How to vizualize and play extremely large MP3 files?

[theozh]

Hello,
following challenge:
I would like to take longterm recordings to check whether some noises appear periodically and what these noises are.
I am having a Zoom H5 set to MP3 128kbps with a 32GB SD-Card. With this I could record several hundreds of hours. If possible I would like to go for even longer times. Although, the H5 has an option to start recording only if a noise is above a certain level, I prefer to just let the recording run. As a pre-test I have a ca. 10h MP3 recording which is ca. 600 MB large.

Now, instead of listen to the file 1:1, I would like to LOOK at it, if and when there are some noise occurences.
Audacity, however, as I understand, loads and uncompresses the MP3 which will take ages and which will probably require disk space which I do not have available.
So, I do not see any chance with Audacity...

In this forum I found links to programs for splitting MP3s without having to load or convert them.
For example: mp3splt or mp3DirectCut ...
However, it's no fun to split a 1000h MP3 and deal even with 100x 10h-files or 1000x 1h-files.

Does anybody know about a convenient solution to visualize and play extremely large MP3s?
Thanks!

Win7/64, Audacity 2.0.6

[steve]

Topic moved to the Audio Technology section as it is not actually about Audacity.

For example: mp3splt or mp3DirectCut ...

Although I don't use it myself, I believe that mp3DirectCut displays the waveform and allows you to play it.

[theozh]

Thanks @steve,
sorry, for posting my question at the "wrong" place. I thought there still might be a way with Audacity.
I only tried mp3splt and thought (as the name says) mp3DirectCut is just for cutting.
Well, it seems like it's exactly what I was looking for.
Great, thanks again.

[Trebor]

I would like to take longterm recordings to check whether some noises appear periodically and what these noises are ... instead of listen to the file 1:1, I would like to LOOK at it, if and when there are some noise occurences.

I think Audacity's spectrogram view , (rather than waveform view), is what you are looking for ...
http://manual.audacityteam.org/man/spec ... _view.html.

The two waveforms shown are identical

Demo of spectrogram-view in Audacity.gif (266.68 KiB) Viewed 987 times

Rendering a spectrogram of a recording which is 10 hours long could take several minutes in Audacity, depending on the spectrogram preferences : the higher the resolution, the longer it will take.

[theozh]

Thanks, @Trebor. This might be good if you have the MP3 already in Audacity.
But the problem is, how to get a >1 GB MP3 into Audacity?

A comment to mp3DirectCut:
It would all be perfect but unfortunately the zoom-levels are very limited.
There are only 6 zoom levels. Apparently, you cannot visualize the whole file in one screen. The largest zoom-out window with a 10 h MP3 is about 4 minutes. That's not very practical to search for single events. In the corresponding mp3DirectCut forum it is mentioned that the zoom-out levels are inherently limited. Too bad...

If anybody has other ideas... please let me know.

[Trebor]

Thanks, @Trebor. This might be good if you have the MP3 already in Audacity.
But the problem is, how to get a >1 GB MP3 into Audacity?...

Provided you have enough spare memory, Audacity will display a 10 hour MP3 ...
It will take about 15 minutes open it* though, and another few minutes to generate a spectrogram at the default resolution ...

opening a 10 hour mp3, mono 44-1kHz)_.gif (848.57 KiB) Viewed 958 times

[ * Mono , 44.1kHz, 224kbps ]

[steve]

Provided you have enough spare memory

and disk space.
10 hours of uncompressed audio data requires a lot of disk space (at the default 32-bit float, about 12.5 GB for a stereo track)

[theozh]

@Trebor, well, I tried to load a 600 MB MP3 file stereo (although mono could be sufficient) 44.1kHz 96kbps and Audacity told me that this will take >2-3 hours. I stopped after 15 minutes.
Maybe my PC is to old and slow or something else. Anyway, it didn't seem very practical.
How should this go with a 100h or even 1000h MP3? Buy new hardware?
Despite of that: would be Audacity capable of loading a 100h or 1000h file?
What is the limit there? Does it depend on my hardware (certainly hard disk space)? If there is a maximum size it would be good to know it beforehand to split the MP3 into managable pieces. As @steve estimates, 100h or 1000h MP3 would then require approx. 125GB or 1.25TB disk space?!

[Gale Andrews]

The decompression from MP3 to lossless PCM takes 20 MB per minute of space by default for stereo.

It's time as well as disk space, even with a Solid State Drive. It just isn't practical with Audacity to import MP3 files lasting half a day or more.

Sonic Visualiser seems to do a "progressive" type of loading of MP3 files so you get to see the start of the file at once or can navigate somewhere else along the file where it has already been loaded, but it takes quite a time to completely load a long file. Audacity can optionally do something like that for WAV files, and you can even jump start the load where it has not started yet, but you would have to convert your MP3 to WAV to benefit from that.



Gale