Thread: Bitrate per channel?

Yo hey!
For over a week searching the web for an answer ...
I was wondering ...
Just for a quick example:
When I create some stereo .mp3 with 320kb/s constant rate, does that mean each channel is playing with 320kb/s or these 320kb/s are divided into two channels with 160kb/s and when the file was recorded it was recorded with 160kb/s per channel, and when listening the song you actualy listening 160kb/s per channel?

The thing i care more is i have bunch of old movies on bluray disks and my bluray reader is gona die soon, already started to be hard for some disks to read, so i want to rip them into .mkv and put them on my hdd.
So most of the movies are in 5.1 48KHz audio channels.
I dont care SO much for the audio quality but atleast I want the quality of the audio track to be the same as if you listening high quality .mp3 file with 320kb/s 48KHz.
Because this quality is more than enought for me and i'm ok with that, but the audio channels of the movie will stay in original as it is 5.1 or 7.1 etc...
So if i rip the movie in AAC audio format with 5.1 48KHz 320kb/s, does that mean all 5.1 channels are playing with 320kb/s or these 320kb/s are divided in 6, and for each channel i have 53,33kb/s per channel, which is terrible ...
I want the quality of high quality .mp3 to be the audio quality in the ripped movie.

I have .mp3 with 320kb/s constant 44.1KHz which is 100Mb in size and the music lenght is 44min.
One movie was also 44min ripped with AAC 320kb/s constant 5.1 48KHz and the audio stream size was 102Mb.
And thats what make me think about bitrate per channel, because it just cant be the same size for stereo and 5.1 channels.
Does AAC has SO much better compress capabilities and makes the stream size pretty much the same as mp3?

I'm sorry if im not into the right place, delete it or move it if needed.
Thanks for the time.

Originally Posted by wklie

The 320kbps figure should include both channels, i.e. each channel gets 160kbps.
44 minutes * 60 seconds * 320kbps / 8 bit / 1024K = 103MB

To squeeze 6 channels into 320kbps is indeed terrible.

I would recommend you not changing the audio format. You should backup the whole thing completely. HDD is cheap.

If you really want to lower the storage requirement, you can try to pick the AC3 5.1 tracks which should be 640kbps, or the basic DTS track or DTS Core (1.5Mbps) inside DTS-HDMA.

I do not think using AAC is a good idea, because a normal Blu-ray player may not be able to play 5.1 AAC from the backup, in case it's too troublesome to find the original media.

I totally agree. Why mess around with changing the audio? Just clone the entire disc and save it to a hard drive.
By the way, if you are digitizing a large collection, consider investing in a NAS.

wklie,
"The 320kbps figure should include both channels"
Yeah, i was almost sure thats the case.
But even this, the audio sounds the same as original, I dont have hi-fi audio system and i wont find the difference anyway with this cheap speakers i am using now.
Well, i decided to leave the audio untouch.
The original audio is around 1,1/1,2Gb.
Not a big deal i guess.

nicoff,
" Just clone the entire disc and save it to a hard drive."
Well, I was going to do just that, to clone the entire disc.
But a bluray disc is around 40GB, my HDD is 2TB and its 72% full, so i had to lower the size, and wanted to maximize the size of single movie by lowering quality of audio track too.
But then i got thinking if that 320kb/s 5.1 quality sounds terible on hi-fi system i will be very sad
I dont have so much movies, but they wont fit into my HDD if i just clone them.
And they will be more than 2TB.

"By the way, if you are digitizing a large collection, consider investing in a NAS."
Was thinking about that too. But im a poor guy. Nas storage is too expensive for me.
I may buy another 2TB HDD in some months and thats pretty much it.
I dont have so much bluray movies anyway.
I just dont want to buy another bluray reader who will last how much? 2-3 years?
The one which is now sometime trying so hard to read a bluray disk is 2,5 years old.
The bluray disk itself is very clean and no scratches what so ever.


Well, thanks guys for the awesome respond
GL and HF