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15 votes

How to recover audio from an incomplete or corrupted AAC/m4a file

This guide worked 100% for me - it takes you through each step. Afterwards, the m4a file plays! Note: this is completely free. http://sysfrontier.com/en/2014/12/31/hello-world/ Also pasting ...
namford's user avatar
  • 251
4 votes

I can choose one of these formats: OPUS 152 kbit/s vs AAC 128 kbit/s vs M4A 128 kbit/s. Which one is better?

This chart https://opus-codec.org/comparison/ shows that above 128 kb/s opus, aac and mp3 are very close in terms of quality. So, as @Tetsujin mentions, the best one would be the one that is closest ...
audionuma's user avatar
  • 2,864
4 votes
Accepted

Audio file in shorter in m4a than in PCM

Raw PCM does not store stream properties, so when you ingest a raw PCM stream, ffmpeg assumes a sampling rate of 44100 Hz whereas your source is 48000 Hz. So new duration = old duration x (48000/44100)...
Gyan's user avatar
  • 694
2 votes
Accepted

Is lossy encoding supposed to produce higher signal level peaks than those present in the original?

Yes, certain compression formats can result in higher peak levels than the same material pre-compression. -1dBTP ("true peak" level, relative to full scale) seems to be the accepted maximum safe level ...
James Langford's user avatar
2 votes

Do Opus And AAC Use Artistic License To Improve Sound Quality By Sacrificing Accuracy?

You can read up on how the Opus codec works here: http://opus-codec.org/ Opus is entirely open-source, so you can even read the source-code to determine how it works. Here is a paper on how MP3 and ...
Mark's user avatar
  • 8,900
1 vote
Accepted

Perceptual Noise Substitution and AAC

2.2.1 Perceptual Noise Substitution(PNS) The PNS tool increases the coding efficiency of AAC by representing noise-like signal components with a compact parametric representation instead of coding ...
Mark's user avatar
  • 8,900
1 vote

mp4 file has no sound

I've had this happen before, howevr it was while recording the screen of my computer. Not certain if you've done the same or used a camera IRL. However easiest way to see if there's audio in a file is ...
Tmanok's user avatar
  • 134
1 vote

mp4 file has no sound

Try opening the file with some advanced video players just to find out if the audio is gone or there's a codec error. Two video players that I use when having this sort of problems is Quick Time and ...
Dalv Olan's user avatar
  • 852
1 vote

Which format for radio station to choose in Shoutcast?

AAC-HE when having low bitrate considerations. MP3 if concerned about compatibility with all devices available. 112kbps mp3 could be a good compromise if you need both. More elaborate version: - ...
Vospi's user avatar
  • 89
1 vote

Does converting an mp3 format audio file to m4a format makes audio quality better?

As far as I know, m4a is also considered to be a lossy format. So converting from lossy to lossy would not make any difference, probably worsen the quality depending on the coding standard being used.
zakalaka's user avatar
1 vote

Does converting an mp3 format audio file to m4a format makes audio quality better?

Just to add & clarify that m4a is a container format, actually the same spec as mp4, merely a different file extension, and therefore can contain either AAC (lossy) or ALAC (lossless) formats -- ...
michael's user avatar
  • 111

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