Transcoding audio -> ffmpeg - besweet - avisynth?

[wiseant]

Hi Everyone

Just curious . . .

what is the difference transcoding a 44,100 mp3 file to an 48,000 ac3 file?

1. using ffmpeg or besweet i.e. decode -> mp3 then encode -> ac3

2. using an avs file with either ffmpeg or besweet where the input is considered uncompressed
decode wav/pcm ? then encode -> ac3

On the surface it seems that transcoding from an avs "uncompressed" file would be better - and would apply to all compressed audio formats?

TIA

[Chris K]

There shouldn't be any difference.

On the decode side, FFmpeg (and I assume Besweet too) always first internally decompress the file to raw PCM.
You cannot re-encode directly from mp3 to ac3.

[AlanHK]

They're all the same, in that they decode/decompress, process (to resample) and reencode.

However while the decoding will the same, there is a difference in quality of encoding.

Besweet hasn't got a great rep for its AC3 encoding, and hasn't been updated for many years.

I like to stream from an AVS file to Aften. This allows me to keep keep exact sync with video if I cut it (with "Trim()"), and there are some simple but powerful audio functions you can use to adjust volume, delay, sampling, downmix, etc. The newish function Soundout() gives you a direct export to AC3 from Avisynth.

But anything fancy, like noise reduction, I export to wave (Soundout() is one good way) and use Audacity.

[wiseant]

Thanks for the info.

@AlanHK - Besweet can use Aften - with the updated bsn.dll

wiseant

[AlanHK]

Thanks for the info.

@AlanHK - Besweet can use Aften - with the updated bsn.dll

wiseant

As far as I can see, that's just using Besweet to decode and piping it into Aften.
It's not really integrated into it. Is it in any of the GUIs?

I just use ffmpeg, like:

for %%I in (%1) do (
ffmpeg -i "%%I" -ar 48000 -f wav -vn -y - | p:\aften\aften.exe -b 192 - "%%~nI.ac3"
)

for just about any audio format. (Or you can use ffmpeg to encode the AC3 if you prefer.)

or use wavi on an AVS file:

for %%I in (%1) do (
wavi %%I - | p:\aften\aften.exe -b 128 -s 1 -w 45 -dnorm 27 - "%%~nI.ac3"
)