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+--- Thread: Extract Audio from Avi files (/Thread-Extract-Audio-from-Avi-files)
Extract Audio from Avi files - heliiaruy - Apr 09, 2016
This is not a tutorial, its a question as to how this can be done. I notice with, say, users' uploads of 'The Teaching Company' video lectures that the users also upload very well compressed m4a audio tracks often. These could be original from the publisher, but is there a way to get such small audio files (6mb for a 30 min lecture!) out of an avi
Having used VLC, i figured out how to get wastefully large mp3 files from these avi s, but upon trying for m4a I essentially crash the program and my computer.
No i do not understand file extensions and the media formatting involved, but a step by step here, if possible, would be very helpful.
Best
Extracting Audio from Avi - heliiaruy - Apr 09, 2016
This is not a tutorial, its a question as to how this can be done. I notice with, say, users' uploads of 'The Teaching Company' video lectures that the users also upload very well compressed m4a audio tracks often. These could be original from the publisher, but is there a way to get such small audio files (6mb for a 30 min lecture!) out of an avi
Having used VLC, i figured out how to get wastefully large mp3 files from these avi s, but upon trying for m4a I essentially crash the program and my computer.
No i do not understand file extensions and the media formatting involved, but a step by step here, if possible, would be very helpful.
Best
RE: Extract Audio from Avi files - bob5695 - Apr 09, 2016
with virtualdubmod:
file > open file
streams > stream list
demux
RE: Extract Audio from Avi files - heliiaruy - Apr 09, 2016
(Apr 09, 2016, 14:14 pm)bob5695 Wrote: with virtualdubmod:
file > open file
streams > stream list
demux
While this is faster in operation than VLC performed, the files are still coming out as big mp3 files; same size nearly. Better specific explanation for small file size to be produced?
RE: Extract Audio from Avi files - bob5695 - Apr 09, 2016
you want to turn a big mp3 file into a small m4a file, is that it?
i use megui for that, but i don't know if you'd want to grab a whole encoding package just for the audio feature.
edit - and i don't think it includes the nero aac encoder, it has to be downloaded separately.
or maybe there's a specific GUI for nero. or maybe you're okay with running it from CMD. i don't know.
edit #2 - i just tested an mp3 track (30 minutes and 0 seconds in length) nearly 26MB in size at about 120kbps
and encoding it 24kbps (m4a output) it turned out at 5.32MB in size.
RE: Extract Audio from Avi files - heliiaruy - Apr 09, 2016
ok, so i want to follow "edit #2".
Before me i have all these roughly 26MB 30 minute tracks: using megui can turn them into comparable audio quality m4a files that are around 6MB? This is what my question is looking for. I'm also looking for a clear explanation for myself and maybe others who want to do this with clearly limited understanding.
RE: Extract Audio from Avi files - bob5695 - Apr 09, 2016
audio quality will always decrease when you use lossy compression.
when aiming at insanely low filesizes, as is the case here, expect to notice substancial quality loss.
edit - if you're going to do it with megui you'll need to add this file: https://www14.zippyshare.com/v/VgOhdgjW/file.html
to the following folder: megui\tools\eac3to
protip #1 - use the scratchpad option to configure every detail of the encoding.
protip #2 - if you're encoding speech instead of music you can go mono instead of stereo.
protip #3 - use the same samplerate as the source for less degradation.
protip #4 - use vbr instead of cbr to squeeze a little extra quality.
protip #5 - configure megui preferences to run encoding jobs immediately instead of sending them to the queue.
RE: Extract Audio from Avi files - heliiaruy - Apr 09, 2016
well in any case s'all moot cause megui will not successfully download from anywhere i try. Thanks besides; it does sound like you know this process well.
and the m4a audio versions of video lectures that are out there are very good quality, unnoticable differences: its that capability i wish was more accessible.
RE: Extract Audio from Avi files - bob5695 - Apr 09, 2016
https://www.videohelp.com/download/MeGUI_2624_x86.zip
RE: Extract Audio from Avi files - Q91 - Apr 10, 2016
(Apr 09, 2016, 17:29 pm)heliiaruy Wrote: well in any case s'all moot cause megui will not successfully download from anywhere i try. Thanks besides; it does sound like you know this process well.
and the m4a audio versions of video lectures that are out there are very good quality, unnoticable differences: its that capability i wish was more accessible.
What's the Bitrate of the m4a audio files you can find? Speeches usually doesnt need all the higher bitrates that music or movies does.
anyways, I would demux the audio from the movie like Bob said, and then use any kind of software that can re-encode. A free software would be Format Factory, which allows for some configurations.
But yea, presumable the m4a are at least at a sample rate of 22kHz (which usually works ok with voices), but I presume it's VBR (not ABR) and mono to keep the size as small as possible.