Post Description

Title : The Ultimate Audio Test DVD RK & EWfan




Description :
This DVD is intended to compare the different Audio formats/bitrates and to see if down-sampling and up-sampling makes any audible differences.

The reason for this was a "small" discussion (FTD# 1236623) about lossless and lossy formats and the fact that down-sampling causes significant loss with 5.1DD DVD to DTS-CD conversions!!
EWfan and I have compiled for that reason this Audio Test DVD.
EWfan supplied me with the CD source.
Too bad I did not receive any track list, so for that reason there is no chapter/track menu or nice backgound pictures.
All conversions and futher DVD-Authoring is done by me ;)

Furthermore this Audio Test DVD can be used to test your audio equipment since it all sounds very clear and the 17 tracks available on this Audio Test DVD are extremely good.




DVD Info (Audio Only) :
Source : Reference CD (received from EWfan)
Video : NTSC 16/9 (150kbps, black picture)
Audio : 5x WAV (1536kbps), 1x 2.0DD (320kbps) en 2x 2.0DD (192kbps)
Tracks : 17 tracks, 1h09m
Menu : Yes, Main and Settings (8x Audio selection)




Technical Info Tracks 1 to 8 :

Track 1 :
I have first up-sampled the CD source from 44.1kHz to 48kHz because a DVD only supports 48kHz sample rate for stereo audio tracks.
The sampling rate conversion is done using Sound Forge 9.0 with interpolation setting 4 and Anti Aliasing. This will result in a maximum quality.
This track 1 is than used as a reference and used as a source for all other tracks.

Track 2 :
This track is converted to 2.0DD (AC3) using Aften 4.1.
The bitrate is 320kbps which will result in an almost identical waveform of the source.
Also the spectrum goes up to 20kHz.

Track 3 :
Same as Track 2 but then the bitrate is 192kbps.
The waveform is almost identical but the frequency response (spectrum) is clearly cut-off from about 18kHz.

Track 4 :
The 192kbps conversion is done using the default SF9.0 AC3 plug-in.
192kbps is the only available bitrate for stereo materials (5.1DD is 448kbps).
The waveform is almost identical but the frequency response (spectrum) is clearly cut-off from about 17kHz.

For tracks 2 to 4 the AC3 track is converted back to a WAV file using Foobar2000.
This will exclude differences caused by a "bad" AC3 converter inside any A/V-Receiver.


Track 5 :
This track is down-converted to 44.1kHz and than back to 48kHz using SF9.0.
In fact these 2 conversion will add each time slight losses.
With a 5.1DD to DTS-CD you will only have one conversion.


Track 6 to 8 :
These are in fact the AC3 tracks of Track 2 to 4 but not converted back to WAV.




Personal Listening Results :
I can not here any differences between tracks 1 to 5.
I can switch almost seamless and even than it is not possible to here differences.

Blind testing will obviously result in NO differences at all.
Tracks 6 to 8 sounds louder on my TX-NR807 receiver compared to track 1 but the sound it self is still very clear and identical.



I hope you will all ENJOY this Audio Test DVD !!


Regards, EWfan and RK