the same audio have different length using different tools (librosa,ffprobe)

Question

I want to measure an audio file's duration.
I'm using two different tools and got different values.

ffprobe:
I'm using this line to get duration using ffprobe

 ffprobe -i audio.m4a -show_entries format=duration -v quiet -of csv="p=0"

result :780.320000 seconds
2. Librosa (python library)
and using this line to get duartion using librosa

y1, sr1 = librosa.load(audio_path, sr=44100)
librosa.get_duration(y1, sr1) * 1000

result 780329.7959183673 milliseconds

Does anyone know what's causing the difference?

I'd have a look at the units. ffprobe returns almost exactly 1/1000th of librosa. — Nathan, Oct 28 '19 at 11:38
@nathan I'm sorry can you clarify more? what do you mean by units? could you provide an example for "ffprobe returns almost exactly 1/1000th of librosa"? — Fathy Eltanany, Oct 28 '19 at 11:41
Are you sure ffprobe returns milliseconds and librosa returns seconds? — Nathan, Oct 28 '19 at 11:42
So why do you mutliply the second with a thousand? Then you're comparing milliseconds to microseconds — Nathan, Oct 28 '19 at 12:05
@Nathan I meant the output of two lines in the question in milliseconds — Fathy Eltanany, Oct 28 '19 at 12:21
@Gyan you are right, I'm multiplying it later by 1000 in my code what I meant is the value still didn't match — Fathy Eltanany, Oct 28 '19 at 12:24
How do you obtain `y1` and `sr1` in the call to `get_duration`? Can you extend your code example to show this? — ROpdebee, Oct 28 '19 at 15:46
@ROpdebee this is how i obtain them `y1, sr1 = librosa.load(audio_path, sr=44100)` — Fathy Eltanany, Oct 29 '19 at 07:04

szatmary · Answer 1 · 2019-10-28T19:32:55.560

2

This is likely just normal floating point error. The two libraries probably make mathematically similar computations, but use different internal representation of the values which produce small rounding errors. This is normal and expected in floating point numbers.

edited Oct 28 '19 at 19:32

answered Oct 28 '19 at 16:03

szatmary

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the same audio have different length using different tools (librosa,ffprobe)

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