I have some uncompressed WAV files that I wan't to compress to a CBR of 8kb/s - which the documentation says is possible by using
-b:a 8k in the ffmpeg command.
however when I run it on my raw audio it compresses only as far as 32kb/s and I get this in the output:
Output #0, mp3, to 'MP3_CBR8__D__48__2019_2_26_T=0940.mp3': Metadata: comment : Recorded at 01:40:06 26/02/2019 (UTC) by AudioMoth 0FE081F80FE081F0 at gain setting 2 while battery state was 4.3V TSSE : Lavf58.20.100 Stream #0:0: Audio: mp3 (libmp3lame), 48000 Hz, mono, s16p, 8 kb/s Metadata: encoder : Lavc58.35.100 libmp3lame size= 4688kB time=00:20:00.00 bitrate= 32.0kbits/s speed=69.9x video:0kB audio:4688kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.007729%
I'm quite new to using libmp3lame but the line starting
Stream #0:0 contains the information that it's meant to be at 8kb/s however in the next couple lines it says
Basically I'm wondering where I'm going wrong and what I can do to get the compression I want?
(Note: I've used this method to reduce quality to 256kb/s, 128kb/s, 64kb/s and 32kb/s I just run in to errors when I try to go lower.)
Thanks in advance for any help you can offer!