Hi;
New here but checked all around and don’t see any answer. Converted 3MB Wav (Original War of the worlds) to FLAC and got a 34.1 FLAC file. Converted 3MB MP3, (Cher Do you believe in love) and got a 21MB FLAC. What is going on?
Brand new installation on Win xp (don’t ask the wife will allow no changes) .
Converted 3MB MP3
The first thing Audacity would have done is convert the MP3 to uncompressed. That works out to about 32MB. Convert then to FLAC might give you around 21MB.
3MB Wav (Original War of the worlds)
WOTW was almost certainly not a WAV file.
War of the Worlds was about a 29 minute mono radio show which works out to about 140MB. So given it’s not modern high fidelity (5KHz AM radio), FLAC might have squeezed it down to 34 MB.
Look up how to force Windows to show you filename extensions. Or download and use Media Info.
Be careful not to download the installer. That might contain malware.
Koz
OK. Cher is four minutes, so it’s even worse.
Koz
Hi;
It turns out the War of the worlds wav was recorded at 8Khz. So that a perfect explanation for that; semi. So I tried a CD 44K level wav and indeed it is half the space when converted. So I think we are good but its also very odd. The Cher 3MB mp3 turned out to be 128K so the FLAC conversion blew it up to 20 MB.
So I think we can safely say that FLAC conversion will not produce smaller files in many cases. Interesting to note!
Hi Moderator Person;
I think it would be very helpful to post a note in the FAQs or wherever that smaller files will only be produced if the original file is; help me out here a bit. Audacity will blow up an 8Khz 3Mb Wav to something huge and then compress the huge file to whatever? The same with a 128K MP3 3mb will be blown up to whatever and then squished to 21MB FLAC. I’m not sure how to write that but perhaps you have an insight? In any event, results may vary depending on the input format and the output format chosen? Sound about right?
There is a page in the manual that provides information about a range of audio formats that are supported by Audacity: https://manual.audacityteam.org/man/export_formats_supported_by_audacity.html
I think it would be very helpful to post a note in the FAQs or wherever that smaller files will only be produced if the original file is; help me out here a bit. Audacity will blow up an 8Khz 3Mb Wav to something huge and then compress the huge file to whatever?
Yes, Audacity will decompress the file and it works internally at 32-bit floating-point.
If you open a file into a new-empty Audacity project, the Project Rate (Hz) shown in the lower-left corner should match the file (8000Hz for your 8kHz file). And, when you export that shouldn’t change.
However, you have to select the bit-depth when you export to FLAC or WAV. And, 16-bit FLAC might be larger than an 8-bit WAV depending on what changes/editing you do and depending on your dither setting.
For uncompressed files you can calculate the file size if you know there are 8 bits in a byte -
File Size (in bytes) = Playing time (seconds) x Sample rate (Hz) x (bit-depth/8) x Number of channels.
For example, “CD quality” WAV files are 16-bits, 44.1kHz, 2-channel stereo. So that’s 176,400 bytes per second.
For MP3 or other compressed files we can calculate the file size if we know the bitrate (kbps = kilo_bits_ per second). A 256kbps MP3 is 32K bytes per second. (About 1/5th the size of the CD quality WAV). …That’s not always exact because there can be metadata such as album artwork embedded in the file and that adds to the file size.
Re-sampling at a higher bit-rate will increase file size, without any increase in sound quality.
Similarly, converting a mono original into dual-mono, (which looks like stereo), will just increase file size without affecting quality.
If you ensure Audacity’s project-rate is 8kHz when you export the file, no “blow up”.
Thanks for the information! I still think that the conversion/size issue deserves lager mention. Especially for newbies, like myself. Again using the 8K War of the Worlds file. For instance the project rate was just set at 8Khz automatically and flac only offers 16 and 24 bit. The results are 33Mb for 16 bit and 60Mb for 24 bit. Looks like wav is the winner but I don’t know why that should be so. Could it just be that this is something outside of Audacity’s competence?
In any event, here is the file itself. Dear Moderator I hope this is OK.
There’s also masses of stuff about digital audio available elsewhere on the Internet.
I think these videos at Xiph.org are particularly good: https://xiph.org/video/