FLAC file size oddity

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nesrad
Posts: 34
Joined: Sun Jan 29, 2017 7:00 pm
Operating System: Linux Debian

FLAC file size oddity

Post by nesrad » Thu Jun 08, 2017 6:43 pm

Hello Audacity experts,

I've made a video with the audio recorded in FLAC. The total file size, including video, is 29.6 MB. The entire thing is done with ffmpeg.

By opening the video file in Audacity, the FLAC track is automatically extracted. Nice!

If I immediately export the track to FLAC, the file size is 29.9 MB. Bigger than the original including video, and I haven't even touched the track. (I should point out that the video file is actually quite small, about 2.9 MB, since it's merely a slideshow.)

Now if I mess around with it by removing noise and normalizing, the file size jumps to 50.3 MB. But I haven't increased the quality in any way.

Can someone explain this behavior?

As a bonus question for those of you who are familiar with ffmpeg: If I try extracting the FLAC file directly from the video using

Code: Select all

ffmpeg -i video_file.mkv -acodec copy audio_file.flac
, the resulting file size is as expected 26.7 MB, but I only get the first 19 seconds of audio out of 18:53. What's going on?

Gale Andrews
Quality Assurance
Posts: 26087
Joined: Fri Jul 27, 2007 12:02 am
Operating System: Windows 10
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Re: FLAC file size oddity

Post by Gale Andrews » Fri Jun 09, 2017 12:42 pm

Have you considered whether you are exporting 24-bit or 16-bit FLAC from Audacity?


Gale
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