NoBackendError despite a backend (specifically FFmpeg) being installed

Hello!

This is my first time posting an issue, so please cut me some slack if I’m not following some protocol!

I was trying to use python’s librosa package on Windows 10 and encountered the following issue.

After running x, _ = librosa.load('data/fma_small/000/000002.mp3', sr = None) I receive this stack trace:

---------------------------------------------------------------------------
NoBackendError                            Traceback (most recent call last)
<ipython-input-2-15a8daa0e7fd> in <module>()
      1 start, end = 7, 17
      2 filename = utils.get_audio_path(AUDIO_DIR, 2)
----> 3 x, sr = librosa.load(filename, sr = None, mono = True)

Q:\Program Files\Anaconda3\lib\site-packages\librosa\core\audio.py in load(path, sr, mono, offset, duration, dtype, res_type)
    105 
    106     y = []
--> 107     with audioread.audio_open(os.path.realpath(path)) as input_file:
    108         sr_native = input_file.samplerate
    109         n_channels = input_file.channels

Q:\Program Files\Anaconda3\lib\site-packages\audioread\__init__.py in audio_open(path)
    112 
    113     # All backends failed!
--> 114     raise NoBackendError()

NoBackendError:

Out of curiosity, I also tried to run audioread.ffdec.FFmpegAudioFile('data/fma_small/000/000002.mp3') (since I know that FFmpeg is installed) but I received:

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
Q:\Program Files\Anaconda3\lib\site-packages\audioread\ffdec.py in __init__(self, filename, block_size)
    126                 stderr=subprocess.PIPE,
--> 127                 stdin=self.devnull,
    128             )

Q:\Program Files\Anaconda3\lib\site-packages\audioread\ffdec.py in popen_multiple(commands, command_args, *args, **kwargs)
     88         try:
---> 89             return subprocess.Popen(cmd, *args, **kwargs)
     90         except OSError:

Q:\Program Files\Anaconda3\lib\subprocess.py in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags, restore_signals, start_new_session, pass_fds)
    946                                 errread, errwrite,
--> 947                                 restore_signals, start_new_session)
    948         except:

Q:\Program Files\Anaconda3\lib\subprocess.py in _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, unused_restore_signals, unused_start_new_session)
   1223                                          cwd,
-> 1224                                          startupinfo)
   1225             finally:

FileNotFoundError: [WinError 2] The system cannot find the file specified

During handling of the above exception, another exception occurred:

NotInstalledError                         Traceback (most recent call last)
<ipython-input-6-be3b460211e8> in <module>()
----> 1 audioread.ffdec.FFmpegAudioFile(filename)

Q:\Program Files\Anaconda3\lib\site-packages\audioread\ffdec.py in __init__(self, filename, block_size)
    129 
    130         except OSError:
--> 131             raise NotInstalledError()
    132 
    133         finally:

NotInstalledError:

Again, I have FFmpeg installed, and ffmpeg works as a command in cmd.

Is anyone able to spot the problem?

Thanks!

[carlthome]

Not really, no. I eventually started calling ffmpeg via subprocess.Popen and am pretty happy with more explicit control for my purposes.

import shlex
import subprocess

import numpy as np


def decoder(path, duration=3.0, channels=2, sample_rate=44100, dtype=np.float32):
    formats = {np.int16: 's16le', np.float32: 'f32le'}
    args = f'''
    ffmpeg 
    -v error
    -n
    -i "{path}" 
    -f {formats[dtype]} 
    -ac {channels} 
    -ar {sample_rate} 
    -
    '''
    args = shlex.split(args)

    buffer_size = int(channels * np.dtype(dtype).itemsize * duration * sample_rate)

    with subprocess.Popen(args, stdout=subprocess.PIPE) as pipe:
        while True:
            buffer = pipe.stdout.read(buffer_size)
            audio = np.frombuffer(buffer, dtype=dtype)
            audio = np.reshape(audio, (-1, channels))
            yield audio
            if len(buffer) < buffer_size:
                break


for x in decoder('piano.wav'):
    print(x.shape)

from IPython.display import Audio

audio = np.concatenate(list(decoder('piano.wav')))
Audio(audio.T, rate=44100)

If you’re having trouble with audioread you could of course try libsoundfile and see if that works:

import soundfile as sf

y, sr = sf.read('audio.ogg')

[raffaelbd]

YES, “fixed” it.

Following this intuition of the PATH environment variable behaving differently from the rest of my system I just copied ffmpeg to the parent folder of the directory and it worked! And then I realized I hardly ever close PyCharm, so I restarted it and it works! This issue also happens with terminals (environment variables don’t take effect unless you open a new one). I m having same problems , despite installing ffmpeg. please give me a solution.

my code was: D = [] # Dataset for row in valid_data.itertuples(): y, sr = librosa.load(‘F:\paper\Bangla ASR\segmented/augmented 1/’ + (row.path))
ps = librosa.feature.mfcc(y=y, sr=sr, n_mfcc=52) if ps.shape != (52, 130): continue D.append( (ps, row.classID) )

---

NoBackendError Traceback (most recent call last) <ipython-input-6-91f60cabb456> in <module> 1 D = [] # Dataset 2 for row in valid_data.itertuples(): ----> 3 y, sr = librosa.load(‘F:\paper\Bangla ASR\segmented/augmented 1/’ + (row.path)) 4 ps = librosa.feature.mfcc(y=y, sr=sr, n_mfcc=52) 5 if ps.shape != (52, 130): continue

~.conda\envs\RaffaelEnv\lib\site-packages\librosa\core\audio.py in load(path, sr, mono, offset, duration, dtype, res_type) 117 118 y = [] –> 119 with audioread.audio_open(os.path.realpath(path)) as input_file: 120 sr_native = input_file.samplerate 121 n_channels = input_file.channels

~.conda\envs\RaffaelEnv\lib\site-packages\audioread_init_.py in audio_open(path) 114 115 # All backends failed! –> 116 raise NoBackendError()

NoBackendError:

N.B: I restarted jupyter notebook so many times but still problem exists