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OMX.broadcom.audio_capture

181
audio_capture
180

This component interacts with platform-specific audio input devices to emit raw PCM samples. It can provide a media reference time to a clock component if connected. If used in this mode, the component will not output data when the clock is stopped, and will send media time updates to the clock by default. Time stamps will only reset once the component is transitioned to loaded. If the audio output port is executing with the capturing enabled when a connected clock is transitioned to stop, the component will stop recording data and transmit its next packet with no data but with the EOS flag set.

PortIndexNotes
180OMX_IndexParamPortDefinition

Query / set the port parameters for the audio output stream. The audio format must not be encoded. nBufferSize must be a multiple of 4 and equal to or larger than 32 (the maximum buffer size is limited by the platform-specific audio input device, but may be 16384). nBufferAlignment must be equal to or larger than 32.

OMX_IndexParamAudioPcm Query / set the PCM format used. nChannels will be 2. eNumData will be OMX_NumericalDataSigned. eEndian will be OMX_EndianLittle. bInterleaved will be OMX_TRUE. nBitPerSample will be 16. ePCMMode will be OMX_AUDIO_PCMModeLinear. nSamplingRate can be set and defaults to 32000.
OMX_IndexConfigBrcmAudioSource Query / set the audio platform-specific source for audio input. Currently only supported when the component is not capturing audio.
OMX_IndexConfigAudioVolume Query / set the volume to be applying using a software scaling after the audio samples have been initially read.
OMX_IndexConfigAudioMute Query / set whether the audio is muted.
OMX_IndexParamAudioPortFormat Query / set the audio port format used on this port. The port supports PCM only.
182OMX_IndexParamPortDefinition Query / set the port parameter to support connecting to a clock component output port.
OMX_IndexParamOtherPortFormat Query / set the other port format used on this port. The port supports time format only.
 OMX_IndexConfigCapturing Query / set whether we are actively capturing audio data, subject to the restrictions given about when connected to a clock component.

N.B. Port 181 is used for audio events. It is defined as an audio port (so that MMAL does not misclassify it as a clock port) although it is really just a generic data port used to send data of type AUDIOPLUS_EVENT_T.