Audio filters

Basic info

This feature is available for MPlatform SDK. For MFormats, support for FFMPEG audio filter was introduced in version 2.10.0.14414 and is available exclusively in the Expert and Ultimate editions. FFMPEG audio filter offer advanced audio processing capabilities, allowing users to apply custom audio effects within the SDK framework.

You can use audio filters for FFmpeg to manage audio of your sources (files, network streams, cameras, etc). With the filters, you can control audio volume, filter noise and so on.

MFormats SDK

The usage of afilters in MFormats SDK is similar to working with plugins such as CG, MCCDisplay, etc. In general, it's needed to create a MFXMediaConverter instance, set its parameters, and during the frame processing pipeline, this converter processes each frame. Below is an example of how to add and apply the "volume" filter in MFormats SDK:

MFReaderClass m_objReader = new MFReaderClass();
MFPreviewClass m_objPreview = new MFPreviewClass();
MFXMediaConverter m_objConverter = new MFXMediaConverter();

m_objReader.ReaderOpen(pathToVideo, "");
m_objPreview.PreviewEnable("", 1, 1);

// "av_filter_graph_desc_out" - Apply audio filter after video processing (e.g. audio conversion)
// It's not possible to apply audio filter before audio processing. "av_filter_graph_desc_in" doesn't work.
String AFilter_ConvProps = @"{""av_filter_graph_desc_out"":""volume=-40dB""}";
(m_objConverter as IMFProps).PropsSet(@"audio::xmedia_conversion_props", AFilter_ConvProps);

M_AV_PROPS m_AV_PROPS = new M_AV_PROPS();
m_AV_PROPS.vidProps.eVideoFormat = eMVideoFormat.eMVF_Custom;

int rest = 0;
do
{
    m_objReader.SourceFrameGet(-1, out MFFrame pFrame, "");
    m_objConverter.ConverterFrameConvert("", pFrame, ref m_AV_PROPS, out var pFrameConverted, out rest, "");
    Marshal.ReleaseComObject(pFrame);
    if (pFrameConverted != null)
    {
        m_objPreview.ReceiverFramePut(pFrameConverted, -1, "");
        Marshal.ReleaseComObject(pFrameConverted);
    }
} while (rest > 0);

Important Note! The MFXMediaConverter class is implemented exclusively for 64-bit environments. Therefore, the use of the MFXMediaConverter class and consequently, afilters are only supported in 64-bit applications.

MPlatform SDK

The property that you should set to enable an audio filter is "object::afilter" with PropsSet method for your object. For example:

myLive.PropsSet("object::afilter", "volume=2");

 If you use several filters in a chain then you should set them in a single value separating by commas:

myLive.PropsSet("object::afilter", "highpass=f=120,acompressor=threshold=0.3:makeup=3:release=50:attack=5:knee=4:ratio=10:detection=peak,alimiter=limit=0.95");

Possible values