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Author Topic: MP4 to Audio  (Read 4031 times)

Cask

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MP4 to Audio
« on: December 09, 2015, 04:57:52 am »

I just converted an MP4 to MP3 320 Constant Bitrate, FLAC & WAV and I cannot tell the difference in quality. Has anyone else noticed this? Any explanation as to why there is no difference?

FYI I'm using MC20. I could not find a forum for 20 hence I have posted here.
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Hendrik

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Re: MP4 to Audio
« Reply #1 on: December 09, 2015, 05:04:16 am »

320kbit MP3s are generally considered "transparent" quality, so while its not a lossless format, its usually very hard to tell the difference.
You would need a really good DAC and speakers and a trained ear on top of that to tell the difference.
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Cask

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Re: MP4 to Audio
« Reply #2 on: December 09, 2015, 05:08:49 am »

Thanks for the info.
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Headcool

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Re: MP4 to Audio
« Reply #3 on: December 09, 2015, 08:23:56 am »

Also don't forget that a mp4 file can hold many different types of audio at different bitrates. Your mp4 file may have contained an audio track with a low bitrate. In such a case the conversion to mp3 and flac would result in an unnecessary upsampling.
The best choice in such cases is to demux the audio track from the container, without converting it at all. This is much faster and there is no loss in audio quality.
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blgentry

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Re: MP4 to Audio
« Reply #4 on: December 09, 2015, 08:46:38 am »

Yeah, MP4 is almost certainly a lossy format.  Presuming this is MP4 video with an audio track?  M4A can be lossy (AAC) or lossless (ALAC), which is super confusing.  But that's how it is.  Verify the source and rate of your original audio first.  Then you can do meaningful experiments.

Brian.
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Hendrik

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Re: MP4 to Audio
« Reply #5 on: December 09, 2015, 08:49:05 am »

The best choice in such cases is to demux the audio track from the container, without converting it at all. This is much faster and there is no loss in audio quality.

The typical audio formats inside an MP4 file (AAC and ALAC) do not work properly without a container. You'll usually encounter them as M4A, which is just a MP4 container with a different extension to signify it contains only audio.
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Headcool

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Re: MP4 to Audio
« Reply #6 on: December 09, 2015, 10:45:10 am »

The typical audio formats inside an MP4 file (AAC and ALAC) do not work properly without a container. You'll usually encounter them as M4A, which is just a MP4 container with a different extension to signify it contains only audio.

I prefer the mkv container over mp4, avi, etc. It is just more future proof and versatile. Of course there are some compatibility problems if you own old/primitive devices. But with MCs transcoding capabilities even that shouldn't be an argument.
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AndrewFG

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Re: MP4 to Audio
« Reply #7 on: December 09, 2015, 12:54:09 pm »

320kbit MP3s are generally considered "transparent" quality, so while its not a lossless format, its usually very hard to tell the difference.
You would need a really good DAC and speakers and a trained ear on top of that to tell the difference.

Hendrik, you are kidding, aren't you, really, ..

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JimH

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Re: MP4 to Audio
« Reply #8 on: December 09, 2015, 01:24:32 pm »

I don't think so.
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Hendrik

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Re: MP4 to Audio
« Reply #9 on: December 09, 2015, 02:48:03 pm »

Hendrik, you are kidding, aren't you, really, ..

Outside of the audiophile circles, who have their own range of beliefs, it's really widely acknowledged that 320kbit MP3 is sufficiently high bitrate to deliver near-transparent quality, at least with a competent encoder.
If you yourself can tell the difference between a lossless file and a 320kbit mp3 encode of the same, I applaud your ears. :)

320kbit is a lot of bandwidth for stereo. Lossless FLAC often only needs ~500kbit at 16-bit 44.1kHz.
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