Rage Audio Quality

[toast]

I've been recording rage lately. I've been recording the AC-3 track instead of the MPEG2 track.

Can someone comment on the audio quality of the Digital Betacam source, and whether it's worth me recording the AC-3 stream, or if the MPEG stream is good enough?

P.S. rage rocks

[Champion_R]

I've been recording rage lately. I've been recording the AC-3 track instead of the MPEG2 track.

Can someone comment on the audio quality of the Digital Betacam source, and whether it's worth me recording the AC-3 stream, or if the MPEG stream is good enough?

P.S. rage rocks

<{POST_SNAPBACK}>

I always record the AC3 stream because it sounds so much better.

[Travis1503559517]

Digital Betacam is generally uncompressed 48Khz/20bit audio. Better than both AC3 or MPEG audio. ABC's & 9's 448kbits/s AC3 is pretty close though.

[toast]

Thanks for these super quick responses!

Glad to see the extra 192kbps aren't going to waste.

I think I'll do a blind test by recording the 11pm The End Has No End - THE STROKES in AC-3 and then the Saturday morning 11am recording in mpeg2..

no better way than testing it for yourself

[Champion_R]

Digital Betacam is generally uncompressed 48Khz/20bit audio.  Better than both AC3 or MPEG audio.  ABC's & 9's 448kbits/s AC3 is pretty close though.

<{POST_SNAPBACK}>

Does the ABC keep the AC3 in 20bit or is it converted to 16bit before it's converted to AC3? Hope it stays in the 20bit domain.

Travis, Nine's AC3 on HD in Brisbane and Melbourne is 384kbits instead of the 448kbits in Sydney, Adelaide and Perth and on SD Sydney, Brisbane and Melbourne are 192kbits and Perth SD is 256kbits.

[Craig M]

Don't forget that MPEG audio & AC-3 audio may go through different compressors/limiters before transmission.

MPEG most likely goes through a compressor, whereas AC-3 shouldn't need to as it can rely on in-built meta-data to control the dynamic range in the home receiver.

That's the beauty of AC-3, it can be compressed in the receiver for a small TV speaker, or left as full dynamic range for a full-blown Home Theatre set-up.

Craig.

[kootaberra]

Digital Betacam is generally uncompressed 48Khz/20bit audio.  Better than both AC3 or MPEG audio.  ABC's & 9's 448kbits/s AC3 is pretty close though.

<{POST_SNAPBACK}>

rage clips come in from a range of sources. Mainly Digital Betacam & some analogue Betacam. These tapes are conformed to an ABC system which comprises 2 Digital Betacam copies. One has WSS added while the sencond clone has WSS and supers. Audio is 48Khz/20bit.

The audio is not changed until it reaches the Mepg encoders. On the SD there are Optimod proccessors for the Mpeg audio, but there is none for any AC3 stream. The old analogue system also has separate Optimods. There are minor differnces in how they compress/limit.

With regards to the 448 on the AC3, we have to have 448 for 5.1, so instead of changing this at a 5.1 program we leave it as 448. Beware if another station is running 192kBits for 2/0, then if that siganl is a Dolby Surround 2/0 of Lt/Rt, the surround/center information will suffer. The minmum is 256 for Dolby Surround, 192 is only good for pure 2 channel stereo.