SDL_BuildAudioCVT

Use this function to initialize an SDL_AudioCVT structure for conversion. 使用这个函数初始化SDL_AudioCVT结构以进行转换。

Syntax 语法

  1. int SDL_BuildAudioCVT(SDL_AudioCVT*   cvt,
  2.                       SDL_AudioFormat src_format,
  3.                       Uint8           src_channels,
  4.                       int             src_rate,
  5.                       SDL_AudioFormat dst_format,
  6.                       Uint8           dst_channels,
  7.                       int             dst_rate)

Function Parameters 函数参数

参数值 解释（EN） 解释（ZH）
cvt an SDL_AudioCVT structure filled in with audio conversion information 一个用音频转换信息填充的 SDL_AudioCVT结构.
src_format the source format of the audio data; for more info see SDL_AudioFormat 音频数据的源格式;详情查看SDL_AudioFormat.
src_channels the number of channels in the source 源中的通道数.
src_rate the frequency (samples-frames-per-second) of the source 源的频率（每秒采样帧数）.
dst_format the destination format of the audio data; for more info see SDL_AudioFormat 音频数据的目标格式 ; 详情查看SDL_AudioFormat.
dst_channels the number of channels in the destination 目标的通道数.
dst_rate the frequency (samples-frames-per-second) of the destination 目标的频率 (每秒采样帧数).

Return Value 返回值

Returns 1 if the audio filter is prepared, 0 if no conversion is needed, or a negative error code on failure; call SDL_GetError() for more information.

如果音频准备填充则返回 1 , 如果不需要转换则返回 0 ,或否定失败的错误代码; 调用 SDL_GetError() 查看更多。|

Code Examples 代码示例

  1. Toggle line numbers
  2. // Change 1024 stereo sample frames at 48000Hz from float32 to int16.
  3. SDL_AudioCVT cvt;
  4. SDL_BuildAudioCVT(&cvt, AUDIO_F32, 2, 48000, AUDIO_S16, 2, 48000);
  5. SDL_assert(cvt.needed); // obviously, this one is always needed.
  6. cvt.len = 1024 * 2 * 4;  // 1024 stereo float32 sample frames.
  7. cvt.buf = (Uint8 *) SDL_malloc(cvt.len * cvt.len_mult);
  8. // read your float32 data into cvt.buf here.
  9. SDL_ConvertAudio(&cvt);
  10. // cvt.buf has cvt.len_cvt bytes of converted data now.

Remarks 注意

Before an SDL_AudioCVT() structure can be used to convert audio data it must be initialized with source and destination information.

在可以使用SDL_AudioCVT结构转换音频数据之前，必须使用源和目标信息进行初始化。

This function will zero out every field of the SDL_AudioCVT(), so it must be called before the application fills in the final buffer information.

此函数将清零SDL_AudioCVT()的每个字段。

Once this function has returned successfully, and reported that a conversion is necessary, the application fills in the rest of the fields in SDL_AudioCVT(), now that it knows how large a buffer it needs to allocate, and then can call SDL_ConvertAudio（） to complete the conversion.

一旦此函数成功返回后，并报告需要进行转换，该应用程式将填充SDL_AudioCVT()的其余字段，现在它知道它需要分配多大的缓冲区，然后可以调用SDL_ConvertAudio（）来完成转换。

Related Functions 相关函数

SDL_ConvertAudio

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