Stereo to 5.1

Audacity Help Forum Windows
1

Ok thanx
I am trying to make stereo to 5.1.
I follow the post in audacity duplicate strereo and make four stereo track.first and last splitted to mono and b/w two are converted stereo to mono and fourth mono track given low pass filter with rollover 24 db/octave and cut freq to 120 HZ but it export as stereo track
Now what should i do to export
front: L C R side: L R LFE

2

This is not about audio / video synchronisation so I started a new topic for you.

What post is that exactly?

Edit > Preferences, choose “Import / Export” then select the “Use custom mix…” option and click OK.

Audacity cannot specify channel mappings related to the order of the tracks. The exact channel mapping for multi-channel files differs from one format to another, and for some formats it is not specified at all. What format are you exporting to exactly?

After you enable “Use custom mix” there is a dialogue where you can assign the audio of each track to each channel, the channels being ordered in the same way as in the main project window.


Gale

3

I follow the post in audacity duplicate strereo and make four stereo track.first and last splitted to mono and b/w two are converted stereo to mono and fourth mono track given low pass filter with rollover 24 db/octave and cut freq to 120 HZ but it export as stereo track

I’m confused about what your 6 tracks are, but the LFE is one track and it needs to be mono.

And in the real world, there is usually no benefit from taking the “normal” bass from the other channels and moving it to the LFE. On a typical home system, your receiver (or computer, etc.) has “bass management” that takes that bass and routes it to the subwoofer anyway. The LFE is supposed to be for Low Frequency Effects… booms & explosions.

In a real theater (or a very high-end home system) the full-size surround speakers can put-out the normal bass, so the sub is used only for the LFE.


Now what should i do to export
front: L C R side: L R LFE

What??? For normal 5.1 you should have:
Front left
Front center
Front right
Back left
Back right
LFE

4

and the correct order of the channels depends on the file format.
Details can be found on Wikipedia: http://en.wikipedia.org/wiki/Surround_sound

5

Thanx steve

6

That does not mention OGG or AC3. Those are both “usually” FL , FC , FR , SL , SR , LFE (the order that @tnehal gave).

I understand the Vorbis 1 specification (for OGG) calls for that order but allows applications to define custom mappings. AC3 seems not to define the mapping but most decoders will use that order and remap if the channels are in some other order.


Gale

7

I m trying to export with ac3 than what is channel ordering?
And original audio is AAC, 48 KHZ, 0KBPS, STEREO from which i try to convert in ac3 so what channel order should be ideal and it works perfectly sync with original aac audio?
And which format is best for export 5.1 (with small storage size and good quality)

8

Please do not post the same questions in multiple topics. I answered this at https://forum.audacityteam.org/t/general-information/33004/8 .

No lossy format has perfect quality.

If you are using the “Copy” option in Avidemux (which is sensible) there may be limitations on the audio formats that it will accept for the particular video format. However we will not give technical support for Avidemux or video encoding on the Audacity Forum.

AAC (M4A), AC3 and MP3 all take up approximately the same file size for comparable quality. See: http://manual.audacityteam.org/o/man/file_export_dialog.html#compare .

It is fairly generally believed that MP3 needs a slightly larger bit rate and hence file size to sound as “good” as M4A or AC3.

I would tend to use AC3 because the AAC encoder in Audacity is slow and removes a small piece of audio at the end (this is a bug in the AAC encoder used in the rather old version of FFmpeg that Audacity supports, not an Audacity bug).


Gale