User`s guide

28 Dialogic
®
Host Media Processing Software Release 4.1LIN Release Guide
Features
• Play to and record from SIP devices, depending on capability of device (audio or
audio/video). Play video only if no audio is required. Play audio only for non-video
devices.
Multimedia file formats
Support for the following file formats for play and record:
• Linear PCM (128 kbps), 16-bit, 8 kHz, mono, LSB-MSB (“little-endian”) for audio
play and record
Note: Voice API audio files may be used as the audio track in a multimedia session;
however, no synchronization between the audio and video file is maintained.
In this case, the ipm device in a multimedia session listens to the dx device to
which the voice API is playing an audio file. This overrides any audio stream
(but not video) from the mm device in the multimedia session. For details, see
the Dialogic
®
Multimedia API Programming Guide.
• Dialogic
®
proprietary native audio file format used for native RTP play and record
and for transcoding. For more information, see the Dialogic
®
Multimedia API
Programming Guide and Dialogic
®
Multimedia File Conversion Tools User Guide.
• Dialogic
®
proprietary video file formats used for video transcoding. For more
information, see the Dialogic
®
Multimedia File Conversion Tools User Guide.
Multimedia file conversion utility
The hmp3gp utility converts multimedia data from Dialogic
®
proprietary file format to
3rd Generation Partnership Project (3GPP) file format conforming to 3GPP
specifications. The reverse direction is also supported.
This utility can be downloaded from the following web site. Check this web site
periodically for any updates to the conversion tools and for any corresponding
updates to the documentation:
http://www.dialogic.com/products/ip_enabled/download/multimedia/omf.htm
Note: The conversion utility performs CPU-intensive tasks and should only be used
when sufficient CPU capacity is available and when it won't impact other
operations on the system.
3.13 Native RTP Hairpinning
Native RTP hairpinning is supported in Dialogic
®
Host Media Processing Software
Release 4.1LIN.
Native RTP hairpinning enables applications to form RTP media stream connections
between IP media streams, allowing the RTP media stream received from one IP media
session to be retransmitted to the outgoing RTP media stream of another IP media
session. This is done without processing or transcoding the RTP payload. The RTP
packets that are hairpinned may be hairpinned as received, with packets out of order or
even missing as long as the RTP stream is retransmitted so that the receiving terminating
endpoint can perform necessary packet loss recovery (PLR) type functions.
Native RTP hairpinning is supported for both audio and video RTP streams.