Error concealment
In order to see how the different drives perform error
concealment, the CDR with random errors must be used.
Comparing waveforms with the reference waveform, it is
possible to see the method used to perform interpolation.
In the following pictures, the blue waveform is the
reference one. It is superimposed over the test waveform.
A common method for concealing errors several samples
long is to hold the last good value, then to perform a
linear interpolation near the end of the error.
Yamaha CRW3200EWK firmware 1.0d burner
The interpolation following the holdings is short. A close up shows that it is a line joining three samples (One rectangle is one sample) :
Therefore it just allows to interpolate isolated
errors.
The other drives use the same method:
Memorex DVD Maxx 1648 firmware GWH2 DVD ROM
Sony DDU1621 DVD ROM firmware S1.6
Teac CD 540E firmware 1.0a CD ROM
Teac CD 540E firmware 3.0a CD ROM
The Memorex has been tested in audio playback instead of audio extraction, recording losslessly the SPDIF output :
Unfortunately, the interpolation performed on errors
is exactly the same as extracting at high speed.
The Yamaha CDX860 hifi CD Player, 1991, 450€, has
also been tested.
Yamaha CDX860 CD Player
This time, the linear interpolation is longer.
It is a line joining ten samples instead of three. Therefore it can interpolate bigger errors than a PC drive.