AC3 re-encoding quality

SpEeDaMiGo · 17th December 2001, 20:05

Hi

I've got a 2h movie with an AC3 Audiotrack (DolbyDigital 5.1), which is encoded at an average of ~448kbps (~390mb). I'd like to make the rip with ac3 5.1 available but the original file is too big for me. What bitrate for re-encoding (using the guide of Doom9) would you recommend me ?
What bitrate to get equal quality of mp3 ~160kbps (stereo)?

Thanks

SpEeDaMiGo · 19th December 2001, 22:20

30 views
No answer

Come on guys ..... don't tell me I'm the only one encoding AC3 tracks.

MaTTeR · 20th December 2001, 20:26

Quote:

Originally posted by SpEeDaMiGo
30 views
No answer

Come on guys ..... don't tell me I'm the only one encoding AC3 tracks.

Actually you might be

Can't help you as I usually keep the AC3 as is and then mux it.

vac · 21st December 2001, 12:36

some time ago, i had the same problem. I tried to downsample ac3 stream from 448kbit to 384kbit or 192kbit. The only program i found was Soft Encode (from Sonic Foundry). This program can open 5.1 ac3, it can even create it (!) and it can also downsample it. But it takes a looong time, and you need A LOT of free hdd space. It temporaly creates some uncompressed pcm/wavs (5.1 creates 6 wavs), so for 2 hours ac3 stream you need approx 9 Gigabytes of free hdd space (6 x 1500=9000), and the opening/decoding is very slow ...

then you can downsample to lower frequency.

maybe i was doing some mistakes, BECAUSE the quality was quite poor :-((

downsampled ac3 from 448 to 384 was acceptable (but still i was recognizing the differencies) but to 192 it sound really awfull :-(((

but maybe i was doing something wrong...

Sherlock Holmes · 21st December 2001, 16:22

Hi guys
I know what you should do.

1 - Run SonicFoundrySoftEncode.
2 - Open the AC3 file.
3 - Decode it to a WAV in WindowsPCM format.
4 - Seperate that WAV to 6 WAV.
5 - Import those 6 WAVs to SonicFoundry
6 - Go and set your settings in SonicFoundry like lowing the bitrate.
7 - Make the AC3

I tested this , and the result was very very good.

I know it takes a lot of time and also a lot of hard disk space. But the result is nice.

DSPguru · 21st December 2001, 16:37

today i will be releasing BeSweet v0.9. it can automaticly create 6 mono wavs of 44.1khz from AC3/VOB input.

17th December 2001, 20:05	#1 \| Link
SpEeDaMiGo Registered User Join Date: Dec 2001 Posts: 66	AC3 re-encoding quality Hi I've got a 2h movie with an AC3 Audiotrack (DolbyDigital 5.1), which is encoded at an average of ~448kbps (~390mb). I'd like to make the rip with ac3 5.1 available but the original file is too big for me. What bitrate for re-encoding (using the guide of Doom9) would you recommend me ? What bitrate to get equal quality of mp3 ~160kbps (stereo)? Thanks

21st December 2001, 12:36	#4 \| Link
vac Registered User Join Date: Oct 2001 Posts: 2	downsample ac3 some time ago, i had the same problem. I tried to downsample ac3 stream from 448kbit to 384kbit or 192kbit. The only program i found was Soft Encode (from Sonic Foundry). This program can open 5.1 ac3, it can even create it (!) and it can also downsample it. But it takes a looong time, and you need A LOT of free hdd space. It temporaly creates some uncompressed pcm/wavs (5.1 creates 6 wavs), so for 2 hours ac3 stream you need approx 9 Gigabytes of free hdd space (6 x 1500=9000), and the opening/decoding is very slow ... then you can downsample to lower frequency. maybe i was doing some mistakes, BECAUSE the quality was quite poor :-(( downsampled ac3 from 448 to 384 was acceptable (but still i was recognizing the differencies) but to 192 it sound really awfull :-((( but maybe i was doing something wrong...

21st December 2001, 16:37	#6 \| Link
DSPguru BeSweet Author Join Date: Oct 2001 Location: On top of a supercompact cardinal Posts: 3,506	today i will be releasing BeSweet v0.9. it can automaticly create 6 mono wavs of 44.1khz from AC3/VOB input. __________________ FAQs : BeSweet, Audio :readfaq: Homepage : DSPguru's Webpage http://dspguru.notrace.dk/cs.gif Guides : Multilingual Guides of my tools http://dspguru.notrace.dk/1zhelp.gif

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19th December 2001, 22:20	#2 \| Link
SpEeDaMiGo Registered User Join Date: Dec 2001 Posts: 66	30 views No answer Come on guys ..... don't tell me I'm the only one encoding AC3 tracks.

21st December 2001, 16:22	#5 \| Link
Sherlock Holmes Banned Join Date: Oct 2001 Location: Iran Posts: 146	Hi guys I know what you should do. 1 - Run SonicFoundrySoftEncode. 2 - Open the AC3 file. 3 - Decode it to a WAV in WindowsPCM format. 4 - Seperate that WAV to 6 WAV. 5 - Import those 6 WAVs to SonicFoundry 6 - Go and set your settings in SonicFoundry like lowing the bitrate. 7 - Make the AC3 I tested this , and the result was very very good. I know it takes a lot of time and also a lot of hard disk space. But the result is nice.