of |
| 132 | output frames. |
| 133 | </P> |
| 134 | <P> |
| 135 | The <B>src_simple</B> function returns a non-zero value when an error occurs. |
| 136 | See <A HREF="api_misc.html#ErrorReporting">here</A> for how to convert the error value into |
| 137 | a text string. |
| 138 | </P> |
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