Archived:Frame length variation for G.711 encoder (Known Issue)

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The length of frames produced by the G.711 encoder has been changed from 20 ms to 10 ms in the Nokia N95 firmware v2.0.015.

Article Metadata

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Tested with

Devices(s): Nokia N95 v2.0.015, Nokia N95 8GB

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Compatibility

Platform(s): S60 3rd Edition, Feature Pack 1

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Article

Created: User:Technical writer 1 (18 Dec 2007)

Last edited: hamishwillee (17 Jul 2012)

Description

Frames produced by the G.711 encoder will have a length of 2+80 bytes (10 ms) in the Nokia N95 firmware v2.0.015 and the Nokia N95 8GB, when it previously was 2+160 bytes (20 ms).

This change was made in order to support all possible G.711 frame sizes (10 ms, 20 ms, 30 ms) in the Nokia Internet Telephony application.

This affects Audio Proxy Server (APS) clients and applications using the G.711 encoder directly when running on the Nokia N95 firmware v2.0.015 (and onwards), as well as the Nokia N95 8GB.

Solution

APS does not provide any means of resolving the frame size used by a codec until the streaming is started. Audio frames passed to G.711 decoder must always have the same length as frames produced by the G.711 encoder.

If the remote party expects G.711 frames in 20 ms mode, the client should combine adjacent 10 ms frames to produce 20 ms frames as needed.

The G.711 encoder uses a fixed frame length, and it cannot be configured dynamically.