PCM Stream Channel Modifier
PCM Stream Channel Modifier library enables users to split pulse-code modulation (PCM) streams from stereo to mono or combine mono streams to form a stereo stream. For more information, see API documentation.
Configuration
To enable the library, set the CONFIG_PSCM Kconfig option to y in the project configuration file prj.conf.
API documentation
include/pcm_stream_channel_modifier.hlib/pcm_stream_channel_modifier/pcm_stream_channel_modifier.c- group pscm
Enables splitting of pulse-code modulation (PCM) streams from stereo to mono or combine mono streams to form a stereo stream.
Functions
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int pscm_zero_pad(void const *const input, size_t input_size, enum audio_channel channel, uint8_t pcm_bit_depth, void *output, size_t *output_size)
Adds a 0 after every sample from *input and writes it to *output.
Note
Use to create stereo stream from a mono source where one channel is silent.
- Parameters:
input – [in] Pointer to the input buffer.
input_size – [in] Number of bytes in input.
channel – [in] Channel to contain the audio data.
pcm_bit_depth – [in] Bit depth of PCM samples (16, 24, or 32).
output – [out] Pointer to the output buffer.
output_size – [out] Number of bytes written to the output.
- Returns:
0 if success.
-
int pscm_copy_pad(void const *const input, size_t input_size, uint8_t pcm_bit_depth, void *output, size_t *output_size)
Adds a copy of every sample from *input and writes it to both channels in *output.
Note
Use to create stereo stream from a mono source where both channels are identical.
- Parameters:
input – [in] Pointer to the input buffer.
input_size – [in] Number of bytes in input.
pcm_bit_depth – [in] Bit depth of PCM samples (16, 24, or 32).
output – [out] Pointer to the output buffer.
output_size – [out] Number of bytes written to output.
- Returns:
0 if success.
-
int pscm_combine(void const *const input_left, void const *const input_right, size_t input_size, uint8_t pcm_bit_depth, void *output, size_t *output_size)
Combines two mono streams into one stereo stream.
- Parameters:
input_left – [in] Pointer to the input buffer for the left channel.
input_right – [in] Pointer to the input buffer for the right channel.
input_size – [in] Number of bytes in the input. Same for both channels.
pcm_bit_depth – [in] Bit depth of PCM samples (16, 24, or 32).
output – [out] Pointer to the output buffer.
output_size – [out] Number of bytes written to the output.
- Returns:
0 if success.
-
int pscm_one_channel_split(void const *const input, size_t input_size, enum audio_channel channel, uint8_t pcm_bit_depth, void *output, size_t *output_size)
Removes every second sample from *input and writes it to *output.
Note
Use to split stereo audio stream to single channel.
- Parameters:
input – [in] Pointer to the input buffer.
input_size – [in] Number of bytes in the input. Must be divisible by two.
channel – [in] Channel to keep the audio data from.
pcm_bit_depth – [in] Bit depth of PCM samples (16, 24, or 32).
output – [out] Pointer to the output buffer.
output_size – [out] Number of bytes written to the output.
- Returns:
0 if success.
-
int pscm_two_channel_split(void const *const input, size_t input_size, uint8_t pcm_bit_depth, void *output_left, void *output_right, size_t *output_size)
Splits a stereo stream to two separate mono streams.
Note
Use to split stereo audio stream to two separate channels.
- Parameters:
input – [in] Pointer to the input buffer.
input_size – [in] Number of bytes in input. Must be divisible by two.
pcm_bit_depth – [in] Bit depth of PCM samples (16, 24, or 32).
output_left – [out] Pointer to the output buffer containing the left channel.
output_right – [out] Pointer to the output buffer containing the right channel.
output_size – [out] Number of bytes written to the output, same for both channels.
- Returns:
0 if success.
-
int pscm_zero_pad(void const *const input, size_t input_size, enum audio_channel channel, uint8_t pcm_bit_depth, void *output, size_t *output_size)