IgorC
12th July 2026, 07:13
AAC-LC 128 kbps Listening Test [CBR/ABR] - (Evaluation of FFmpeg 9.1 new AAC encoder) (https://www.reddit.com/r/AudioCodecLab/comments/1uu5vtp/aaclc_128_kbps_listening_test_cbrabr_evaluation/)
Hello everyone! This is my personal listening test.
The test contains 12 audio samples and compares five AAC encoders at approximately 128 kbps:
FFmpeg NMR - new FFmpeg 9.1 AAC encoder - https://github.com/BtbN/FFmpeg-Builds/releases/tag/latest - ffmpeg-master-latest-win64-gpl.zip (tested build is July-10-2026)
FFmpeg twoloop
FDK-AAC CBR
Apple AAC CBR
Apple AAC ABR
Settings using foobar2000 converter :
FFmpeg NMR:
--hide_banner -loglevel error -i pipe:0 -c:a aac -b:a 128k -aac_coder nmr -cutoff 16000 %d
FFmpeg twoloop
-hide_banner -loglevel error -i pipe:0 -c:a aac -b:a 128k -aac_coder twoloop -cutoff 16000 %d
FDK-AAC CBR
fdkaac 1.0.5, libfdk-aac 4.0.1, CBR 128kbps
Apple AAC CBR
qaac 2.70, CoreAudioToolbox 7.10.9.0, AAC-LC Encoder, CBR 128kbps, Quality 96
Apple AAC ABR
qaac 2.70, CoreAudioToolbox 7.10.9.0, AAC-LC Encoder, ABR 128kbps, Quality 96
Download: Audio samples and logs (https://drive.google.com/file/d/1MNHc5LIQQG6bWayXMl7d0VCJ42EyUpyg/view)
Sample-Rate Handling for the FFmpeg NMR AAC Encoder
According to an FFmpeg developer, the NMR AAC encoder is optimized for 48 kHz. Therefore, all test files were resampled to 48 kHz using SoX with the Very High, 168 dB quality setting.
The processing chain was:
Original WAV → SoX resampling to 48 kHz/24-bit → FFmpeg NMR AAC encoding → AAC decoding to 48 kHz/24-bit WAV → SoX resampling back to 44.1 kHz/24-bit
This process is safe and transparent. At these quality settings, the SoX resampling and 24-bit intermediate files don't introduce any audible differences.
Hardware used during testing
Topping E70 DAC
Topping L70 Headphone amplifier
Headphones Sennheiser HD 800.
Cabling: Balanced DAC-to-headphone amplifier connection; original Sennheiser HD 800 headphone cable.
-
IgorC
AudioCodecLab
Hello everyone! This is my personal listening test.
The test contains 12 audio samples and compares five AAC encoders at approximately 128 kbps:
FFmpeg NMR - new FFmpeg 9.1 AAC encoder - https://github.com/BtbN/FFmpeg-Builds/releases/tag/latest - ffmpeg-master-latest-win64-gpl.zip (tested build is July-10-2026)
FFmpeg twoloop
FDK-AAC CBR
Apple AAC CBR
Apple AAC ABR
Settings using foobar2000 converter :
FFmpeg NMR:
--hide_banner -loglevel error -i pipe:0 -c:a aac -b:a 128k -aac_coder nmr -cutoff 16000 %d
FFmpeg twoloop
-hide_banner -loglevel error -i pipe:0 -c:a aac -b:a 128k -aac_coder twoloop -cutoff 16000 %d
FDK-AAC CBR
fdkaac 1.0.5, libfdk-aac 4.0.1, CBR 128kbps
Apple AAC CBR
qaac 2.70, CoreAudioToolbox 7.10.9.0, AAC-LC Encoder, CBR 128kbps, Quality 96
Apple AAC ABR
qaac 2.70, CoreAudioToolbox 7.10.9.0, AAC-LC Encoder, ABR 128kbps, Quality 96
Download: Audio samples and logs (https://drive.google.com/file/d/1MNHc5LIQQG6bWayXMl7d0VCJ42EyUpyg/view)
Sample-Rate Handling for the FFmpeg NMR AAC Encoder
According to an FFmpeg developer, the NMR AAC encoder is optimized for 48 kHz. Therefore, all test files were resampled to 48 kHz using SoX with the Very High, 168 dB quality setting.
The processing chain was:
Original WAV → SoX resampling to 48 kHz/24-bit → FFmpeg NMR AAC encoding → AAC decoding to 48 kHz/24-bit WAV → SoX resampling back to 44.1 kHz/24-bit
This process is safe and transparent. At these quality settings, the SoX resampling and 24-bit intermediate files don't introduce any audible differences.
Hardware used during testing
Topping E70 DAC
Topping L70 Headphone amplifier
Headphones Sennheiser HD 800.
Cabling: Balanced DAC-to-headphone amplifier connection; original Sennheiser HD 800 headphone cable.
-
IgorC
AudioCodecLab