AC-3 Bitrate

[Nelson37]

Is AC-3 sound required to be at a bitrate of 384 for DVD? I record audio at 48 Khz and 224 bitrate, converting to AC-3 at 384 seems a waste of bits. Does AC-3 have increased file overhead which justifies the additional bitrate? With the given source, would using 224 result in any significant loss in audio quality? My current speaker system is not exactly hi-budget, but I hope to have better equipment in the future which might make any loss more obvious.

[thayne]

224 should work fine. I have gone down to 128K with no problems

[FulciLives]

Most commercially made studio grade DVD discs use 192kbps for 2.0 AC-3 audio tracks. From what I've read you really only need a higher bitrate when you have something more than a 2.0 source such as a 5.1 source which needs a higher bitrate since there is more information. Most commercially made studio grade DVD discs seem to use 448kbps for 5.1 AC-3 but I've seen some use 384kbps as well.

Please note that the PANASONIC line of stand alone DVD recorders record to a 2.0 AC-3 with a bitrate of 256kbps

Perhaps the extra bitrate is needed since the encoding is being done on the fly?

I have seen a few commercial DVD discs use 224 or 256 but almost ALL use 192 for 2.0 AC-3 audio streams.

- John "FulciLives" Coleman

P.S.
I watch a lot of strange "older" movies that were originally made in mono or stereo at best (but not surround) so I see many 192kbps 2.0 AC-3 audio streams with the FULL SOUNDTRACK not just AUDIO COMMENTARY tracks (which also tend to be 192kbps 2.0 AC-3 streams).

[Nelson37]

Excellent, thanks, guys. I am indeed doing 2.0 AC-3 from a captured Prologic input, but hope soon to be able to either cap or re-encode to true 5.1. Will go with 192 for now, or thereabouts.

[nyijedi]

Be careful using 192 kbps. I used it for some DVDs, and in certain players (PS2 and WinDVD w/ my PC player), when I'd use scene selection or fast forward in a scene, I would lose ALL audio. I re-did the same exact DVD w/ 224 kbps, and everything worked perfectly. Just a heads up.

[yysie]

I think it's fine... 128 = around 192 mp3 I think.... 192 would be around 224 mp3 so the quality is still great!