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Dialogic® Multimedia Platform for AdvancedTCA

Enable m3g Trace to capture and view a video stream from/to a 3G endpoint

Symptom:

With Dialogic® Multimedia Platform for AdvancedTCA, Dialogic® Multimedia Kit for PCIe and Dialogic Host Media Processing (HMP) Software for Linux with 3G-324m interfaces (m3g devices), users may experience absence of video or video quality issues to or from 3G endpoints such as a 3G cell phone. 

Some example issues:
  • In a 3G Multimedia scenario:
    • No video on a record from a 3G endpoint
    • Poor video quality (blocky, pixelated) video on a record from a 3G endpoint 
    • No video playing out to a 3G endpoint
    • Poor video quality playing out to a 3G endpoint
  • In a 3G Gateway scenario:
    • Video is present in a Wireshark capture from a remote SIP endpoint, but no video is sent to or from the 3G endpoint at the local SIP endpoint.
Reason for Issue:

The absence of video during a 3G call may be due to some type of device connection issue or can be as a result of an internal component dropping the video stream. Poor video quality issues can be due to many factors, but a trace at the m3g device may indicate that the poor quality is due to data corruption in the 3G network rather than being caused by the handling of video data by a Dialogic® product. 

Background:

A possible troubleshooting technique is to enable and capture the full m3g trace and extract the raw video stream. The raw video stream can be played on a raw video player, such as 'VLC media player', to visually inspect the video captured in both the receive and transmit directions at the m3g device. The video captured at the m3g device can be used to debug video issues by comparing video at this point to video in a played or recorded multimedia file or video from a Wireshark capture. 

A full m3g trace contains the m3g firmware trace along with a 3G (H.245) stack trace, raw video and audio data, and 3G-324m session call statistics.

Procedure:

1. Enable m3g_Tracing in an application

To start a trace, use the following API calls:
  • m3g_StartTrace()
  • m3g_StartH245().
To enable full tracing - including raw audio and video data - use the value 0x3F in the bitmask field of the M3G_TRACE_INFO data structure that is passed in the m3g_StartTrace() API call.

The default location for the logfile is /usr/dialogic/log; this can be overridden by setting values in the M3G_TRACE_INFO data structure.

To stop tracing, use the following API calls: 
  • m3g_StopH245()
  • m3g_StopTrace()
2. Parse the m3gTrace by running m3g_parser on the trace file.  

The m3g_parser utility is included with the build in the /usr/dialogic/bin path (for example: 'm3g_parser ep_3g_trace.txt') 

The m3g_parser utility will break down the m3gTrace into a subset of files per channel if there are multiple channels captured in the trace. 

The output files from the m3g_parser utility for channel1 may look like this:

stats_1.txt - m3g session statistics for channel 1
h245_1.txt - h245 messages for channel 1
h223tx_1.bin - h223 raw binary transmit data for channel 1
h223rx_1.bin - h223 raw binary receive data for channel 1
videotx_1.bin - raw binary video in the transmit direction (to 3G network) for channel 1
videorx_1.bin - raw binary video in the receive direction (from 3G network) for channel 1
audiotx_1.bin - raw binary audio in the transmit direction (to 3G network) for channel 1audiorx_1.bin - raw binary audio in the receive direction (from 3G network) for channel 1

3. Rename the file with the proper extension

For H.263 video captures, use .h263 or .263 extension.  For MPEG4 video captures, use .mp4v or .mp4 extension. 

4. Play the file using a raw video player

The video player must be able to play raw video files.  VLC media player is an example open source utility that plays raw video files.

Product List

Dialogic® Multimedia Platform for AdvancedTCA
Dialogic® Multimedia Kit for PCIe
Dialogic® Host Media Processing (HMP) Software for Linux

Glossary of Acronyms / Terms

m3g device -  the Dialogic® 3G-324m R4 component
H.263 - Video codec
MPEG4 - Video codec
 

Related Documentation

Dialogic® 3G-324M API Programming Guide and Library Reference






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