Re: normalize audio in mp4s
On Mon 09 Mar 2020 at 14:23:54 (-0600), ghe wrote:
>
> > Please note that the subject of this conversation is mp4 (not mp3).
>
> It's claimed that sox will handle mp4:
>
> https://stackoverflow.com/questions/2666425/how-to-i-configure-sox-to-work-on-mp4
>
> (You do have to install LAME.)
All I read there is that someone, 11 years ago, had heard you needed
LAME, and someone else expressed their doubts.
> > If you only process uncompressed audio then sox is fine.
>
> It will do the mp's and flac. That I know of -- there may be others.
>
> It normalizes things too. I do that in flac. I don't know if it
> normalizes mp's.
I don't know what an "mp" is.
My version of sox (which AFAIK is teamed up with libsox-fmt-mp3 and
libmp3lame0; lame is also present, but I have no idea what liblame,
mentioned elsewhere, is) claims to handle:
AUDIO FILE FORMATS: 8svx aif aifc aiff aiffc al amb amr-nb amr-wb
anb au avr awb caf cdda cdr cvs cvsd cvu dat dvms f32 f4 f64 f8 fap
flac fssd gsm gsrt hcom htk ima ircam la lpc lpc10 lu mat mat4 mat5
maud mp2 mp3 nist ogg paf prc pvf raw s1 s16 s2 s24 s3 s32 s4 s8 sb
sd2 sds sf sl sln smp snd sndfile sndr sndt sou sox sph sw txw u1
u16 u2 u24 u3 u32 u4 u8 ub ul uw vms voc vorbis vox w64 wav wavpcm
wv wve xa xi
PLAYLIST FORMATS: m3u pls
No mention of mp4a and aac. And I don't see any method for getting at
the audio inside its container, whether that's mp4 or mkv. That's why
I used ffmpeg to unpack the audio in the recipe I posted yesterday.
One could in principle unpack the audio into an MP3 file instead of
a WAV file (the latter can get seriously large, and I need two copies),
but that would only increase the loss in quality that's already
occurring with all this processing.
So I'm treating your suggestion as vapourware at the moment.
Cheers,
David.
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