Hi again! Here are some audio samples that you can compare.
Three sets of 30 second audio test files are available. In each case, three different bitpools are chosen, i.e. bitpool=[20, 35, 53]. Subbands are chosen from nrof_subbands=[4, 8]. The other parameters are fixed for all version to these values: Joint_stereo, nrof_blocks=16, Loudness bit allocation.
Each of the three sets of audio files were created with the original .wav file from a music CD, then edited in Audacity for length, plus using its standard fade-in and fade-out effects. The shortened file is then re-exported as a .wav file, with the string “test” appended to the file name, e.g. OFortuna_test.wav. The file is then used for a series of encodings and decodings by the Windows executables sbc_encoder.exe and sbc_decoder.exe, each time with a pre-determined set (see above) of encoding parameters. All operations were performed on a Windows 10 PC. Details can be found in the batch.txt file that accompanies each set. In addition, here are the parameters for both the encoder and decoder.
>sbc_encoder -help
SBC Encoder LIB Version 1.5
Copyright (c) 2002 Philips Consumer Electronics, ASA Labs
Usage:
sbc_encoder [-jsv] [-lblk_len] [-nsubbands] [-p] [-rrate] [-ooutputfile] inputfile
[-s] use the stereo mode for stereo signals
[-v] verbose mode
[-j] allow the use of joint coding for stereo signals
[-lblk_len] blk_len specifies the APCM block length, out of [4,8,12,16]
[-nsubbands] subbands specifies the number of subbands, out of [4,8]
[-p] a simple psycho acoustic model is used
[-rrate] specifies the bit rate in bps
[-ooutputfile] specifies the name of the bitstream output file
inputfile specifies the audio input file, the major audio formats are supported
>sbc_decoder -help
SBC Decoder LIB Version 1.5
Copyright (c) 2002 Philips Consumer Electronics, ASA Labs
Usage:
sbc_decoder [-v] [-ooutputfile] [-pstartpos] inputfile
[-v] verbose mode
[-pstartpos] startpos specifies the byte offset to start with decoding
[-ooutputfile] specifies the name of the audio output file
inputfile specifies the name of the bitstream input file
Note that each set includes a version with the suggested “Medium Quality” [-j -p -n8 -l16 -r228800] and “High Quality” [-j -p -n8 -l16 -r328000] parameter choices. One of these are the versions most likely produced with legacy audio equipment. These parameter choices are consistent with the suggested settings in the original specification, as shown here:
[Figure (attached) from Considering Bluetooth’s Subband Codec (SBC) for Wideband Speech and Audio on the Internet, by Christian Hoene, Mansoor Hyder October 2009]
Test Set 1: Classical Music, Full Orchestra and SATB Chorus, Loud Volume
https://drive.google.com/open?id=1bnXtniYsnSlMbMbD16ZdzjjPgHPdJ_nF
Test Set 2: Classical Music, Female Soloist with Orchestra, Soft Volume
https://drive.google.com/open?id=1QVW-GbcoKP4BStgu1DOkmcMN87ebKRpf
Test Set 3: Jazzy Pop, Female Soloist with Guitar, Piano, Bass, and Drums, Medium Volume
https://drive.google.com/open?id=113wjTJ2mDZfIj3_NgL4IHd94hNxrCXn8