We have run into a problem with the TI Opus encoder for the c6678. The following is how to reproduce on the 6678 EVM using the TI Opus demo program:
- The atttached “txt” file was used to specify encoder configuration when reproducing the issue.
- The configuration is as follows: 48000Hz, 2ch, 110kbit/s, FB, no FEC, DTX, voip mode.
- The attached “testvector04 … .dec” file is the pcm input vector (stereo 48 kHz). It is based on “testvector04” from Opus official test vector collection from the website.
- The attached “output_ti.bit” file is the Opus encoded output from the TI encoder.
- The attached “output_ti.bit.dec” is the TI encoded output decoded by the Opus reference codec.
- The first 14 seconds of the decoded output are OK and then the amplitude gets really high and the output is distorted for 6-7 seconds. If the same input is encoded and decoded with the Opus reference codec using the same configuration there is no distortion.
The TI codec version is C66x_OPUS_01_00_00_02_BE_COFF. Not that we are running the DSP in big endian mode.