audio streaming with IMFSourceReader (Microsoft Media Foundation)

Question

I use MFCreateSourceReaderFromByteStream to create an IMFSourceReader with a custom IMFByteStream getting data from a remote HTTP source.

When the source is an m4a file, everything works as expected. However, When the source is mp3, the function MFCreateSourceReaderFromByteStream does not return until the whole file is downloaded. Any idea on how to avoid that behavior and start to decode audio before the end of the download?

Answer 1

Assuming you are using default mediafoundation source, perhaps this is the default behaviour for the MP3 File Source and MPEG-4 File Source.

To confirm this, you can try using a custom audio mpeg file source, like this one I implemented : MFSrMpeg12Decoder

This mediafoundation source only manages mp1/mp2 audio file, and performs the decoding.This is not mp3, but it provides the bytestream once there is a valid audio mpeg header, and does not read full file (you can trust me...).

This will confirm that default MP3 File Source needs to read full file before provided the bytestream.

One possible answer would be that the MP3 file source reads the entire file to see if there is a variable bit rate, and thus provides the correct duration of the file (MF_PD_DURATION). For m4a audio file, the duration is provided by the moov atom, so no need to read full file.