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Subject: Re: [AE] rendering issue
From: Jim Curtis <jpcurtis@me.com>
In-reply-to: <list-5169445@media-motion.tv>
Date: Thu, 08 Aug 2013 08:12:23 -0500
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Message-id: <C3B28049-DF97-4BC7-AC3D-81AB1EB4D847@me.com>
References: <list-5169445@media-motion.tv>
To: After Effects Mail List <AE-List@media-motion.tv>

AC3 is usually preferred because it has a lower bit rate than AIF or =
WAV.  DVDs play best on all players with a combined (audio + video) bit =
rate of around 7 Mbps.  I forget off hand what uncompressed WAV and AIF =
are, but if you choose them, you have to adjust the video bit rate =
downward to accommodate the combined optimum ceiling.

I think the limit for DVDs is 9 Mbps, but that will choke a lot of =
players and make them skip, or drop frames during playback.  I've had =
good luck with 8, but that may be pressing it.  So, 6-7 is the target I =
go for (for video when using AC3 audio), and don't often hear complaints =
about playback issues from clients.

In my experience, the more expensive the DVD players are more sensitive =
to playback skipping.  I've had fewer issues on cheaper players than the =
high end models.


On Aug 8, 2013, at 7:54 AM, Chris Zwar <chris@chriszwar.com> wrote:

> On 08/08/2013, at 10:08 AM, Jeanette Barekman <jsbarekman@yahoo.com> =
wrote:
>> Would like to know what are the pluses for using an AC3 file.
>=20
> AC3 is the Dolby Digital codec used on DVDs.  It's a compressed =
format, in the same way that MP3s and AAC (iTunes) are compressed files, =
however AC3 was specifically designed for 5.1 surround sound.  It =
supports a range of channels - including stereo and 5.1 - and the =
bitrate can be adjusted to balance file size and quality.  On DVDs it's =
always 48K, but I think in software it can handle different sample =
rates.
>=20
> WAV and AIFFs are uncompressed files, taking up roughly 600meg for 1 =
hour of stereo audio.  If a DVD used uncompressed audio then a 2 hour =
feature film with 5.1 surround sound would need 3.6 gig just for the =
audio tracks, which is pretty pointless as a single layer disc only =
holds 4.3 gig in total.
>=20
> On paper DVDs support a few different types of audio, but in general =
AC3 IS the DVD audio standard.  Commercial DVDs that don't use AC3 for =
audio are extremely uncommon.
>=20
>=20
> -Chris
>=20
>=20
> +---End of message---+
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